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Literature review
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abstracts
Literature Powder production and preparation Pressing Fundamentals Carbon Iron and Steel Nickel Titanium Tungsten Bearing and friction materials Ceramic materials Composite materials Electrical and magnetic materials Hard materials and tool steels Laser processing Mechanical alloying Metal injection moulding PM components Miscellaneous Materials Testing
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LITERATURE REVIEW Powder production and preparation Fabrication and microstructure of spherical germanium semi-conductor particles A.Kawasaki et al. (Tohoku University, Sendai, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 646-654. In Japanese. It is reported that a pulsed orifice-ejection technique had been used to make spherical Ge particles several hundreds of ìm in size. Molten droplets of Ge are ejected from an enclosed chamber, under pressure, by movement of a rod controlled by a piezoelectric actuator. Particles were polycrystalline with structures derived from dendritic growth, at high undercooling or lateral growth at low undercooling. Preparation of functional powders using interfacial chemical techniques M.Abe, H.Sakai. (Tokyo University of Science, Tokyo, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 671-679. In Japanese. Chemical reactions at interfaces between two phases are discussed and it is noted that control of the interface allows control of microstructure and properties of the materials produced. Production methods for nano-functional powders using interface reactions are described. TiB2 is given as an example. Production of nano-porous SiO2 is also described. Synthesis of composite gold-magnetic iron oxide nano-particles by ã ray irradiation S.Seino et al. (Osaka University, Ibaraki, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 680-684. In Japanese. It is reported that a composite Au-Fe3O4 particulate had been produced by ã ray irradiation of a solution containing Au ions and a dispersion of fine Fe oxide particles. Metallic Au was deposited on the oxide particle surfaces as 5nm grains which could be grown to cover the oxide particles. Synthesis procedure and characterisation are described. Composite and core/shell cluster assemblies prepared with two cluster sources
K.Sumiyama et al. (Nagoya Inst. of Technology, Nagoya, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 685-690. In Japanese. A plasma-gas condensation system, with two sources, was used to prepare Co, Si and Co-Si cluster assemblies. With a separation plate in position individual Co and Si clusters were produced. Without the plate core shell clusters were obtained consisting of Co cores covered by small Si crystallites. Coercive force of the Co-Si clusters is much less than for the Co clusters. Use of the CoSi clusters for making nano-structure controlled materials is suggested. Synthesis of perovskite-type lanthanum-cobalt oxide particles by mechanochemical treatment F.Saito et al. (Tohoku University, Sendai, Japan.) Powder Technol., Vol 143-144, 2004, 170-173. Two methods of making LaCoO3 are described. The first uses high energy milling of La and Co oxides to synthesise LaCoO3 directly, the yield increasing with milling time. The other has three stages. LaCl3, CoCl2 and NaOH are milled together to synthesise La(OH)3, Co(OH)2 and NaCl. The mixture is calcined at 600°C to synthesise LaCoO3 and NaCl is leached out with water. Agglomerates are formed with both processes. Preparation of nickel particles from nickel nitrate by spray pyrolysis with and without urea K.N.Kim, S-G.Kim. (Chung Ang University, Seoul, Korea.) Powder Technol., Vol 145, No 3, 2004, 155-162. It is reported that Ni powders had been produced from Ni(NO3)2 solution, with/without CO(NH2)2, by spray pyrolysis. The product was Ni powder when processed at 410°C. A temperature of 850°C was required to produce fully densified and crystallised spherical particles. CO(NH2)2 enhanced solidity and surface smoothness. Production of hollow manganese oxide spheres Jisen Wang et al. (Shandong University of Science and Technology, Jinan, China.) Powder Technol., Vol 145, No 3, 2004, 172-175.
0026-0657/05 ©2005 Elsevier Ltd. All rights reserved.
It is reported that hollow crystalline Mn oxide spheres had been produced by action of heat on Mn carbonate in a one-step solid state method. Effects of adding NaCl and surfactant, nonylphenyl ether, heating time and temperature are shown to be significant. The product was characterised by X-ray diffraction and electron microscopy. Investigation of agglomeration in preparation of nano-scale powders Zou Xing. (University of Science and Technology, Beijing, China.) PM Industry, Vol 14, No 5, 2004, 24-27. In Chinese. Conditions leading to agglomeration during processing of nano-scale powders, and properties of agglomerates, were investigated. Counter-measures are suggested.
Pressing New technique for fabrication of high density PM parts by cold pressing and sintering A.T.Mamedov, V.A.Mamedov. (Azerbaijan Technical University, Baku, Azerbaijan.) Powder Metall., Vol 47, No 3, 2004, 278-284. Development of a new technique for pressing PM parts, in a porous die to allow removal of entrapped pore gas, is described. Effects of pore gas on green density and sintered properties are evaluated experimentally and mathematically. Steels were pressed with different lubricants, or none, but with die wall lubrication. Use of the porous die is reported to improve green and sintered properties, even without admixed lubricant, in comparison with compaction in conventional dies. Guidelines for modelling cold compaction behaviour of various powders V.Bonnefoy, P.Doremus. (Domaine Universitaire, Grenoble, France.) Powder Metall., Vol 47, No 3, 2004, 285-290. Fe, Al2O3, WC-Co and W-Ni-Fe powder materials were cold pressed to determine powder behaviour and to establish guidelines for modelling of powder compaction. An overview of powder behaviour is proposed, based on two sub-types regarding powder hardness. The main features are analysed and a new concept is introduced. It is possible to simplify characterisation and modelling of any powder behaviour. Numerical simulation of warm compaction of metal powder Zhao Wei-bin et al. (South China University of Technology, Guangzhou,
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China.) PM Industry, Vol 14, No 5, 2004, 28-32. In Chinese. Warm compaction was simulated using software for finite element methods. Data was obtained by thermo-mechanical analysis based on a Lagrange formulation for optimisation of the process. Approaches to service life of PM dies Zhang Jiangjuan, Duan Zhanrong. (Southern Inst. of Metallurgy, Ganzhou, China.) PM Industry, Vol 14, No 5, 2004, 38-41. In Chinese. Approaches to prolong the service life of PM compaction dies are reported. There are use of a new material, a 12%Cr steel, and improvements in the heat treatment of the die. Design of a forming die for an injector plate Pan Chun-lei. (PM DFM Corporation, Hubei Danjiangko, China.) PM Industry, Vol 14, No 5, 2004, 42-45. In Chinese. It is noted that productivity in making an injector plate in manually operated dies is low and the green part is liable to crack during ejection. It is reported that surveys and theoretical analysis had resulted in improvements and use of automatic forming dies.
Fundamentals Measurement and characterisation of particle strength B.Scarlett et al. (University of Florida, Gainsville, USA.) Powder Technol., Vol 143-144, 2004, 56-64. Strength of particles and granules and fracture depend on material properties and factors such as shape, size and loading patterns. These are reviewed together with an outline of breakage mechanisms. Materials are either ductile, brittle or intermediate semi-brittle. Experimental studies, using a novel test rig on some nonmetallic materials, are described and the results used in discussion of strength. How do agglomerates break? L.Liu, C.Thornton. (University of Birmingham, Birmingham, UK.) Powder Technol., Vol 143-144, 2004, 110-116. Simulations of cuboidal agglomerate impinging on a target are described. The object was to identify breakage mechanisms for granules. Fracture is shown to be related to the manner in which inter-particle forces are transmitted through the
granule and development of primary particle velocities. Heterogeneous velocity fields produce discontinuities along which shear weakening occurs. Strong velocity discontinuities become potential fracture planes. Effects of ball diameter and feed size on grinding rate constant for solid materials in a ball mill K.Kanda et al. (Yamagata University, Yamagata, Japan.) Powder Technol., Vol 143-144, 2004, 196-203. Effects of ball diameter and particle size in the feed were investigated in a tumbling ball mill with Al2O3 balls 3mm, 5mm, 10mm, 20mm and 36mm in diameter. A grinding rate constant was determined, for each material, for a range of brittle nonmetallic materials. Grinding rate constant varied with the feed size but not with the ball diameter. Simulation of wet grinding in tumbling ball mill and relation to grinding rate F.Saito et al. (Tohoku University, Sendai, Japan.) Powder Technol., Vol 143-144, 2004, 230-239. A method for simulation, by finite element methods, of ball motion in a tumbling ball mill, under wet conditions is described. Drag force and buoyancy are considered. Impact energy for bell collisions allows prediction of grinding rate. Experimental milling of a steel powder and Al2O3 was observed through a transparent end window. Applicability of a new equation for fracture toughness to hard brittle and ductile alloy tool steels Y.Yanaba. K.Hayashi. (University of Tokyo, Tokyo-to Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 499-503. In English. It is reported that a new equation calculation of K1c had been developed for unnotched samples of hard and brittle materials which break into fragments. This is óm=øK1cSmf½ where óm is transverse rupture strength, K1c is fracture toughness, Smf is the total macroscopic surface area of all fragments and ø is a factor related to sample size and test method. Tests were conducted to determine if the equation could be applied to a ductile alloy hot tool steel which only breaks into two pieces and not into numerous fragments. The equation could be applied
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with sharply notched specimens, which showed brittle fracture. Poisson’s ratio sintered materials for structural machine parts A.Fujiki et al. (Nissan Motor Co. Ltd., Yokohama, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 515-521. In English. Relationships between Young’s modulus, shear modulus, Poisson’s ratio and porosity, of sintered steels for structural machine parts, were investigated. Porosity affected elastic properties and pore shape had more influence on Poisson’s ratio. Pore shape was determined by powder type and process conditions. Sintering atmosphere had little effect on Poisson’s ratio of as-sintered or heat treated samples.
Carbon Structure and texture of carbon materials M.Inagaki, M.Toyoda. (Oita University, Oita, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 589-594. In Japanese. Structures and nano-textures of C materials are described. Destruction of the nanotexture is shown to open new functions and applications through emphasis on exfoliation. It is shown that exfoliated graphite has high absorption for oils and gave high capacitance in electrochemical devices. Synthesis of nano-carbons by a template method T.Kyotani. (Tohoku University, Sendai, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 595-602. In Japanese. A method of making C nano-tubes is described. This uses nano-channels in anodic Al2O3 films as a template for deposition of C from various gases. Al2O3 is removed by dissolution in NaOH. Control of nano-tube dimensions is possible and nano-tubes with a double coaxial structure can be made. The inner surface, only, can be modified chemically. Nano-porous C nano-tubes and metal and metal oxide filled C nano-tubes can also be made. Diamond-like carbon films K.Oda. (Sumitomo Electric Industries Ltd., Itami, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 603-610. In Japanese. Applications of diamond-like C films are reviewed. This is shown to have good
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tribological properties when applied to mechanical parts requiring wear resistance and low friction. The films can be deposited on a wide range of metallic and nonmetallic materials, including cutting tools and can be used in automotive applications to improve fuel consumption. Preparation of fullerenes (four papers) R.Otsuki et al. (Kanazawa Inst. of Technology, Ishikawa, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 622-625, 626-629, 630-632 and 633-634. In English. Aspects of the production of fullerenes, C60 and C70, are described in terms of material and process parameters. DC resistive heating of graphite between W electrodes and arc discharge between graphite anodes and W cathodes were used. Both methods resulted in volatilisation of C. The process is carried out in He. Four types of C were used.
