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Shock wave compaction of powders and porous bodies — dynamic compaction of powders in rigid dies
nology, Vol 10, No 1, 1992, 49-53. (In Chinese)~ The use of HREM in t h e s t u d y of ultrafine powder production is discussed a n d t h e a p p l i c a t i o n to Fe p o w d e r s described. The microstructures a n d lattice images which can be o b t a i n e d are said to emphasize t h e value of t h e technique.
MANUFACTURE O F S U P E R F I N E SILVER POWDER BY F O R M I C ACID REDUCTION J. Zhang et al, (Northwest Inst for t h e NonFerrous Metals, China), Rare Metals and Materials Engineering, No 5, 1990, 51-53. (In Chinese). A description is given of t h e p r o d u c t i o n of 0.4 p m Ag p o w d e r from a solution c o n t a i n i n g formic acid r e d u c t a n t . The optimum process parameters are described. The factors influencing powder particle size are analysed.
PRESSING CONTINUOUS COMPACTION OF NON-FERROUS METALS BY ROLLING V.N. Kornilov et al, Tsvetn Metall, No 5, 1992, 56-60. (In Russian). The mill and tooling design for continuous roll compaction is described. The forces acting on t h e mill are calculated. The p r o d u c t i o n of A1 alloy wires is reported. E F F E C T S O F LUBRICANTS AND COMPACTING P R E S S U R E ON T H E G R E E N P R O P E R T I E S OF IRON POWDER P R E M I X E S
M ~ Siddiqui a n d M. Hamiuddin, (College of Engineering a n d Technology, Aligarh, India), Powder Metall Int, Vol 24, No 2, 1992, 79-83. An i n v e s t i g a t i o n into t h e effects of c o m p a c t i n g p r e s s u r e (400 to 800 MPa), lubricant used (Li or Zn stearate) a n d composition of t h e powers ( a d d i t i o n of up to 4 wt% Cu, Ni a n d / o r Mo) on the green s t r e n g t h of pressed c o m p a c t s is described. It is reported t h a t (a) green s t r e n g t h a n d density increase up to 70MPa a n d above this remain constant, (b) l u b r i c a n t type h a d only a minimal effect b u t l u b r i c a n t concentration improved compatibility up to 0.8 wt% lubricant with no effect a t higher concentrations, (c) t h e r e was no elastic recovery below 500 MPa b u t this increased at higher compacting pressures, ( d ) s c a n n i n g e l e c t r o n m i c r o s c o p y of fractured green compacts showed no cold welding, p a r t i c l e s b e i n g d e f o r m e d b u t separate, a n d (e) particle interlocking was observed in c o m p a c t s with a m e a s u r a b l e green strength. Higher green s t r e n g t h was noted for u n l u b r i c a t e d c o m p a c t s a n d this is a t t r i b u t e d to interlocking a n d cold welding.
