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Sintering of copper-chromium alloys
RESISTMTY STATE PM
TESTING PARTS
OF
GREEN
R.Ludwig et al. (Worcester Polytechnic Inst., USA.) A method of testing green PM parts, using resistivity to detect defects, was proposed. A multi-probe sensor makes point contacts with a specimen. A current sets up a potential distribution, which is affected by defects. Statistical or neural network techniques are used to determine if the part is defective or acceptable.
T.Cadle et al. (Zenith Sintered Products Inc, Germantown, USA.) A novel approach to production of high performance PM parts was described. The method used selective application of dissimilar but compatible alloys to optimize properties and minimize cost. An example, a camshaft timing sprocket, with a hardenable steel for the teeth and a low-density low-cost core, was presented. This gave reduced weight and inertia, better sound damping, lower overall cost and allowed a lower capacity press to be used.
RESONANT OF PM PARTS
Powder
W.Hansen, U.Schlengermann. (Krautkramer GmbH, Germany.) The need for 100% testing of parts produced, not a representative sample, was noted. It was suggested that ultrasonic resonant testing could satisfy this demand. A technique, using digital electronics to generate signals, in which the frequency is changed at intervals and which looks for resonances in the sample was described. This enables parts to be accepted or rejected automatically. Examples of automotive components were given to illustrate the method.
ATOMIZATION ALLOY
ULTRASONIC INSPECTION
Applications SINTERED AUTOMOTIVE
PARTS IN THE INDUSTRY
A.Rundel. (Dorst Maschinen und Anlagenbau, Kochel am See, Germany.) The use of sintered parts in automotive applications was reviewed in the light of improved reliability of PM technology and continuous development of powders and processes. New fabrication processes, warm compaction and dense sintering were discussed with respect to example parts. Bearing caps and connecting rods were considered. PRODUCTION AND PROPERTIES HIGH-STRENGTH HIGH-DENSITY HELICAL GEARS
OF
A.Mahn, H.Cohrt. (Schunk Sintermetalltechnik GmbH, Germany.) Warm compaction of high-density, highstrength ferrous PM parts was reviewed. High strength and density were attributed to enhanced plastic deformation giving better density distribution, particularly with toothed gears. Increased green strength reduces risk of damage during ejection. Production experience was discussed with two examples. A DUAL MATERIAL ‘DUPLEX’ APPROACH TO PM AUTOMOTIVE CAMSHAFT TIMING SPROCKETS
40 MPR June 1998
production OF AUSTENITIC
IRON
was described, including equipment and process parameters. Powders were spherical, with a dendritic structure and the size distribution curve had two maxima. 0 content was below 1% and decreased with increased particle size. ALLOYING BY BALL
OF SILVER-TIN MILLING
POWDERS
R.Orban et al. (University of ClujNapoca, Romania.) Mechanical alloying of metal powders was discussed. An investigation of MA of Ag-Sn powder mixtures was described. Structural evolution during MA was monitored. The powder was nanocrystalline after 39 hours.
Sintering
A.Ozols et al. (Facultad de Ingenieria, Argentina.) A feasibility study of combining atomization in N and the plasma rotating electrode process for production of Fe-(25 to 32)%Mn-(5 to 13)%Al-0.2%Si(0.1 to 0.5)%C alloy powders, on a laboratory scale, was reported. The alloy is intended as a substitute for Fe-Ni-Cr steels. Electrodes were rotated rapidly in a flow of Ar-N with applied plasma. A rapidly solidified powder, with a dendritic structure containing austenite and ferrite, was produced. Particles had a smooth surface, were spherical or filamentary and were 20 to 170 pm in size.
R.Orban et al. (Technical University of Cluj-Napoca, Romania.) Sintering by infiltration of molten metal into loose powders was discussed with respect to a range of materials. The method involves filling a mould cavity with a loose powder mixture followed by infiltration with a suitable alloy which can liquid phase sinter the powder. Possible lines of development were given. Studies on WC-W-N1 loose powders with brass or bronze infiltrant were reported.
