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Alternative production of diamond tools by laser cladding
MICROSTRUCTURE AND PROPERTIES OF TITXNHJM.ALUMXNIUM-BORON ALLOYS
through crack, single edge V-notched beam and indentation micro-fracture testing. The single edged notched beam test was shown to be the most reliable.
S.J.Hwang et aE. (Dae-Jin University, Kyunggi-Do, Korea.) J. Korean Inst. MetaEslMater., Vol 36, No 12, 1998, 2091-2101. (In Korean.) Ti-48at%Al alloys, with 0, 0.5, 2 and 5%B were prepared from mechanically alloyed powders by vacuum hot pressing. As pressed, the alloys contained a2, and g phases, Ti&lN and Al,O, with borides in the alloys with 2 and 5%B. Compressive tests at ambient temperature showed low ductility and yield strength of 2100 MPa, higher than in alloys made from unmilled powders and cast/wrought materials after annealing. At ambient temperature B increased strength but lowered strength at 850 “C. It is concluded that USA interests in standards are satisfactory, for the time being at any rate. EURO PM 99. The Abstracts that follow are from papers presented at the European Conference on Advances in Hard Materials Production and International Workshop on Diamond Tool Production, which was held in Turin, Italy, in November 1999.
Hard materials COMPOSITION, MICROSTRUCTURE, PROPERTIES AND APPLICATIONS CERMETS
OF
VRichter, M. von Ruthendorf. (Fraunhofer Inst., IKTS, Dresden, Germany.) Characteristics of hardmetals were discussed with regard to the properties of the constituent hard phases and binders and the possibility of adjusting the binder content to give materials with specified properties. The effects of adding TaC and/or NbC and the pre-sintering atmosphere - vacuum, N or cracked NH, - were investigated. It was shown that the cubic carbide additives and grain growth inhibitors control grain growth but lower transverse rupture strength. Samples presintered in cracked NH, had higher hardness, due to higher N content, than samples sintered in N or vacuum. FRACTURE TOUGHNESS HARDMETALS
TESTING
OF
L.Llanes et al. (Catalunya Polytechnical University, Barcelona, Spain.) Three methods of fracture toughness testing for WC-Co hardmetals were compared with regard to underlying theory and experimental features. The methods were single edge notched beam with a
40 MPR December
2000
ALTEBNATIVE PRODUCTION GF DIAMOND TOOLS BY LASER CLADDING CWallmann, H.W.Bergman. (Bayreuth University, Bayreuth, Germany.) It was noted that a method of making diamond tools, by pressing and sintering of tool tips, which are joined to a substrate, is expensive and lacks flexibility. Laser cladding with a powdered filler material is reported to allow generation of a diamond containing layer joined to a metallic workpiece in a single operation. The technique was discussed with reference to applications. PREPARATION OF BORON BASED CERMETS
CARBIDE
M.Daniel et al. (Ben-Gurion University of the Negev, Beer-Sheva, Israel.) It is reported that addition of TiO, to B,C accelerates sintering response due to chemical reaction which produces a non-stoichiometric B,CX, x being less than unity, and TiB,. An alloy with an initial 40wt%TiO,, smtered at 2190 “C for 1 hour, gave a material with 95% density. Carburization, at high temperatures, restores the carbide to B,C. The density is controllable and the material can be infiltrated with Al to a Vickers hardness of 800 to 2500 and a flexural strength of 350 to 750 MPa depending on metal:ceramic ratio. WETTING AND ADHESION OF METALS AND ALLOYS ON CARBON GRAPHITE VITREOUS CARBON DIAMOND
-
N.Eustathopoulos. (INPG - CRNS, St. Martin d’Heres, France.) Metal/carbon interfaces were discussed with consideration of wetting. It was said that, for good mechanical properties, there should be effective wetting at interfaces, and good adhesion. Pure metals often exhibit poor wetting against C. It was shown that wetting can be improved by alloying where a wettable compound is formed at the interface and that alloying can also enhance adhesion. Examples of a range of alloys with C, graphite, diamond and vitreous C were described. DIFFUSION CONTROLLED FABRICATION OF FUNCTIONALLY GRADED CERMETS AND HARDMETALS W.Lengauer Technology,
et al. (Vienna University Vienna, Austria.)