E F F E C T S O F C O M P L E X LOADING PATTERNS IN HOT C O M P A C T I O N ON STRUCTURE AND P R O P E R T I E S S.N. Kulkov a n d A.G. Melnikov, (Academy of Sciences, Moscow, Russia). Poroshkovaya Metallurgiya, No 5, 1991, 1-4. (In Russian). An investigation of hot uniaxial compaction, of TiC-NiTi, with a n d w i t h o u t a s h e a r element introduced by r o t a t i o n of die a n d lower punch, t h e u p p e r p u n c h being fixed, is described. The c o m p l e x loading makes it possible to break up t h e h a r d c a r b i d e p a r t i c l e s in t h e TiC-NiTi powder a n d to produce a finer s t r u c t u r e of carbide particles which are uniformly distributed in t h e matrix. SHOCK WAVE COMPACTION OF POWDERS AND POROUS BODIES -DYNAMIC COMPACTION OF POWDERS IN RIGID D I E S L.A. Masimenko et al, Poroshkovaya Metallurgiya, No 7, 1991, 25-30. (In Russian). Characteristics of dynamic compaction in rigid cylindrical dies is discussed. A model is p r o p o s e d which allows e x p l a n a t i o n of shock wave initiation in ideal p l a s t i c materials. A l g o r i t h m s are constructed for d e t e r m i n a t i o n of process p a r a m e t e r s with respect to time. A solution for h o m o g e n e o u s billets is presented. D E S I G N OF D I E S FOR P R O D U C T I O N OF PM PARTS WITH MULTI-PARALLEL HOLES
W. Shiyuan, ( C h e n g d u Die a n d Mould Works, Chengdu, China), PM Technology, Vol 10, No 1, 1992, 30-32. (In Chinese). The difficulties of making PM p a r t s with m u l t i - p a r a l l e l holes are d e s c r i b e d a n d discussed. The design of dies i n t e n d e d to facilitate the p r o d u c t i o n of such p a r t s with holes is described. SHOCK WAVE CONSOLIDATION O F METALLIC GLASS POWDERS O F NICKEL-CHROMIUM-SILICON-BORON ALLOYS J. Bach et al, ( C a l i f o r n i a I n s t i t u t e of Technology, California, USA), Materials Letters, No 11, 1991, 383-388. An investigation of t h e effects of shock wave parameters, energy a n d duration, in t h e explosive compaction of Ni-19% Cr-2.3% Si-1.5% B-0.08%C metallic glass powders is described. It is shown t h a t the a m o r p h o u s s t r u c t u r e is retained, the porosity of the consolidated material is a b o u t 1% a n d t h a t the shock wave p r o p a g a t e s in a p l a n a r manner. HOT AND COLD ISOSTATIC P R E S S I N G -- COMPETITIVE OR COMPLEMENTARY D. Barron, Advanced Materials J, Vol 1, No 4, 1990, 28-30.
A comparison is m a d e between HIP a n d CIP. It is suggested t h a t t h e two techniques can be c o m b i n e d with a d v a n t a g e to produce full density materials.
D E V E L O P M E N T S IN HOT ISOSTATIC PRESSING
D~I. Stephenson, (Cranfield Inst of Technology, Cranfleld, UK), Advanced Materials J., Vol 1, No 4, 1990, 25-27. The uses of HIP, PM p a r t s production, healing of defects in casting, p r o d u c t i o n of C-C composites, joining, diffusion b o n d i n g a n d r e p l a c e m e n t of W/Re t h e r m o c o u p l e s in HIP e q u i p m e n t by BaC/C are reviewed. A comparison of t h e properties of cast a n d HIP IMI829 alloy with wrought material is given.
FUNDAMENTALS CHARACTERIZATION OF NANOS T R U C T U R E S BY SMALL ANGLE SCATTERING J. Dore et al. (University of Kent, Canterbury, UK), Metals and Materials, Vol 8, No 5, 1992, 262-265. The use of small angle X-ray a n d n e u t r o n s c a t t e r i n g for c h a r a c t e r i z a t i o n of n a n o structures is described. The t e c h n i q u e is r e p o r t e d to be a b l e to reveal s p a t i a l i n h o m o g e n e i t i e s in m a t e r i a l s . C u r r e n t applications and possible future developments are considered. The technique is relevant to porous materials and for t h e s t u d y of surface texture.
SCANNING A U G E R MICROSCOPY J. Castle, (University of Surrey, Guildford, UK, Metals and Materials, Vol 8, No 5, 1992, 268-272. Scanning Auger microscopy, in which the e l e m e n t distribution in a specimen is determined in a s c a n n i n g e l e c t r o n m i c r o s c o p e , is d e s c r i b e d . E x a m p l e s c o n s i d e r e d i n c l u d e s t u d i e s of m e t a l l i c embrittlement, corrosion and fibre reinforced composite materials.
CONFOCAL SCANNING OPTICAL MICROSCOPY ( C S O M ) IN MATERIALS SCIENCE
NJ. McCormick, (National Physical Laboratory, Teddington, UK). Metals and Materials, Vol 8, No 5, 1992, 274-275. Surface p r o p e r t y investigations using c o m p u t e r image analysis of d a t a from CSOM is described. Applications of t h e t e c h n i q u e c i t e d in t h e p a p e r i n c l u d e e x a m i n a t i o n of w e a r t r a c k s , f r a c t u r e surfaces a n d crack location.
