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Analysis of thermal debinding
reported to have fallen. Use of soft metal tooling for short production runs was outlined. Methods and case studies were discussed.
Analysis of thermal debinding S V.Atre, RM.German. (Penn State University, USA.) Decomposition of organic compounds, in porous media, used as injection moulding binders, was investigated using a thermal analyser with infrared spectroscopy. Binder degradation kinetics and gases evolved were studied as functions of process conditions. The results were used to extend the understanding of the effects of pore structure on binder decomposition and the influence of part geometry on debinding. The results were used to refine the finite element model for heat and mass transfer and stresses in the parts.
Anisotropic shrinkage during sintering of injection moulded parts J.LaSalle et al. (Honeywell PowderFloTechnologies, USA.) Anisotropic shrinkage in injection moulded parts was discussed with regard to the underlying causes. Knowledge of this is required in determination of tool dimensions to satisfy specified parts dimensions. A stainless steel part was analysed in terms of interplay of forces involved during sintering.
Martensite formation in injection moulded precipitation hardening stainless steel J.LaSaIle et al. (Honeywell PowderFloTechnologies, USA.) It was reported that use of an agar-based binder had enabled production of large, netshape and near-net-shape parts with properties similar to those of cast alloys. Martensite formation in and mechanical properties of 174PH stainless steel were examined as functions of process conditions. It was shown that there is a robust production window for uniform formation of martensite. Tensile and fatigue properties were described.
Response of feedstocks to first stage debinding K.MKulkarni, V~R.Mossner. (Advanced Metalworking Practices, lnc, USA.) Debinding of injection moulded parts was discussed. It was noted that some feedstocks are amenable to debinding by different methods. Data were presented for steel and stainless steel test bars debound in air, N, vacuum and by solvents. Data for weight loss, dimensional changes and sintered %C were presented.
Effect of atmosphere type on thermal debinding J.A.Grohowski, J. T.Strauss. (HJE Company, USA.) Thermal debinding of MIM parts was discussed with reference to effects of atmosphere type on binder decomposition, binder removal
36
MPR September 2ool
and residual binder in parts. An understanding of these factors was shown to allow process optimization and consideration of carburization/ decarburization. Effects of reducing, neutral and oxidizing atmospheres were investigated for a stainless steel-polyolefin binder feedstock.
A new plasma based furnace for processing MIM parts L.Mendes et al. (Federal University of St. Caterina, Brazil.) It was reported that a new furnace for debinding and sintering had been developed. Plasma heating technology is used and contamination is avoided. Heating of parts is more uniform and debinding more complete due to the higher activity of plasma gases than the molecules of gases in conventional atmospheres.
Coatings Thermal spray coatings for cylinder liners R.Gadow et al. (University of Stuttgart, Germany.) The need to reduce fuel consumption by automobiles was discussed with regard to means of achieving this by weight reduction and reduction of friction in moving parts. Use of sprayed coatings on cylinder bores, to reduce friction and to increase service life, was reviewed with reference to methods and materials used. It was reported that studies had been made of residual stresses in coatings and effects of materials properties and bonding to substrates.
Development of highly wear resistant coatings
Flame spray deposition of refractory metal carbides and oxides A.Killinger et al. (University of Stuttgart, Germany.) Historical development of flame spraying was outlined and the need for improved coatings was emphasized. A review of current technology for high velocity flame spraying and new industrial applications was presented.
In situ production of iron based surface composite G.V.Savka, M.Gurynenko. (Inst. for Problems of Materials Science, Kiev, Ukraine.) Production of Fe base composites with carbide particle reinforcements by PM, and more recently by liquid based routes involving in situ synthesis of VC and TiC, was discussed. It was shown that the latter method may confer improved wear resistance while retaining strength and toughness. It was suggested that the composite should consist of an Fe based martensite and the carbides contain Cr as well as Ti and V.