Iron and steel Role of sintering atmospheres and graphite addition in reduction of oxides in chromium steel P.Ortiz, F.Castro. (CEIT, San Sebastián, Spain.) Powder Metall., Vol 47, No 3, 2004, 291-298. Samples of AstaloyCrM, with/without additions of graphite, were sintered at 1100°C to 1240°C in various N-H atmospheres, with/without addition of CH4. Attention was given to reduction of oxides and the role of C in the reduction process. Powder and sintered specimens were characterised by microscopy, AstaloyCrM powder is shown to contain surface and internal oxides. Tensile samples were produced with 0 to 0.4%C to assess neck development by strength and elongation as functions of atmosphere composition and sintering temperatures. Quantitative expression of fracture surfaces of sinter-forged steels T.Futagawa, N.Kawai. (Fukui University of Technology, Fukui, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 522-526. In Japanese. Fracture of sinter forged steels was investigated with respect to composition, heat treatment and conditions of fracture. It is reported that: fracture surface roughness can be described quantitatively with fractal dimensions, fractal dimensions are affected by grain size, fractal dimensions
for a fracture split connecting rod are low and the surfaces matched well. Effects of secondary operations on mechanical properties of low alloy sintered steel A.Bergmark et al. (Höganäs AB, Höganäs, Sweden.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 527-535. In Japanese. Effects of partial diffusion prealloying and secondary operations on properties of steel parts are reviewed. A study of a 3%Cr-0.5%Mo steel is described. Fatigue strength of 520MPa was attained by control of cooling rate from sintering temperature followed by shot peening. Effects of sintering conditions on final composition and of cooling rate on fatigue are discussed. Prealloyed 1.5%Cr-0.5%Mo steel was also investigated. Simulation methods for residual stress are described. Magnetic properties and microstructure of warm compacted sintered iron with die wall lubrication S.Tajima et al. (Toyota Central R & D, Aichi, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 542-547. In Japanese. Magnetic properties of sintered Fe and cast/wrought Fe are compared. Sintered Fe has low flux density due to low sintered density. Warm compaction with die wall lubrication results in density increased to up to 7.76gm.cm-3 after compaction at 1176MPa and sintering at 1250°C. There was some anisotropic dimensional change and abnormal grain growth. The abnormality was greater at higher green density. Ferrous powders for wheel rings Luo Yi-bing. (Central South University, Changsha, China.) PM Industry, Vol 14, No 5, 2004, 9-12. In Chinese. Changes in powder morphology and the relationship between green density and milling time of Fe-2%Mn-2%Cu-Mo-C-P, prepared by high energy ball milling were investigated. After 8hours milling and sintering density of 7.21gm.cm-3 and a Vicker’s hardness of 240 to 250 were attained. The alloy is considered to be suitable for wheel rings.
Nickel Mechanical alloying of nickel-iron to nano-crystalline state
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Yu Yang et al. (Harbin Inst. of Technology, Harbin, China.) PM Technology, Vol 22, No 6, 2004, 328-332. In Chinese. Ni-30wt%Fe powders was mechanically alloyed in Ar to a nano-crystalline condition. Milled powders were characterised as a function of milling time. Structures, as they evolved were coarse lamellar, fine lamellar and after 25 hours milling a Ni rich solid solution was formed with a particle size of 10nm. This melted at 1444°C.
Titanium Infra red brazing of titanium-aluminiumvanadium and molybdenum with a titanium-copper-nickel alloy R K Shiue, C T Chang. (National Dong Hwa University Hualien, Taiwan.) .) Int J Refract. Metals/Hard Mater, Vol 23, No 3, 2005, 161-170. Brazing of Ti-6%Al-4%V and Mo with Ti15%Cu-15%Ni was investigated. Infra red and conventional furnace brazing are compared. The brazing alloy had good wettability for Ti-Al-V at 970°C. Wettability for the brazing alloy improved above 1000°C. The brazed joint consisted of a Ti rich phase with no reaction layer with the substrate. Mo samples fractures at the Mobraze metal interface. Residual stresses were modelled using ABAQUS software. Semi-isostatic high velocity compaction for preparation of titanium dental copings M.Eriksson et al. (Swedish Ceramic Inst., Göteborg, Sweden.) Powder Metall., Vol 47, No 4, 2004, 335-342. It is reported that a new method for preparation of dental prostheses had been developed. High velocity compaction of powder enclosed in elastomer moulds, with a mandrel to form the inner shape and surface of the prosthesis. The assembly is enclosed in a die and punch. Soft flexible elastomers worked best of the several tested. Density variations were investigated with up to 98 per cent to 99 per cent being attained locally. Production of sintered titanium from fibre M.Kaneko et al. (Japan Inst. of Technology, Saitama, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 570-575. In Japanese. Production of Ti sintered from fibres is described. Ti foil is coated with a water soluble resin, dried and coiled. The coils
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are end turned to produce fibre which is washed, chopped and formed into a lacelike from and sintered to porosity of 75 per cent. The application is for battery electrodes with high surface area.
Tungsten Production of nano-metre tungsten based alloy powder Ma Yun-zhu et al. (Central South University, Changsha, China.) PM Industry, Vol 14, No 5, 2004, 17-23. In Chinese. Methods used in production of nano-crystalline W base alloys are reviewed including mechanical alloying, sol-gel techniques, freeze drying, chemical vapour deposition, spray drying and reaction spray processing.
Bearing and friction materials Development of sintered bearing material resistant to sulphidisation T.Nozu et al. (DENSO Corporation, Kariya, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 536-541. In Japanese. It is noted that automotive fuels are declining in quality, increased S content, in some countries and that this may cause failure in Cu-Sn-C bearings due to contamination by S. It is reported that a Cu-Ni-Zn-C alloy, with improved resistance to S corrosion and good tribological properties had been developed. Effects of sliding surface temperature on frictional behaviour of sintered iron friction materials Chen Jie et al. (Central South University, Changsha, China.) PM Technology, Vol 22, No 4, 2004, 223-227. In Chinese. Effect of sliding surface temperature on friction of PM Fe base materials was investigated. As sliding speed increased so did the temperature. Coefficient of friction and wear decreased at first and then increased, accompanied by structural changes in the material surface. At high speeds a layer, beneficial to wear rate, was formed.
Ceramic materials Thermo-gravimetric study of oxidation of silicon carbide powders at high temperatures M.Ito et al. (National Inst. Advanced Industrial Science and Technology, Nagoya, Japan.) J.Jpn. Soc.
Powder/Powder Metall., Vol 51, No 8, 2004, 565-569. In Japanese. Oxidation of áSiC powders, at elevated temperatures was investigated by thermogravimetry. Two mechanisms were observed oxidation of free C at about 700°C and oxidation of SiC, to SiO2, at about 1000°C. The amount of SiO2 formed depended on particle size. Initiation of oxidation started at lower temperatures as the particle size increased. Oxidation of SiC, per unit area was independent of particle size. Effects of alumina on tetragonal to monoclinic transformation in zirconia-yttria T.Tanaka et al. (Himeji Inst. of Technology, Himeji, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 641-645. In Japanese. Effects of 5mol% to 30mol% Al2O3 on the martensitic tetragonal to monoclinic transformation in ZrO2-(2 or 3)% Y2O3, pressed at 100MPa, sintered at 1650°C and aged at 300°C, were investigated. Al2O3 increased grain size. Dimensional changes due to the martensitic transformation were determined. The amount of martensitic change increased with ageing time and %Al2O3. Textures were determined. Atomic force microscopy was used in the study. Crystallisation and phase changes in liquid phase sintered silicon nitride Luo Junting et al. (Harbin Inst. of Technology, Harbin, China.) PM Technology, Vol 22, No 4, 2004, 212-217. In Chinese. Amorphous Si3N4 powders were liquid phase sintered with additions of Al2O3 and/or Y2O3. Sintering at 1500°C resulted in partial crystallisation, which was complete at 1600°C. Crystalline phases were αSi3N4 and Si2N2O. Higher temperatures reduce the amount of Si2N2O. Grain size of the materials crystallised at 1600°C was mostly in the range 150 to 200nm with a few grains less than 100nm. Self propagating high temperature synthesis of alumina-zirconia composite ceramics Wang Jianjiang et al. (Xi’an Jiaotong University, Xi’an, China.) PM Technology, Vol 22, No 4, 2004, 218-222. In Chinese. It is reported that an Al2O3-ZrO2 composite liner had been applied to a pipe by in situ crystallisation out of gravitational separation in a self propagating high temperature synthesis process. The composite
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matrix was Al2O3-ZrO2 eutectic with ZrO2 fibres. Indentation tests showed a fracture toughness of 15.96MPa.m½. Crack propagation was controlled by toughening mechanisms and cracks were deflected along interfaces in the structure.
Composite materials Strengthening and toughening of titanium carbide-mullite composite materials Chen Yang et al. (North Eastern University, Shenyang, China.) PM Technology, Vol 22, No 4, 2004, 210-213. In Chinese. Relationships between mechanical properties and TiC particle size in TiC-mullite, 3Al2O3.2SiO2, composites were investigated, with effects of cold treatment. It is shown that in the TiC particle size range 14 m to 26 m toughness is increased and below TiC particle size 14 m strength is increased. Investigation of tungsten-copper and molybdenum-copper prepared from coreduced oxide powders Mu Keqiang. (Central Iron and Steel Research Inst., Beijing, China.) PM Industry, Vol 14, No 5, 2004, 13-16. In Chinese. It is noted that W-Cu and Mo-Cu composites, with fine dispersion of the constituents, are widely produced. When made from co-reduced oxide powder near full density can be attained at low sintering temperatures. These have fine grain size, homogeneous structures and improved properties. Factors in production are reviewed, including precursors, process conditions, powder characteristics and composite properties.