SEGREGATION ALLOY POWDERS
SINTERING ALLOYS
IN
COBALT
BASE
A.Ozols et al. (Facultad de Ingenieria, Argentina.) The effect of centrifugal atomization on the structure of Stellite6, Co28wt%Cr-4.5%W-l.l%C, made by the plasma rotating electrode process, was analysed. Structures of electrodes and powders were determined. Unmelted electrodes contained dendrites of Corich solid solution and Co-carbides eutectic. In partially melted electrodes only skeletal solid solution dendrites remained. Two types of powder particle were observed. The bulk of the powder was dendritic, the rest being eutectic. This is attributed to simultaneous melting and ejection of primary dendrites and eutectic material. PRODUCTION BY ATOMIZATION
OF METAL UNDER
POWDERS WATER
G.Matei et al. (University of ClujNapoca, Cluj-Napoca, Romania.) A method of preparing metal powder by centrifugal pulverization of molten metal, in an electric arc, under water
SINTERING BY INFILTRATION LOOSE POWDERS
OF
OF
COPPER-CHROMIUM
B.Tarik et al. (Tubitak-MAM, Turkey.) Sintering of Cu-25wt%Cr-0.5%Ni powders in liquid and solid states was investigated with regard to process parameters and structure. Formation of the liquid phase started at 1089°C and sintering was at 1080 to 1100°C. Density of 98% and electrical conductivity of 39% of the international standard were attained. Cr was uniformly distributed in the matrix. SINTERING OF HIGH SPEED STEELS UNDER PRESSURE OF NITROGEN
F.Castro et al. (CEIT, Spain.) Sintering of T15, with high V and C, and M35M high speed steels was investigated. Compacts were pressed at 650 MPa and sintered to 99% density at 1040°C under N pressure of 8 bar. Up to 1.8wt% and 1.3% N were absorbed in the Tl5 and M35M steels respectively during sintering. After sintering the structures were reported to contain M,C and M,C carbides and MX carbonitrides in a pearlitic matrix.
TESTING PARTS
OF
GREEN
R.Ludwig et al. (Worcester Polytechnic Inst., USA.) A method of testing green PM parts, using resistivity to detect defects, was proposed. A multi-probe sensor makes point contacts with a specimen. A current sets up a potential distribution, which is affected by defects. Statistical or neural network techniques are used to determine if the part is defective or acceptable.
T.Cadle et al. (Zenith Sintered Products Inc, Germantown, USA.) A novel approach to production of high performance PM parts was described. The method used selective application of dissimilar but compatible alloys to optimize properties and minimize cost. An example, a camshaft timing sprocket, with a hardenable steel for the teeth and a low-density low-cost core, was presented. This gave reduced weight and inertia, better sound damping, lower overall cost and allowed a lower capacity press to be used.
RESONANT OF PM PARTS
Powder
W.Hansen, U.Schlengermann. (Krautkramer GmbH, Germany.) The need for 100% testing of parts produced, not a representative sample, was noted. It was suggested that ultrasonic resonant testing could satisfy this demand. A technique, using digital electronics to generate signals, in which the frequency is changed at intervals and which looks for resonances in the sample was described. This enables parts to be accepted or rejected automatically. Examples of automotive components were given to illustrate the method.
