- Email: [email protected]
Preparation of tungsten-titanium carbide by self-propagating high temperature synthesis
PM
POWDER PRODUCTION CHARACTERIZATION OF LASER S P U T T E R E D NANO-SIZED OXIDE POWDERS
B.L. Mordike et al (Technical University Clausthal, Clausthal-Zellerfeld, Germany), Zf~ir Metallkunde, Vol 84, No 2, 1993, 7984. (In G e r m a n ) . It is shown t h a t ultrafine oxide powders can be p r o d u c e d by laser illumination of metals or ceramics. Mean particle sizes of 20 n m of A1203, MgO ZrO2 were o b t a i n e d with spherical to polyhedral shapes. The Mg0 was a single periclase phase. The ZrO was 70% t e t r a g o n a l a n d 30% monoclinic t h e h1203 w a s 70% a n d 30%. PREPARATION OF TUNGSTENTITANIUM CARBIDE BY SELFPROPAGATING HIGH TEMPERATURE SYNTHESIS
LITERATURE
REVIEW
PRODUCTION OF FINE CARBIDE POWDERS BY VAPOUR PHASE REACTION
S-S, Kim et al (InHa University, Incheon, Korea) J Korean Inst of Metals, Vol 30, No 9, 1992, 1144-1149. (In Korean). It is r e p o r t e d t h a t WC powder h a s b e e n p r o d u c e d by gas p h a s e reaction between Wcl m CC14 a n d H 2 in Ar at 800 to 1300°C. The effects of r e a c t i o n c o n d i t i o n s o n particle size a n d s h a p e were determined. A p r o d u c t containing 97% WC was o b t a i n e d a t l l 0 0 ° C with gas flows of 200 m l / m i n of Ar, 100 m l / m i n H2 a n d 40 m l / m i n of CC14 giving 0.05 ~m spherical powders. Increased temperature reduced the particle size a n d increased t h e crystalline size. STRUCTURE AND P R O P E R T I E S OF AMORPHOUS ALLOYS P R O D U C E D BY IMPACT WAVE COMPACTION
S.G. Ko et al ( C h u n g n a m National University, Daejon, Korea) J Korean Inst of Metals, Vol 30, No 9, 1992, 1087-1103. (In Korean). A study of t h e p r o d u c t i o n of (W, Ti) C by self-propagating high temperature synthesis (SPTHS) is described. It was found t h a t t h e o p t i m u m molecular ratio of W, Ti, a n d C is 0.2, 0.7 a n d 1.2. Excess C above stoichiometry is required to m a k e up t h e deficiency during reaction. Where t h e Ti to W ratio is large t h e reaction is found not to proceed. The particle size and compressibility are c o n s t a n t regardless of reaction product.
N.V. Edneral et al, Poroshkovaya Metallurgiya, No 5, 1992, 66-70. (In Russian). A study of t h e effects of m e c h a n i c a l c o m m i n u t i o n of a m o r p h o u s a n n e a l e d melts p u n m e t a l , to f o r m p o w d e r , o n t h e properties of impact consolidation material, is described. It is shown t h a t t h e r e is o r i e n t a t i o n in t h e laying down of particles during compaction. Properties of t h e a m o r p h o u s c o m p a c t s were investigated as f u n c t i o n s of p o w d e r d i s p e r s i o n a n d loading pressure d u r i n g compaction.
PRODUCTION OF UNIFORMLY SIZED SPHERICAL POWDERS BY PLASMA ELECTRODE PROCESS
X. Zhang a n d A. Atrens, (University of Queensland, Australia), Int J Rapid Solidification, Vol 7, No 2, 1992, 83-107. A s o l u t i o n to a b o u n d a r y p r o b l e m , arising in rapid solidification with c h a n g i n g conditions, making use of h e a t transfer equations and recrystallization kinetics is presented. The m e t h o d used a l l o w s c o n s i d e r a t i o n of u n d e r c o o l i n g effects a n d i n t e r f a c e t e m p e r a t u r e s a n d velocity. T h e s e a r e of i m p o r t a n c e in determination of the resulting microstructure, numerical results are presented. An a p p r o a c h to d e t e r m i n a t i o n of nucleation t e m p e r a t u r e a n d crystalline kinetics, u s i n g m e a s u r e m e n t of surface t e m p e r a t u r e , is proposed.
M. Tokizane a n d K. Isonishi. (Ritsumeikan University, Kyoto, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 39, No 12, 1992, 1137-1144. (In J a p a n e s e ) . Mechanisms of atomization and p r o d u c t i o n of powder by p l a s m a r o t a t i n g electrode process (PREP) are discussed. Drop formation, film d i s i n t e g r a t i o n a n d ligament disintegration are identified as m e c h a n i s m s a n d t h e effects of process conditions a n d m a t e r i a l p a r a m e t e r s are considered. Drop formation is shown to produce highest quality powders consisting of uniform particle size, spherical in s h a p e a n d free from c o n t a m i n a t i o n . The process was applied to the production of i n t e r m e t a l l i c m a t e r i a l s i n c l u d i n g Ti a l u m i n i d e s a n d nitrides. The properties of consolidated materials are r e p o r t e d to be superior in c o m p a r i s o n with conventional powder products.
