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Material with increased damping capacity for superhard cutting tools
abstracts z5TH INTERNATIONALPLANSEESEMINAR. The following Abstracts are from papers presented at the Seminar, which was held in Reutte, Austria, in May 2ooI.
Hard materials Gradient structures in SiAION for improved cutting performance Z.Lances et al. (Slovak Academy of Sciences, Bratistava, Slovakia.) Use of Si-A1-O-N materials was discussed with note of properties of a and b types. It was repored that a material consisting of a tough a/b core with a rim of a had been made and properties and microstructure evaluated• It was suggested that such a material with tough core and hard rim would have good cutting performance.
Effects of addition of chromium oxide on sintering of boron carbide N.Frage et al. (Ben-Gurion University of the Negev, Beer-Sheva, Israel.) Effects of additions of Cr20 ~ and CrB 2 on sintering of B4C at 2050"C to 2130°C were investigated. Thermodynamically Cr oxide is reduced by (: from the B carbide, thus depleting the carbide of C. CrB 2 is formed in the reaction. The material is two-phase B4-xC and CrB 2 with a bend strength of 170MPa a lou value attributed to cracks formed at the CrB2/B4C interface during cooling.
Phase reactions in diffusion couples formed in systems based on titaniumtungsten-molybdenum-carbon-nitrogennickel-cobalt B.Wotlein, W.Lengauer. (University of Technology, Vienna, Austria.) Diffusion couples were used to investigate reactions of (Ti,W)(CN) and (Ti,Mo)(C,N) with Co or Ni binders. Reaction zones were thinuer with Ni than Co. Reaction rates were slowed by N in the hard phases. In absence of N and with Co binder elongated microstructural constituents, with the long axis perpendicular to the interface, were found in the reaction zone. Similar features were found m t~resence of N and the Ni binder. Rim structures were also detected.
Tungsten carbide grain growth and grain growth inhibition in nickel and iron binder hardmetals B,Wittmann et al. (University of Technology, Vienna, Austria.)
metal-powder.net
Effects of up to 2wt%VC, Cr2C3 , TaC, TiC and ZrC on growth of WC grains in WC10wt%(Ni or Fe) were investigated with respect to gross %C. Grain growth was more pronounced at higher percentage C. The most effective inhibitor was VC in WCNi. In the case of WC-Fe grain growth was strongly restricted even without inhibitor. It was deduced that the bmder, Ni or Fe, affects grain growth and that the gross C content must be considered.
Hard physical vapour deposited coatings based on (titanium, aluminium) nitride-silicon nitride M.Jilek et ai. (SHM Ltd., Novy Malin, Czech Republic.) It is reported that a nano-composite coatmg of (Ti,AI)N-Si3N 4 had been deposited by physical methods. Effects of process conditions on structures and properties were studied. Decreased reactor voltage and increased percentage Ti increased crystallite size from 3nm to 100nm. Vicker's hardness was in the range 30 to 47GPa. Mechanical properties were measured after annealing at 800°C.
Chemical vapour deposition of boroncarbon-nitrogen from single precursors R.Weissenbacher, R.Haubner. (University of Technology, Vienna, Austria.) Chemical vapour deposition of BCN phases from a single precursor, tris(dimeth>lammo)borane, with H, on Si or WC-Co substrates, in a hot Ta filament apparatus was investigated. Deposits on Si grew faster than on WC-Co under the same conditions. Increase in filament temperature increased growth rate but deposits were contaminated with Ta. Increase in flow rate of the precursor gases increased the growth rate. Deposits were examined by scanning electron microscopy.
Tungsten carbide hardmetals produced from complex tungsten-carbon-cobalt compounds K.Kitamura et al. (Toshiba Tungaloy Co. Ltd., Fukushima, Japan.) It was reported that WC-Co hardmetals had been produced from Co2W4C and Co3W9C4, rather than WC and Co powders. WC in the products was shown to be plate-like triangular prisms. The fracture toughness was 10 to 15% higher than conventinoal WC-Co at the same hardness and transverse rupture strength.
Material with increased damping capacity for superhard cutting tools A.D.Shavchenko. (Inst. Metal Physics, Kiev, Ukraine.) Development of a TiNi all()} with high damping capacity, from Ti and Ni powders, was reported. The alloy was for a range of cutting tool applications.
Advances in diamond tools for cutting lithoid materials M.Rosso et al. (Politecnico di Torino, Torino, Italy.) Attempts to produce diamond tools for working lithoid materials, stone and similar materials, with a sintered steel binder are described. Previous attempts had been unsuccessful due to catalytic effects of Fe and degradation of the diamond. Yhe study concentrated on use of infiltration at a temperature low enough not to harm the diamonds.
Chemical treatment of tungsten carbide-cobalt prior to diamond coating L.Sha et al. (Central South University of Technology, Changsha, China.) Diamond films were applied to WC15%Co by hot filamant chemical wlpour deposition. The substrate was chemically pretreated, with Murakami's reagent and then with HCI-HNO~, prior to diamond deposition. A surface layer was depleted of Co down from 15% to 0.8 to 6.0% t o a depth of 5 to 10mm, surface roughness increased and surface Rockwell hardness reduced from 89A to 83A. This gave good adhesion between coating and substrate.
Diamond coating of tungsten carbide-cobalt by DC plasma jet Z.Kesong et al. (Research Inst. of NonFerrous Metals, Guangzhou, China.) Diamond films were deposited on ~'C-Co by D C plasma jet chemical vapour deposition. Substrate surfaces were chemically pretreated to remove Co or treated b} ArH plasma etching. Coated and uncoated tools were used to machine AI-22%Si alloys. Coated material had better cutting performance.
