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Electronic flow meters and valve applications in the PM industry
PM compaction pressures leading to reduced die w e a r a n d c o n s i s t e n t p a r t quality. The n u m e r i c a l control system is discussed. E F F E C T O F D E F O R M A T I O N ON COMPACTION O F POROUS MATERIALS DURING H O T STAMPING V~A. Pavlov a n d M.I. Nosenko Poroshkovaya Metallurgiya, No 2, 1992, 8-13. (In Russian). The effect of d e f o r m a t i o n in compaction, in closed die h o t stamping, ofTi, Cu a n d AI m a t e r i a l s was investigated. Zones of i n t e n s e and retarded deformation, optimum s t a m p i n g p a t t e r n s are identified for t h e p r o d u c t i o n of d e n s e m e t a l . E f f e c t of stamping parameters on shear d e f o r m a t i o n a n d density are reported.
SINTERING E L E C T R O N I C FLOW M E T E R S A N D VALVE APPLICATIONS IN T H E PM INDUSTRY J.E. Powalisz (Waubee Engineering Co Inc, Milwaukee, Wisconsin, USA), Int J Powder Metallurgy, Vol 29, No 1, 1993, 29-34. Sintering a t m o s p h e r e s in r e l a t i o n to part quality are discussed. Recent advances in gas flow measurement technology used in m o n i t o r i n g a n d control of s i n t e r i n g a t m o s p h e r e s are described. E l e c t r o n i c c o n t r o l o f flow m e t e r s a n d valves are considered. PARTICLE SIZE E F F E C T S IN S I N T E R I N G O F SILVER-TIN COMPACTS T. Piszczek ( I n s t M e t a l l Niezelaznych, Gliwice, Poland), Metal Proszkow, Vol 25, No 3, 1992, 87-91. (In Polish). The effects of particle size a n d sintering t i m e a n d t e m p e r a t u r e o n t h e sintering of Ag-Sn alloys was investigated by m e a n s of dilatometry a n d m e a s u r e m e n t s of density a n d electrical resistivity. The use of finer Ag powders is r e p o r t e d to e n h a n c e sintering b e c a u s e of p h a s e f o r m a t i o n a t l o w e r t e m p e r a t u r e s resulting in h i g h e r electrical conductivity a n d density. Sintering t i m e was also influenced by particle size.
FUNDAMENTALS I
H O T PLANE STRAIN C O M P R E S S I O N T E S T I N G OF PARTIALLY C O N S O L I D A T E D POWDER COMPACTS H. Shi a n d _h. Greasley ( U n i v e r s i t y of Sheffield, UK), Powder Metallurgy, Vol 35, No 4, 1992, 269-274. It is s h o w n t h a t h o t p l a n e s t r a i n c o m p r e s s i o n t e s t i n g is more reliable t h a n h o t torsion t e s t i n g for t h e m e a s u r e m e n t of flow stress d a t a for 2014A1 alloy p o w d e r compacts. Activation energies and c o n s t a n t s in t h e constitutive e q u a t i o n s are
44
MPR May 1993
LITERATURE
REVIEW
derived for use in process models. It is suggested t h a t t h e t e c h n i q u e may be used t o m o n i t o r flow b e h a v i o u r of p o w d e r m a t e r i a l s w h i c h a r e n o t a m e n d a b l e to o t h e r t e s t methods. PLASTIC YIELD BEHAVIOUR OR P O R O U S METALS D.N. Lee a n d H.S. Kim (National University, Seoul, Korea), Powder Metallurgy, Vol 35, No 4, 1992, 275-279. A new yield criterion for p o r o u s m e t a l s is p r o p o s e d . T h e e q u a t i o n c o n t a i n s a variable parameter, which may be d e t e r m i n e d from u n i a x i a l yield s t r e s s / density data, w h i c h allows t h e p r e d i c t i o n of e x p e r i m e n t a l r e s u l t s of c o m b i n e d t e n s i o n a n d torsion t e s t s of p o r o u s metals. O t h e r yield criteria are reviewed a n d are considered to, unreasonably, suggest zero yield stress a t zero relative density. I M P R O V E M E N T S IN T H E ACCURACY O F SUB-MICRON PARTICLE SIZE DISTRIBUTION MEASUREMENT P. Bowen et al (Swiss Federal I n s t of Technology, Lausanne, Switzerland), Powder Technology, Vol 74, No 1 1993, 67-71. Work to improve t h e accuracy of submicron particle size distribution m e a s u r e m e n t using a Horiba CAPA-700 i n s t r u m e n t is described. The device used s e d i m e n t a t i o n a n d l i g h t a b s o r b t i o n to measure particle size. A computer program, w h i c h allows correction for light scattering by particles below 5 ~tm