Electrical and magnetic materials Phosphorus as an additive in iron based soft PM magnets R.M.Larsen. (Aarlborg University, Aarlborg, Denmark.) Powder Metall, Vol 47, No 4, 2004, 332-334. Effects of adding P to Fe powders on properties of soft magnetic alloys were investigated. Results showed that P is beneficial when sintering is in a carburising atmosphere by inhibiting up-take of C. P also reduced tendency to magnetic ageing. Design of magnesium chromate high temperature thermistor materials from calculation and experiment
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I.Tanaka et al. (Kyoto University, Kyoto, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 487-491. In Japanese. Chemical stabilisation of MgCr2O4, a high temperature thermistor material, is noted. Material design by experiment and calculation is discussed. MgCr2O4 is known to exhibit Cr-deficit p-type semiconduction at elevated temperatures. Calculation of energy of formation of Cr vacancies showed stability in oxidising conditions and instability in reducing. Stable semi-conducting region at 1000°C was determined experimentally. The study demonstrated the importance of both calculation and experiment. Microstructures and magnetic properties of spark plasma sintered ironchromium-cobalt magnets H.Matsumoto et al. (NEC TOKIN Corporation, Sendai, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 554-558. In Japanese. Effects of material and process parameters on microstructure and magnetic properties of Fe-Cr-Co, processed by spark plasma sintering were investigated. Powders smaller than 80ìm were made by a spray conversion process. 98 per cent density was attained at 39MPa and 950°C in seven minutes. αFe and α2Cr rich phases were detected. Spark plasma sintering is considered to be a viable method for this material. Mechano-chemical synthesis of silverion conducting materials in silver iodide-silver tungstate N.Machida et al. (Konan University, Kobe, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 655-661. In Japanese. Amorphous Ag-ion conducting materials, Ag2WO4-(30 to 70)mol%AgI, were prepared by high energy ball milling. This gave a wider composition range than melt spinning. The material was characterised by Raman spectroscopy. Conductivity increased with %AgI. Amorphous Ag2WO4-70%AgI, had a conductivity 1.8x10-2S.cm-1 at 25C. Vitrification of silver-ion conducting materials silver tungstate-silver iodide by ball milling N.Machida et al. (Konan University, Kobe, Japan.) J.Jpn. Soc. Powder/Powder
Metall., Vol 51, No 9, 2004, 662-667. In Japanese. Vitrification of Ag2WO4-(30 to 70)mol%AgI was investigated by ball milling. Ag-ion conductivities were measured and were at a maximum when the milling time gave samples containing an amorphous phase, with a high concentration of AgI, and Ag2WO4. A not fully amorphous sample of Ag2WO4-70%AgI, milled for 20 hours had a conductivity of 4.8x10-2S.cm-1 at 25°C. Development of 460kJ.m-3 neodymiumiron-boron magnets Y.Kaneko et al. (NEOMAX Co. Ltd., Osaka, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 698-702. In Japanese. Maximum energy product of Nd-Fe-B magnetic materials is discussed. Theoretically this is calculated at 512kJ.m-3. Steps required to attain this are outlined. It is reported that 460kJ.m-3 had been attained by reducing impurity levels, improvement in microstructure and development of a method of aligning particles, inclined magnetic pulsing. Preparation of âiron silicide by mechanical alloying Zhou Yun et al. (Kunming University of Science and Technology, Kunming, China.) PM Technology, Vol 22, No 4, 2004, 229-231. In Chinese. It is reported that a thermoelectric material, âFeSi2 had been prepared from elemental powders by mechanical alloying, pressing and sintering. Sintered samples were characterised by X-ray diffraction and differential scanning calorimetry. Milling for 20 hours resulted in formation of αFeSi and αFeSi2 appeared after 40 hours, the amount increasing with milling time. Current state of development of bulk nano-crystalline soft magnetic materials Fan Hongbe et al. (Harbin Inst. of Technology, Harbin, China.) PM Technology, Vol 22, No 4, 2004, 241-248. In Chinese. Developments and applications of bulk nano-crystalline soft magnetic materials are reviewed, Mechanisms of structure formation, fabrication and properties are discussed. Possible future trends are indicated.
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Production by sintering of a copper-aluminium oxide p-type semi-conductor Zhao Daqing, Yao Wei. (Tsinghua University, Beijing, China.) PM Technology, Vol 22, No 6, 2004, 333-336. In Chinese. It is reported that a p-type transparent semiconducting oxide, CuAlO2 had been prepared from fine Al2O3 and Cu2O powders by sintering in Ar. Effect of sintering temperature on the reaction was investigated. The sintered material was used as a target to make a p-type transparent semi-conducting film by vacuum magnetron sputtering.
Hard materials and tool steels Study of ‘core/rim’ structures in titanium carbide-molybdenum carbide-nickel cermets Y.Yanaba et al. (University of Tokyo, Tokyo, Japan.) J. Japan Soc. Powder/Powder Metall., Vol 51, No 5, 2004, 374-384. In English. Development of TiC (core) and (Ti,Mo)C (rim) structures in TiC(Ti,Mo)C-Ni cermets is discussed with regard to mechanisms, not solid state diffusion but solution/precipitation reactions. Core/rim structures in Fe66.7at%Si are noted. Investigations of evolution of core/rim structures are described. A hypothesis ‘exhaustion of diffusion-controllable atomic vacancies in core/rim structures’ is proposed and applied to TiC-(Ti,Mo)C-Ni and Fe-Si alloys. It is concluded that the hypothesis is valid when the rim is a stoichiometric phase which cannot dissolve the core elements. Development of polycrystalline cubic boron nitride for interrupted cutting of hardened steel K.Okamura et al. (Sumitomo Electric Hardmetal Corporation, Japan.) SEI (Sumitomo Electric Industries Ltd.,) Technical Review, No 59, 2005, 66-70. Use of polycrystalline cBN for machining hardened steels is discussed with regard to advantages over grinding. In interrupted cutting tool life may be reduced due to breakage of the cutting edge. It is reported that two new grades of polycrystalline cBN, with improved toughness had been developed specifically for interrupted machining, and with increased tool life. Cutting performance is described.
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Development of cubic boron nitride insert with new chip breaker ‘type SV’ Y.Okita et al. (Sumitomo Electric Hardmetal Corporation, Japan.) SEI (Sumitomo Electric Industries Ltd.,) Technical Review, No 59, 2005, 71-76. Machining of hard carburised layers through to the soft core is discussed with regard to chip formation and removal. It is reported that by combining cBN with a new from of chip breaker feature had been developed for improved control of chip formation and increased tool life. Design, and performance, of the chip breaker are described. Effects of additives in prealloyed iron powder on properties of metal-diamond composite Xia Zhimeng et al. (Northwestern University, Shenyang, China.) PM Technology, Vol 22, No 2, 2004, 67-70. In Chinese. The effects of using prealloyed Fe-P or Fe-Cu on properties of Metal diamond composites were investigated. The prealloyed powder gave increased density, strength and wear resistance. With Fe-P density was 99.6 per cent, three-point bend strength 1567MPa and wear rate 1.25x10-2gm.min.
Correlation of transverse rupture strength of tungsten carbide-cobalt with Vicker’s hardness Z.Z.Fang. (University of Utah, Salt Lake City, USA.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 2, 2005, 119-127. Use of transverse rupture strength, which increases as hardness diminishes, an indicator of toughness of WC-Co is noted. Experimental data showed that in the range of hardness 800 to 1500 TRS increases at first, then decreases reaching a peak at hardness of 1300. TRS has also been related to porosity. Porosity is low in WC-Co with modern processing methods and TRS is determined by structure and composition. Relationships between hardness, TRS and fracture toughness are discussed with reference to work hardening and flow stress of the Co phase.
Progress in PM tool steels Wu Yuan-chang. (Chengdu Tool Research Inst., Chengdu, China.) PM Industry, Vol 14, No 4, 2004, 24-28. In Chinese Production equipment and technique, types of steel grades and inspection for non-metallic inclusions in a non-Chinese tool steel are described. Tool steel output for tool steels is reported.
Passivity and pseudo-passivity of cemented carbides G.Mori et al. (University of Leoben, Leoben, Austria.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 2, 2005, 129-136. Corrosion of cemented carbides is described, dissolution of the binder and removal of carbide particles. It is noted that Co does not passivate but in potentiodynamic study shows anodic behaviour, critical potential and breakthrough potential. The behaviour, related to current density is referred to as pseudo-passivity. It is shown that addition of Cr3C2 improves corrosion resistance of WC-Co due to presence of a Co-Cr oxide layer, which is considered to be true passivity, decreasing the rate of dissolution of binder. Addition of V also improved corrosion resistance.
Thermal characterisation of tungsten carbide-cobalt sintered at high temperature and pressure R.T.Faria et al. (Universidade Estadual do Norte Fluminense, Califórnia, Brazil.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 2, 2005, 115-118. A new method of processing WC-15wt% at high pressure, 5GPa and high temperature, 1350°C, is described. Microstructure, density and Vicker’s hardness were determined. Thermal diffusivity was measured by an open photoacoustic cell technique. Heat capacity and thermal conductivity are calculated. Results agreed with values in the literature.
Abrasive wear of tungsten carbide-aluminide-boron composites D.Wexler et al. (Wollagong University, Wollagong, Australia.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 3, 2005, 155-159. An investigation of abrasive wear, by pin-ondisc tests, of WC-40vol%FeAl, WC40%Ni3Al, WC-40%Co and WC10wt%Co, made from ultrafine powders by hot pressing, is described. Samples were also prepared with 250ppm, 500ppm, 750ppm or 1000ppm B added. Wear resistance increased with amount of B added. Highest abrasive wear resistance was found for WC-FeAl-B, which was near to that for WC-10%Co, followed by WC-Ni3Al-B and WC-40%Co.
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Inorganic interfacial engineering – processing of hard materials G.Westin et al. (Uppsala University, Uppsala, Sweden.) Powder Metall, Vol 47, No 4, 2004, 317-331. Interfacial engineering is discussed with regard to processing of hard materials. A co-operative investigation between universities, industrial companies and other institutes is reported. Experimental work on aqueous processing of powders and use of surface active reagents using hardmetals and colloidal processing of ceramics is described. Pressing and sintering were studied experimentally and by simulation. Models are presented. Results using spark plasma sintering of ceramics and resistance to thermal shock are reported. Effect of sintering cooling rate on vanadium segregation at tungsten carbide/cobalt interface K.Hayashi et al. (University of Tokyo, Tokyo, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 576-585. In English. Segregation of V in fine grained WC-CoVC was investigated with regard to effects of cooling rate after sintering in the light of published studies. Previous work had shown that V segregated at the WC(0001 plane)/Co interface and attributed the grain growth inhibition effect of VC to this. The amount of V deposited at this interface depended on cooling rate. The rate of deposition decreased with increase in cooling rate. It is suggested that V adsorbs/desorbs, intermittently, at lattice defects. Study of sintering of diamond on to tungsten carbide-cobalt substrate Deng Fuming et al. (University of Mining and Technology, Beijing, China.) PM Technology, Vol 22, No 4, 2004, 205-209. In Chinese. Polycrystalline diamond coatings were deposited on to WC-Co substrates at 1300°C to 1660°C and 5.8GPa and were analysed by X-ray diffraction. The diffraction spectra are described and showed peaks for diamond, graphite, Co and WC. C dissolved in Co to 3.6 per cent. The diamond crystallites were about 0.059ìm. Status and prospects for titanium carbonitride based cermets Liu Yong et al. (Central South University, Changsha, China.) PM Technology, Vol 22, No 4, 2004, 236-240. In Chinese.