MPR July/August 1992 55
MANUFACTURE O F S U P E R F I N E SILVER POWDER BY F O R M I C ACID REDUCTION J. Zhang et al, (Northwest Inst for t h e NonFerrous Metals, China), Rare Metals and Materials Engineering, No 5, 1990, 51-53. (In Chinese). A description is given of t h e p r o d u c t i o n of 0.4 p m Ag p o w d e r from a solution c o n t a i n i n g formic acid r e d u c t a n t . The optimum process parameters are described. The factors influencing powder particle size are analysed.
PRESSING CONTINUOUS COMPACTION OF NON-FERROUS METALS BY ROLLING V.N. Kornilov et al, Tsvetn Metall, No 5, 1992, 56-60. (In Russian). The mill and tooling design for continuous roll compaction is described. The forces acting on t h e mill are calculated. The p r o d u c t i o n of A1 alloy wires is reported. E F F E C T S O F LUBRICANTS AND COMPACTING P R E S S U R E ON T H E G R E E N P R O P E R T I E S OF IRON POWDER P R E M I X E S
M ~ Siddiqui a n d M. Hamiuddin, (College of Engineering a n d Technology, Aligarh, India), Powder Metall Int, Vol 24, No 2, 1992, 79-83. An i n v e s t i g a t i o n into t h e effects of c o m p a c t i n g p r e s s u r e (400 to 800 MPa), lubricant used (Li or Zn stearate) a n d composition of t h e powers ( a d d i t i o n of up to 4 wt% Cu, Ni a n d / o r Mo) on the green s t r e n g t h of pressed c o m p a c t s is described. It is reported t h a t (a) green s t r e n g t h a n d density increase up to 70MPa a n d above this remain constant, (b) l u b r i c a n t type h a d only a minimal effect b u t l u b r i c a n t concentration improved compatibility up to 0.8 wt% lubricant with no effect a t higher concentrations, (c) t h e r e was no elastic recovery below 500 MPa b u t this increased at higher compacting pressures, ( d ) s c a n n i n g e l e c t r o n m i c r o s c o p y of fractured green compacts showed no cold welding, p a r t i c l e s b e i n g d e f o r m e d b u t separate, a n d (e) particle interlocking was observed in c o m p a c t s with a m e a s u r a b l e green strength. Higher green s t r e n g t h was noted for u n l u b r i c a t e d c o m p a c t s a n d this is a t t r i b u t e d to interlocking a n d cold welding.
E F F E C T S O F C O M P L E X LOADING PATTERNS IN HOT C O M P A C T I O N ON STRUCTURE AND P R O P E R T I E S S.N. Kulkov a n d A.G. Melnikov, (Academy of Sciences, Moscow, Russia). Poroshkovaya Metallurgiya, No 5, 1991, 1-4. (In Russian). An investigation of hot uniaxial compaction, of TiC-NiTi, with a n d w i t h o u t a s h e a r element introduced by r o t a t i o n of die a n d lower punch, t h e u p p e r p u n c h being fixed, is described. The c o m p l e x loading makes it possible to break up t h e h a r d c a r b i d e p a r t i c l e s in t h e TiC-NiTi powder a n d to produce a finer s t r u c t u r e of carbide particles which are uniformly distributed in t h e matrix. SHOCK WAVE COMPACTION OF POWDERS AND POROUS BODIES -DYNAMIC COMPACTION OF POWDERS IN RIGID D I E S L.A. Masimenko et al, Poroshkovaya Metallurgiya, No 7, 1991, 25-30. (In Russian). Characteristics of dynamic compaction in rigid cylindrical dies is discussed. A model is p r o p o s e d which allows e x p l a n a t i o n of shock wave initiation in ideal p l a s t i c materials. A l g o r i t h m s are constructed for d e t e r m i n a t i o n of process p a r a m e t e r s with respect to time. A solution for h o m o g e n e o u s billets is presented. D E S I G N OF D I E S FOR P R O D U C T I O N OF PM PARTS WITH MULTI-PARALLEL HOLES
