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Plastic forming of porous materials
i
PM
POWDER P R O D U C T I O N GAS-JET SPRAYING OF MOLTEN METAL J E T U N D E R F R E E DISCHARGE
Y.F. Ternovoi et al, Poroshkovaya Metallurgiya, No 7, 1992, 1-5. (In Russian). A design of a p p a r a t u s for dispersion of a freely f a l l i n g j e t of m o l t e n m e t a l is proposed. Increased dispersion is o b t a i n e d from the use of translational, rotational a n d oscillatory m o v e m e n t s of t h e gas j e t s ( s ) . The r e s u l t a n t powders are said to have a high proportion of small particles less t h a n 180 ~m. STRUCTURE OF SILICON CARBIDE POWDERS PRODUCED BY REACTION BETWEEN SILICA AND CARBON BLACK
M.V. Vlasova et al, Poroshkovaya Metallurgiya, No 7, 1992, 47-52. (In Russian). A study of t h e evolution of grain a n d sub-grain s t r u c t u r e s in SiC, produced by c a r b o - t h e r m a l reduction of dispersed SiO2 in Ar at 1200 to 1800°C is described. It is shown t h a t cubic SiC forms by solid p h a s e contact between SiO2 a n d C. SiC grain growth a n d formation of SiO2-SiO2 contacts are related to synthesis t e m p e r a t u r e a n d s i n t e r i n g of n o n - c o m p a c t e d p o w d e r is noted. Microplastic sub-structures, at synthesis t e m p e r a t u r e s above 15O0°C, are demonstrated to be connected with twinning a n d stacking faults in < 111 > planes.
PRESSING MOULD FOR COMPACTION OF RECTANGULAR BILLETS BY ALLROUND REDUCTION
S.M. Vaitsekhovich, Poroshkovaya MetalInrgiya, No 7, 1992, 94-97. (In Russian). A die d e s i g n for w a r m a n d c o l d compaction of powders is described. It is reported that die wall and punch m o v e m e n t s are possible a n d p e r m i t allr o u n d reduction of the c o m p a c t e d powder leading to improved quality of r e c t a n g u l a r a n d rhombic compacts. RESEARCH IN ALUMINIUM POWDER FORGING
C.C. Wang et al (Metal Industries Developm e n t Centre, Taiwan), Metal Industries (China), Vol 25, No 2, 1991, 40-59. (In Chinese). Powder forging (PF) of A1 alloys is reviewed. The process, press-sinter-repress, a n d design principles for compaction a n d
40 MPR September 1993
LITERATURE
REVIEW
forging dies are discussed. An investigation of PF a n d a n A1 alloy, to d e t e r m i n e effects of p r o c e s s v a r i a b l e s , is d e s c r i b e d . T h e o p t i m u m conditions are reported to be, for a 2014 alloy, compact at 5000 kg/cm 2, sinter at 610°C for 1 hour, forge at 400°C a n d h e a t t r e a t to T6 condition giving a tensile s t r e n g t h of 45 k g f / m m with 2% elongation. ANALYSIS OF DENSIFICATION AND STRAINS IN UNIAXIAL COMPRESSION OF SINTERED MATERIALS
S. Szczepanic (University of Mining a n d Metallurgy, Cracow, Poland), J Materials Process Technology, Vol 34, No 1-4, 1992, 365-372. The effects of strain rate a n d density of s i n t e r e d p o r o u s m a t e r i a l s in u n i a x i a l compression were investigated. It is shown t h a t t h e d e n s i f i c a t i o n curve for a PM p r e f o r m c a n be d e t e r m i n e d f r o m t h e initial relative density and the deformation. The analytical function r e l a t i n g d e n s i t y to d e f o r m a t i o n a n d s t a r t i n g density is elaborated. PLASTIC FORMING OF POROUS MATERIALS
J. Lokowski a n d F. Grosman, J Materials Process Technology, Vol 34, No 1-4, 1992, 373-380. A model for p l a s t i c flow of axially symmetrical forgings a n d a m e t h o d for e x p e r i m e n t a l v e r i f i c a t i o n are r e p o r t e d . The stereological parameters of distribution of surface discontinuities are applied to analysis of material flow.
SlNTERING CONTINUOUS CARBON CONTROL SYSTEM FOR SINTERING ATMOSPHERES
M.A. P h i l i p s ( L i q u i d Air, C o u n t r y s i d e , Illinois, USA), Industrial Heating, Vol 59, No 5, 1992, 47-49. A new system for control of C c o n c e n t r a t i o n in sintering a t m o s p h e r e s is described. The system uses c o n t i n u o u s feedback loop control a n d d a t a acquisition to m a i n t a i n a n a t m o s p h e r e which n e i t h e r carburizes n o r d e c a r b u r i z e s ferrous PM parts. Furnace zoning a n d gas reactions are taken into account. Carbon and stainless steels are discussed. DEVELOPMENT OF A CERAMIC BELT FOR CONTINUOUS HIGH TEMPERATURE SINTERING
B. Cole (Gasbarre Products Inc, Dubois,
P(nnsylvania, USA), Industrial Heating, V(4 59, No 6, 1992, 51-53. The development, design and p( rformance of a n AEO3 conveyor belt for u~e in c o n t i n u o u s s i n t e r i n g f u r n a c e s operating at 1200 to 1260°C is described. TtLe s t r e n g t h required in the belt is reported b( a t t a i n e d by t h e use of A12Oa-0.5%SiO 2. Further development, using whisker r e i n f o r c e m e n t a n d m e t a l / c e r a m i c s is considered.