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Constitution and structures of Ti(C,N)cermets are discussed. Recent researches on microstructures, additives and fabrication are reviewed. Future prospects and applications are identified. Synthesis of silicon nitride by self-propagating high temperature synthesis Wang Shenghong et al. (GangTuo Metallurgical Inst., Beijing, China.) PM Industry, Vol 14, No 5, 2004, 1-5. In Chinese. Self-propagating synthesis of Si3N4 from Si in N at high temperature and pressure was investigated with regard to process conditions. The rate of reaction was found to fluctuate. The amount of N absorbed depended on pressure of N and permeability of the Si. Measurement of sulphur in (titanium,tungsten) carbide powders by combustion and electrical conductivity He Ying. (Hunan Metallurgical Technology College, Hunan, China.) PM Industry, Vol 14, No 5, 2004, 46-48. In Chinese. A method for determination of S in (Ti,W)C is reported. This uses combustion and electrical conductivity methods. Standard deviation is said to be 5per cent, sensitivity 3x10-6g.ìs and minimum measurable S 0.0001 per cent.
Laser processing A powder jet printer for deposition of powder Shoufeng Yang, J.R.G.Evans. (Queen Mary College, London, UK.) Powder Technol., Vol 142, No 2-3, 2004, 219-222. A device built from an ultrasonic generator and a capillary, that can ‘jet’ dry powders down to 0.05mg, is described. Using a tri-axis table it is possible to place powders with high precision and can be used in free-forming techniques such as laser sintering. Composition of the deposited powder can be varied. Shape and composition of a part can be down-loaded from a computer file. Wide-band laser hardening of sintered iron base materials Li Yueying et al. (JiLin University, Changchun, China.) PM Technology, Vol 22, No 4, 2004, 232-235. In Chinese. It is reported that wide-band laser transformation hardening of sintered Fe materials had been performed with a CO2 laser.
Effects of laser process conditions on microstructure, microhardness, depth of hardened surface and wear resistance of the hardened layer were investigated. It is shown that an evenly hardened layer can be produced under optimised conditions.
Mechanical alloying Magnetic properties of mechanically alloyed manganese-aluminium-carbon powders T.Saito. (Chiba Inst. of Technology, Chiba, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 548-553. In Japanese. Elemental Mn-Al-C powder mixtures were processed in either conventional or high energy ball mills. Conventional milling left elemental particles and high energy milling synthesised αMn with no τ or ε phases. Both powders formed the magnetic τphase on annealing with more in the high energy milled powder. Magnetic properties depended on the annealing temperature. Optimum annealing temperature resulted in high saturation magnetisation.
Metal injection moulding Monitoring polymer burnout at the macroscale S.L.Elder. (Centre for Innovative Sintered Products, Pennsylvania, USA.) Powder Metall., Vol 47, No 3, 2004, 302-303. It is reported that novel rig has been constructed for monitoring and optimising burnout during processing of real PM parts and that this will enhance production in the sintered materials industry. Effects of gate dimensions in metal injection moulding Jiang Bingyan et al. (Central South University, Changsha, China.) PM Technology, Vol 22, No 6, 2004, 323-327. In Chinese. Effects of gate dimensions in metal injection moulding were investigated with regard to variations in injection pressure, injection rate and feedstock temperature. Variation of gate depth with Archimedes flow length was non-linear. Gate depths of 0.5 to 2.1mm were studied. A gate depth of 1.8mm gave the largest flow length. Powder injection moulding of molybdenum-copper alloy for electronics packaging Nan Hai et al. (University of Science and Technology, Beijing, China.) PM Industry, Vol 14, No 6, 2004, 1-5. In Chinese.
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It is reported that Mo-Cu alloys had been made by injection moulding. Effects of process variables on density, microstructure and thermal conductivity were investigated. Density increased with sintering temperature up to 1450°C and then decreased. The alloy sintered at 1450°C for three hours had 98 per cent density and thermal conductivity of 158W.m =1.degK-1. Evaluation of feedstock for micro-sized injection moulded parts H.Miura et al. (Kyusyu University, Fukuoka, Japan.) J. Japan Soc. Powder/Powder Metall., Vol 51, No 6, 2004, 455-440. In Japanese. Production of micro-sized parts by injection moulding is more demanding than conventional MIM. Homogeneity of the feedstock is a major factor in micro MIM. Feedstock preparation was evaluated using measurements of density and binder content of pellets and variations are discussed in terms of a coefficient of variation. Micro dumbbell specimens were fabricated and evaluated for strength and density. The feedstock was improved by further processing.
PM components Development of warm compacted sintered sprockets for automotive engines A.Fujiki et al. (Nissan Motor Co. Ltd., Yokohama, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 507-514. In Japanese. Development of warm compaction for sprockets for roller chain systems of internal combustion engines is described. Warm compaction is followed by high temperature sintering. Operation of the chain system is described as ‘silent’. Forming of a miniature cylinder by PM Mo Sheng-qin. (Changzhou College of Information Technology, Changzhou, China.) PM Industry, Vol 14, No 5, 2004, 33-37. In Chinese. Shape and forming technology for a miniature PM cylinder are described with emphasis on mould design Copper-base PM double-cone synchronising ring Qu Zai-gang. (Hangzhou PM Inst., Hangzhou, China.) PM Industry, Vol 14, No 6, 2004, 6-11. In Chinese. The importance of the synchroniser in automotive transmission systems is
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emphasised and discussed. A Cu base PM alloy for a double-cone synchroniser ring is considered and compared with a Mo steel ring. Preparation of large electronic sputtering targets Ge Qilu et al. (Advanced Technology and Materials Co. Ltd., Beijing, China.) PM Technology, Vol 22, No 2, 2004, 87-90. In Chinese. Production of electronic sputtering targets is discussed with regard to difficulties in production, including tendency to fracture, properties and performance required. It is reported that a satisfactory target had been produced after due attention to composition, preprocessing of the powders used and processing conditions using hot pressing and hot isostatic pressing. Cases of surface problems of sintered components Yu Yang. (Höganäs AB, Höganäs, Sweden.) PM Technology, Vol 22, No 2, 2004, 109-115. In Chinese. Surface defects in sintered parts, such as pinholes, holes and stains, which appear during processing of PM parts are identified. Factors affecting the surface quality of sintered are discussed with respect to practical PM processes. Some case studies, including solutions, are described. Repressing and resintering of a passive ratchet part Guo Zheng-jun et al. (Dong Feng Automobile Co. Ltd., Dan Jiang Kou, China.) PM Industry, Vol 14, No 4, 2004, 21-23. In Chinese. It is reported that correct density distribution of teeth in a ratchet component had been attained by varying the tooth angle and repressing and resintering. The part is shown to satisfy specification requirements.
Miscellaneous Industry / University co-operation B.Lindqvist et al. (Höganäs AB, Höganäs, Sweden.) Powder Metall., Vol 47, No 3, 2004, 304-308. A research co-operation between Höganäs AB and universities in Spain, Italy and Austria, the Höganäs Chair, is reported. Arising from the co-operation three PhD theses and 31 research papers have been published. These have dealt with aspects of Cr-Mo steels including prealloying, processing and properties.
Powder metallurgy research institutions in Austria H.Danninger. (Vienna University of Technology, Vienna, Austria.) Powder Metall., Vol 47, No 3, 2004, 216-220. Three universities in Austria, with a significant role in PM are identified, Vienna University of Technology, University of Vienna and the University of Mining and Metallurgy at Loeben, together with two non-university institutes, the Austrian Research Institute at Seibersdorf and Joanneum Research. Facilities and expertise are outlined together with collaborative links with other organisations. Competence Centres for Materials and Light Materials are also reviewed. Trials and tribulations in editing Int. J. Refractory Metals/Hard Materials for 13 years (1991-2004) H.M.Ortner. (Darmstadt University of Technology, Darmstadt, Germany.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 1, 2005, 3-16. The work of the editor is critically reviewed with regard to difficulties encountered, such as poor quality English in submitted papers, and his wishes for improvements, notably in the use, or misuse of statistics. (A paper which should be read, and acted on, by anyone about to submit a paper to a learned Journal! – Abstracts Ed.) Fascination of the micro- and macro-cosmos – morphologies of science and the Tyrolean Alps H.M.Ortner. (Darmstadt University of Technology, Darmstadt, Germany.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 1, 2005, 17-66. The paper presents and describes a number of photomicrographs, and other figures, of intrinsic structural beauty. These are compared and contrasted with photographs of other things including landscapes, architecture and people. *Formulation in the PM industry S.le Mezec. (Matcon Inc., USA.) Human errors in manual preparation of powder mixtures were noted in the light of complexity and minimisation of PM part size. It was reported that high speed-high accuracy weighing equipment is available and which allows full product traceability. The capabilities of the powder-mix preparation machinery were reviewed.
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*Direct-write ink-jet microdeposition technology D.J.Hayes. (MicroFab Technologies, Inc., USA.) Applications of ink-jet technology were reviewed. It was noted that these inks may contain nano- or micro-sized metal powders in production of electronic devices. *Complex three-dimensional parts by printing techniques H.A.Kuhn, J.Liu (Extrudehone/Prometal, USA.) It was reported that complex three-dimensional parts can be made by a printing process using inks containing 60vol% metal powder. Parts can be sintered to full density or infiltrated. Examples of parts were presented including an engine vane with internal holes 0.3mm in diameter. The process was described. *PM technologies for growth H.Sonderhjelm. (N.American Höganäs, USA.) Segments of manufacturing industry, which could make greater use of PM, were identified, including recreational vehicles, household appliances and gardening equipment. These have a part in common, namely gears. Potential PM methods of making gears were reviewed. Soft magnetic composites were also considered.
Environmental application of carbides produced from biomass waste Y.Yamaguchi, M.Yukumoto. (JFE Holdings Corp., Tokyo, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 611617. In Japanese. Use of fuel derived from refuse is discussed with consideration of a carbonisation for production of a carbide. The carbide has been added to pulverised fuel injected into a blast furnace. It is suggested that the carbide could be added to raw materials for sintering.
Materials testing Method of testing of weld strength between sintered metals and a pipe flange Wang Jian-yong et al. (Northwestern Inst. for NonFerrous Metals Research, Xi’an, China.) PM Industry, Vol 14, No 4, 2004, 18—20. In Chinese. A new type of test for strength of welds is introduced. This measures strength between porous metals and a pipe flange. Weld penetration can be deduced. Weld quality is evaluated by combining the test result and minimum weld pool depth. Data concerning welding practice and post-weld heat treatment can be determined.
For copies of full papers you are recommended to contact individual authors, use an interlibrary loan system or for conference papers to contact the conference organisers. *Papers marked * were presented at EURO PM 2003, organised by the European Powder Metallurgy Association, Old Bank Buildings, Bellstone, Shrewsbury, SY1 1HU, UK.