uses modified Mie t h e o r y to calculate t h e light e x t e n s i o n coefficient. S o m e r e s u l t s for m o n o d i s p e r s e d SiO2 p o w d e r s are given a n d t h e accuracy is r e p o r t e d to be + 5%. The l i m i t a t i o n s of t h e work are discussed. EVALUATION OF SPATIAL P H A S E DISTRIBUTION K. Pelikan e t al ( U s t a v M a t e r i a l o v e h o ~yskumu SAV, Kosice, Czechoslovia), Pokroky Psaskove Metalurgie, No 1-2, 1992, 32-39. (In Czech). An evaluation of t h e spatial d i s t r i b u t i o n of p h a s e s in h e t e r o g e n e o u s s t r u c t u r e s is presented. Two m e t h o d s are considered, testing of p o i n t s processes a n d evaluation of interparticle distances. It is s h o w n t h a t no single s t r u c t u r a l p a r a m e t e r describes t h e different processes a n d it is suggested that 'classical' interpretation may be misleading. E F F E C T S O F INITIAL POWDER P R O P E R T I E S ON STRUCTURAL CHARACTERISTICS OF P O R O U S MATERIALS V.K. Sheleg et al Poroshkovaya Metallurgiya, No 2, 1992, 47-52. (In Russian) An investigation of t h e effects of p o w d e r p r o p e r t i e s on t h e s t r u c t u r a l p r o p e r t i e s of porous powder materials ( P P M ) is d e s c r i b e d . It is s h o w n t h a t t h e b u l k
porosity is d e p e n d e n t on t h e form factor of t h e p o w d e r a n d t h e r e l a t i o n s h i p between bulk porosity a n d PPM porosity. M a x i m u m pore size is shown to d e p e n d on p o w d e r form factor. It is suggested t h a t t h e results of t h e s t u d y may be used to predict PPM properties. D E T E R M I N A T I O N OF TOTAL PORE A R E A FOR P O R E S OF MAXIMUM SIZE IN P E R M E A B L E MATERIAL Y.L. Goblin et al, Poroshkovaya Metallurgiya, No 2, 1992, 84-88. (In Russian). A gas flow m e t h o d for t h e d e t e r m i n a t i o n of total pore a r e a of m a x i m u m size p o r e s in a p e r m e a b l e m e d i u m is p r o p o s e d . The m e t h o d is b a s e d on m e a s u r e m e n t of t h e p r o p o r t i o n o f t h e g a s flow w h i c h is turbulent. The m e t h o d is claimed to have increased accuracy because of l a m i n a r a n d t u r b u l e n t flow c o m p o n e n t s of t h e gas flow are t a k e n into account.
PRODUCTS: Aluminium VOLUME D E F O R M A T I O N O F ALUMINIUM-COPPER AND ALUMINIUM-COPPER-MAGNE SIUM COMPACTS D U R I N G S I N T E R I N G V.B. Brodov et al, Poroshkovaya Metallurgiya, No 2, 1992, 13-17. (In Russian). Dimensional changes during the s i n t e r i n g o f A1-4.4 wt% Cu a n d A14.4% Co-0.5% Mg alloys were investigated in t h e r a n g e 530 to 620°C. The a p p e a r a n c e of a liquid p h a s e a t 543°C a n d 530°C, for t h e Mg alloy was detected. If t h e liquid p h a s e is a b s o r b e d t h e c o m p a c t s e x h i b i t g r o w t h , o t h e r w i s e t h e r e is s h r i n k a g e . Growth is r e p o r t e d to be e n h a n c e d by s p r e a d i n g of t h e liquid p h a s e o n grain boundaries and surfaces and by the p r e s e n c e of Mg. E n h a n c e d growth in t h e t e r n a r y alloy is a t t r i b u t e d to t h e g r e a t e r volume of t r a n s i e n t liquid. C R E E P D E F O R M A T I O N IN PM ALUMINIUM-IRON ALLOY F. Yoshida et al (Kyushi University, Kyushi, J a p a n ) , J Japan Inst of Metals, Vol 55, No 4, 1992, 390-398. (In J a p a n e s e ) . High t e m p e r a t u r e creep a n d tensile t e s t s were carried o u t on PM AI-8 wt% Fe allows w i t h r e g a r d to t h e d e p e n d e n c e of creep r a t e on t e m p e r a t u r e , stress a n d grain size. It is r e p o r t e d t h a t t h e m i n i m u m creep r a t e increased rapidly at high stresses above a certain critical stress which did n o t d e p e n d on temperature but was related to s p e c i m e n condition. A c t i v a t i o n energies for t h e m i n i m u m creep r a t e were found to be similar to t h o s e for diffusion. The 0 projection m e t h o d was used to describe t h e creep curves a n d t h e 0 p a r a m e t e r for each curve showed stress and temperature d e p e n d e n c e below t h e critical stress.
