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Surface hardening of sintered stainless steel
tion, in which the VC content was increased up to 28 vol%, was described. The steels with very high %VC were reported to have markedly increased wear resistance.
Magnetic
WEAR BEIIAVIOUR OF A PM HIGH SPEED STEEL PRODUCT
V.M.Vasilyev, V.G.Lulko. (Don State Technical University, Russia.) It was noted that in producing magnetic materials for AC applications dynamics of domain walls, hysteresis and eddy current losses must be considered in order to prepare improved materials. It was shown that reduction annealing of powder reduced eddy current loss. The effects of additives on eddy current losses were investigated and it was reported that Fe powders, coated with P, gave good results.
SAshok et al. (Sundram Fasteners Ltd, India.) An investigation of the sintering of a high speed steel, in various atmospheres, with and without sintering aids, was described. Wear behaviour was studied by pin-on-disc tests and the results discussed. MICROSTRUCTURAL CHARACTERIZATION OF CARBIDES IN SINTERED COBALT BASE STELLITE ALLOYS S.Basri et al. (Pertanian University, Malaysia.) Vaccum sintering, at 1180°C for 2 hours, of stellite type alloys, with 10 to lSwt%W, 1.6 to 3.l%C and 0.5 to l%B, was investigated with the object of optimization. Alloys with W and C at the upper end of the ranges were reported to have the best combina.tion of densification and mechanical proprties. The structures were characterized and wear assessed by cutting tests. Properties were correlated with structure, carbide size and type and matrix composition. Comparison was made with commercial stellite alloys. SINTERING OF MODIFIED M36 M HIGH SPEED STEELS IN NITROGEN-RICH ATMOSPHERES M.C.Oliviera et al. (LNETI, Lisbon, Portugal.) Sintering, in N-H or N-H-CH,, of a modified M35 M HSS with high C and V, made from water atomized powder, was investigated. Sintering in N rich gas gave density of 99%. N content and nature of the carbides were determined. A high proportion of M& was found with M(C,N). M(C,N) is resistant to coarsening and inhibits austenitic grain growth. SINTERING AND PROPERTIES OF M2 AND T16 HIGH SPPED STEELS O.C.S.Ribeiro. (IPEN-CNEN/SP, Brazil.) Liquid phase sintering, in vacuum at 122 to 1285”C, of Tl5 and M2 high speed steels, made from water atomized powder, was investigated. 3-point bend tests, before and after heat treatment, were carried out. Comparison was made with commercially available alloys.
materials
SOFT MAGNETIC MATERIALS FOR TRANSFORMERS SINTERED FROM IRON BASE POWDERS
GAS ATOMIZATION OF NEODYMIUM-IRON-BORON MAGNETIC MATERIALS
HARD
L.Henderson et al. (Brookhaven National Laboratory, USA.) Investigations of Nd-Fe-B based powders, prepared by inert gas atomization, were described. Structure and magnetic properties were studied as functions of particle size, before and after heat treatment in order to attain optimum properties. Properties and microstructures were shown to depend on particle size. It was reported that some conventional compositions do not yield the best properties but with optimization of composition and process condit,ions isotropic powders with good properties can be made. DENSIFICATION OF IRONZIRCONIUM -BORON-NICKEL POWDERS UNDER UNIAXIAL HOT PRESSING T.Masumoto et al. (Tohoku University, Sendai, Japan.) It was reported that nanocrystalline materials had been produced from amorphous Fe-7at%Zr-3%B-2%Ni powders and this exhibited soft magnetic properties. A study of processing was described and it was shown that complex shaped parts can be made. Densities above 99% were attained. Magnetic properties were described. CORRELATION OF MECHANICAL AND MAGNETIC PROPERTIES OF DIELECTROMAGNETS A.Kordecki, B.Slusarek. (Tele-Radio Research Inst., Poland.) Dielectromagnets, made by bonding hard magnetic powders in resin, were discussed. Comparison was made with materials made from different powder materials. It was suggested that there
could be advantages in using more than one powder. The objective of the study was to make parts with exactly the specified magnetic and mechanical properties. Correlations between the magnetic and mechanical properties of dielectromagnets, made from Nd-Fe-B and Sr ferrite were presented.
Surface treatments TRIBOLOGICAL BEHAVIOUR OF SPRAYED CARBIDE COATINGS G.Strafelini et al. (University of Trento, Italy.) Applications of thermally sprayed carbide coatings were reviewed with regard to chemical, mechanical and tribological properties. An investigation of microstructure and tribological properties of a range of WC and Cr2C3 coatings was described with emphasis on process conditions. Friction, wear and adhesion to substrate were studied. PROPERTIES OF MINERAL PARTICLES COATED WITH METAL
D.V.Nekrasov, V.G.Lulko. (Don State Technical University, Russia.) Use of mineral powders, coated with a metal film, was discussed. The metal films, a few nm thick, were deposited from a vapour phase in a fluidized bed. SURFACE HARDENING OF SINTERED STAINLESS STEEL O.Morandi, M.Rosso. (Politechnic of Turin, Turin, Italy. 1 Processing of sintered ferrous materials was discussed with reference to corrosion and mechanical properties. Note was taken of difficulties arising from the use of surface treatments in reducing properties. New plasma surface treatments, applied to stainless steels, were investigated by a wide range of techniques. EFFECTS OF DIFFERENT NITROCARBURIZING PROCESSES ON PROPERTIES OF SINTERED STEELS M.Drozda, M.Rosso. (Polytechnic of Turin, Turin, Italy.) Nitriding and nitrocarburizing treatments for sintered steel were reviewed. Properties and dimensional changes arising from these were investigated using different media. Some specimens were steam treated. Surface characteristics were determined and some specimens were impact tested.