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abstracts
Literature Powder production and preparation Pressing Fundamentals Carbon Iron and Steel Nickel Titanium Tungsten Bearing and friction materials Ceramic materials Composite materials Electrical and magnetic materials Hard materials and tool steels Laser processing Mechanical alloying Metal injection moulding PM components Miscellaneous Materials Testing
page P32 P33 P33 P34 P34 P34 P35 P35 P35 P35 P36 P36 P37 P38 P38 P38 P39 P39 P40
For copies of full papers you are recommended to contact individual authors, use the Interlibrary Loan system or, for conference papers, to contact the conference organizers
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LITERATURE REVIEW Powder production and preparation Fabrication and microstructure of spherical germanium semi-conductor particles A.Kawasaki et al. (Tohoku University, Sendai, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 646-654. In Japanese. It is reported that a pulsed orifice-ejection technique had been used to make spherical Ge particles several hundreds of ìm in size. Molten droplets of Ge are ejected from an enclosed chamber, under pressure, by movement of a rod controlled by a piezoelectric actuator. Particles were polycrystalline with structures derived from dendritic growth, at high undercooling or lateral growth at low undercooling. Preparation of functional powders using interfacial chemical techniques M.Abe, H.Sakai. (Tokyo University of Science, Tokyo, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 671-679. In Japanese. Chemical reactions at interfaces between two phases are discussed and it is noted that control of the interface allows control of microstructure and properties of the materials produced. Production methods for nano-functional powders using interface reactions are described. TiB2 is given as an example. Production of nano-porous SiO2 is also described. Synthesis of composite gold-magnetic iron oxide nano-particles by ã ray irradiation S.Seino et al. (Osaka University, Ibaraki, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 680-684. In Japanese. It is reported that a composite Au-Fe3O4 particulate had been produced by ã ray irradiation of a solution containing Au ions and a dispersion of fine Fe oxide particles. Metallic Au was deposited on the oxide particle surfaces as 5nm grains which could be grown to cover the oxide particles. Synthesis procedure and characterisation are described. Composite and core/shell cluster assemblies prepared with two cluster sources
K.Sumiyama et al. (Nagoya Inst. of Technology, Nagoya, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 685-690. In Japanese. A plasma-gas condensation system, with two sources, was used to prepare Co, Si and Co-Si cluster assemblies. With a separation plate in position individual Co and Si clusters were produced. Without the plate core shell clusters were obtained consisting of Co cores covered by small Si crystallites. Coercive force of the Co-Si clusters is much less than for the Co clusters. Use of the CoSi clusters for making nano-structure controlled materials is suggested. Synthesis of perovskite-type lanthanum-cobalt oxide particles by mechanochemical treatment F.Saito et al. (Tohoku University, Sendai, Japan.) Powder Technol., Vol 143-144, 2004, 170-173. Two methods of making LaCoO3 are described. The first uses high energy milling of La and Co oxides to synthesise LaCoO3 directly, the yield increasing with milling time. The other has three stages. LaCl3, CoCl2 and NaOH are milled together to synthesise La(OH)3, Co(OH)2 and NaCl. The mixture is calcined at 600°C to synthesise LaCoO3 and NaCl is leached out with water. Agglomerates are formed with both processes. Preparation of nickel particles from nickel nitrate by spray pyrolysis with and without urea K.N.Kim, S-G.Kim. (Chung Ang University, Seoul, Korea.) Powder Technol., Vol 145, No 3, 2004, 155-162. It is reported that Ni powders had been produced from Ni(NO3)2 solution, with/without CO(NH2)2, by spray pyrolysis. The product was Ni powder when processed at 410°C. A temperature of 850°C was required to produce fully densified and crystallised spherical particles. CO(NH2)2 enhanced solidity and surface smoothness. Production of hollow manganese oxide spheres Jisen Wang et al. (Shandong University of Science and Technology, Jinan, China.) Powder Technol., Vol 145, No 3, 2004, 172-175.
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It is reported that hollow crystalline Mn oxide spheres had been produced by action of heat on Mn carbonate in a one-step solid state method. Effects of adding NaCl and surfactant, nonylphenyl ether, heating time and temperature are shown to be significant. The product was characterised by X-ray diffraction and electron microscopy. Investigation of agglomeration in preparation of nano-scale powders Zou Xing. (University of Science and Technology, Beijing, China.) PM Industry, Vol 14, No 5, 2004, 24-27. In Chinese. Conditions leading to agglomeration during processing of nano-scale powders, and properties of agglomerates, were investigated. Counter-measures are suggested.
Pressing New technique for fabrication of high density PM parts by cold pressing and sintering A.T.Mamedov, V.A.Mamedov. (Azerbaijan Technical University, Baku, Azerbaijan.) Powder Metall., Vol 47, No 3, 2004, 278-284. Development of a new technique for pressing PM parts, in a porous die to allow removal of entrapped pore gas, is described. Effects of pore gas on green density and sintered properties are evaluated experimentally and mathematically. Steels were pressed with different lubricants, or none, but with die wall lubrication. Use of the porous die is reported to improve green and sintered properties, even without admixed lubricant, in comparison with compaction in conventional dies. Guidelines for modelling cold compaction behaviour of various powders V.Bonnefoy, P.Doremus. (Domaine Universitaire, Grenoble, France.) Powder Metall., Vol 47, No 3, 2004, 285-290. Fe, Al2O3, WC-Co and W-Ni-Fe powder materials were cold pressed to determine powder behaviour and to establish guidelines for modelling of powder compaction. An overview of powder behaviour is proposed, based on two sub-types regarding powder hardness. The main features are analysed and a new concept is introduced. It is possible to simplify characterisation and modelling of any powder behaviour. Numerical simulation of warm compaction of metal powder Zhao Wei-bin et al. (South China University of Technology, Guangzhou,
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China.) PM Industry, Vol 14, No 5, 2004, 28-32. In Chinese. Warm compaction was simulated using software for finite element methods. Data was obtained by thermo-mechanical analysis based on a Lagrange formulation for optimisation of the process. Approaches to service life of PM dies Zhang Jiangjuan, Duan Zhanrong. (Southern Inst. of Metallurgy, Ganzhou, China.) PM Industry, Vol 14, No 5, 2004, 38-41. In Chinese. Approaches to prolong the service life of PM compaction dies are reported. There are use of a new material, a 12%Cr steel, and improvements in the heat treatment of the die. Design of a forming die for an injector plate Pan Chun-lei. (PM DFM Corporation, Hubei Danjiangko, China.) PM Industry, Vol 14, No 5, 2004, 42-45. In Chinese. It is noted that productivity in making an injector plate in manually operated dies is low and the green part is liable to crack during ejection. It is reported that surveys and theoretical analysis had resulted in improvements and use of automatic forming dies.
Fundamentals Measurement and characterisation of particle strength B.Scarlett et al. (University of Florida, Gainsville, USA.) Powder Technol., Vol 143-144, 2004, 56-64. Strength of particles and granules and fracture depend on material properties and factors such as shape, size and loading patterns. These are reviewed together with an outline of breakage mechanisms. Materials are either ductile, brittle or intermediate semi-brittle. Experimental studies, using a novel test rig on some nonmetallic materials, are described and the results used in discussion of strength. How do agglomerates break? L.Liu, C.Thornton. (University of Birmingham, Birmingham, UK.) Powder Technol., Vol 143-144, 2004, 110-116. Simulations of cuboidal agglomerate impinging on a target are described. The object was to identify breakage mechanisms for granules. Fracture is shown to be related to the manner in which inter-particle forces are transmitted through the
granule and development of primary particle velocities. Heterogeneous velocity fields produce discontinuities along which shear weakening occurs. Strong velocity discontinuities become potential fracture planes. Effects of ball diameter and feed size on grinding rate constant for solid materials in a ball mill K.Kanda et al. (Yamagata University, Yamagata, Japan.) Powder Technol., Vol 143-144, 2004, 196-203. Effects of ball diameter and particle size in the feed were investigated in a tumbling ball mill with Al2O3 balls 3mm, 5mm, 10mm, 20mm and 36mm in diameter. A grinding rate constant was determined, for each material, for a range of brittle nonmetallic materials. Grinding rate constant varied with the feed size but not with the ball diameter. Simulation of wet grinding in tumbling ball mill and relation to grinding rate F.Saito et al. (Tohoku University, Sendai, Japan.) Powder Technol., Vol 143-144, 2004, 230-239. A method for simulation, by finite element methods, of ball motion in a tumbling ball mill, under wet conditions is described. Drag force and buoyancy are considered. Impact energy for bell collisions allows prediction of grinding rate. Experimental milling of a steel powder and Al2O3 was observed through a transparent end window. Applicability of a new equation for fracture toughness to hard brittle and ductile alloy tool steels Y.Yanaba. K.Hayashi. (University of Tokyo, Tokyo-to Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 499-503. In English. It is reported that a new equation calculation of K1c had been developed for unnotched samples of hard and brittle materials which break into fragments. This is óm=øK1cSmf½ where óm is transverse rupture strength, K1c is fracture toughness, Smf is the total macroscopic surface area of all fragments and ø is a factor related to sample size and test method. Tests were conducted to determine if the equation could be applied to a ductile alloy hot tool steel which only breaks into two pieces and not into numerous fragments. The equation could be applied
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with sharply notched specimens, which showed brittle fracture. Poisson’s ratio sintered materials for structural machine parts A.Fujiki et al. (Nissan Motor Co. Ltd., Yokohama, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 515-521. In English. Relationships between Young’s modulus, shear modulus, Poisson’s ratio and porosity, of sintered steels for structural machine parts, were investigated. Porosity affected elastic properties and pore shape had more influence on Poisson’s ratio. Pore shape was determined by powder type and process conditions. Sintering atmosphere had little effect on Poisson’s ratio of as-sintered or heat treated samples.
Carbon Structure and texture of carbon materials M.Inagaki, M.Toyoda. (Oita University, Oita, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 589-594. In Japanese. Structures and nano-textures of C materials are described. Destruction of the nanotexture is shown to open new functions and applications through emphasis on exfoliation. It is shown that exfoliated graphite has high absorption for oils and gave high capacitance in electrochemical devices. Synthesis of nano-carbons by a template method T.Kyotani. (Tohoku University, Sendai, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 595-602. In Japanese. A method of making C nano-tubes is described. This uses nano-channels in anodic Al2O3 films as a template for deposition of C from various gases. Al2O3 is removed by dissolution in NaOH. Control of nano-tube dimensions is possible and nano-tubes with a double coaxial structure can be made. The inner surface, only, can be modified chemically. Nano-porous C nano-tubes and metal and metal oxide filled C nano-tubes can also be made. Diamond-like carbon films K.Oda. (Sumitomo Electric Industries Ltd., Itami, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 603-610. In Japanese. Applications of diamond-like C films are reviewed. This is shown to have good
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tribological properties when applied to mechanical parts requiring wear resistance and low friction. The films can be deposited on a wide range of metallic and nonmetallic materials, including cutting tools and can be used in automotive applications to improve fuel consumption. Preparation of fullerenes (four papers) R.Otsuki et al. (Kanazawa Inst. of Technology, Ishikawa, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 622-625, 626-629, 630-632 and 633-634. In English. Aspects of the production of fullerenes, C60 and C70, are described in terms of material and process parameters. DC resistive heating of graphite between W electrodes and arc discharge between graphite anodes and W cathodes were used. Both methods resulted in volatilisation of C. The process is carried out in He. Four types of C were used.
