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Microstructure evolution in aluminium-titanium aluminide composite
Composite materials PREPARATION OF COPPER-CARBON NANO-COMPOSITES BY GASEVAPORATION TECHNIQUE
T.Ohno. (Gifu National College of Technology, Gifu, Japan.) J Jpn Sot. Powder Powder Metall., Vol 44, No 10, 1997, 970-973. (In Japanese.) It is reported that CU-C,~ nano-composites had been prepared by condensation of Cc, vapour onto Cu nano-particles. Electron microscopy was used to study structure and morphology. The composite particles consisted of Cu spheres with C crystallites adhering. It is deduced that C clusters, not vapour, condense on the Cu particles. MICROSTRUCTURE EVOLUTION IN ALUMINIUM-TITANIUM ALUMINIDE COMPOSITE
(Tohoku C.M.Wang, R. Watanabe. University, Sendai, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 44, No 12, 1997, 1100-1106. (In English.) Infiltration of green Ti compacts, by immersion in molten Al, was investigated. Exothermic synthesis of TiAl, occurred and a temperature of 1185°C was reached, lower than the calculated adiabatic temperature of 1307°C. Structures of the infiltrated materials were examined. Original Ti particles had disintegrated and combined with Al as TiAl,. 75%~ of the structure was TiAl, particles with a mean size of 12 pm in an Al rich matrix.
EIectrical materials
and magnetic
MAGNETIC PROPERTIES OF NEODYMIUM-IRON-BORON SINTERED FROM GRANULATED POWDERS Y.Kishimoto, Special Metals
O.Yamashita.
(Sumitomo
Co Ltd, Osaka, Japan.1 J.
Jpn Sot. Powder Powder Metall., Vol 44, No 10, 1997,951-957. (In Japanese.) An investigation in which Nd-Fe-B powders were spray dried to granules, using an organic binder, is described. The compressibility of the granules was determined. The composition of the binder was varied to control its strength. The flowability of the powder increased with increase in binder strength, which also determined the strength of the granules, which in turn influenced the magnetic properties of sintered magnets. ELECTRICAL CHARACTERISTICS OF ZINC OXIDE VARISTOR SINTERED AT LOW TEMPERATURE
A.Iga. (Zinctopia Laboratory, Takasuki, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 44, No 12, 1997, 1075-1077. (In Japanese.) A study of sintering and electrical characteristics of ZnO ceramic varistors is described. It is reported that the material ZnO-B&O.,-Sb,O, could be sintered at 850 to 950°C instead of 1200°C if the Bi and Sb oxides were heat treated before adding to the ZnO. This prevents formation of Sb compounds on the surface of the ZnO, which inhibits sintering. Various Bi:Sb ratios were used.
Hard materials steels
and tool
DIAMOND AND CUBIC BORON NITRIDE COATINGS FOR TOOLS C.P.Klages et al. (Fraunhofer Inst., Braunschweig, Germany.) Znt. J. Refractory Metals Hard Mater., Vol 16, No 3, 1998, 171-176. It is noted that the development of diamond and cubic BN coatings for tools has been impeded with the substrates ments
have
been
by lack of adhesion and that improvemade.
Nevertheless
much work is still needed before service testing
of tools, with diamond
BN coatings, can be undertaken. of recent studies are discussed.
