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Microstructure and properties of chemical vapour deposited γ alumina coatings
Iron and steel Microstructural control for high-performance sintered low-alloy steels M.Matsuda, H.Miura. (Kumamoto University, Kumamoto, Japan.) J.Japan Soc Powder/Powder Metall., Vo[ 48, No 5, 2ooi,451-455. In Japanese. It is reported that addition of up to 8%Ni to 4600-0.4%C injection moulded steel increased mechanical properties, but only up to 6%Ni. This is attributed to solid solution hardening and to a microstructure consisting of a Ni-rich martensire in a network of tempered martensite. Effects of different types of Ni powder, spherical or acicular, on tensile and fatigue properties of Fe-6%Ni-0.5%Mo-0.2%Mn steel were investigated. Use of the acicular powder resulted in higher values of mechanical properties due to segregation of Ni when the spherical powder was used.
High-performance sintered low-alloy steels by high densification and microstructural control H.Miura et al, (Kumamoto University, Kumarnoto, Japan.) J.lapan Soc Powder/ Powder Metal/., Vol 48, No 5, 2ool,456460. In Japanese. Bi-modal Fe powders, 8 parts atomised angular 53 to 74ram and 2 parts carbonyl spherical 5ram, and acicular 4mm Ni powders were used to make steel samples. High density was attained by double press-double sinter means. This resulted in improved mechanical properties without loss of ductility due to solid solution hardenmg and a duplex microstructure. Use of nine parts coarse and one part fine powder lowered properties.
Magnesium Solid state reactions in Mg mechanically alloyed with addition of low melting point oxides A.Yamazaki et al. (Nihon University, Narashino, japan.) J.lapan Soc. Powder/Powder MetaH., Vol 48, No 5, 2ooi, 397-4o3 • In Japanese. Mg powder was mechanically alloyed, in At, with additions of SnO2, PbO or Sb203 and consolidated by vacuum hot pressing. Solid state reactions during pressing and subsequent heat treatment were investigated. Mg 2Sn, Mg2Pb, Mg2Sb3 and MgO wet formed. Microstructures and mechanical properties were studied.
metal-powder.net
Solid state reactions in Mg mechanically alloyed with metal silicides A.Yamazaki et al. (Nihon University, Narashino, Japan.) J.lapan Soc. Powder/Powder Metali., Vol 48, No 5, 2om,4o4-411. In Japanese. Mg powder was mechanically alloyed, in Ar, with additions of Ti, Cr and W silicides and consolidated by vacuum hot pressing. Precipitates of Mg silicides were formed by solid state reaction and Ti, Cr and W were dispersed in the Mg matrix.
Tungsten Nanometre high-density tungsten alloy EJingiian et al. (Central South University, Hunan, China.) PM Techno[ogy,Vol 19, No 4, 2001, 238-241. In Chinese. The current state of research into nanometre W alloys is reviewed with reference to production and processing of powder, sintering and applications of these materials.
Ceramic materials Graded mullite coatings S.N.Basu et al. (Boston University, Boston, USA.) Int. J. Refract. Metals/Hard Mater., Vo119, No 4-6, 2ool, 467-477. It is reported that compositionally graded, dense, uniform and crack free mullite, 3A1203.SiO2, coatings had been deposited on SiC by chemical vapour deposition. The AhSi ratio increased towards the outer surface. The structure was a mixture of yAl203 crystallites in a vitreous SiO 2 rich matrix. Phase changes in the coating during heat treatment at 1100°C to 1400°C were studied. Changes identified included a tetragonal to orthorhombic change, synthesis of mullite, devitrification of SiO 2, precipitation of At203 and twinning.
MuUite coatings on silicon based ceramics V.K.Sarin, M.L.Auger. (lonBond AG, Oiten, Switzerland.) Int. J. Refract. Metals/Hard Mater., Vo119, No 4-6, 2ooi, 479-494. Mullite coatings were deposited on SiC substrates by chemical vapour deposition from a mixture of A1CI3, SiC]4, CO 2 and H gases in a hot-wall vertical reactor. Intermediate reactions are shown to be significant to growth of mullite. Growth rate and structure of mullite depended on process conditions and gas mixture composition.
Coatings Coating properties optimised for tribological performance in cold forging and fine blanking applications F .Klocke, H.-W. Raedt. (RWl-H, Aachen, Germany.) int. ]. Refract. Metals/Hard Mater., Vol 19, No 4-6, 2ore, 495-5o5. Hard ceramic coatings on metal forming tools are reviewed. Results of characterisation of tribological conditions m cold forging and fine blanking are presented and models for friction and wear processes are developed. Coating properties are optimised and measured.
Microstructure and properties of chemical vapour deposited y alumina coatings A.Larsson, S.Ruppi. (Chalmers University of Technology, G6teborg, Sweden.) Int. J. Refract. Metals/Hard Mater., Vo119, No 4-6, 2ooi, 515-522. Microstructures and properties of CVD 7AIzO3 on TiN and Ti(C,N) precoated cemented carbides were investigated. The alumina was fine grained with {1,1,1} growth twins epitaxially grown on the substrates. Cutting performance is evaluated and compared with 1¢A12()3 coatings. The g coatings had slightly lower adhesion and a tendency for edge chipping but better crater wear reistance on the rake face.
Electrical and magnetic materials Effects of barium titanate on sintering and electrical properties of nickel electrode materials R.Ueyama et al. (Daiken Chemical Industry Corp., Osaka, Japan.) ].Japan Soc. Powder/Powder Metall., Vol 48, No 5, 2ool 392-396. In Japanese. Dispersability of BaTiO 3 ill Ni paste and the effects of the amount added oll sintering and electrical properties of Ni electrodes, for multi-layer capicitors, were investigated. BaTiO 3 reduced sintering shrinkage and increased the electrical resistivity. The amount of BaTiO 3 should not exceed 30%, above this the resistivity increased rapidly.
