- Email: [email protected]
Effect of sintering and microstructure on magnetic properties of barium ferrite ceramics
Ferrite materials
SOLID STATE D E N S I F I C A T I O N OF T U N G S T E N HEAVY ALLOYS
E F F E C T OF S I N T E R I N G AND MICROSTRUCTURE ON MAGNETIC P R O P E R T I E S OF BARIUM FERRITE CERAMICS
R.V. R a m a n et al (Ceracon Inc, Sacrametno, USA). The use of W alloys, i n s t e a d of depleted U, was discussed. P r o d u c t i o n of alloys which undergo adiabatic shear during d e f o r m a t i o n a n d w h i c h h a d a novel b i n d e r was reported. The Ceracon process was said to have been used to s h o r t e n process t i m e s and minimize formation of brittle intermetallic phases. Process details were described.
M.C. d a Rocha et al (Centro de Tecnologia Brazil). A study of t h e magnetic p r o p e r t i e s of Ba ferrite, with respect to particle size a n d shape, microstructure and process p a r a m e t e r s was described. Coercive force, residual magnetization, magnetic i n d u c t i o n a n d p e a k energy were m e a s u r e d a t each p r o c e s s s t a g e . It w a s r e p o r t e d t h a t compaction pressure h a d small effects b u t particle size a n d s i n t e r i n g t e m p e r a t u r e strongly influenced the magnetic properties. IMPROVEMENT O F MAGNETIC P R O P E R T I E S FOR HOT ISOSTATIC PRESSING OF FERRITES C.L. Wang (Inst. of Metal Research, China). It was r e p o r t e d t h a t sintered ferrites can be fully dens[fled by HIP b u t t h a t m a g n e t i c properties m a y be d a m a g e d by o x i d a t i o n during HIP. HIP u p to 200 MPa h a d little effect of p r o p e r t i e s of fully d e n s i f i e d ferrites. Permeability could be increased by h e a t t r e a t m e n t in a n O / N b a l a n c i n g a t m o s p h e r e a t 500 to 1050°C.
Full density materials C O M P U T E R M O D E L L I N G OF S T R E S S / STRAIN STAGES IN DIE D U R I N G ROTARY COLD R E P R E S S I N G G. Pregowski, J. Szymborski ( R o t a p r e s s I n t e r n a t i o n a l Inc, USA). Strain a n d stress in t h e dies used in r o t a r y cold r e p r e s s i n g was analyzed by finite element m e t h o d s for non-symmetric loading conditions. E x a m p l e s were given of p a r t s subjected to symmetric a n d nons y m m e t r i c p r e s s i n g . The u n i f o r m i t y of stress d i s t r i b u t i o n was d e m o n s t r a t e d a n d t h e i m p o r t a n c e of correct die c o n s t r u c t i o n was emphasized. ADVANCES IN FULL DENSITY CONSOLIDATION OF E N G I N E E R E D MATERIALS R.V. R a m a n ( C e r a c o n Inc, S a c r a m e t n o , USA). The use of recently developed technologies for t h e p r o d u c t i o n of high p e r f o r m a n c e PM p a r t s was discussed. The Ceracon process was r e p o r t e d to have been used to consolidate a n u m b e r of a d v a n c e d PM systems including rapidly solidified A1 alloys, s t e e l s , A l u m i n a , a n d h i g h T¢ superconductors. Issues relating to processing were discussed.