Iron and steel Role of sintering atmospheres and graphite addition in reduction of oxides in chromium steel P.Ortiz, F.Castro. (CEIT, San Sebastián, Spain.) Powder Metall., Vol 47, No 3, 2004, 291-298. Samples of AstaloyCrM, with/without additions of graphite, were sintered at 1100°C to 1240°C in various N-H atmospheres, with/without addition of CH4. Attention was given to reduction of oxides and the role of C in the reduction process. Powder and sintered specimens were characterised by microscopy, AstaloyCrM powder is shown to contain surface and internal oxides. Tensile samples were produced with 0 to 0.4%C to assess neck development by strength and elongation as functions of atmosphere composition and sintering temperatures. Quantitative expression of fracture surfaces of sinter-forged steels T.Futagawa, N.Kawai. (Fukui University of Technology, Fukui, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 522-526. In Japanese. Fracture of sinter forged steels was investigated with respect to composition, heat treatment and conditions of fracture. It is reported that: fracture surface roughness can be described quantitatively with fractal dimensions, fractal dimensions are affected by grain size, fractal dimensions
for a fracture split connecting rod are low and the surfaces matched well. Effects of secondary operations on mechanical properties of low alloy sintered steel A.Bergmark et al. (Höganäs AB, Höganäs, Sweden.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 527-535. In Japanese. Effects of partial diffusion prealloying and secondary operations on properties of steel parts are reviewed. A study of a 3%Cr-0.5%Mo steel is described. Fatigue strength of 520MPa was attained by control of cooling rate from sintering temperature followed by shot peening. Effects of sintering conditions on final composition and of cooling rate on fatigue are discussed. Prealloyed 1.5%Cr-0.5%Mo steel was also investigated. Simulation methods for residual stress are described. Magnetic properties and microstructure of warm compacted sintered iron with die wall lubrication S.Tajima et al. (Toyota Central R & D, Aichi, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 542-547. In Japanese. Magnetic properties of sintered Fe and cast/wrought Fe are compared. Sintered Fe has low flux density due to low sintered density. Warm compaction with die wall lubrication results in density increased to up to 7.76gm.cm-3 after compaction at 1176MPa and sintering at 1250°C. There was some anisotropic dimensional change and abnormal grain growth. The abnormality was greater at higher green density. Ferrous powders for wheel rings Luo Yi-bing. (Central South University, Changsha, China.) PM Industry, Vol 14, No 5, 2004, 9-12. In Chinese. Changes in powder morphology and the relationship between green density and milling time of Fe-2%Mn-2%Cu-Mo-C-P, prepared by high energy ball milling were investigated. After 8hours milling and sintering density of 7.21gm.cm-3 and a Vicker’s hardness of 240 to 250 were attained. The alloy is considered to be suitable for wheel rings.
Nickel Mechanical alloying of nickel-iron to nano-crystalline state
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Yu Yang et al. (Harbin Inst. of Technology, Harbin, China.) PM Technology, Vol 22, No 6, 2004, 328-332. In Chinese. Ni-30wt%Fe powders was mechanically alloyed in Ar to a nano-crystalline condition. Milled powders were characterised as a function of milling time. Structures, as they evolved were coarse lamellar, fine lamellar and after 25 hours milling a Ni rich solid solution was formed with a particle size of 10nm. This melted at 1444°C.
Titanium Infra red brazing of titanium-aluminiumvanadium and molybdenum with a titanium-copper-nickel alloy R K Shiue, C T Chang. (National Dong Hwa University Hualien, Taiwan.) .) Int J Refract. Metals/Hard Mater, Vol 23, No 3, 2005, 161-170. Brazing of Ti-6%Al-4%V and Mo with Ti15%Cu-15%Ni was investigated. Infra red and conventional furnace brazing are compared. The brazing alloy had good wettability for Ti-Al-V at 970°C. Wettability for the brazing alloy improved above 1000°C. The brazed joint consisted of a Ti rich phase with no reaction layer with the substrate. Mo samples fractures at the Mobraze metal interface. Residual stresses were modelled using ABAQUS software. Semi-isostatic high velocity compaction for preparation of titanium dental copings M.Eriksson et al. (Swedish Ceramic Inst., Göteborg, Sweden.) Powder Metall., Vol 47, No 4, 2004, 335-342. It is reported that a new method for preparation of dental prostheses had been developed. High velocity compaction of powder enclosed in elastomer moulds, with a mandrel to form the inner shape and surface of the prosthesis. The assembly is enclosed in a die and punch. Soft flexible elastomers worked best of the several tested. Density variations were investigated with up to 98 per cent to 99 per cent being attained locally. Production of sintered titanium from fibre M.Kaneko et al. (Japan Inst. of Technology, Saitama, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 570-575. In Japanese. Production of Ti sintered from fibres is described. Ti foil is coated with a water soluble resin, dried and coiled. The coils
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are end turned to produce fibre which is washed, chopped and formed into a lacelike from and sintered to porosity of 75 per cent. The application is for battery electrodes with high surface area.
Tungsten Production of nano-metre tungsten based alloy powder Ma Yun-zhu et al. (Central South University, Changsha, China.) PM Industry, Vol 14, No 5, 2004, 17-23. In Chinese. Methods used in production of nano-crystalline W base alloys are reviewed including mechanical alloying, sol-gel techniques, freeze drying, chemical vapour deposition, spray drying and reaction spray processing.
Bearing and friction materials Development of sintered bearing material resistant to sulphidisation T.Nozu et al. (DENSO Corporation, Kariya, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 536-541. In Japanese. It is noted that automotive fuels are declining in quality, increased S content, in some countries and that this may cause failure in Cu-Sn-C bearings due to contamination by S. It is reported that a Cu-Ni-Zn-C alloy, with improved resistance to S corrosion and good tribological properties had been developed. Effects of sliding surface temperature on frictional behaviour of sintered iron friction materials Chen Jie et al. (Central South University, Changsha, China.) PM Technology, Vol 22, No 4, 2004, 223-227. In Chinese. Effect of sliding surface temperature on friction of PM Fe base materials was investigated. As sliding speed increased so did the temperature. Coefficient of friction and wear decreased at first and then increased, accompanied by structural changes in the material surface. At high speeds a layer, beneficial to wear rate, was formed.
Ceramic materials Thermo-gravimetric study of oxidation of silicon carbide powders at high temperatures M.Ito et al. (National Inst. Advanced Industrial Science and Technology, Nagoya, Japan.) J.Jpn. Soc.
Powder/Powder Metall., Vol 51, No 8, 2004, 565-569. In Japanese. Oxidation of áSiC powders, at elevated temperatures was investigated by thermogravimetry. Two mechanisms were observed oxidation of free C at about 700°C and oxidation of SiC, to SiO2, at about 1000°C. The amount of SiO2 formed depended on particle size. Initiation of oxidation started at lower temperatures as the particle size increased. Oxidation of SiC, per unit area was independent of particle size. Effects of alumina on tetragonal to monoclinic transformation in zirconia-yttria T.Tanaka et al. (Himeji Inst. of Technology, Himeji, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 641-645. In Japanese. Effects of 5mol% to 30mol% Al2O3 on the martensitic tetragonal to monoclinic transformation in ZrO2-(2 or 3)% Y2O3, pressed at 100MPa, sintered at 1650°C and aged at 300°C, were investigated. Al2O3 increased grain size. Dimensional changes due to the martensitic transformation were determined. The amount of martensitic change increased with ageing time and %Al2O3. Textures were determined. Atomic force microscopy was used in the study. Crystallisation and phase changes in liquid phase sintered silicon nitride Luo Junting et al. (Harbin Inst. of Technology, Harbin, China.) PM Technology, Vol 22, No 4, 2004, 212-217. In Chinese. Amorphous Si3N4 powders were liquid phase sintered with additions of Al2O3 and/or Y2O3. Sintering at 1500°C resulted in partial crystallisation, which was complete at 1600°C. Crystalline phases were αSi3N4 and Si2N2O. Higher temperatures reduce the amount of Si2N2O. Grain size of the materials crystallised at 1600°C was mostly in the range 150 to 200nm with a few grains less than 100nm. Self propagating high temperature synthesis of alumina-zirconia composite ceramics Wang Jianjiang et al. (Xi’an Jiaotong University, Xi’an, China.) PM Technology, Vol 22, No 4, 2004, 218-222. In Chinese. It is reported that an Al2O3-ZrO2 composite liner had been applied to a pipe by in situ crystallisation out of gravitational separation in a self propagating high temperature synthesis process. The composite
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matrix was Al2O3-ZrO2 eutectic with ZrO2 fibres. Indentation tests showed a fracture toughness of 15.96MPa.m½. Crack propagation was controlled by toughening mechanisms and cracks were deflected along interfaces in the structure.
Composite materials Strengthening and toughening of titanium carbide-mullite composite materials Chen Yang et al. (North Eastern University, Shenyang, China.) PM Technology, Vol 22, No 4, 2004, 210-213. In Chinese. Relationships between mechanical properties and TiC particle size in TiC-mullite, 3Al2O3.2SiO2, composites were investigated, with effects of cold treatment. It is shown that in the TiC particle size range 14 m to 26 m toughness is increased and below TiC particle size 14 m strength is increased. Investigation of tungsten-copper and molybdenum-copper prepared from coreduced oxide powders Mu Keqiang. (Central Iron and Steel Research Inst., Beijing, China.) PM Industry, Vol 14, No 5, 2004, 13-16. In Chinese. It is noted that W-Cu and Mo-Cu composites, with fine dispersion of the constituents, are widely produced. When made from co-reduced oxide powder near full density can be attained at low sintering temperatures. These have fine grain size, homogeneous structures and improved properties. Factors in production are reviewed, including precursors, process conditions, powder characteristics and composite properties.