Hard materials and tool steels Thermodynamics in chemical vapour deposition of hard materials J.T.Wang et al. (Fudan University, Shanghai, China.) Int. J. Refract. Metals/Hard Mater., Vol 19, No 4-6, 2ool, 464-466 •
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High-performance sintered low-alloy steels by high densification and microstructural control H.Miura et al, (Kumamoto University, Kumarnoto, Japan.) J.lapan Soc Powder/ Powder Metal/., Vol 48, No 5, 2ool,456460. In Japanese. Bi-modal Fe powders, 8 parts atomised angular 53 to 74ram and 2 parts carbonyl spherical 5ram, and acicular 4mm Ni powders were used to make steel samples. High density was attained by double press-double sinter means. This resulted in improved mechanical properties without loss of ductility due to solid solution hardenmg and a duplex microstructure. Use of nine parts coarse and one part fine powder lowered properties.
Magnesium Solid state reactions in Mg mechanically alloyed with addition of low melting point oxides A.Yamazaki et al. (Nihon University, Narashino, japan.) J.lapan Soc. Powder/Powder MetaH., Vol 48, No 5, 2ooi, 397-4o3 • In Japanese. Mg powder was mechanically alloyed, in At, with additions of SnO2, PbO or Sb203 and consolidated by vacuum hot pressing. Solid state reactions during pressing and subsequent heat treatment were investigated. Mg 2Sn, Mg2Pb, Mg2Sb3 and MgO wet formed. Microstructures and mechanical properties were studied.
metal-powder.net
Solid state reactions in Mg mechanically alloyed with metal silicides A.Yamazaki et al. (Nihon University, Narashino, Japan.) J.lapan Soc. Powder/Powder Metali., Vol 48, No 5, 2om,4o4-411. In Japanese. Mg powder was mechanically alloyed, in Ar, with additions of Ti, Cr and W silicides and consolidated by vacuum hot pressing. Precipitates of Mg silicides were formed by solid state reaction and Ti, Cr and W were dispersed in the Mg matrix.
Tungsten Nanometre high-density tungsten alloy EJingiian et al. (Central South University, Hunan, China.) PM Techno[ogy,Vol 19, No 4, 2001, 238-241. In Chinese. The current state of research into nanometre W alloys is reviewed with reference to production and processing of powder, sintering and applications of these materials.
Ceramic materials Graded mullite coatings S.N.Basu et al. (Boston University, Boston, USA.) Int. J. Refract. Metals/Hard Mater., Vo119, No 4-6, 2ool, 467-477. It is reported that compositionally graded, dense, uniform and crack free mullite, 3A1203.SiO2, coatings had been deposited on SiC by chemical vapour deposition. The AhSi ratio increased towards the outer surface. The structure was a mixture of yAl203 crystallites in a vitreous SiO 2 rich matrix. Phase changes in the coating during heat treatment at 1100°C to 1400°C were studied. Changes identified included a tetragonal to orthorhombic change, synthesis of mullite, devitrification of SiO 2, precipitation of At203 and twinning.
MuUite coatings on silicon based ceramics V.K.Sarin, M.L.Auger. (lonBond AG, Oiten, Switzerland.) Int. J. Refract. Metals/Hard Mater., Vo119, No 4-6, 2ooi, 479-494. Mullite coatings were deposited on SiC substrates by chemical vapour deposition from a mixture of A1CI3, SiC]4, CO 2 and H gases in a hot-wall vertical reactor. Intermediate reactions are shown to be significant to growth of mullite. Growth rate and structure of mullite depended on process conditions and gas mixture composition.
Coatings Coating properties optimised for tribological performance in cold forging and fine blanking applications F .Klocke, H.-W. Raedt. (RWl-H, Aachen, Germany.) int. ]. Refract. Metals/Hard Mater., Vol 19, No 4-6, 2ore, 495-5o5. Hard ceramic coatings on metal forming tools are reviewed. Results of characterisation of tribological conditions m cold forging and fine blanking are presented and models for friction and wear processes are developed. Coating properties are optimised and measured.
Microstructure and properties of chemical vapour deposited y alumina coatings A.Larsson, S.Ruppi. (Chalmers University of Technology, G6teborg, Sweden.) Int. J. Refract. Metals/Hard Mater., Vo119, No 4-6, 2ooi, 515-522. Microstructures and properties of CVD 7AIzO3 on TiN and Ti(C,N) precoated cemented carbides were investigated. The alumina was fine grained with {1,1,1} growth twins epitaxially grown on the substrates. Cutting performance is evaluated and compared with 1¢A12()3 coatings. The g coatings had slightly lower adhesion and a tendency for edge chipping but better crater wear reistance on the rake face.
Electrical and magnetic materials Effects of barium titanate on sintering and electrical properties of nickel electrode materials R.Ueyama et al. (Daiken Chemical Industry Corp., Osaka, Japan.) ].Japan Soc. Powder/Powder Metall., Vol 48, No 5, 2ool 392-396. In Japanese. Dispersability of BaTiO 3 ill Ni paste and the effects of the amount added oll sintering and electrical properties of Ni electrodes, for multi-layer capicitors, were investigated. BaTiO 3 reduced sintering shrinkage and increased the electrical resistivity. The amount of BaTiO 3 should not exceed 30%, above this the resistivity increased rapidly.
Hard materials and tool steels Thermodynamics in chemical vapour deposition of hard materials J.T.Wang et al. (Fudan University, Shanghai, China.) Int. J. Refract. Metals/Hard Mater., Vol 19, No 4-6, 2ool, 464-466 •
January 2003 ~
35