- Email: [email protected]
Pore filling theory and microstructural evolution during liquid phase sintering
Design of atomizer equipment was discussed with regard to the size of the condenstion chamber, which must be large enough to avoid impact of molten droplets with the wall but small enough to minimize costs and the factors which must be considered. Development of a computer program to predict particle trajectories, with respect to size, thermal history and point of solidification was reported. Heat exchange processes and nozzle behaviour were considered. Calculations were presented and application to determination of equipment size and operating parameters were shown. PRODUCTION OF IRON-BORON POWDERS BY ROTATING ELECTRODE PROCESS E.Sukhovaya, I.Spridonova. (State University, Dniepropetrovsk, Ukraine.) Process conditions for rotating electrode production of Fe-B, Fe-B-C and FeB-(0, MO, V or Nb) were investigated for powders 100 to 1000 pm in size. Powders contained solid solutions based on FeB, Fe,B, Mo,B and NbB,, according to composition. Mechanical properties were dependent on %B and alloy element content. Optimum process conditions were established. PRODUCTION OF INTERMETALLIC POWDERS BY SELF-DISINTEGRATION F.Binczyk et al. (Silesian Technical University, Katowice, Poland.) Properties of Cu, Cr and Ni aluminides were outlined. Production of aluminide powders by spontaneous disintegration of aluminides was investigated. Presence of C is required and Fe can act as a catalyst. Applications for powders made by this method were given. Compacfion MODELLING OF PROCESSES DURING DETONATION COMPACTION BY GAS COMBUSTION A.N.Potapenko et aZ. (Technological Academy, Belgorod, Russia.) Pulse compaction of metal powders, using detonation in combustible gas mixtures, was described. A two-chamber tool set is used. One contains powder and the other the gas mixture. Control of the process was investigated and a mathematical model was developed. HIGH ACCURACY MASS PART PRODUCTION VLeshchinsky et al. (East Ukraine State University, Lugansk, Ukraine.) A novel approach to conventional pressing, sintering, repressing, heat treatment and process control was described. The development makes use of automatic 48
MPR May 2000
rotary machinery. The objective was to mass produce parts with high dimensional accuracy at high production rates. ANALYSIS OF SINGLE PUNCH COMPACTION OF MULTICOMPONENT PM PARTS M.Richman, D.Apelian. (Worcester Polytechnic Inst, Worcester, USA.) Production of a multi-component PM part, with single punch tooling, was discussed. The cylindrical part had a core of one powder and an annular case of another. The process was modelled mathematically assuming zero friction at die walls. The model considered a number of process parameters. FINITE ELEMENT SIMULATION OF WARM COMPACTION R.Koeller, J.Massinger. (Fraunhofer Inst., Bremen, Germany.) Warm compaction, allowing high green densities to be attained, was discussed. A constitutive model was developed, to describe warm compaction, which allowed calculation of density and stress distribution. Finite element methods were used. Data about specific materials were used in the analysis. EXPERIMENTAL EQUIPMENT FOR MEASUREMENT OF FRICTION P.Doremus. (L3S Laboratory, Grenoble, France.) Friction in compaction was discussed with regard to detrimental effects, efforts to reduce friction between powder and tools and attempts to control friction. Experimental methods, and equipment, for measuring friction were compared. Influences of process and material parameters were illustrated for W, Fe and WC. MEASUREMENT OF FRICTION DURING COMPACTION OF METAL POWDERS N.Solimannezhad, R.Larrson. (Lulea University of Technology, Lulea, Sweden.1 Tooling costs, tool wear and lubrication during compaction were discussed. Lubrication reduces friction at the expense of part properties. Other factors affecting friction were noted as was the need for quantitative data concerning friction. Studies of measurement of fricby various methods, were tion, described. Powder/tooling and interpartitle frictions were considered. The investigation was reported to allow a cost effective means for in situ measurement of friction during compaction. MODELLING OF SELECTIVE FULL DENSIFICATION OF PM PARTS R.Naidu et al. (Indian Technology, Madras, India.)
Inst.
of
Replacement of wrought steel by PM steel was discussed with regard to selective attainment of full density in load bearing parts, such as transmission gears, where full density is required on mating surfaces. Finite element methods were used to model gear rolling. It was reported that tests to validate the model were in progress. DENSIFICATION OF PARTICLES UNDER ISOSTATIC COMPACTION A.Eksi, S.Saritas. (Gazi University, Turkey.) Densification of Fe, Al and Also, powder, in flexible containers, by cold isostatic pressing at 100 to 150 MPa, was investigated by measurement of volume change. Optical and electron microscopy were used to study particle deformation.