ATOMIZATION ALLOY
ULTRASONIC INSPECTION
Applications SINTERED AUTOMOTIVE
PARTS IN THE INDUSTRY
A.Rundel. (Dorst Maschinen und Anlagenbau, Kochel am See, Germany.) The use of sintered parts in automotive applications was reviewed in the light of improved reliability of PM technology and continuous development of powders and processes. New fabrication processes, warm compaction and dense sintering were discussed with respect to example parts. Bearing caps and connecting rods were considered. PRODUCTION AND PROPERTIES HIGH-STRENGTH HIGH-DENSITY HELICAL GEARS
OF
A.Mahn, H.Cohrt. (Schunk Sintermetalltechnik GmbH, Germany.) Warm compaction of high-density, highstrength ferrous PM parts was reviewed. High strength and density were attributed to enhanced plastic deformation giving better density distribution, particularly with toothed gears. Increased green strength reduces risk of damage during ejection. Production experience was discussed with two examples. A DUAL MATERIAL ‘DUPLEX’ APPROACH TO PM AUTOMOTIVE CAMSHAFT TIMING SPROCKETS
40 MPR June 1998
production OF AUSTENITIC
IRON
was described, including equipment and process parameters. Powders were spherical, with a dendritic structure and the size distribution curve had two maxima. 0 content was below 1% and decreased with increased particle size. ALLOYING BY BALL
OF SILVER-TIN MILLING
POWDERS
R.Orban et al. (University of ClujNapoca, Romania.) Mechanical alloying of metal powders was discussed. An investigation of MA of Ag-Sn powder mixtures was described. Structural evolution during MA was monitored. The powder was nanocrystalline after 39 hours.
Sintering
A.Ozols et al. (Facultad de Ingenieria, Argentina.) A feasibility study of combining atomization in N and the plasma rotating electrode process for production of Fe-(25 to 32)%Mn-(5 to 13)%Al-0.2%Si(0.1 to 0.5)%C alloy powders, on a laboratory scale, was reported. The alloy is intended as a substitute for Fe-Ni-Cr steels. Electrodes were rotated rapidly in a flow of Ar-N with applied plasma. A rapidly solidified powder, with a dendritic structure containing austenite and ferrite, was produced. Particles had a smooth surface, were spherical or filamentary and were 20 to 170 pm in size.
R.Orban et al. (Technical University of Cluj-Napoca, Romania.) Sintering by infiltration of molten metal into loose powders was discussed with respect to a range of materials. The method involves filling a mould cavity with a loose powder mixture followed by infiltration with a suitable alloy which can liquid phase sinter the powder. Possible lines of development were given. Studies on WC-W-N1 loose powders with brass or bronze infiltrant were reported.
SEGREGATION ALLOY POWDERS
SINTERING ALLOYS
IN
COBALT
BASE
A.Ozols et al. (Facultad de Ingenieria, Argentina.) The effect of centrifugal atomization on the structure of Stellite6, Co28wt%Cr-4.5%W-l.l%C, made by the plasma rotating electrode process, was analysed. Structures of electrodes and powders were determined. Unmelted electrodes contained dendrites of Corich solid solution and Co-carbides eutectic. In partially melted electrodes only skeletal solid solution dendrites remained. Two types of powder particle were observed. The bulk of the powder was dendritic, the rest being eutectic. This is attributed to simultaneous melting and ejection of primary dendrites and eutectic material. PRODUCTION BY ATOMIZATION
OF METAL UNDER
POWDERS WATER
G.Matei et al. (University of ClujNapoca, Cluj-Napoca, Romania.) A method of preparing metal powder by centrifugal pulverization of molten metal, in an electric arc, under water
SINTERING BY INFILTRATION LOOSE POWDERS
OF
OF
COPPER-CHROMIUM
B.Tarik et al. (Tubitak-MAM, Turkey.) Sintering of Cu-25wt%Cr-0.5%Ni powders in liquid and solid states was investigated with regard to process parameters and structure. Formation of the liquid phase started at 1089°C and sintering was at 1080 to 1100°C. Density of 98% and electrical conductivity of 39% of the international standard were attained. Cr was uniformly distributed in the matrix. SINTERING OF HIGH SPEED STEELS UNDER PRESSURE OF NITROGEN
F.Castro et al. (CEIT, Spain.) Sintering of T15, with high V and C, and M35M high speed steels was investigated. Compacts were pressed at 650 MPa and sintered to 99% density at 1040°C under N pressure of 8 bar. Up to 1.8wt% and 1.3% N were absorbed in the Tl5 and M35M steels respectively during sintering. After sintering the structures were reported to contain M,C and M,C carbides and MX carbonitrides in a pearlitic matrix.