44 MPR January 1993
Superconducting materials S I N T E R I N G O F H I G H CRITICAL TEMPERATURE SUPERCONDUCTING MATERIALS K.C. G o r e t t a e t al ( A r g o n n e N a t i o n a l Laboratory, USA). The u s e of l i q u i d a n d solid p h a s e sintering processes for oxide superconductors was discussed with respect to microstructural evolution. Results were p r e s e n t e d for Bi2Sr2CaCu2Ox in pressed a n d worked conditions. S I N T E R I N G O F BULK H I G H CRITICAL TEMPERATURE SUPERCONDUCTING MATERIALS K.C. G o r e t t a e t al ( A r g o n n e N a t i o n a l Laboratory, USA). The effect of O p a r t i a l p r e s s u r e on s i n t e r i n g k i n e t i c s of YBazCu3Ox w a s investigated. Anisotropy of grain growth d u r i n g s i n t e r i n g was r e p o r t e d a n d t h i s c o u l d b e m i n i m i z e d by c o n t r o l of 0 p r e s s u r e a n d sintering t e m p e r a t u r e . SINTERING OF SUPERCONDUCTIVE MATERIAL A T O M I Z E D FROM M O L T E N OXIDE I~ H a l a d a et al (National research Inst. for Metals, Tokyo, J a p a n ) . The use of PM t e c h n o l o g i e s in t h e p r o d u c t i o n of oxide s u p e r c o n d u c t o r s was described. Gas a n d centrifugal a t o m i z a t i o n were used to p r o d u c e a m o r p h o u s powders. Heating of t h e powders was r e p o r t e d to cause crystallization above 500°C, s h r i n k a g e above 650°C, e x p a n s i o n above 800°C a n d s h r i n k a g e above 860°C. The microstructure after heating were described. A liquid p h a s e was r e p o r t e d to be formed above 860°C.
Machinability
The role of MnS in significantly improving t h e m a c h i n a b i l i t y of s i n t e r e d steels at t h e e x p e n s e of t o u g h n e s s a n d s t r e n g t h was discussed. The objective of t h e study described was to optimize t h e MnS content and particle size for good m a c h i n a b i l i t y a n d minimize t h e loss of t r a n s v e r s e r u p t u r e s t r e n g t h . R3755 low alloy steel of t h r e e densities with t h r e e c o n c e n t r a t i o n s of MnS at t h r e e particle sizes was studied. Statistical e x p e r i m e n t a l design was used to assess all empirical variables. Optimum conditions were predicted a n d confirmed experimentally. E F F E C T S OF M I C R O S T R U C T U R E ON T H E MACHINABILITY OF FC-0208 COPPER STEEL J~l. Fulmer, M. B l a n t o n (Burgess-Norton Manufacturing Co, Geneva, Illinois, USA). T h e s t u d y e x a m i n e d t h e effects of m i c r o s t r u c t u r e on t h e m a c h i n a b i l i t y of FC0 2 0 8 steel. E m p h a s i s w a s p l a c e d o n s t a t i s t i c a l t r e a t m e n t of e x p e r i m e n t a l t e c h n i q u e s a n d data. Effects of m a c h i n e control p a r a m e t e r s were m e a s u r e d a n d t h e results were discussed. EFFECTS OF MANGANESE SULPHIDE ON T H E P R O P E R T I E S OF HIGH P E R F O R M A N C E PM ALLOYS D.S. M a d a n (Elkem D e v e l o p m e n t Centre, USA). The machinability and mechanical p r o p e r t i e s of high p e r f o r m a n c e PM steel p a r t s were discussed with regard to t h e a d d i t i o n of MnS. The effects of MnS on tensile strength, ductility, densification a n d structure/property relationship were investigated. The use of MnS in PM alloys was evaluated a n d its i m p a c t on p a r t design was considered. I N F L U E N C E O F POWDER P R O C E S S I N G ON INCLUSION F O R M A T I O N IN RELATION TO MACHINABILITY O F M A N G A N E S E S U L P H I D E PREALLOYED PM S T E E L PARTS S. Nigarura et al (Ecole Polytechnique de Montreal, C a n a d a ) . The influence of MnS on the m a c h i n a b i l i t y of PM steels was discussed with respect to size, s h a p e a n d d i s t r i b u t i o n of MnS inclusions. The effect of powder processing, at all stages, on the characteristics of t h e inclusions in w a t e r a t o m i z e d (WA) c a s t i r o n p o w d e r w a s investigated. It was r e p o r t e d t h a t oxide inclusions were found in a d d i t i o n to t h e MnS in WA a n d MnS prealloyed powders. The influence of process conditions on t h e inclusions was investigated in o r d e r to control f o r m a t i o n d u r i n g processing.
OPTIMIZATION O F MACHINABILITY OF A PM ALLOY U S I N G STATISTICAL ANALYSIS
M A C H I N I N G OF U N L E A D E D PM BRASS PARTS
Y.T. Chen et al (Pitney Bowes Inc, Stamford, USA).