42 MPR July\August 1993
THERMOKINETIC MODEL FOR RAPID SOLIDIFICATION
PRESSING THERMAL CONDITIONS FOR COMPACTION OF VISCOUS POROUS MEDIA
L,M. Buchatsky a n d L.M. Stolin, Poroshko-
vaya Metallurgiya, No 5, 1992, 23-28. (In Russian). An analysis of non-isothermal c o m p a c t i o n of p o r o u s powder m a t e r i a l s is p r e s e n t e d for conditions of non-uniform change of porosity a n d t e m p e r a t u r e . Heat dissipation u n d e r a d i a b a t i c conditions is s h o w n to be equivalent to a b o u t 2% of t h e initial t e m p e r a t u r e a n d can be neglected. N o n - i s o t h e r m a l c o m p a c t i o n is shown to lead to a residual porosity resulting from slowing down of pore reduction m e c h a n i s m s d u r i n g final r a p i d cooling. D E S I G N OF P R E S S E S FOR COMPACTION OF POWDER MATERIALS
K.A. Gogaev et al, Poroshkovaya Metallurgiya, No 5, 1992, 100-101. (In Russian). The d e s i g n of a p r e s s for b i l a t e r a l c o m p a c t i o n of p o w d e r is d e s c r i b e d . Bilateral c o m p a c t i o n is realized by m e a n s of m u l t i p l e p r e s s u r e c y l i n d e r s a n d a m e c h a n i c a l cross h e a d on t h e m a c h i n e frame. The design is said to allow s m o o t h s y n c h r o n i z a t i o n of b o t h p a r t s of t h e bilateral c o m p a c t i o n process. USE OF REPETITIVE COMPACTION FOR PRODUCTION OF HIGH S P E E D S T E E L PARTS
H. Tsuru a n d T. Nakagawa (University of Tokyo, Tokyo, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 40, No 1, 1993, 8-11. (In J a p a n e s e ) . Repetitive compaction in which additional p o w d e r is charged to a die on t o p of previously c o m p a c t e d powder w i t h up to four increments, is described. The uniformity of green density a n d t h e effects on s h r i n k a g e during v a c u u m sintering were investigated. It is shown t h a t use of a c o m p u t e r controlled press can minimize variation in green density. The process is said to have p o t e n t i a l for p r o d u c t i o n of p a r t s with a large height. HOT P R E S S I N G OF TITANIUM CARBIDE AND TITANIUM CARBIDEALUMINA CERAMICS
T. Nishida et al (Kyoto Inst of Technology, Kyoto, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 40 No 1, 1993, 2428. (In J a p a n e s e ) . E q u i a t o m i c p r o p o r t i o n s of Ti a n d C powders were m i x e d with 0 to 40% A1203 were consolidated in a p r e s s u r e r e s i s t a n t die w i t h a C liner for insulation. The powder m i x t u r e was ignited a n d p r e s s u r e of 1 GPa applied. The microstructure of the p r o d u c t s , f o r m e d by t h e h e a t of self-
POWDER PRODUCTION CHARACTERIZATION OF LASER S P U T T E R E D NANO-SIZED OXIDE POWDERS
B.L. Mordike et al (Technical University Clausthal, Clausthal-Zellerfeld, Germany), Zf~ir Metallkunde, Vol 84, No 2, 1993, 7984. (In G e r m a n ) . It is shown t h a t ultrafine oxide powders can be p r o d u c e d by laser illumination of metals or ceramics. Mean particle sizes of 20 n m of A1203, MgO ZrO2 were o b t a i n e d with spherical to polyhedral shapes. The Mg0 was a single periclase phase. The ZrO was 70% t e t r a g o n a l a n d 30% monoclinic t h e h1203 w a s 70% a n d 30%. PREPARATION OF TUNGSTENTITANIUM CARBIDE BY SELFPROPAGATING HIGH TEMPERATURE SYNTHESIS
LITERATURE
REVIEW
PRODUCTION OF FINE CARBIDE POWDERS BY VAPOUR PHASE REACTION
S-S, Kim et al (InHa University, Incheon, Korea) J Korean Inst of Metals, Vol 30, No 9, 1992, 1144-1149. (In Korean). It is r e p o r t e d t h a t WC powder h a s b e e n p r o d u c e d by gas p h a s e reaction between Wcl m CC14 a n d H 2 in Ar at 800 to 1300°C. The effects of r e a c t i o n c o n d i t i o n s o n particle size a n d s h a p e were determined. A p r o d u c t containing 97% WC was o b t a i n e d a t l l 0 0 ° C with gas flows of 200 m l / m i n of Ar, 100 m l / m i n H2 a n d 40 m l / m i n of CC14 giving 0.05 ~m spherical powders. Increased temperature reduced the particle size a n d increased t h e crystalline size. STRUCTURE AND P R O P E R T I E S OF AMORPHOUS ALLOYS P R O D U C E D BY IMPACT WAVE COMPACTION
S.G. Ko et al ( C h u n g n a m National University, Daejon, Korea) J Korean Inst of Metals, Vol 30, No 9, 1992, 1087-1103. (In Korean). A study of t h e p r o d u c t i o n of (W, Ti) C by self-propagating high temperature synthesis (SPTHS) is described. It was found t h a t t h e o p t i m u m molecular ratio of W, Ti, a n d C is 0.2, 0.7 a n d 1.2. Excess C above stoichiometry is required to m a k e up t h e deficiency during reaction. Where t h e Ti to W ratio is large t h e reaction is found not to proceed. The particle size and compressibility are c o n s t a n t regardless of reaction product.
