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Strength evolution during sintering — a basis for densification
Confere pro PM2TEC2000.The Abstractsthat follow are of papers presented at the 2000 International Conference on Powder Metallurgy and Particulate Materials, which was held in New York, USA,in June 200o. For further details contact the MPIF: 105 College Road East, Princeton, NJ, o854o-77oo, USA;tel: +~-6o9-452-
77oo; fax: +1-6o9-987-8523; e-maih [email protected].
Modelling technology Radial and axial variations on pressure and density in PM hollow cylinders M. W Richman, E .Gaboriault. (Worcester Polytechnic Inst., USA.) A model that predicts variations in pressure and density throughout hollow cylindrical parts, instead of mean values, was described. The model is not computationally demanding and makes point-to-point predictions of pressure and density. Axial and radial force balances are satisfied and friction is taken into account. The model was used to predict pressure and density distributions and dependencies on friction, tool/part geometry and powder properties.
Prediction of tool strength during compaction M.Guillot et al. (Laval University, Ca~da.) The mechanical properties of materials used for compaction tooling were discussed in terms of possible tool failure. Modelling of tool design by finite element methods is timeconsuming and needs consideration of a range of conditions such as the possibility of buckling of tool parts. The paper described a rapid theoretical/empirical approach to calculate stresses and stress concentrations in tool parts. The method was validated by finite element analysis and demonstrated industrially.
Finite element analysis of wire mesh furnace belts R.Riva, M.Coyle. (Pennsylvania State University, USA.) The conditions in which wire mesh belts are used was discussed with regard to elongation of the belt whilst in motion. Deformation of the belt may be permanent
34
MPR September 2ool
@
Jngs
Featuring selected abstracts from PM2TEC 2000 and EUROPM2000.
and failure may occur. Minimizing the stress on the belt can extend service life. The paper described finite element analysis of wire mesh belts in terms of the shape of the wire used. A model was constructed for interactions of wires in the belt.
Sintering Strength evolution during sintering - a basis for densification R.M. German. (Pennsylvania State University, USA.) Sintering to full density was discussed in terms of densification, use of fine powders with high sinterability, and costs. It was noted that coarse powders resist sintering densification due to sintering stress being inadequate to overcome material strength resulting in slow densification. Sintering stress and evolution of part strength during sintering were considered and investigated. A model was created to calculate conditions for densification. This showed that for sintering of coarse powders thermal softening is required to compensate for low sintering stress.
Dimensional change control through metal sulphate additions G.LeComte, M.R.Haas. (Kobelco Metal Powder of America, USA.) Dimensional changes in PM materials during processing were reviewed. A n investigation of the effects of metal sulphate additions on dimensional change of a steel was described. The intention was to determine the type and concentration of sulphate additions to control dimensional changes without reduction in mechanical properties.
Novel consolidation methods Structural changes in combustion synthesis of titanium nitride S.Deevi. (Philip Morris, USA.) A n investigation of combustion of Ti in N to form TiN was described. The synthesis was stopped after initiation by rapid evacuation of N from the reaction chamber. The sample was analysed at various distances from the reaction front to determine changes occurring with passage of the reaction wave in order to understand the reaction in greater detail.
Dense nanoscale single and two-phase ceramics WE.Mayo eta[. (Rutgers University, USA.) It was reported that dense AI203 and TiO 2 had been prepared by high pressure low temperature sintering. The nanoscale structure was attributed to the high pressure, which reduces transformation temperature. Coupled with enhanced nucleation AlzO 3 had a grain size of 49 nm and TiO 2 25 nm. The same technique was applied to Si2N 4 and composites of two nanophases. The objective was to produce materials with enhanced wear resistance.
Hot consolidation of B base powders and structure and properties C.O.Politis et al. (University of Patras, Greece.) B base powders were subjected to hot shockwave and static consolidation techniques in order to attain high density. Temperatures of 20 to 2000 °C and intensities of loading up to 10 GPa were used. Structures and properties depended on loading conditions and geometry of loading. Densities up to 97.8% were attained. Influence of process and powder parameters on structure and properties were discussed.
Sintering - time-at-temperature M.C.Thomason et al. (Gasbarre Products Inc, USA.) It was noted that there are many different sintering profiles in use and that a common description is 'time-at-temperature'. This can be influenced by a wide range of variables such as speed through the furnace and part size. A study of furnace performance at various production rates was described. Models were used to explain variation in part properties with production rate. It was shown that proper understanding of 'time-at-temperature' is needed to ensure part consistency.