of
Demands for cutting tools wit11 improved performance and the cost of applying coatings were noted. It was suggested that coatings could be applied in situ during sintering. Experiments on IX-W-C-Co and Ti-W-C-N-Co were carried out with N and other reactive gases added to the sintering atmosphere at various stages. A range of surface and near-surface structures, which differed from the bulk material, were formed. These comprised (Ti,W)(N,C) smoothly graded with WC-Co. Improved performance was expected. STRUCTURE OF THE SURFACE ZONE IN GRADIENT SINTERED CEMENTED CARBIDE R.Frykholm et al. (Chalmers University of Technology, Gothenburg, Sweden.) The surface zone in gradient sintered WC-Ti(C,N)-Co was studied experimentally and by computer simulation. The simulation is based on solution of multi-component diffusion equations and thermodynamics. Composition and structure were determined by a range of methods. Good agreement between simulation and experiment was reported. NITROGEN CONTAINING AND HARDMETALS
CERMETS
W.Lengauer et al. (Vienna University of Technology, Vienna, Austria.) The influence of N in optimizing micro- and macro-structures of cermets and the complications in sintering, caused by nitriding and de-nitriding, were discussed. A wide range of techniques was used to study carbide and carbo-nitride-Co/Ni cermets. It was reported that a new range of materials had arisen from the studies. These were identified as cubic-phase-free layered surfaces, graded materials with a hard cermet case and a tough hardmetal core, complex multi-layer graded structures and a TiN based self-lubricating alloy The need for precise control during processing was emphasized. CORROSION RESISTANCE OF THERMALLY SPRAYED TUNGSTEN CARBIDE CHROMIUM CARBIDE AND INCONEL M.Rosso et al. (Politecnico di Torino, Italy) The importance of materials, notably WC, Cr,C, and Incone applied by thermal spraying, capable of withstanding the aggressive environments found in the petrochemical industry was emphasized. The need for test procedures was noted. A test method based on immersion, weight loss and surface damage was outlined. Corrosion of WC, Cr,C, and Incone were compared.
through crack, single edge V-notched beam and indentation micro-fracture testing. The single edged notched beam test was shown to be the most reliable.
S.J.Hwang et aE. (Dae-Jin University, Kyunggi-Do, Korea.) J. Korean Inst. MetaEslMater., Vol 36, No 12, 1998, 2091-2101. (In Korean.) Ti-48at%Al alloys, with 0, 0.5, 2 and 5%B were prepared from mechanically alloyed powders by vacuum hot pressing. As pressed, the alloys contained a2, and g phases, Ti&lN and Al,O, with borides in the alloys with 2 and 5%B. Compressive tests at ambient temperature showed low ductility and yield strength of 2100 MPa, higher than in alloys made from unmilled powders and cast/wrought materials after annealing. At ambient temperature B increased strength but lowered strength at 850 “C. It is concluded that USA interests in standards are satisfactory, for the time being at any rate. EURO PM 99. The Abstracts that follow are from papers presented at the European Conference on Advances in Hard Materials Production and International Workshop on Diamond Tool Production, which was held in Turin, Italy, in November 1999.