K.B. Patel, D.S. Madan (Elkem D e v e l o p m e n t Centre, USA).
SOLID STATE D E N S I F I C A T I O N OF T U N G S T E N HEAVY ALLOYS
E F F E C T OF S I N T E R I N G AND MICROSTRUCTURE ON MAGNETIC P R O P E R T I E S OF BARIUM FERRITE CERAMICS
R.V. R a m a n et al (Ceracon Inc, Sacrametno, USA). The use of W alloys, i n s t e a d of depleted U, was discussed. P r o d u c t i o n of alloys which undergo adiabatic shear during d e f o r m a t i o n a n d w h i c h h a d a novel b i n d e r was reported. The Ceracon process was said to have been used to s h o r t e n process t i m e s and minimize formation of brittle intermetallic phases. Process details were described.
M.C. d a Rocha et al (Centro de Tecnologia Brazil). A study of t h e magnetic p r o p e r t i e s of Ba ferrite, with respect to particle size a n d shape, microstructure and process p a r a m e t e r s was described. Coercive force, residual magnetization, magnetic i n d u c t i o n a n d p e a k energy were m e a s u r e d a t each p r o c e s s s t a g e . It w a s r e p o r t e d t h a t compaction pressure h a d small effects b u t particle size a n d s i n t e r i n g t e m p e r a t u r e strongly influenced the magnetic properties. IMPROVEMENT O F MAGNETIC P R O P E R T I E S FOR HOT ISOSTATIC PRESSING OF FERRITES C.L. Wang (Inst. of Metal Research, China). It was r e p o r t e d t h a t sintered ferrites can be fully dens[fled by HIP b u t t h a t m a g n e t i c properties m a y be d a m a g e d by o x i d a t i o n during HIP. HIP u p to 200 MPa h a d little effect of p r o p e r t i e s of fully d e n s i f i e d ferrites. Permeability could be increased by h e a t t r e a t m e n t in a n O / N b a l a n c i n g a t m o s p h e r e a t 500 to 1050°C.
Full density materials C O M P U T E R M O D E L L I N G OF S T R E S S / STRAIN STAGES IN DIE D U R I N G ROTARY COLD R E P R E S S I N G G. Pregowski, J. Szymborski ( R o t a p r e s s I n t e r n a t i o n a l Inc, USA). Strain a n d stress in t h e dies used in r o t a r y cold r e p r e s s i n g was analyzed by finite element m e t h o d s for non-symmetric loading conditions. E x a m p l e s were given of p a r t s subjected to symmetric a n d nons y m m e t r i c p r e s s i n g . The u n i f o r m i t y of stress d i s t r i b u t i o n was d e m o n s t r a t e d a n d t h e i m p o r t a n c e of correct die c o n s t r u c t i o n was emphasized. ADVANCES IN FULL DENSITY CONSOLIDATION OF E N G I N E E R E D MATERIALS R.V. R a m a n ( C e r a c o n Inc, S a c r a m e t n o , USA). The use of recently developed technologies for t h e p r o d u c t i o n of high p e r f o r m a n c e PM p a r t s was discussed. The Ceracon process was r e p o r t e d to have been used to consolidate a n u m b e r of a d v a n c e d PM systems including rapidly solidified A1 alloys, s t e e l s , A l u m i n a , a n d h i g h T¢ superconductors. Issues relating to processing were discussed.