FUNDAMENTALS CHARACTERIZATION OF NONSPHERICAL PARTICLES FROM PACKING BEHAVIOUR
A~B. Yu a n d N. S t a n d i s h (University of Wollongong, New South Wales, Australia), Powder Technology, Vol 74, No 3, 1993, 2()5-213. A m e t h o d for t h e d e t e r m i n a t i o n of effective packing diameter of nonspherical particles is proposed. This is shown to be related to the sphericity a n d such factors as volume, surface a n d surface volume diameters. A relationship between p o r o s i t y a n d s p h e r i c i t y of m o n o s i z e d particles is formulated based on p u b l i s h e d data. The application to the prediction of porosity of non-spherical powder m i x t u r e s is discussed. SOLUTION AND EXPERIMENTAL VALIDATION OF A MATHEMATICAL MODEL FOR VIBRATION MILLING
S.K. M o o t h e d a t h a n d K.V.S. Sastry (University of California, Berkeley, California, USA), Powder Technology, Vol 75, No 1, 1993, 89-96. A model for grinding of metal powders incorporating t h r e e m e c h a n i s m s of particle size reduction, flattening, a t t r i t i o n a n d f r a c t u r e , is p r e s e n t e d . T h e a n a l y t i c a l solutions for pure flattening, attrition a n d pure a t t r i t i o n were determined. Flattening is n o t e d in the case of t h e early stages of A1 grinding. Pure a t t r i t i o n is reported for brass a n d t h e initial stage of Cu grinding. The pure fracture model is established for the later stages of Al grinding. USE OF FINITE ELEMENT METHODS FOR ELASTIC-PLASTIC COMPRESSIBLE MATERIALS ALLOWING LARGE INCREMENTAL DEFORMATIONS
H. Matsumoto a n d T. Kikuma, Nippon Steel Tech Rep, No 52, 1992, 42-49. (In Japanese). T h e a x i s y m m e t r i c d e f o r m a t i o n of
PM
POWDER P R O D U C T I O N GAS-JET SPRAYING OF MOLTEN METAL J E T U N D E R F R E E DISCHARGE
Y.F. Ternovoi et al, Poroshkovaya Metallurgiya, No 7, 1992, 1-5. (In Russian). A design of a p p a r a t u s for dispersion of a freely f a l l i n g j e t of m o l t e n m e t a l is proposed. Increased dispersion is o b t a i n e d from the use of translational, rotational a n d oscillatory m o v e m e n t s of t h e gas j e t s ( s ) . The r e s u l t a n t powders are said to have a high proportion of small particles less t h a n 180 ~m. STRUCTURE OF SILICON CARBIDE POWDERS PRODUCED BY REACTION BETWEEN SILICA AND CARBON BLACK
M.V. Vlasova et al, Poroshkovaya Metallurgiya, No 7, 1992, 47-52. (In Russian). A study of t h e evolution of grain a n d sub-grain s t r u c t u r e s in SiC, produced by c a r b o - t h e r m a l reduction of dispersed SiO2 in Ar at 1200 to 1800°C is described. It is shown t h a t cubic SiC forms by solid p h a s e contact between SiO2 a n d C. SiC grain growth a n d formation of SiO2-SiO2 contacts are related to synthesis t e m p e r a t u r e a n d s i n t e r i n g of n o n - c o m p a c t e d p o w d e r is noted. Microplastic sub-structures, at synthesis t e m p e r a t u r e s above 15O0°C, are demonstrated to be connected with twinning a n d stacking faults in < 111 > planes.