W. Shiyuan, ( C h e n g d u Die a n d Mould Works, Chengdu, China), PM Technology, Vol 10, No 1, 1992, 30-32. (In Chinese). The difficulties of making PM p a r t s with m u l t i - p a r a l l e l holes are d e s c r i b e d a n d discussed. The design of dies i n t e n d e d to facilitate the p r o d u c t i o n of such p a r t s with holes is described. SHOCK WAVE CONSOLIDATION O F METALLIC GLASS POWDERS O F NICKEL-CHROMIUM-SILICON-BORON ALLOYS J. Bach et al, ( C a l i f o r n i a I n s t i t u t e of Technology, California, USA), Materials Letters, No 11, 1991, 383-388. An investigation of t h e effects of shock wave parameters, energy a n d duration, in t h e explosive compaction of Ni-19% Cr-2.3% Si-1.5% B-0.08%C metallic glass powders is described. It is shown t h a t the a m o r p h o u s s t r u c t u r e is retained, the porosity of the consolidated material is a b o u t 1% a n d t h a t the shock wave p r o p a g a t e s in a p l a n a r manner. HOT AND COLD ISOSTATIC P R E S S I N G -- COMPETITIVE OR COMPLEMENTARY D. Barron, Advanced Materials J, Vol 1, No 4, 1990, 28-30.
A comparison is m a d e between HIP a n d CIP. It is suggested t h a t t h e two techniques can be c o m b i n e d with a d v a n t a g e to produce full density materials.
D E V E L O P M E N T S IN HOT ISOSTATIC PRESSING
D~I. Stephenson, (Cranfield Inst of Technology, Cranfleld, UK), Advanced Materials J., Vol 1, No 4, 1990, 25-27. The uses of HIP, PM p a r t s production, healing of defects in casting, p r o d u c t i o n of C-C composites, joining, diffusion b o n d i n g a n d r e p l a c e m e n t of W/Re t h e r m o c o u p l e s in HIP e q u i p m e n t by BaC/C are reviewed. A comparison of t h e properties of cast a n d HIP IMI829 alloy with wrought material is given.
FUNDAMENTALS CHARACTERIZATION OF NANOS T R U C T U R E S BY SMALL ANGLE SCATTERING J. Dore et al. (University of Kent, Canterbury, UK), Metals and Materials, Vol 8, No 5, 1992, 262-265. The use of small angle X-ray a n d n e u t r o n s c a t t e r i n g for c h a r a c t e r i z a t i o n of n a n o structures is described. The t e c h n i q u e is r e p o r t e d to be a b l e to reveal s p a t i a l i n h o m o g e n e i t i e s in m a t e r i a l s . C u r r e n t applications and possible future developments are considered. The technique is relevant to porous materials and for t h e s t u d y of surface texture.
SCANNING A U G E R MICROSCOPY J. Castle, (University of Surrey, Guildford, UK, Metals and Materials, Vol 8, No 5, 1992, 268-272. Scanning Auger microscopy, in which the e l e m e n t distribution in a specimen is determined in a s c a n n i n g e l e c t r o n m i c r o s c o p e , is d e s c r i b e d . E x a m p l e s c o n s i d e r e d i n c l u d e s t u d i e s of m e t a l l i c embrittlement, corrosion and fibre reinforced composite materials.
CONFOCAL SCANNING OPTICAL MICROSCOPY ( C S O M ) IN MATERIALS SCIENCE
NJ. McCormick, (National Physical Laboratory, Teddington, UK). Metals and Materials, Vol 8, No 5, 1992, 274-275. Surface p r o p e r t y investigations using c o m p u t e r image analysis of d a t a from CSOM is described. Applications of t h e t e c h n i q u e c i t e d in t h e p a p e r i n c l u d e e x a m i n a t i o n of w e a r t r a c k s , f r a c t u r e surfaces a n d crack location.
MPR July/August 1992 55