H!gh-performance M materials
Doped tungsten cathodes for power grid tubes F.Millot et al. (Centre for Research in High Temperature Materials-CRNS, Orleans, France.)
January 2003 ~
37
Hard materials Gradient structures in SiAION for improved cutting performance Z.Lances et al. (Slovak Academy of Sciences, Bratistava, Slovakia.) Use of Si-A1-O-N materials was discussed with note of properties of a and b types. It was repored that a material consisting of a tough a/b core with a rim of a had been made and properties and microstructure evaluated• It was suggested that such a material with tough core and hard rim would have good cutting performance.
Effects of addition of chromium oxide on sintering of boron carbide N.Frage et al. (Ben-Gurion University of the Negev, Beer-Sheva, Israel.) Effects of additions of Cr20 ~ and CrB 2 on sintering of B4C at 2050"C to 2130°C were investigated. Thermodynamically Cr oxide is reduced by (: from the B carbide, thus depleting the carbide of C. CrB 2 is formed in the reaction. The material is two-phase B4-xC and CrB 2 with a bend strength of 170MPa a lou value attributed to cracks formed at the CrB2/B4C interface during cooling.
Phase reactions in diffusion couples formed in systems based on titaniumtungsten-molybdenum-carbon-nitrogennickel-cobalt B.Wotlein, W.Lengauer. (University of Technology, Vienna, Austria.) Diffusion couples were used to investigate reactions of (Ti,W)(CN) and (Ti,Mo)(C,N) with Co or Ni binders. Reaction zones were thinuer with Ni than Co. Reaction rates were slowed by N in the hard phases. In absence of N and with Co binder elongated microstructural constituents, with the long axis perpendicular to the interface, were found in the reaction zone. Similar features were found m t~resence of N and the Ni binder. Rim structures were also detected.
Tungsten carbide grain growth and grain growth inhibition in nickel and iron binder hardmetals B,Wittmann et al. (University of Technology, Vienna, Austria.)
metal-powder.net
Effects of up to 2wt%VC, Cr2C3 , TaC, TiC and ZrC on growth of WC grains in WC10wt%(Ni or Fe) were investigated with respect to gross %C. Grain growth was more pronounced at higher percentage C. The most effective inhibitor was VC in WCNi. In the case of WC-Fe grain growth was strongly restricted even without inhibitor. It was deduced that the bmder, Ni or Fe, affects grain growth and that the gross C content must be considered.
Hard physical vapour deposited coatings based on (titanium, aluminium) nitride-silicon nitride M.Jilek et ai. (SHM Ltd., Novy Malin, Czech Republic.) It is reported that a nano-composite coatmg of (Ti,AI)N-Si3N 4 had been deposited by physical methods. Effects of process conditions on structures and properties were studied. Decreased reactor voltage and increased percentage Ti increased crystallite size from 3nm to 100nm. Vicker's hardness was in the range 30 to 47GPa. Mechanical properties were measured after annealing at 800°C.
Chemical vapour deposition of boroncarbon-nitrogen from single precursors R.Weissenbacher, R.Haubner. (University of Technology, Vienna, Austria.) Chemical vapour deposition of BCN phases from a single precursor, tris(dimeth>lammo)borane, with H, on Si or WC-Co substrates, in a hot Ta filament apparatus was investigated. Deposits on Si grew faster than on WC-Co under the same conditions. Increase in filament temperature increased growth rate but deposits were contaminated with Ta. Increase in flow rate of the precursor gases increased the growth rate. Deposits were examined by scanning electron microscopy.
Tungsten carbide hardmetals produced from complex tungsten-carbon-cobalt compounds K.Kitamura et al. (Toshiba Tungaloy Co. Ltd., Fukushima, Japan.) It was reported that WC-Co hardmetals had been produced from Co2W4C and Co3W9C4, rather than WC and Co powders. WC in the products was shown to be plate-like triangular prisms. The fracture toughness was 10 to 15% higher than conventinoal WC-Co at the same hardness and transverse rupture strength.
Material with increased damping capacity for superhard cutting tools A.D.Shavchenko. (Inst. Metal Physics, Kiev, Ukraine.) Development of a TiNi all()} with high damping capacity, from Ti and Ni powders, was reported. The alloy was for a range of cutting tool applications.
Advances in diamond tools for cutting lithoid materials M.Rosso et al. (Politecnico di Torino, Torino, Italy.) Attempts to produce diamond tools for working lithoid materials, stone and similar materials, with a sintered steel binder are described. Previous attempts had been unsuccessful due to catalytic effects of Fe and degradation of the diamond. Yhe study concentrated on use of infiltration at a temperature low enough not to harm the diamonds.
Chemical treatment of tungsten carbide-cobalt prior to diamond coating L.Sha et al. (Central South University of Technology, Changsha, China.) Diamond films were applied to WC15%Co by hot filamant chemical wlpour deposition. The substrate was chemically pretreated, with Murakami's reagent and then with HCI-HNO~, prior to diamond deposition. A surface layer was depleted of Co down from 15% to 0.8 to 6.0% t o a depth of 5 to 10mm, surface roughness increased and surface Rockwell hardness reduced from 89A to 83A. This gave good adhesion between coating and substrate.
Diamond coating of tungsten carbide-cobalt by DC plasma jet Z.Kesong et al. (Research Inst. of NonFerrous Metals, Guangzhou, China.) Diamond films were deposited on ~'C-Co by D C plasma jet chemical vapour deposition. Substrate surfaces were chemically pretreated to remove Co or treated b} ArH plasma etching. Coated and uncoated tools were used to machine AI-22%Si alloys. Coated material had better cutting performance.
H!gh-performance M materials
Doped tungsten cathodes for power grid tubes F.Millot et al. (Centre for Research in High Temperature Materials-CRNS, Orleans, France.)
January 2003 ~
37