PRESSING MOULD FOR COMPACTION OF RECTANGULAR BILLETS BY ALLROUND REDUCTION
S.M. Vaitsekhovich, Poroshkovaya MetalInrgiya, No 7, 1992, 94-97. (In Russian). A die d e s i g n for w a r m a n d c o l d compaction of powders is described. It is reported that die wall and punch m o v e m e n t s are possible a n d p e r m i t allr o u n d reduction of the c o m p a c t e d powder leading to improved quality of r e c t a n g u l a r a n d rhombic compacts. RESEARCH IN ALUMINIUM POWDER FORGING
C.C. Wang et al (Metal Industries Developm e n t Centre, Taiwan), Metal Industries (China), Vol 25, No 2, 1991, 40-59. (In Chinese). Powder forging (PF) of A1 alloys is reviewed. The process, press-sinter-repress, a n d design principles for compaction a n d
40 MPR September 1993
LITERATURE
REVIEW
forging dies are discussed. An investigation of PF a n d a n A1 alloy, to d e t e r m i n e effects of p r o c e s s v a r i a b l e s , is d e s c r i b e d . T h e o p t i m u m conditions are reported to be, for a 2014 alloy, compact at 5000 kg/cm 2, sinter at 610°C for 1 hour, forge at 400°C a n d h e a t t r e a t to T6 condition giving a tensile s t r e n g t h of 45 k g f / m m with 2% elongation. ANALYSIS OF DENSIFICATION AND STRAINS IN UNIAXIAL COMPRESSION OF SINTERED MATERIALS
S. Szczepanic (University of Mining a n d Metallurgy, Cracow, Poland), J Materials Process Technology, Vol 34, No 1-4, 1992, 365-372. The effects of strain rate a n d density of s i n t e r e d p o r o u s m a t e r i a l s in u n i a x i a l compression were investigated. It is shown t h a t t h e d e n s i f i c a t i o n curve for a PM p r e f o r m c a n be d e t e r m i n e d f r o m t h e initial relative density and the deformation. The analytical function r e l a t i n g d e n s i t y to d e f o r m a t i o n a n d s t a r t i n g density is elaborated. PLASTIC FORMING OF POROUS MATERIALS
J. Lokowski a n d F. Grosman, J Materials Process Technology, Vol 34, No 1-4, 1992, 373-380. A model for p l a s t i c flow of axially symmetrical forgings a n d a m e t h o d for e x p e r i m e n t a l v e r i f i c a t i o n are r e p o r t e d . The stereological parameters of distribution of surface discontinuities are applied to analysis of material flow.
SlNTERING CONTINUOUS CARBON CONTROL SYSTEM FOR SINTERING ATMOSPHERES
M.A. P h i l i p s ( L i q u i d Air, C o u n t r y s i d e , Illinois, USA), Industrial Heating, Vol 59, No 5, 1992, 47-49. A new system for control of C c o n c e n t r a t i o n in sintering a t m o s p h e r e s is described. The system uses c o n t i n u o u s feedback loop control a n d d a t a acquisition to m a i n t a i n a n a t m o s p h e r e which n e i t h e r carburizes n o r d e c a r b u r i z e s ferrous PM parts. Furnace zoning a n d gas reactions are taken into account. Carbon and stainless steels are discussed. DEVELOPMENT OF A CERAMIC BELT FOR CONTINUOUS HIGH TEMPERATURE SINTERING
B. Cole (Gasbarre Products Inc, Dubois,
P(nnsylvania, USA), Industrial Heating, V(4 59, No 6, 1992, 51-53. The development, design and p( rformance of a n AEO3 conveyor belt for u~e in c o n t i n u o u s s i n t e r i n g f u r n a c e s operating at 1200 to 1260°C is described. TtLe s t r e n g t h required in the belt is reported b( a t t a i n e d by t h e use of A12Oa-0.5%SiO 2. Further development, using whisker r e i n f o r c e m e n t a n d m e t a l / c e r a m i c s is considered.
FUNDAMENTALS CHARACTERIZATION OF NONSPHERICAL PARTICLES FROM PACKING BEHAVIOUR
A~B. Yu a n d N. S t a n d i s h (University of Wollongong, New South Wales, Australia), Powder Technology, Vol 74, No 3, 1993, 2()5-213. A m e t h o d for t h e d e t e r m i n a t i o n of effective packing diameter of nonspherical particles is proposed. This is shown to be related to the sphericity a n d such factors as volume, surface a n d surface volume diameters. A relationship between p o r o s i t y a n d s p h e r i c i t y of m o n o s i z e d particles is formulated based on p u b l i s h e d data. The application to the prediction of porosity of non-spherical powder m i x t u r e s is discussed. SOLUTION AND EXPERIMENTAL VALIDATION OF A MATHEMATICAL MODEL FOR VIBRATION MILLING
S.K. M o o t h e d a t h a n d K.V.S. Sastry (University of California, Berkeley, California, USA), Powder Technology, Vol 75, No 1, 1993, 89-96. A model for grinding of metal powders incorporating t h r e e m e c h a n i s m s of particle size reduction, flattening, a t t r i t i o n a n d f r a c t u r e , is p r e s e n t e d . T h e a n a l y t i c a l solutions for pure flattening, attrition a n d pure a t t r i t i o n were determined. Flattening is n o t e d in the case of t h e early stages of A1 grinding. Pure a t t r i t i o n is reported for brass a n d t h e initial stage of Cu grinding. The pure fracture model is established for the later stages of Al grinding. USE OF FINITE ELEMENT METHODS FOR ELASTIC-PLASTIC COMPRESSIBLE MATERIALS ALLOWING LARGE INCREMENTAL DEFORMATIONS
H. Matsumoto a n d T. Kikuma, Nippon Steel Tech Rep, No 52, 1992, 42-49. (In Japanese). T h e a x i s y m m e t r i c d e f o r m a t i o n of