SINTERING E L E C T R O N I C FLOW M E T E R S A N D VALVE APPLICATIONS IN T H E PM INDUSTRY J.E. Powalisz (Waubee Engineering Co Inc, Milwaukee, Wisconsin, USA), Int J Powder Metallurgy, Vol 29, No 1, 1993, 29-34. Sintering a t m o s p h e r e s in r e l a t i o n to part quality are discussed. Recent advances in gas flow measurement technology used in m o n i t o r i n g a n d control of s i n t e r i n g a t m o s p h e r e s are described. E l e c t r o n i c c o n t r o l o f flow m e t e r s a n d valves are considered. PARTICLE SIZE E F F E C T S IN S I N T E R I N G O F SILVER-TIN COMPACTS T. Piszczek ( I n s t M e t a l l Niezelaznych, Gliwice, Poland), Metal Proszkow, Vol 25, No 3, 1992, 87-91. (In Polish). The effects of particle size a n d sintering t i m e a n d t e m p e r a t u r e o n t h e sintering of Ag-Sn alloys was investigated by m e a n s of dilatometry a n d m e a s u r e m e n t s of density a n d electrical resistivity. The use of finer Ag powders is r e p o r t e d to e n h a n c e sintering b e c a u s e of p h a s e f o r m a t i o n a t l o w e r t e m p e r a t u r e s resulting in h i g h e r electrical conductivity a n d density. Sintering t i m e was also influenced by particle size.
FUNDAMENTALS I
H O T PLANE STRAIN C O M P R E S S I O N T E S T I N G OF PARTIALLY C O N S O L I D A T E D POWDER COMPACTS H. Shi a n d _h. Greasley ( U n i v e r s i t y of Sheffield, UK), Powder Metallurgy, Vol 35, No 4, 1992, 269-274. It is s h o w n t h a t h o t p l a n e s t r a i n c o m p r e s s i o n t e s t i n g is more reliable t h a n h o t torsion t e s t i n g for t h e m e a s u r e m e n t of flow stress d a t a for 2014A1 alloy p o w d e r compacts. Activation energies and c o n s t a n t s in t h e constitutive e q u a t i o n s are
44
MPR May 1993
LITERATURE
REVIEW
derived for use in process models. It is suggested t h a t t h e t e c h n i q u e may be used t o m o n i t o r flow b e h a v i o u r of p o w d e r m a t e r i a l s w h i c h a r e n o t a m e n d a b l e to o t h e r t e s t methods. PLASTIC YIELD BEHAVIOUR OR P O R O U S METALS D.N. Lee a n d H.S. Kim (National University, Seoul, Korea), Powder Metallurgy, Vol 35, No 4, 1992, 275-279. A new yield criterion for p o r o u s m e t a l s is p r o p o s e d . T h e e q u a t i o n c o n t a i n s a variable parameter, which may be d e t e r m i n e d from u n i a x i a l yield s t r e s s / density data, w h i c h allows t h e p r e d i c t i o n of e x p e r i m e n t a l r e s u l t s of c o m b i n e d t e n s i o n a n d torsion t e s t s of p o r o u s metals. O t h e r yield criteria are reviewed a n d are considered to, unreasonably, suggest zero yield stress a t zero relative density. I M P R O V E M E N T S IN T H E ACCURACY O F SUB-MICRON PARTICLE SIZE DISTRIBUTION MEASUREMENT P. Bowen et al (Swiss Federal I n s t of Technology, Lausanne, Switzerland), Powder Technology, Vol 74, No 1 1993, 67-71. Work to improve t h e accuracy of submicron particle size distribution m e a s u r e m e n t using a Horiba CAPA-700 i n s t r u m e n t is described. The device used s e d i m e n t a t i o n a n d l i g h t a b s o r b t i o n to measure particle size. A computer program, w h i c h allows correction for light scattering by particles below 5 ~tm uses modified Mie t h e o r y to calculate t h e light e x t e n s i o n coefficient. S o m e r e s u l t s for m o n o d i s p e r s e d SiO2 p o w d e r s are given a n d t h e accuracy is r e p o r t e d to be + 5%. The l i m i t a t i o n s of t h e work are discussed. EVALUATION OF SPATIAL P H A S E DISTRIBUTION K. Pelikan e t al ( U s t a v M a t e r i a l o v e h o ~yskumu SAV, Kosice, Czechoslovia), Pokroky