or cubic
Results
INTERACTIONS OF HARD METAL SUBSTRATES DURING DEPOSITION OF DIAMOND R.Haubner et al. (Technical University of Vienna, Austria.) Int. J Refractory Metals Hard Mater., Vol 16, No 3, 1998, 177-185. Adhesion of diamond coatings to hard metal substrates is discussed in terms of interactions between coating and substrate. In particular C may be picked up by a substrate low in %C from an environment rich in C. Deposition is retarded and adhesion weakened. Investigations of deposition of diamond on low C substrates are described. Diffusion of C into the substrate is demonstrated by conversion of ncarbides (Co3W,C) into Co(W,C) and WC. The Co binder becomes saturated with C during deposition and there is partial dissolution of the diamond layer. A NEW PROCESS FOR PRODUCTION OF ADHERENT DIAMOND COATINGS
et al. (CemeCon, Aachen, Germany.) Int. J. Refractory Metals Hard Mater., Vol 16, No 3, 1998,187-190. It is reported that a novel diamond coating technique, using Uniform Space Excitation, had been developed. This deposits crystalline diamond and it is A.Layendecker
shown that good service can be obtained. PROCESS CONTROL DIAMOND COATING
performance
DURING OF TOOLS
F.Deuerler et al. (Fachhochschule Gelsenkirchen, Bocholt, Germany.) Znt. J. Refractory Metals Hard Mater., Vol16, No 3, 1998, 191-199. Plasma jet chemical vapour deposition of diamond is shown to give high deposition rates at low pressure. The importance of close control of process parameters is emphasized. These are discussed with respect to process optimization. MICROSTRUCTURE AND STRENGTH OF INTERFACE BETWEEN TUNGSTEN CARBIDE-COBALT AND STEEL Y.Miyakoshi et al. (Hokkaido Industrial Research Centre, Sapporo, Japan.) J Jpn Sot. Powder Powder Metall., Vol 44, No 10, 1997,958-962. (In Japanese.) Bonding between (0.23 to 0.96)%C steel and WC-4O%Co was investigated. Microstructures and bond strength were determined. A reaction layer between the two materials was detected and this was where fracture tended to occur.
lntermetallic
materials
MECHANICAL PROPERTIES OF TRI-NICKEL ALUMINIDE PRODUCED FROM BLENDED ELEMENTAL POWDERS S.Ochiai.
(Teikyo
and Technology,
University Yamanashi,
of Science Japan.
1J
Jpn Sot. Powder Powder Metall., Vol44, No 10, 1997,939-944. (In Japanese.) It is reported that N&Al had been prepared by blending elemental powders and hot pressing. Some alloys were homogenized by heat treatment. Structures and properties were determined. As hot pressed, the flow stress was 300 MPa, which was increased to 700 MPa by the heat treatment. PM2TEC’98. The Abstracts that follow are of papers which were presented at the 1998 International Conference on Powder Metallurgy and Particulate Materials, which was held in Las Vegas, USA, in June 1998.
Powder injection moulding APPLICATION OF INJECTION MOULDED PARTS TO MEET SPECIFIC PROPERTIES K.H.Moyer
Laboratories,
et al. (Magna USA.)
Tech
PM
MPR April 1999 37
T.Ohno. (Gifu National College of Technology, Gifu, Japan.) J Jpn Sot. Powder Powder Metall., Vol 44, No 10, 1997, 970-973. (In Japanese.) It is reported that CU-C,~ nano-composites had been prepared by condensation of Cc, vapour onto Cu nano-particles. Electron microscopy was used to study structure and morphology. The composite particles consisted of Cu spheres with C crystallites adhering. It is deduced that C clusters, not vapour, condense on the Cu particles. MICROSTRUCTURE EVOLUTION IN ALUMINIUM-TITANIUM ALUMINIDE COMPOSITE
(Tohoku C.M.Wang, R. Watanabe. University, Sendai, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 44, No 12, 1997, 1100-1106. (In English.) Infiltration of green Ti compacts, by immersion in molten Al, was investigated. Exothermic synthesis of TiAl, occurred and a temperature of 1185°C was reached, lower than the calculated adiabatic temperature of 1307°C. Structures of the infiltrated materials were examined. Original Ti particles had disintegrated and combined with Al as TiAl,. 75%~ of the structure was TiAl, particles with a mean size of 12 pm in an Al rich matrix.
EIectrical materials
and magnetic
MAGNETIC PROPERTIES OF NEODYMIUM-IRON-BORON SINTERED FROM GRANULATED POWDERS Y.Kishimoto, Special Metals
O.Yamashita.
(Sumitomo
Co Ltd, Osaka, Japan.1 J.
Jpn Sot. Powder Powder Metall., Vol 44, No 10, 1997,951-957. (In Japanese.) An investigation in which Nd-Fe-B powders were spray dried to granules, using an organic binder, is described. The compressibility of the granules was determined. The composition of the binder was varied to control its strength. The flowability of the powder increased with increase in binder strength, which also determined the strength of the granules, which in turn influenced the magnetic properties of sintered magnets. ELECTRICAL CHARACTERISTICS OF ZINC OXIDE VARISTOR SINTERED AT LOW TEMPERATURE
A.Iga. (Zinctopia Laboratory, Takasuki, Japan.) J. Jpn Sot. Powder Powder Metall., Vol 44, No 12, 1997, 1075-1077. (In Japanese.) A study of sintering and electrical characteristics of ZnO ceramic varistors is described. It is reported that the material ZnO-B&O.,-Sb,O, could be sintered at 850 to 950°C instead of 1200°C if the Bi and Sb oxides were heat treated before adding to the ZnO. This prevents formation of Sb compounds on the surface of the ZnO, which inhibits sintering. Various Bi:Sb ratios were used.