Electrical and magnetic materials Phosphorus as an additive in iron based soft PM magnets R.M.Larsen. (Aarlborg University, Aarlborg, Denmark.) Powder Metall, Vol 47, No 4, 2004, 332-334. Effects of adding P to Fe powders on properties of soft magnetic alloys were investigated. Results showed that P is beneficial when sintering is in a carburising atmosphere by inhibiting up-take of C. P also reduced tendency to magnetic ageing. Design of magnesium chromate high temperature thermistor materials from calculation and experiment
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I.Tanaka et al. (Kyoto University, Kyoto, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 487-491. In Japanese. Chemical stabilisation of MgCr2O4, a high temperature thermistor material, is noted. Material design by experiment and calculation is discussed. MgCr2O4 is known to exhibit Cr-deficit p-type semiconduction at elevated temperatures. Calculation of energy of formation of Cr vacancies showed stability in oxidising conditions and instability in reducing. Stable semi-conducting region at 1000°C was determined experimentally. The study demonstrated the importance of both calculation and experiment. Microstructures and magnetic properties of spark plasma sintered ironchromium-cobalt magnets H.Matsumoto et al. (NEC TOKIN Corporation, Sendai, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 554-558. In Japanese. Effects of material and process parameters on microstructure and magnetic properties of Fe-Cr-Co, processed by spark plasma sintering were investigated. Powders smaller than 80ìm were made by a spray conversion process. 98 per cent density was attained at 39MPa and 950°C in seven minutes. αFe and α2Cr rich phases were detected. Spark plasma sintering is considered to be a viable method for this material. Mechano-chemical synthesis of silverion conducting materials in silver iodide-silver tungstate N.Machida et al. (Konan University, Kobe, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 655-661. In Japanese. Amorphous Ag-ion conducting materials, Ag2WO4-(30 to 70)mol%AgI, were prepared by high energy ball milling. This gave a wider composition range than melt spinning. The material was characterised by Raman spectroscopy. Conductivity increased with %AgI. Amorphous Ag2WO4-70%AgI, had a conductivity 1.8x10-2S.cm-1 at 25C. Vitrification of silver-ion conducting materials silver tungstate-silver iodide by ball milling N.Machida et al. (Konan University, Kobe, Japan.) J.Jpn. Soc. Powder/Powder
Metall., Vol 51, No 9, 2004, 662-667. In Japanese. Vitrification of Ag2WO4-(30 to 70)mol%AgI was investigated by ball milling. Ag-ion conductivities were measured and were at a maximum when the milling time gave samples containing an amorphous phase, with a high concentration of AgI, and Ag2WO4. A not fully amorphous sample of Ag2WO4-70%AgI, milled for 20 hours had a conductivity of 4.8x10-2S.cm-1 at 25°C. Development of 460kJ.m-3 neodymiumiron-boron magnets Y.Kaneko et al. (NEOMAX Co. Ltd., Osaka, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 9, 2004, 698-702. In Japanese. Maximum energy product of Nd-Fe-B magnetic materials is discussed. Theoretically this is calculated at 512kJ.m-3. Steps required to attain this are outlined. It is reported that 460kJ.m-3 had been attained by reducing impurity levels, improvement in microstructure and development of a method of aligning particles, inclined magnetic pulsing. Preparation of âiron silicide by mechanical alloying Zhou Yun et al. (Kunming University of Science and Technology, Kunming, China.) PM Technology, Vol 22, No 4, 2004, 229-231. In Chinese. It is reported that a thermoelectric material, âFeSi2 had been prepared from elemental powders by mechanical alloying, pressing and sintering. Sintered samples were characterised by X-ray diffraction and differential scanning calorimetry. Milling for 20 hours resulted in formation of αFeSi and αFeSi2 appeared after 40 hours, the amount increasing with milling time. Current state of development of bulk nano-crystalline soft magnetic materials Fan Hongbe et al. (Harbin Inst. of Technology, Harbin, China.) PM Technology, Vol 22, No 4, 2004, 241-248. In Chinese. Developments and applications of bulk nano-crystalline soft magnetic materials are reviewed, Mechanisms of structure formation, fabrication and properties are discussed. Possible future trends are indicated.
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Production by sintering of a copper-aluminium oxide p-type semi-conductor Zhao Daqing, Yao Wei. (Tsinghua University, Beijing, China.) PM Technology, Vol 22, No 6, 2004, 333-336. In Chinese. It is reported that a p-type transparent semiconducting oxide, CuAlO2 had been prepared from fine Al2O3 and Cu2O powders by sintering in Ar. Effect of sintering temperature on the reaction was investigated. The sintered material was used as a target to make a p-type transparent semi-conducting film by vacuum magnetron sputtering.
Hard materials and tool steels Study of ‘core/rim’ structures in titanium carbide-molybdenum carbide-nickel cermets Y.Yanaba et al. (University of Tokyo, Tokyo, Japan.) J. Japan Soc. Powder/Powder Metall., Vol 51, No 5, 2004, 374-384. In English. Development of TiC (core) and (Ti,Mo)C (rim) structures in TiC(Ti,Mo)C-Ni cermets is discussed with regard to mechanisms, not solid state diffusion but solution/precipitation reactions. Core/rim structures in Fe66.7at%Si are noted. Investigations of evolution of core/rim structures are described. A hypothesis ‘exhaustion of diffusion-controllable atomic vacancies in core/rim structures’ is proposed and applied to TiC-(Ti,Mo)C-Ni and Fe-Si alloys. It is concluded that the hypothesis is valid when the rim is a stoichiometric phase which cannot dissolve the core elements. Development of polycrystalline cubic boron nitride for interrupted cutting of hardened steel K.Okamura et al. (Sumitomo Electric Hardmetal Corporation, Japan.) SEI (Sumitomo Electric Industries Ltd.,) Technical Review, No 59, 2005, 66-70. Use of polycrystalline cBN for machining hardened steels is discussed with regard to advantages over grinding. In interrupted cutting tool life may be reduced due to breakage of the cutting edge. It is reported that two new grades of polycrystalline cBN, with improved toughness had been developed specifically for interrupted machining, and with increased tool life. Cutting performance is described.
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Development of cubic boron nitride insert with new chip breaker ‘type SV’ Y.Okita et al. (Sumitomo Electric Hardmetal Corporation, Japan.) SEI (Sumitomo Electric Industries Ltd.,) Technical Review, No 59, 2005, 71-76. Machining of hard carburised layers through to the soft core is discussed with regard to chip formation and removal. It is reported that by combining cBN with a new from of chip breaker feature had been developed for improved control of chip formation and increased tool life. Design, and performance, of the chip breaker are described. Effects of additives in prealloyed iron powder on properties of metal-diamond composite Xia Zhimeng et al. (Northwestern University, Shenyang, China.) PM Technology, Vol 22, No 2, 2004, 67-70. In Chinese. The effects of using prealloyed Fe-P or Fe-Cu on properties of Metal diamond composites were investigated. The prealloyed powder gave increased density, strength and wear resistance. With Fe-P density was 99.6 per cent, three-point bend strength 1567MPa and wear rate 1.25x10-2gm.min.
Correlation of transverse rupture strength of tungsten carbide-cobalt with Vicker’s hardness Z.Z.Fang. (University of Utah, Salt Lake City, USA.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 2, 2005, 119-127. Use of transverse rupture strength, which increases as hardness diminishes, an indicator of toughness of WC-Co is noted. Experimental data showed that in the range of hardness 800 to 1500 TRS increases at first, then decreases reaching a peak at hardness of 1300. TRS has also been related to porosity. Porosity is low in WC-Co with modern processing methods and TRS is determined by structure and composition. Relationships between hardness, TRS and fracture toughness are discussed with reference to work hardening and flow stress of the Co phase.
Progress in PM tool steels Wu Yuan-chang. (Chengdu Tool Research Inst., Chengdu, China.) PM Industry, Vol 14, No 4, 2004, 24-28. In Chinese Production equipment and technique, types of steel grades and inspection for non-metallic inclusions in a non-Chinese tool steel are described. Tool steel output for tool steels is reported.
Passivity and pseudo-passivity of cemented carbides G.Mori et al. (University of Leoben, Leoben, Austria.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 2, 2005, 129-136. Corrosion of cemented carbides is described, dissolution of the binder and removal of carbide particles. It is noted that Co does not passivate but in potentiodynamic study shows anodic behaviour, critical potential and breakthrough potential. The behaviour, related to current density is referred to as pseudo-passivity. It is shown that addition of Cr3C2 improves corrosion resistance of WC-Co due to presence of a Co-Cr oxide layer, which is considered to be true passivity, decreasing the rate of dissolution of binder. Addition of V also improved corrosion resistance.
Thermal characterisation of tungsten carbide-cobalt sintered at high temperature and pressure R.T.Faria et al. (Universidade Estadual do Norte Fluminense, Califórnia, Brazil.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 2, 2005, 115-118. A new method of processing WC-15wt% at high pressure, 5GPa and high temperature, 1350°C, is described. Microstructure, density and Vicker’s hardness were determined. Thermal diffusivity was measured by an open photoacoustic cell technique. Heat capacity and thermal conductivity are calculated. Results agreed with values in the literature.
Abrasive wear of tungsten carbide-aluminide-boron composites D.Wexler et al. (Wollagong University, Wollagong, Australia.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 3, 2005, 155-159. An investigation of abrasive wear, by pin-ondisc tests, of WC-40vol%FeAl, WC40%Ni3Al, WC-40%Co and WC10wt%Co, made from ultrafine powders by hot pressing, is described. Samples were also prepared with 250ppm, 500ppm, 750ppm or 1000ppm B added. Wear resistance increased with amount of B added. Highest abrasive wear resistance was found for WC-FeAl-B, which was near to that for WC-10%Co, followed by WC-Ni3Al-B and WC-40%Co.
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Inorganic interfacial engineering – processing of hard materials G.Westin et al. (Uppsala University, Uppsala, Sweden.) Powder Metall, Vol 47, No 4, 2004, 317-331. Interfacial engineering is discussed with regard to processing of hard materials. A co-operative investigation between universities, industrial companies and other institutes is reported. Experimental work on aqueous processing of powders and use of surface active reagents using hardmetals and colloidal processing of ceramics is described. Pressing and sintering were studied experimentally and by simulation. Models are presented. Results using spark plasma sintering of ceramics and resistance to thermal shock are reported. Effect of sintering cooling rate on vanadium segregation at tungsten carbide/cobalt interface K.Hayashi et al. (University of Tokyo, Tokyo, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 576-585. In English. Segregation of V in fine grained WC-CoVC was investigated with regard to effects of cooling rate after sintering in the light of published studies. Previous work had shown that V segregated at the WC(0001 plane)/Co interface and attributed the grain growth inhibition effect of VC to this. The amount of V deposited at this interface depended on cooling rate. The rate of deposition decreased with increase in cooling rate. It is suggested that V adsorbs/desorbs, intermittently, at lattice defects. Study of sintering of diamond on to tungsten carbide-cobalt substrate Deng Fuming et al. (University of Mining and Technology, Beijing, China.) PM Technology, Vol 22, No 4, 2004, 205-209. In Chinese. Polycrystalline diamond coatings were deposited on to WC-Co substrates at 1300°C to 1660°C and 5.8GPa and were analysed by X-ray diffraction. The diffraction spectra are described and showed peaks for diamond, graphite, Co and WC. C dissolved in Co to 3.6 per cent. The diamond crystallites were about 0.059ìm. Status and prospects for titanium carbonitride based cermets Liu Yong et al. (Central South University, Changsha, China.) PM Technology, Vol 22, No 4, 2004, 236-240. In Chinese.