Psaskove Metalurgie, No 1-2, 1992, 32-39. (In Czech). An evaluation of t h e spatial d i s t r i b u t i o n of p h a s e s in h e t e r o g e n e o u s s t r u c t u r e s is presented. Two m e t h o d s are considered, testing of p o i n t s processes a n d evaluation of interparticle distances. It is s h o w n t h a t no single s t r u c t u r a l p a r a m e t e r describes t h e different processes a n d it is suggested that 'classical' interpretation may be misleading. E F F E C T S O F INITIAL POWDER P R O P E R T I E S ON STRUCTURAL CHARACTERISTICS OF P O R O U S MATERIALS V.K. Sheleg et al Poroshkovaya Metallurgiya, No 2, 1992, 47-52. (In Russian) An investigation of t h e effects of p o w d e r p r o p e r t i e s on t h e s t r u c t u r a l p r o p e r t i e s of porous powder materials ( P P M ) is d e s c r i b e d . It is s h o w n t h a t t h e b u l k
porosity is d e p e n d e n t on t h e form factor of t h e p o w d e r a n d t h e r e l a t i o n s h i p between bulk porosity a n d PPM porosity. M a x i m u m pore size is shown to d e p e n d on p o w d e r form factor. It is suggested t h a t t h e results of t h e s t u d y may be used to predict PPM properties. D E T E R M I N A T I O N OF TOTAL PORE A R E A FOR P O R E S OF MAXIMUM SIZE IN P E R M E A B L E MATERIAL Y.L. Goblin et al, Poroshkovaya Metallurgiya, No 2, 1992, 84-88. (In Russian). A gas flow m e t h o d for t h e d e t e r m i n a t i o n of total pore a r e a of m a x i m u m size p o r e s in a p e r m e a b l e m e d i u m is p r o p o s e d . The m e t h o d is b a s e d on m e a s u r e m e n t of t h e p r o p o r t i o n o f t h e g a s flow w h i c h is turbulent. The m e t h o d is claimed to have increased accuracy because of l a m i n a r a n d t u r b u l e n t flow c o m p o n e n t s of t h e gas flow are t a k e n into account.
PRODUCTS: Aluminium VOLUME D E F O R M A T I O N O F ALUMINIUM-COPPER AND ALUMINIUM-COPPER-MAGNE SIUM COMPACTS D U R I N G S I N T E R I N G V.B. Brodov et al, Poroshkovaya Metallurgiya, No 2, 1992, 13-17. (In Russian). Dimensional changes during the s i n t e r i n g o f A1-4.4 wt% Cu a n d A14.4% Co-0.5% Mg alloys were investigated in t h e r a n g e 530 to 620°C. The a p p e a r a n c e of a liquid p h a s e a t 543°C a n d 530°C, for t h e Mg alloy was detected. If t h e liquid p h a s e is a b s o r b e d t h e c o m p a c t s e x h i b i t g r o w t h , o t h e r w i s e t h e r e is s h r i n k a g e . Growth is r e p o r t e d to be e n h a n c e d by s p r e a d i n g of t h e liquid p h a s e o n grain boundaries and surfaces and by the p r e s e n c e of Mg. E n h a n c e d growth in t h e t e r n a r y alloy is a t t r i b u t e d to t h e g r e a t e r volume of t r a n s i e n t liquid. C R E E P D E F O R M A T I O N IN PM ALUMINIUM-IRON ALLOY F. Yoshida et al (Kyushi University, Kyushi, J a p a n ) , J Japan Inst of Metals, Vol 55, No 4, 1992, 390-398. (In J a p a n e s e ) . High t e m p e r a t u r e creep a n d tensile t e s t s were carried o u t on PM AI-8 wt% Fe allows w i t h r e g a r d to t h e d e p e n d e n c e of creep r a t e on t e m p e r a t u r e , stress a n d grain size. It is r e p o r t e d t h a t t h e m i n i m u m creep r a t e increased rapidly at high stresses above a certain critical stress which did n o t d e p e n d on temperature but was related to s p e c i m e n condition. A c t i v a t i o n energies for t h e m i n i m u m creep r a t e were found to be similar to t h o s e for diffusion. The 0 projection m e t h o d was used to describe t h e creep curves a n d t h e 0 p a r a m e t e r for each curve showed stress and temperature d e p e n d e n c e below t h e critical stress.