Hard materials steels
and tool
DIAMOND AND CUBIC BORON NITRIDE COATINGS FOR TOOLS C.P.Klages et al. (Fraunhofer Inst., Braunschweig, Germany.) Znt. J. Refractory Metals Hard Mater., Vol 16, No 3, 1998, 171-176. It is noted that the development of diamond and cubic BN coatings for tools has been impeded with the substrates ments
have
been
by lack of adhesion and that improvemade.
Nevertheless
much work is still needed before service testing
of tools, with diamond
BN coatings, can be undertaken. of recent studies are discussed.
or cubic
Results
INTERACTIONS OF HARD METAL SUBSTRATES DURING DEPOSITION OF DIAMOND R.Haubner et al. (Technical University of Vienna, Austria.) Int. J Refractory Metals Hard Mater., Vol 16, No 3, 1998, 177-185. Adhesion of diamond coatings to hard metal substrates is discussed in terms of interactions between coating and substrate. In particular C may be picked up by a substrate low in %C from an environment rich in C. Deposition is retarded and adhesion weakened. Investigations of deposition of diamond on low C substrates are described. Diffusion of C into the substrate is demonstrated by conversion of ncarbides (Co3W,C) into Co(W,C) and WC. The Co binder becomes saturated with C during deposition and there is partial dissolution of the diamond layer. A NEW PROCESS FOR PRODUCTION OF ADHERENT DIAMOND COATINGS
et al. (CemeCon, Aachen, Germany.) Int. J. Refractory Metals Hard Mater., Vol 16, No 3, 1998,187-190. It is reported that a novel diamond coating technique, using Uniform Space Excitation, had been developed. This deposits crystalline diamond and it is A.Layendecker
shown that good service can be obtained. PROCESS CONTROL DIAMOND COATING
performance
DURING OF TOOLS
F.Deuerler et al. (Fachhochschule Gelsenkirchen, Bocholt, Germany.) Znt. J. Refractory Metals Hard Mater., Vol16, No 3, 1998, 191-199. Plasma jet chemical vapour deposition of diamond is shown to give high deposition rates at low pressure. The importance of close control of process parameters is emphasized. These are discussed with respect to process optimization. MICROSTRUCTURE AND STRENGTH OF INTERFACE BETWEEN TUNGSTEN CARBIDE-COBALT AND STEEL Y.Miyakoshi et al. (Hokkaido Industrial Research Centre, Sapporo, Japan.) J Jpn Sot. Powder Powder Metall., Vol 44, No 10, 1997,958-962. (In Japanese.) Bonding between (0.23 to 0.96)%C steel and WC-4O%Co was investigated. Microstructures and bond strength were determined. A reaction layer between the two materials was detected and this was where fracture tended to occur.
lntermetallic
materials
MECHANICAL PROPERTIES OF TRI-NICKEL ALUMINIDE PRODUCED FROM BLENDED ELEMENTAL POWDERS S.Ochiai.
(Teikyo
and Technology,
University Yamanashi,
of Science Japan.
1J
Jpn Sot. Powder Powder Metall., Vol44, No 10, 1997,939-944. (In Japanese.) It is reported that N&Al had been prepared by blending elemental powders and hot pressing. Some alloys were homogenized by heat treatment. Structures and properties were determined. As hot pressed, the flow stress was 300 MPa, which was increased to 700 MPa by the heat treatment. PM2TEC’98. The Abstracts that follow are of papers which were presented at the 1998 International Conference on Powder Metallurgy and Particulate Materials, which was held in Las Vegas, USA, in June 1998.
Powder injection moulding APPLICATION OF INJECTION MOULDED PARTS TO MEET SPECIFIC PROPERTIES K.H.Moyer
Laboratories,
et al. (Magna USA.)
Tech
PM
MPR April 1999 37