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Production of iron doped-titania powders in flame aerosol reactors
hours, in Ar, in a planetary ball mill. There was agglomeration of Mg-lO%Be powder. The other alloys were fine
to cause a large amount. 5%B amorphised quickly.
Ti-35%Fe-5%Si-
Injection moulding and cold isostatic pressing of sintered titanium-molydenum alloy N Sakurai, J.Takekawa. (Ishinomaki Senshu University, lshinomaki, Japan.) J.Japan sec. Powder/Powder Metal., Vol47, No 6, 2000, 653-657. In Japanese.
Molybdenum Structure and hardness of molybdenum consolidated by plasma pressure compaction T.S.Srivatsan et al. (University of Akron, Ohio, USA.) Powder Technol., Vol 114, No J-2, 2001, J36144.
Consolidated MO samples were prepared by plasma pressure compaction that is described. Samples were made under pulsed and non-pulsed conditions at two temperatures. Micro- and nano-hardnesses showed marginal decrease with increase in temperature. Effects of process variables on strucvtural evolution and hardness were described and discussed.
Nickel
R.H.de
TendleT et al. (National Atomic Energy Beunos Aires, Argentina.) Int. J. Non-E& Proc., Vol 1 In No 3, 2000, 299-322. Commision,
The metastable free energy diagram for NiZr was calculated and the theory extended to calculate free energies of amorphous and crystalline phases of Ni-Zr-Fe at 27°C. The calculated data are compared with published experimental results. The Ni-Zr metastable free energy diagram is shown to be consistent with measured glass transitions and succession of phases could be predicted for Ni-Zr and Ni-Zr-Fe.
Titanium Mechanical grinding of titanium-iron alloys Y.Hondn et al. (Nagoya Inst. of Technology, Nagoya, Japan.) J.Japan Sot. Powder/Powder Metal., Vof 47, No 6, 2000, 636,640. In Japanese.
Ti-(20, 30 and 40)at%Fe alloys were mechanically alloyed and phase changes investigated. There was little amorphisation. Amorphisation of Ti-40%Fe requires addition of B and/or Si. At 5%Si there was considerable amorphisation in 25 hours with recrystallisation beyond this time. Amorphisation with 5%B proceeded according to milling time, long times being needed
MPR
Ceramic materials Surface area and porosity of sol-gel derived titania, silica-alumina A.R.Boccaccini et al. (Technical University, Ilmenau, Germany.) Powder Technol., Vol 114, No J-2, ZOOf, 106-111.
Analysis of glass forming behaviour of nickel-zirconium and nickel-zirconium-iron
36
In order to make a Ti-MO with high density by sintering at the lowest possible temperature use of injection moulding and cold isostatic pressing was investigated. Ti-12%Mo alloys were injection moulded, rebound and cold isostatically pressed after pre-sintering at 900°C. Sintering was at temperatures up to 13OO’C. Cold isostatic pressing is shown to increase sintered density by 10%. Ti-12%Mo was chosen for the study because of it’s high corrosion resistance and strength.
May
2002
Surface characteristics of TiO2SiO2A1203 ceramics, made by a sol-gel technique, were investigated by absorption of N at liquid N temperatures and analysed by application of Brunauer-EmmettHTeller equation. Total surface area, total pore volume and pore radius were calculated. The results are shown to allow detection of different pores. Effects of thermal processing were evaluated.
Production of iron doped-titania powders in flame aerosol reactors P.Biswas er al. (Uniwrsity of Cincinnati, Cincinnati, USA.) Powder Tech&., Vol 114, No 1-2, 2001, J97204. It is reported that Fe-TiO, materials, with different Fe:Ti ratios had been produced by a flame aerosol process. Fe3+ was incorporated into the TiO, lattice and promoted the anatase to rutile phase change. Increase in %Fe reduced grain size and promoted amorphisa, tion. Spectral changes are described. At Fe:Ti greater than 0.8 the material had super-para, magnetic properties.
Composite materials Fabrication and tribological properties of aluminium reinforced with carbon fibre L.Froyen et al. (Katholic University Leuven, Hewerlee, Belgium.) Rev. Metal. Madrid, Vol36, No 5,2000,375384. In English.