44 MPR January 1993
Superconducting materials S I N T E R I N G O F H I G H CRITICAL TEMPERATURE SUPERCONDUCTING MATERIALS K.C. G o r e t t a e t al ( A r g o n n e N a t i o n a l Laboratory, USA). The u s e of l i q u i d a n d solid p h a s e sintering processes for oxide superconductors was discussed with respect to microstructural evolution. Results were p r e s e n t e d for Bi2Sr2CaCu2Ox in pressed a n d worked conditions. S I N T E R I N G O F BULK H I G H CRITICAL TEMPERATURE SUPERCONDUCTING MATERIALS K.C. G o r e t t a e t al ( A r g o n n e N a t i o n a l Laboratory, USA). The effect of O p a r t i a l p r e s s u r e on s i n t e r i n g k i n e t i c s of YBazCu3Ox w a s investigated. Anisotropy of grain growth d u r i n g s i n t e r i n g was r e p o r t e d a n d t h i s c o u l d b e m i n i m i z e d by c o n t r o l of 0 p r e s s u r e a n d sintering t e m p e r a t u r e . SINTERING OF SUPERCONDUCTIVE MATERIAL A T O M I Z E D FROM M O L T E N OXIDE I~ H a l a d a et al (National research Inst. for Metals, Tokyo, J a p a n ) . The use of PM t e c h n o l o g i e s in t h e p r o d u c t i o n of oxide s u p e r c o n d u c t o r s was described. Gas a n d centrifugal a t o m i z a t i o n were used to p r o d u c e a m o r p h o u s powders. Heating of t h e powders was r e p o r t e d to cause crystallization above 500°C, s h r i n k a g e above 650°C, e x p a n s i o n above 800°C a n d s h r i n k a g e above 860°C. The microstructure after heating were described. A liquid p h a s e was r e p o r t e d to be formed above 860°C.
Machinability
The role of MnS in significantly improving t h e m a c h i n a b i l i t y of s i n t e r e d steels at t h e e x p e n s e of t o u g h n e s s a n d s t r e n g t h was discussed. The objective of t h e study described was to optimize t h e MnS content and particle size for good m a c h i n a b i l i t y a n d minimize t h e loss of t r a n s v e r s e r u p t u r e s t r e n g t h . R3755 low alloy steel of t h r e e densities with t h r e e c o n c e n t r a t i o n s of MnS at t h r e e particle sizes was studied. Statistical e x p e r i m e n t a l design was used to assess all empirical variables. Optimum conditions were predicted a n d confirmed experimentally. E F F E C T S OF M I C R O S T R U C T U R E ON T H E MACHINABILITY OF FC-0208 COPPER STEEL J~l. Fulmer, M. B l a n t o n (Burgess-Norton Manufacturing Co, Geneva, Illinois, USA). T h e s t u d y e x a m i n e d t h e effects of m i c r o s t r u c t u r e on t h e m a c h i n a b i l i t y of FC0 2 0 8 steel. E m p h a s i s w a s p l a c e d o n s t a t i s t i c a l t r e a t m e n t of e x p e r i m e n t a l t e c h n i q u e s a n d data. Effects of m a c h i n e control p a r a m e t e r s were m e a s u r e d a n d t h e results were discussed. EFFECTS OF MANGANESE SULPHIDE ON T H E P R O P E R T I E S OF HIGH P E R F O R M A N C E PM ALLOYS D.S. M a d a n (Elkem D e v e l o p m e n t Centre, USA). The machinability and mechanical p r o p e r t i e s of high p e r f o r m a n c e PM steel p a r t s were discussed with regard to t h e a d d i t i o n of MnS. The effects of MnS on tensile strength, ductility, densification a n d structure/property relationship were investigated. The use of MnS in PM alloys was evaluated a n d its i m p a c t on p a r t design was considered. I N F L U E N C E O F POWDER P R O C E S S I N G ON INCLUSION F O R M A T I O N IN RELATION TO MACHINABILITY O F M A N G A N E S E S U L P H I D E PREALLOYED PM S T E E L PARTS S. Nigarura et al (Ecole Polytechnique de Montreal, C a n a d a ) . The influence of MnS on the m a c h i n a b i l i t y of PM steels was discussed with respect to size, s h a p e a n d d i s t r i b u t i o n of MnS inclusions. The effect of powder processing, at all stages, on the characteristics of t h e inclusions in w a t e r a t o m i z e d (WA) c a s t i r o n p o w d e r w a s investigated. It was r e p o r t e d t h a t oxide inclusions were found in a d d i t i o n to t h e MnS in WA a n d MnS prealloyed powders. The influence of process conditions on t h e inclusions was investigated in o r d e r to control f o r m a t i o n d u r i n g processing.
OPTIMIZATION O F MACHINABILITY OF A PM ALLOY U S I N G STATISTICAL ANALYSIS
M A C H I N I N G OF U N L E A D E D PM BRASS PARTS
Y.T. Chen et al (Pitney Bowes Inc, Stamford, USA).
K.B. Patel, D.S. Madan (Elkem D e v e l o p m e n t Centre, USA).