Powder injection moulding Alternative manufacturing methods to rapid tooling J.T.Strauss, J.A.Grokowski. (HJE Company Inc, USA.) The long lead times in production of tooling for MIM were discussed. Attention was given to rapid methods to reduce lead times and costs. Methods and materials were outlined. It was noted that some lack the ability to reproduce fine detail in parts and that traditional methods provide the best means to tool making. Costs of using computers in design, manufacture and numerical control were
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77oo; fax: +1-6o9-987-8523; e-maih [email protected].
Modelling technology Radial and axial variations on pressure and density in PM hollow cylinders M. W Richman, E .Gaboriault. (Worcester Polytechnic Inst., USA.) A model that predicts variations in pressure and density throughout hollow cylindrical parts, instead of mean values, was described. The model is not computationally demanding and makes point-to-point predictions of pressure and density. Axial and radial force balances are satisfied and friction is taken into account. The model was used to predict pressure and density distributions and dependencies on friction, tool/part geometry and powder properties.
Prediction of tool strength during compaction M.Guillot et al. (Laval University, Ca~da.) The mechanical properties of materials used for compaction tooling were discussed in terms of possible tool failure. Modelling of tool design by finite element methods is timeconsuming and needs consideration of a range of conditions such as the possibility of buckling of tool parts. The paper described a rapid theoretical/empirical approach to calculate stresses and stress concentrations in tool parts. The method was validated by finite element analysis and demonstrated industrially.
Finite element analysis of wire mesh furnace belts R.Riva, M.Coyle. (Pennsylvania State University, USA.) The conditions in which wire mesh belts are used was discussed with regard to elongation of the belt whilst in motion. Deformation of the belt may be permanent
34
MPR September 2ool
@
Jngs
Featuring selected abstracts from PM2TEC 2000 and EUROPM2000.
and failure may occur. Minimizing the stress on the belt can extend service life. The paper described finite element analysis of wire mesh belts in terms of the shape of the wire used. A model was constructed for interactions of wires in the belt.
Sintering Strength evolution during sintering - a basis for densification R.M. German. (Pennsylvania State University, USA.) Sintering to full density was discussed in terms of densification, use of fine powders with high sinterability, and costs. It was noted that coarse powders resist sintering densification due to sintering stress being inadequate to overcome material strength resulting in slow densification. Sintering stress and evolution of part strength during sintering were considered and investigated. A model was created to calculate conditions for densification. This showed that for sintering of coarse powders thermal softening is required to compensate for low sintering stress.
Dimensional change control through metal sulphate additions G.LeComte, M.R.Haas. (Kobelco Metal Powder of America, USA.) Dimensional changes in PM materials during processing were reviewed. A n investigation of the effects of metal sulphate additions on dimensional change of a steel was described. The intention was to determine the type and concentration of sulphate additions to control dimensional changes without reduction in mechanical properties.
Novel consolidation methods Structural changes in combustion synthesis of titanium nitride S.Deevi. (Philip Morris, USA.) A n investigation of combustion of Ti in N to form TiN was described. The synthesis was stopped after initiation by rapid evacuation of N from the reaction chamber. The sample was analysed at various distances from the reaction front to determine changes occurring with passage of the reaction wave in order to understand the reaction in greater detail.
Dense nanoscale single and two-phase ceramics WE.Mayo eta[. (Rutgers University, USA.) It was reported that dense AI203 and TiO 2 had been prepared by high pressure low temperature sintering. The nanoscale structure was attributed to the high pressure, which reduces transformation temperature. Coupled with enhanced nucleation AlzO 3 had a grain size of 49 nm and TiO 2 25 nm. The same technique was applied to Si2N 4 and composites of two nanophases. The objective was to produce materials with enhanced wear resistance.
Hot consolidation of B base powders and structure and properties C.O.Politis et al. (University of Patras, Greece.) B base powders were subjected to hot shockwave and static consolidation techniques in order to attain high density. Temperatures of 20 to 2000 °C and intensities of loading up to 10 GPa were used. Structures and properties depended on loading conditions and geometry of loading. Densities up to 97.8% were attained. Influence of process and powder parameters on structure and properties were discussed.
Sintering - time-at-temperature M.C.Thomason et al. (Gasbarre Products Inc, USA.) It was noted that there are many different sintering profiles in use and that a common description is 'time-at-temperature'. This can be influenced by a wide range of variables such as speed through the furnace and part size. A study of furnace performance at various production rates was described. Models were used to explain variation in part properties with production rate. It was shown that proper understanding of 'time-at-temperature' is needed to ensure part consistency.
Powder injection moulding Alternative manufacturing methods to rapid tooling J.T.Strauss, J.A.Grokowski. (HJE Company Inc, USA.) The long lead times in production of tooling for MIM were discussed. Attention was given to rapid methods to reduce lead times and costs. Methods and materials were outlined. It was noted that some lack the ability to reproduce fine detail in parts and that traditional methods provide the best means to tool making. Costs of using computers in design, manufacture and numerical control were
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