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Constitution and structures of Ti(C,N)cermets are discussed. Recent researches on microstructures, additives and fabrication are reviewed. Future prospects and applications are identified. Synthesis of silicon nitride by self-propagating high temperature synthesis Wang Shenghong et al. (GangTuo Metallurgical Inst., Beijing, China.) PM Industry, Vol 14, No 5, 2004, 1-5. In Chinese. Self-propagating synthesis of Si3N4 from Si in N at high temperature and pressure was investigated with regard to process conditions. The rate of reaction was found to fluctuate. The amount of N absorbed depended on pressure of N and permeability of the Si. Measurement of sulphur in (titanium,tungsten) carbide powders by combustion and electrical conductivity He Ying. (Hunan Metallurgical Technology College, Hunan, China.) PM Industry, Vol 14, No 5, 2004, 46-48. In Chinese. A method for determination of S in (Ti,W)C is reported. This uses combustion and electrical conductivity methods. Standard deviation is said to be 5per cent, sensitivity 3x10-6g.ìs and minimum measurable S 0.0001 per cent.
Laser processing A powder jet printer for deposition of powder Shoufeng Yang, J.R.G.Evans. (Queen Mary College, London, UK.) Powder Technol., Vol 142, No 2-3, 2004, 219-222. A device built from an ultrasonic generator and a capillary, that can ‘jet’ dry powders down to 0.05mg, is described. Using a tri-axis table it is possible to place powders with high precision and can be used in free-forming techniques such as laser sintering. Composition of the deposited powder can be varied. Shape and composition of a part can be down-loaded from a computer file. Wide-band laser hardening of sintered iron base materials Li Yueying et al. (JiLin University, Changchun, China.) PM Technology, Vol 22, No 4, 2004, 232-235. In Chinese. It is reported that wide-band laser transformation hardening of sintered Fe materials had been performed with a CO2 laser.
Effects of laser process conditions on microstructure, microhardness, depth of hardened surface and wear resistance of the hardened layer were investigated. It is shown that an evenly hardened layer can be produced under optimised conditions.
Mechanical alloying Magnetic properties of mechanically alloyed manganese-aluminium-carbon powders T.Saito. (Chiba Inst. of Technology, Chiba, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 548-553. In Japanese. Elemental Mn-Al-C powder mixtures were processed in either conventional or high energy ball mills. Conventional milling left elemental particles and high energy milling synthesised αMn with no τ or ε phases. Both powders formed the magnetic τphase on annealing with more in the high energy milled powder. Magnetic properties depended on the annealing temperature. Optimum annealing temperature resulted in high saturation magnetisation.
Metal injection moulding Monitoring polymer burnout at the macroscale S.L.Elder. (Centre for Innovative Sintered Products, Pennsylvania, USA.) Powder Metall., Vol 47, No 3, 2004, 302-303. It is reported that novel rig has been constructed for monitoring and optimising burnout during processing of real PM parts and that this will enhance production in the sintered materials industry. Effects of gate dimensions in metal injection moulding Jiang Bingyan et al. (Central South University, Changsha, China.) PM Technology, Vol 22, No 6, 2004, 323-327. In Chinese. Effects of gate dimensions in metal injection moulding were investigated with regard to variations in injection pressure, injection rate and feedstock temperature. Variation of gate depth with Archimedes flow length was non-linear. Gate depths of 0.5 to 2.1mm were studied. A gate depth of 1.8mm gave the largest flow length. Powder injection moulding of molybdenum-copper alloy for electronics packaging Nan Hai et al. (University of Science and Technology, Beijing, China.) PM Industry, Vol 14, No 6, 2004, 1-5. In Chinese.
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It is reported that Mo-Cu alloys had been made by injection moulding. Effects of process variables on density, microstructure and thermal conductivity were investigated. Density increased with sintering temperature up to 1450°C and then decreased. The alloy sintered at 1450°C for three hours had 98 per cent density and thermal conductivity of 158W.m =1.degK-1. Evaluation of feedstock for micro-sized injection moulded parts H.Miura et al. (Kyusyu University, Fukuoka, Japan.) J. Japan Soc. Powder/Powder Metall., Vol 51, No 6, 2004, 455-440. In Japanese. Production of micro-sized parts by injection moulding is more demanding than conventional MIM. Homogeneity of the feedstock is a major factor in micro MIM. Feedstock preparation was evaluated using measurements of density and binder content of pellets and variations are discussed in terms of a coefficient of variation. Micro dumbbell specimens were fabricated and evaluated for strength and density. The feedstock was improved by further processing.
PM components Development of warm compacted sintered sprockets for automotive engines A.Fujiki et al. (Nissan Motor Co. Ltd., Yokohama, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 7, 2004, 507-514. In Japanese. Development of warm compaction for sprockets for roller chain systems of internal combustion engines is described. Warm compaction is followed by high temperature sintering. Operation of the chain system is described as ‘silent’. Forming of a miniature cylinder by PM Mo Sheng-qin. (Changzhou College of Information Technology, Changzhou, China.) PM Industry, Vol 14, No 5, 2004, 33-37. In Chinese. Shape and forming technology for a miniature PM cylinder are described with emphasis on mould design Copper-base PM double-cone synchronising ring Qu Zai-gang. (Hangzhou PM Inst., Hangzhou, China.) PM Industry, Vol 14, No 6, 2004, 6-11. In Chinese. The importance of the synchroniser in automotive transmission systems is
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emphasised and discussed. A Cu base PM alloy for a double-cone synchroniser ring is considered and compared with a Mo steel ring. Preparation of large electronic sputtering targets Ge Qilu et al. (Advanced Technology and Materials Co. Ltd., Beijing, China.) PM Technology, Vol 22, No 2, 2004, 87-90. In Chinese. Production of electronic sputtering targets is discussed with regard to difficulties in production, including tendency to fracture, properties and performance required. It is reported that a satisfactory target had been produced after due attention to composition, preprocessing of the powders used and processing conditions using hot pressing and hot isostatic pressing. Cases of surface problems of sintered components Yu Yang. (Höganäs AB, Höganäs, Sweden.) PM Technology, Vol 22, No 2, 2004, 109-115. In Chinese. Surface defects in sintered parts, such as pinholes, holes and stains, which appear during processing of PM parts are identified. Factors affecting the surface quality of sintered are discussed with respect to practical PM processes. Some case studies, including solutions, are described. Repressing and resintering of a passive ratchet part Guo Zheng-jun et al. (Dong Feng Automobile Co. Ltd., Dan Jiang Kou, China.) PM Industry, Vol 14, No 4, 2004, 21-23. In Chinese. It is reported that correct density distribution of teeth in a ratchet component had been attained by varying the tooth angle and repressing and resintering. The part is shown to satisfy specification requirements.
Miscellaneous Industry / University co-operation B.Lindqvist et al. (Höganäs AB, Höganäs, Sweden.) Powder Metall., Vol 47, No 3, 2004, 304-308. A research co-operation between Höganäs AB and universities in Spain, Italy and Austria, the Höganäs Chair, is reported. Arising from the co-operation three PhD theses and 31 research papers have been published. These have dealt with aspects of Cr-Mo steels including prealloying, processing and properties.
Powder metallurgy research institutions in Austria H.Danninger. (Vienna University of Technology, Vienna, Austria.) Powder Metall., Vol 47, No 3, 2004, 216-220. Three universities in Austria, with a significant role in PM are identified, Vienna University of Technology, University of Vienna and the University of Mining and Metallurgy at Loeben, together with two non-university institutes, the Austrian Research Institute at Seibersdorf and Joanneum Research. Facilities and expertise are outlined together with collaborative links with other organisations. Competence Centres for Materials and Light Materials are also reviewed. Trials and tribulations in editing Int. J. Refractory Metals/Hard Materials for 13 years (1991-2004) H.M.Ortner. (Darmstadt University of Technology, Darmstadt, Germany.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 1, 2005, 3-16. The work of the editor is critically reviewed with regard to difficulties encountered, such as poor quality English in submitted papers, and his wishes for improvements, notably in the use, or misuse of statistics. (A paper which should be read, and acted on, by anyone about to submit a paper to a learned Journal! – Abstracts Ed.) Fascination of the micro- and macro-cosmos – morphologies of science and the Tyrolean Alps H.M.Ortner. (Darmstadt University of Technology, Darmstadt, Germany.) Int. J. Refract. Metals/Hard Mater., Vol 23, No 1, 2005, 17-66. The paper presents and describes a number of photomicrographs, and other figures, of intrinsic structural beauty. These are compared and contrasted with photographs of other things including landscapes, architecture and people. *Formulation in the PM industry S.le Mezec. (Matcon Inc., USA.) Human errors in manual preparation of powder mixtures were noted in the light of complexity and minimisation of PM part size. It was reported that high speed-high accuracy weighing equipment is available and which allows full product traceability. The capabilities of the powder-mix preparation machinery were reviewed.
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*Direct-write ink-jet microdeposition technology D.J.Hayes. (MicroFab Technologies, Inc., USA.) Applications of ink-jet technology were reviewed. It was noted that these inks may contain nano- or micro-sized metal powders in production of electronic devices. *Complex three-dimensional parts by printing techniques H.A.Kuhn, J.Liu (Extrudehone/Prometal, USA.) It was reported that complex three-dimensional parts can be made by a printing process using inks containing 60vol% metal powder. Parts can be sintered to full density or infiltrated. Examples of parts were presented including an engine vane with internal holes 0.3mm in diameter. The process was described. *PM technologies for growth H.Sonderhjelm. (N.American Höganäs, USA.) Segments of manufacturing industry, which could make greater use of PM, were identified, including recreational vehicles, household appliances and gardening equipment. These have a part in common, namely gears. Potential PM methods of making gears were reviewed. Soft magnetic composites were also considered.
Environmental application of carbides produced from biomass waste Y.Yamaguchi, M.Yukumoto. (JFE Holdings Corp., Tokyo, Japan.) J.Jpn. Soc. Powder/Powder Metall., Vol 51, No 8, 2004, 611617. In Japanese. Use of fuel derived from refuse is discussed with consideration of a carbonisation for production of a carbide. The carbide has been added to pulverised fuel injected into a blast furnace. It is suggested that the carbide could be added to raw materials for sintering.
Materials testing Method of testing of weld strength between sintered metals and a pipe flange Wang Jian-yong et al. (Northwestern Inst. for NonFerrous Metals Research, Xi’an, China.) PM Industry, Vol 14, No 4, 2004, 18—20. In Chinese. A new type of test for strength of welds is introduced. This measures strength between porous metals and a pipe flange. Weld penetration can be deduced. Weld quality is evaluated by combining the test result and minimum weld pool depth. Data concerning welding practice and post-weld heat treatment can be determined.
For copies of full papers you are recommended to contact individual authors, use an interlibrary loan system or for conference papers to contact the conference organisers. *Papers marked * were presented at EURO PM 2003, organised by the European Powder Metallurgy Association, Old Bank Buildings, Bellstone, Shrewsbury, SY1 1HU, UK.
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MPR September 2005
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