MPR September 1997 45
Magnetic
WEAR BEIIAVIOUR OF A PM HIGH SPEED STEEL PRODUCT
V.M.Vasilyev, V.G.Lulko. (Don State Technical University, Russia.) It was noted that in producing magnetic materials for AC applications dynamics of domain walls, hysteresis and eddy current losses must be considered in order to prepare improved materials. It was shown that reduction annealing of powder reduced eddy current loss. The effects of additives on eddy current losses were investigated and it was reported that Fe powders, coated with P, gave good results.
SAshok et al. (Sundram Fasteners Ltd, India.) An investigation of the sintering of a high speed steel, in various atmospheres, with and without sintering aids, was described. Wear behaviour was studied by pin-on-disc tests and the results discussed. MICROSTRUCTURAL CHARACTERIZATION OF CARBIDES IN SINTERED COBALT BASE STELLITE ALLOYS S.Basri et al. (Pertanian University, Malaysia.) Vaccum sintering, at 1180°C for 2 hours, of stellite type alloys, with 10 to lSwt%W, 1.6 to 3.l%C and 0.5 to l%B, was investigated with the object of optimization. Alloys with W and C at the upper end of the ranges were reported to have the best combina.tion of densification and mechanical proprties. The structures were characterized and wear assessed by cutting tests. Properties were correlated with structure, carbide size and type and matrix composition. Comparison was made with commercial stellite alloys. SINTERING OF MODIFIED M36 M HIGH SPEED STEELS IN NITROGEN-RICH ATMOSPHERES M.C.Oliviera et al. (LNETI, Lisbon, Portugal.) Sintering, in N-H or N-H-CH,, of a modified M35 M HSS with high C and V, made from water atomized powder, was investigated. Sintering in N rich gas gave density of 99%. N content and nature of the carbides were determined. A high proportion of M& was found with M(C,N). M(C,N) is resistant to coarsening and inhibits austenitic grain growth. SINTERING AND PROPERTIES OF M2 AND T16 HIGH SPPED STEELS O.C.S.Ribeiro. (IPEN-CNEN/SP, Brazil.) Liquid phase sintering, in vacuum at 122 to 1285”C, of Tl5 and M2 high speed steels, made from water atomized powder, was investigated. 3-point bend tests, before and after heat treatment, were carried out. Comparison was made with commercially available alloys.
materials
SOFT MAGNETIC MATERIALS FOR TRANSFORMERS SINTERED FROM IRON BASE POWDERS
GAS ATOMIZATION OF NEODYMIUM-IRON-BORON MAGNETIC MATERIALS
HARD
L.Henderson et al. (Brookhaven National Laboratory, USA.) Investigations of Nd-Fe-B based powders, prepared by inert gas atomization, were described. Structure and magnetic properties were studied as functions of particle size, before and after heat treatment in order to attain optimum properties. Properties and microstructures were shown to depend on particle size. It was reported that some conventional compositions do not yield the best properties but with optimization of composition and process condit,ions isotropic powders with good properties can be made. DENSIFICATION OF IRONZIRCONIUM -BORON-NICKEL POWDERS UNDER UNIAXIAL HOT PRESSING T.Masumoto et al. (Tohoku University, Sendai, Japan.) It was reported that nanocrystalline materials had been produced from amorphous Fe-7at%Zr-3%B-2%Ni powders and this exhibited soft magnetic properties. A study of processing was described and it was shown that complex shaped parts can be made. Densities above 99% were attained. Magnetic properties were described. CORRELATION OF MECHANICAL AND MAGNETIC PROPERTIES OF DIELECTROMAGNETS A.Kordecki, B.Slusarek. (Tele-Radio Research Inst., Poland.) Dielectromagnets, made by bonding hard magnetic powders in resin, were discussed. Comparison was made with materials made from different powder materials. It was suggested that there
could be advantages in using more than one powder. The objective of the study was to make parts with exactly the specified magnetic and mechanical properties. Correlations between the magnetic and mechanical properties of dielectromagnets, made from Nd-Fe-B and Sr ferrite were presented.
Surface treatments TRIBOLOGICAL BEHAVIOUR OF SPRAYED CARBIDE COATINGS G.Strafelini et al. (University of Trento, Italy.) Applications of thermally sprayed carbide coatings were reviewed with regard to chemical, mechanical and tribological properties. An investigation of microstructure and tribological properties of a range of WC and Cr2C3 coatings was described with emphasis on process conditions. Friction, wear and adhesion to substrate were studied. PROPERTIES OF MINERAL PARTICLES COATED WITH METAL
D.V.Nekrasov, V.G.Lulko. (Don State Technical University, Russia.) Use of mineral powders, coated with a metal film, was discussed. The metal films, a few nm thick, were deposited from a vapour phase in a fluidized bed. SURFACE HARDENING OF SINTERED STAINLESS STEEL O.Morandi, M.Rosso. (Politechnic of Turin, Turin, Italy. 1 Processing of sintered ferrous materials was discussed with reference to corrosion and mechanical properties. Note was taken of difficulties arising from the use of surface treatments in reducing properties. New plasma surface treatments, applied to stainless steels, were investigated by a wide range of techniques. EFFECTS OF DIFFERENT NITROCARBURIZING PROCESSES ON PROPERTIES OF SINTERED STEELS M.Drozda, M.Rosso. (Polytechnic of Turin, Turin, Italy.) Nitriding and nitrocarburizing treatments for sintered steel were reviewed. Properties and dimensional changes arising from these were investigated using different media. Some specimens were steam treated. Surface characteristics were determined and some specimens were impact tested.
MPR September 1997 45