Hard materials COMPOSITION, MICROSTRUCTURE, PROPERTIES AND APPLICATIONS CERMETS
OF
VRichter, M. von Ruthendorf. (Fraunhofer Inst., IKTS, Dresden, Germany.) Characteristics of hardmetals were discussed with regard to the properties of the constituent hard phases and binders and the possibility of adjusting the binder content to give materials with specified properties. The effects of adding TaC and/or NbC and the pre-sintering atmosphere - vacuum, N or cracked NH, - were investigated. It was shown that the cubic carbide additives and grain growth inhibitors control grain growth but lower transverse rupture strength. Samples presintered in cracked NH, had higher hardness, due to higher N content, than samples sintered in N or vacuum. FRACTURE TOUGHNESS HARDMETALS
TESTING
OF
L.Llanes et al. (Catalunya Polytechnical University, Barcelona, Spain.) Three methods of fracture toughness testing for WC-Co hardmetals were compared with regard to underlying theory and experimental features. The methods were single edge notched beam with a
40 MPR December
2000
ALTEBNATIVE PRODUCTION GF DIAMOND TOOLS BY LASER CLADDING CWallmann, H.W.Bergman. (Bayreuth University, Bayreuth, Germany.) It was noted that a method of making diamond tools, by pressing and sintering of tool tips, which are joined to a substrate, is expensive and lacks flexibility. Laser cladding with a powdered filler material is reported to allow generation of a diamond containing layer joined to a metallic workpiece in a single operation. The technique was discussed with reference to applications. PREPARATION OF BORON BASED CERMETS
CARBIDE
M.Daniel et al. (Ben-Gurion University of the Negev, Beer-Sheva, Israel.) It is reported that addition of TiO, to B,C accelerates sintering response due to chemical reaction which produces a non-stoichiometric B,CX, x being less than unity, and TiB,. An alloy with an initial 40wt%TiO,, smtered at 2190 “C for 1 hour, gave a material with 95% density. Carburization, at high temperatures, restores the carbide to B,C. The density is controllable and the material can be infiltrated with Al to a Vickers hardness of 800 to 2500 and a flexural strength of 350 to 750 MPa depending on metal:ceramic ratio. WETTING AND ADHESION OF METALS AND ALLOYS ON CARBON GRAPHITE VITREOUS CARBON DIAMOND
-
N.Eustathopoulos. (INPG - CRNS, St. Martin d’Heres, France.) Metal/carbon interfaces were discussed with consideration of wetting. It was said that, for good mechanical properties, there should be effective wetting at interfaces, and good adhesion. Pure metals often exhibit poor wetting against C. It was shown that wetting can be improved by alloying where a wettable compound is formed at the interface and that alloying can also enhance adhesion. Examples of a range of alloys with C, graphite, diamond and vitreous C were described. DIFFUSION CONTROLLED FABRICATION OF FUNCTIONALLY GRADED CERMETS AND HARDMETALS W.Lengauer Technology,
et al. (Vienna University Vienna, Austria.)
of
Demands for cutting tools wit11 improved performance and the cost of applying coatings were noted. It was suggested that coatings could be applied in situ during sintering. Experiments on IX-W-C-Co and Ti-W-C-N-Co were carried out with N and other reactive gases added to the sintering atmosphere at various stages. A range of surface and near-surface structures, which differed from the bulk material, were formed. These comprised (Ti,W)(N,C) smoothly graded with WC-Co. Improved performance was expected. STRUCTURE OF THE SURFACE ZONE IN GRADIENT SINTERED CEMENTED CARBIDE R.Frykholm et al. (Chalmers University of Technology, Gothenburg, Sweden.) The surface zone in gradient sintered WC-Ti(C,N)-Co was studied experimentally and by computer simulation. The simulation is based on solution of multi-component diffusion equations and thermodynamics. Composition and structure were determined by a range of methods. Good agreement between simulation and experiment was reported. NITROGEN CONTAINING AND HARDMETALS
CERMETS
W.Lengauer et al. (Vienna University of Technology, Vienna, Austria.) The influence of N in optimizing micro- and macro-structures of cermets and the complications in sintering, caused by nitriding and de-nitriding, were discussed. A wide range of techniques was used to study carbide and carbo-nitride-Co/Ni cermets. It was reported that a new range of materials had arisen from the studies. These were identified as cubic-phase-free layered surfaces, graded materials with a hard cermet case and a tough hardmetal core, complex multi-layer graded structures and a TiN based self-lubricating alloy The need for precise control during processing was emphasized. CORROSION RESISTANCE OF THERMALLY SPRAYED TUNGSTEN CARBIDE CHROMIUM CARBIDE AND INCONEL M.Rosso et al. (Politecnico di Torino, Italy) The importance of materials, notably WC, Cr,C, and Incone applied by thermal spraying, capable of withstanding the aggressive environments found in the petrochemical industry was emphasized. The need for test procedures was noted. A test method based on immersion, weight loss and surface damage was outlined. Corrosion of WC, Cr,C, and Incone were compared.