It is reported that AI-C fibre reinforced composites had been made by squeeze casting. Process conditions were optimised to minimize formation of Al&. Friction and wear tests were carried out and conditions for formation of a tribofilm were established. Increased resistance to abrasion was found. Design criteria are recommended.
Electrical and magnetic materials Thermoelectric properties of zinc-aluminium-oxygen made by polymerized complex method M.lto et al. (Osaka University, Suita, Japan.) J.Japan Sot. Powder/Powder Metal., Vol47, No 6, 2000, 619s 624. In Japanese.
Znl -xAlxO ceramics were made by a poly merized complex technique and the thermo, electric properties and structure investigated and compared with samples made by solid state reaction. A spine1 phase was detected and the grain size, electrical resistivity and coefficient were smaller than in Seebeck samples made by solid state reaction. The dif+ ferences are attributed to differences in carrier concentration.
Magnetic properties of spark plasma sintered neodymiumiron-cobalt-vanadium-boron H.Gno et al. (Nissan Motor Co.Ltd., Yokosuka, Japan.) j.Japan Sot. Powder/Powder Metal., Vof 47, No 6, 2000, 667-673. In Japanese.
Nd-Fe-Co-V-B bulk exchange-spring mag nets were prepared from rapidly quenched ribbon powders by spark plasma sintering. Effects of sintering conditions on structure and magnetic properties were investigated. Spark plasma sintering has similarities to hot pressing but can be completed in less time at lower temperatures. Optimum process conditions were described.
Hard materials and tool steels Influence of oxygen and cobalt on early stages of sintering of tungsten carbide-cobalt S.Haglund et al. (Swedish Inst. for Metals Research, Stockholm, Sweden.) Acta Mater., Vol48, No 17, 2000, 4357-4362.
Effect of 0 on early stages of sintering of WC-Co was investigated. It was found that Co is deposited on the WC (0001) grains at 650°C and deposits grow. Excess Co is removed at 850°C. 0 reacts with Co to form COO. Co0 decomposes as Co wets the surface of the WC grains.
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to cause a large amount. 5%B amorphised quickly.
Ti-35%Fe-5%Si-
Injection moulding and cold isostatic pressing of sintered titanium-molydenum alloy N Sakurai, J.Takekawa. (Ishinomaki Senshu University, lshinomaki, Japan.) J.Japan sec. Powder/Powder Metal., Vol47, No 6, 2000, 653-657. In Japanese.
Molybdenum Structure and hardness of molybdenum consolidated by plasma pressure compaction T.S.Srivatsan et al. (University of Akron, Ohio, USA.) Powder Technol., Vol 114, No J-2, 2001, J36144.
Consolidated MO samples were prepared by plasma pressure compaction that is described. Samples were made under pulsed and non-pulsed conditions at two temperatures. Micro- and nano-hardnesses showed marginal decrease with increase in temperature. Effects of process variables on strucvtural evolution and hardness were described and discussed.
Nickel
R.H.de
TendleT et al. (National Atomic Energy Beunos Aires, Argentina.) Int. J. Non-E& Proc., Vol 1 In No 3, 2000, 299-322. Commision,
The metastable free energy diagram for NiZr was calculated and the theory extended to calculate free energies of amorphous and crystalline phases of Ni-Zr-Fe at 27°C. The calculated data are compared with published experimental results. The Ni-Zr metastable free energy diagram is shown to be consistent with measured glass transitions and succession of phases could be predicted for Ni-Zr and Ni-Zr-Fe.
Titanium Mechanical grinding of titanium-iron alloys Y.Hondn et al. (Nagoya Inst. of Technology, Nagoya, Japan.) J.Japan Sot. Powder/Powder Metal., Vof 47, No 6, 2000, 636,640. In Japanese.