Sintering REACTION SINTERING OF METAL POWDERS BKieback et al. (Technological University of Dresden, Dresden, Germany.) Reaction sintering was discussed with reference to effects that inhibit homogeneous densification of elemental powders. Studies of alloys containing up to electron 50at%Al, using various microscopy techniques, were described. Swelling in aluminides was investigated and a four-step mechanism was identified in which redistribution of Al melt and particle disintegration were shown to be the main processes. It was reported that the amount of swelling could be calculated. PORE FILLING THEORY AND MICROSTRUCTURAL EVOLUTION DURING LIQUID PHASE SINTERING S.W.Jung et al. (Korea Advanced Inst. of Science and Technology, Korea.) Structure evolution during liquid phase sintering was discussed with filling theory. regard to pore Correlations between sintered density and grain size with material and process parameters were described. The slope of the density/grain size and is curve is near constant unchanged with initial porosity, the slope being inversely proportional to pore size and to increase with volume fraction of liquid. LIQUID PHASE SINTERING C.H.Allibert. (INPG, ENSEEG, France.) Mechanisms leading to densification and microstructural evolution during liquid phase sintering of mixed and prealloyed powders were reviewed. Recent reincluding particle approaches, and arrangement, in solid state with a liquid, shrinkage by solution/
MPR May 2000
rotary machinery. The objective was to mass produce parts with high dimensional accuracy at high production rates. ANALYSIS OF SINGLE PUNCH COMPACTION OF MULTICOMPONENT PM PARTS M.Richman, D.Apelian. (Worcester Polytechnic Inst, Worcester, USA.) Production of a multi-component PM part, with single punch tooling, was discussed. The cylindrical part had a core of one powder and an annular case of another. The process was modelled mathematically assuming zero friction at die walls. The model considered a number of process parameters. FINITE ELEMENT SIMULATION OF WARM COMPACTION R.Koeller, J.Massinger. (Fraunhofer Inst., Bremen, Germany.) Warm compaction, allowing high green densities to be attained, was discussed. A constitutive model was developed, to describe warm compaction, which allowed calculation of density and stress distribution. Finite element methods were used. Data about specific materials were used in the analysis. EXPERIMENTAL EQUIPMENT FOR MEASUREMENT OF FRICTION P.Doremus. (L3S Laboratory, Grenoble, France.) Friction in compaction was discussed with regard to detrimental effects, efforts to reduce friction between powder and tools and attempts to control friction. Experimental methods, and equipment, for measuring friction were compared. Influences of process and material parameters were illustrated for W, Fe and WC. MEASUREMENT OF FRICTION DURING COMPACTION OF METAL POWDERS N.Solimannezhad, R.Larrson. (Lulea University of Technology, Lulea, Sweden.1 Tooling costs, tool wear and lubrication during compaction were discussed. Lubrication reduces friction at the expense of part properties. Other factors affecting friction were noted as was the need for quantitative data concerning friction. Studies of measurement of fricby various methods, were tion, described. Powder/tooling and interpartitle frictions were considered. The investigation was reported to allow a cost effective means for in situ measurement of friction during compaction. MODELLING OF SELECTIVE FULL DENSIFICATION OF PM PARTS R.Naidu et al. (Indian Technology, Madras, India.)
Inst.
of
Replacement of wrought steel by PM steel was discussed with regard to selective attainment of full density in load bearing parts, such as transmission gears, where full density is required on mating surfaces. Finite element methods were used to model gear rolling. It was reported that tests to validate the model were in progress. DENSIFICATION OF PARTICLES UNDER ISOSTATIC COMPACTION A.Eksi, S.Saritas. (Gazi University, Turkey.) Densification of Fe, Al and Also, powder, in flexible containers, by cold isostatic pressing at 100 to 150 MPa, was investigated by measurement of volume change. Optical and electron microscopy were used to study particle deformation.
Sintering REACTION SINTERING OF METAL POWDERS BKieback et al. (Technological University of Dresden, Dresden, Germany.) Reaction sintering was discussed with reference to effects that inhibit homogeneous densification of elemental powders. Studies of alloys containing up to electron 50at%Al, using various microscopy techniques, were described. Swelling in aluminides was investigated and a four-step mechanism was identified in which redistribution of Al melt and particle disintegration were shown to be the main processes. It was reported that the amount of swelling could be calculated. PORE FILLING THEORY AND MICROSTRUCTURAL EVOLUTION DURING LIQUID PHASE SINTERING S.W.Jung et al. (Korea Advanced Inst. of Science and Technology, Korea.) Structure evolution during liquid phase sintering was discussed with filling theory. regard to pore Correlations between sintered density and grain size with material and process parameters were described. The slope of the density/grain size and is curve is near constant unchanged with initial porosity, the slope being inversely proportional to pore size and to increase with volume fraction of liquid. LIQUID PHASE SINTERING C.H.Allibert. (INPG, ENSEEG, France.) Mechanisms leading to densification and microstructural evolution during liquid phase sintering of mixed and prealloyed powders were reviewed. Recent reincluding particle approaches, and arrangement, in solid state with a liquid, shrinkage by solution/