Mechanical alloying Transformation m mechanically alloyed nickel-aluminium H.B.Kim et al. (Gyeong Sang University, Korea.) Hi-A1 powders were mechanically alloyed and consolidated by vacuum hot pressing. Transformations in powders and bulk alloys were investigated. NiAI and Ni3A1 intermetallic compounds were detected after solution treatment of bulk materials at 1000 °C. A martensitic structure was also formed and was considered to be caused by stored strain in powders.
R. Gadow, A.KiUinger. (University of Stuttgart, Germany.) A severe application in paper manufacture, where ceramic blades are used to guide pulp slurry over a sieve, was discussed with regard to failure of these parts due to fracture of the ceramics and costs. It was proposed that the blades could be replaced by coated components with extremely high wear resistance and which would minimize wear of the sieves. The paper described ceramic and ceramic-metallic coatings made by thermal spray and physical and/or chemical vapour deposition.
P.S.Goodwin. (Defence Evaluation and Research Agency, UK.) Increased interest in materials processed by mechanical alloying and sensitivity to contamination were noted. The need to avoid contamination and means to this end were discussed. Progress in production of Ti based materials, free from contamination, was reported. Recent developments were described.
Laser generation of compositionally graded layers
Stellite bearings by conventional PM and mechanical alloying
C.Theiler, O.Sepold. (inst. of Applied Beam Technology, Bremen, Germany.) Application of functionally graded layers, made up of a transition from a metallic material through graded metal/ceramic layers to a ceramic outer layer, was discussed. Graded coatings, made up of Cr3C2-Ni layers, deposited by laser technology, were investigated with regard to structure and properties as functions of carbide content and process conditions.
H.Zoz et al. (Zoz GmbH, Germany.) Coating of steel strip, in large coils, with various metals and alloys, such as Zn, A1 and ZnA1, was reviewed with regard to problems that arise from un-rolling, cleaning, coating and rerolling. It was reported that Stellite materials had been prepared by mechanical alloying and deposited onto substrates by PM techniques. The materials were characterized for structure and properties, particularly wear resistance.
Clean mechanical alloying of advanced materials
www.metal-powder.net
Analysis of thermal debinding S V.Atre, RM.German. (Penn State University, USA.) Decomposition of organic compounds, in porous media, used as injection moulding binders, was investigated using a thermal analyser with infrared spectroscopy. Binder degradation kinetics and gases evolved were studied as functions of process conditions. The results were used to extend the understanding of the effects of pore structure on binder decomposition and the influence of part geometry on debinding. The results were used to refine the finite element model for heat and mass transfer and stresses in the parts.
Anisotropic shrinkage during sintering of injection moulded parts J.LaSalle et al. (Honeywell PowderFloTechnologies, USA.) Anisotropic shrinkage in injection moulded parts was discussed with regard to the underlying causes. Knowledge of this is required in determination of tool dimensions to satisfy specified parts dimensions. A stainless steel part was analysed in terms of interplay of forces involved during sintering.
Martensite formation in injection moulded precipitation hardening stainless steel J.LaSaIle et al. (Honeywell PowderFloTechnologies, USA.) It was reported that use of an agar-based binder had enabled production of large, netshape and near-net-shape parts with properties similar to those of cast alloys. Martensite formation in and mechanical properties of 174PH stainless steel were examined as functions of process conditions. It was shown that there is a robust production window for uniform formation of martensite. Tensile and fatigue properties were described.
Response of feedstocks to first stage debinding K.MKulkarni, V~R.Mossner. (Advanced Metalworking Practices, lnc, USA.) Debinding of injection moulded parts was discussed. It was noted that some feedstocks are amenable to debinding by different methods. Data were presented for steel and stainless steel test bars debound in air, N, vacuum and by solvents. Data for weight loss, dimensional changes and sintered %C were presented.