Ti-(20, 30 and 40)at%Fe alloys were mechanically alloyed and phase changes investigated. There was little amorphisation. Amorphisation of Ti-40%Fe requires addition of B and/or Si. At 5%Si there was considerable amorphisation in 25 hours with recrystallisation beyond this time. Amorphisation with 5%B proceeded according to milling time, long times being needed
MPR
Ceramic materials Surface area and porosity of sol-gel derived titania, silica-alumina A.R.Boccaccini et al. (Technical University, Ilmenau, Germany.) Powder Technol., Vol 114, No J-2, ZOOf, 106-111.
Analysis of glass forming behaviour of nickel-zirconium and nickel-zirconium-iron
36
In order to make a Ti-MO with high density by sintering at the lowest possible temperature use of injection moulding and cold isostatic pressing was investigated. Ti-12%Mo alloys were injection moulded, rebound and cold isostatically pressed after pre-sintering at 900°C. Sintering was at temperatures up to 13OO’C. Cold isostatic pressing is shown to increase sintered density by 10%. Ti-12%Mo was chosen for the study because of it’s high corrosion resistance and strength.
May
2002
Surface characteristics of TiO2SiO2A1203 ceramics, made by a sol-gel technique, were investigated by absorption of N at liquid N temperatures and analysed by application of Brunauer-EmmettHTeller equation. Total surface area, total pore volume and pore radius were calculated. The results are shown to allow detection of different pores. Effects of thermal processing were evaluated.
Production of iron doped-titania powders in flame aerosol reactors P.Biswas er al. (Uniwrsity of Cincinnati, Cincinnati, USA.) Powder Tech&., Vol 114, No 1-2, 2001, J97204. It is reported that Fe-TiO, materials, with different Fe:Ti ratios had been produced by a flame aerosol process. Fe3+ was incorporated into the TiO, lattice and promoted the anatase to rutile phase change. Increase in %Fe reduced grain size and promoted amorphisa, tion. Spectral changes are described. At Fe:Ti greater than 0.8 the material had super-para, magnetic properties.
Composite materials Fabrication and tribological properties of aluminium reinforced with carbon fibre L.Froyen et al. (Katholic University Leuven, Hewerlee, Belgium.) Rev. Metal. Madrid, Vol36, No 5,2000,375384. In English.
It is reported that AI-C fibre reinforced composites had been made by squeeze casting. Process conditions were optimised to minimize formation of Al&. Friction and wear tests were carried out and conditions for formation of a tribofilm were established. Increased resistance to abrasion was found. Design criteria are recommended.
Electrical and magnetic materials Thermoelectric properties of zinc-aluminium-oxygen made by polymerized complex method M.lto et al. (Osaka University, Suita, Japan.) J.Japan Sot. Powder/Powder Metal., Vol47, No 6, 2000, 619s 624. In Japanese.
Znl -xAlxO ceramics were made by a poly merized complex technique and the thermo, electric properties and structure investigated and compared with samples made by solid state reaction. A spine1 phase was detected and the grain size, electrical resistivity and coefficient were smaller than in Seebeck samples made by solid state reaction. The dif+ ferences are attributed to differences in carrier concentration.
Magnetic properties of spark plasma sintered neodymiumiron-cobalt-vanadium-boron H.Gno et al. (Nissan Motor Co.Ltd., Yokosuka, Japan.) j.Japan Sot. Powder/Powder Metal., Vof 47, No 6, 2000, 667-673. In Japanese.
Nd-Fe-Co-V-B bulk exchange-spring mag nets were prepared from rapidly quenched ribbon powders by spark plasma sintering. Effects of sintering conditions on structure and magnetic properties were investigated. Spark plasma sintering has similarities to hot pressing but can be completed in less time at lower temperatures. Optimum process conditions were described.
Hard materials and tool steels Influence of oxygen and cobalt on early stages of sintering of tungsten carbide-cobalt S.Haglund et al. (Swedish Inst. for Metals Research, Stockholm, Sweden.) Acta Mater., Vol48, No 17, 2000, 4357-4362.
Effect of 0 on early stages of sintering of WC-Co was investigated. It was found that Co is deposited on the WC (0001) grains at 650°C and deposits grow. Excess Co is removed at 850°C. 0 reacts with Co to form COO. Co0 decomposes as Co wets the surface of the WC grains.
www.metal-powdernet