Effect of atmosphere type on thermal debinding J.A.Grohowski, J. T.Strauss. (HJE Company, USA.) Thermal debinding of MIM parts was discussed with reference to effects of atmosphere type on binder decomposition, binder removal
36
MPR September 2ool
and residual binder in parts. An understanding of these factors was shown to allow process optimization and consideration of carburization/ decarburization. Effects of reducing, neutral and oxidizing atmospheres were investigated for a stainless steel-polyolefin binder feedstock.
A new plasma based furnace for processing MIM parts L.Mendes et al. (Federal University of St. Caterina, Brazil.) It was reported that a new furnace for debinding and sintering had been developed. Plasma heating technology is used and contamination is avoided. Heating of parts is more uniform and debinding more complete due to the higher activity of plasma gases than the molecules of gases in conventional atmospheres.
Coatings Thermal spray coatings for cylinder liners R.Gadow et al. (University of Stuttgart, Germany.) The need to reduce fuel consumption by automobiles was discussed with regard to means of achieving this by weight reduction and reduction of friction in moving parts. Use of sprayed coatings on cylinder bores, to reduce friction and to increase service life, was reviewed with reference to methods and materials used. It was reported that studies had been made of residual stresses in coatings and effects of materials properties and bonding to substrates.
Development of highly wear resistant coatings
Flame spray deposition of refractory metal carbides and oxides A.Killinger et al. (University of Stuttgart, Germany.) Historical development of flame spraying was outlined and the need for improved coatings was emphasized. A review of current technology for high velocity flame spraying and new industrial applications was presented.
In situ production of iron based surface composite G.V.Savka, M.Gurynenko. (Inst. for Problems of Materials Science, Kiev, Ukraine.) Production of Fe base composites with carbide particle reinforcements by PM, and more recently by liquid based routes involving in situ synthesis of VC and TiC, was discussed. It was shown that the latter method may confer improved wear resistance while retaining strength and toughness. It was suggested that the composite should consist of an Fe based martensite and the carbides contain Cr as well as Ti and V.
Mechanical alloying Transformation m mechanically alloyed nickel-aluminium H.B.Kim et al. (Gyeong Sang University, Korea.) Hi-A1 powders were mechanically alloyed and consolidated by vacuum hot pressing. Transformations in powders and bulk alloys were investigated. NiAI and Ni3A1 intermetallic compounds were detected after solution treatment of bulk materials at 1000 °C. A martensitic structure was also formed and was considered to be caused by stored strain in powders.
R. Gadow, A.KiUinger. (University of Stuttgart, Germany.) A severe application in paper manufacture, where ceramic blades are used to guide pulp slurry over a sieve, was discussed with regard to failure of these parts due to fracture of the ceramics and costs. It was proposed that the blades could be replaced by coated components with extremely high wear resistance and which would minimize wear of the sieves. The paper described ceramic and ceramic-metallic coatings made by thermal spray and physical and/or chemical vapour deposition.
P.S.Goodwin. (Defence Evaluation and Research Agency, UK.) Increased interest in materials processed by mechanical alloying and sensitivity to contamination were noted. The need to avoid contamination and means to this end were discussed. Progress in production of Ti based materials, free from contamination, was reported. Recent developments were described.
Laser generation of compositionally graded layers
Stellite bearings by conventional PM and mechanical alloying
C.Theiler, O.Sepold. (inst. of Applied Beam Technology, Bremen, Germany.) Application of functionally graded layers, made up of a transition from a metallic material through graded metal/ceramic layers to a ceramic outer layer, was discussed. Graded coatings, made up of Cr3C2-Ni layers, deposited by laser technology, were investigated with regard to structure and properties as functions of carbide content and process conditions.
H.Zoz et al. (Zoz GmbH, Germany.) Coating of steel strip, in large coils, with various metals and alloys, such as Zn, A1 and ZnA1, was reviewed with regard to problems that arise from un-rolling, cleaning, coating and rerolling. It was reported that Stellite materials had been prepared by mechanical alloying and deposited onto substrates by PM techniques. The materials were characterized for structure and properties, particularly wear resistance.
Clean mechanical alloying of advanced materials
www.metal-powder.net