N.V. Edneral et al, Poroshkovaya Metallurgiya, No 5, 1992, 66-70. (In Russian). A study of t h e effects of m e c h a n i c a l c o m m i n u t i o n of a m o r p h o u s a n n e a l e d melts p u n m e t a l , to f o r m p o w d e r , o n t h e properties of impact consolidation material, is described. It is shown t h a t t h e r e is o r i e n t a t i o n in t h e laying down of particles during compaction. Properties of t h e a m o r p h o u s c o m p a c t s were investigated as f u n c t i o n s of p o w d e r d i s p e r s i o n a n d loading pressure d u r i n g compaction.
PRODUCTION OF UNIFORMLY SIZED SPHERICAL POWDERS BY PLASMA ELECTRODE PROCESS
X. Zhang a n d A. Atrens, (University of Queensland, Australia), Int J Rapid Solidification, Vol 7, No 2, 1992, 83-107. A s o l u t i o n to a b o u n d a r y p r o b l e m , arising in rapid solidification with c h a n g i n g conditions, making use of h e a t transfer equations and recrystallization kinetics is presented. The m e t h o d used a l l o w s c o n s i d e r a t i o n of u n d e r c o o l i n g effects a n d i n t e r f a c e t e m p e r a t u r e s a n d velocity. T h e s e a r e of i m p o r t a n c e in determination of the resulting microstructure, numerical results are presented. An a p p r o a c h to d e t e r m i n a t i o n of nucleation t e m p e r a t u r e a n d crystalline kinetics, u s i n g m e a s u r e m e n t of surface t e m p e r a t u r e , is proposed.
M. Tokizane a n d K. Isonishi. (Ritsumeikan University, Kyoto, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 39, No 12, 1992, 1137-1144. (In J a p a n e s e ) . Mechanisms of atomization and p r o d u c t i o n of powder by p l a s m a r o t a t i n g electrode process (PREP) are discussed. Drop formation, film d i s i n t e g r a t i o n a n d ligament disintegration are identified as m e c h a n i s m s a n d t h e effects of process conditions a n d m a t e r i a l p a r a m e t e r s are considered. Drop formation is shown to produce highest quality powders consisting of uniform particle size, spherical in s h a p e a n d free from c o n t a m i n a t i o n . The process was applied to the production of i n t e r m e t a l l i c m a t e r i a l s i n c l u d i n g Ti a l u m i n i d e s a n d nitrides. The properties of consolidated materials are r e p o r t e d to be superior in c o m p a r i s o n with conventional powder products.
42 MPR July\August 1993
THERMOKINETIC MODEL FOR RAPID SOLIDIFICATION
PRESSING THERMAL CONDITIONS FOR COMPACTION OF VISCOUS POROUS MEDIA
L,M. Buchatsky a n d L.M. Stolin, Poroshko-
vaya Metallurgiya, No 5, 1992, 23-28. (In Russian). An analysis of non-isothermal c o m p a c t i o n of p o r o u s powder m a t e r i a l s is p r e s e n t e d for conditions of non-uniform change of porosity a n d t e m p e r a t u r e . Heat dissipation u n d e r a d i a b a t i c conditions is s h o w n to be equivalent to a b o u t 2% of t h e initial t e m p e r a t u r e a n d can be neglected. N o n - i s o t h e r m a l c o m p a c t i o n is shown to lead to a residual porosity resulting from slowing down of pore reduction m e c h a n i s m s d u r i n g final r a p i d cooling. D E S I G N OF P R E S S E S FOR COMPACTION OF POWDER MATERIALS
K.A. Gogaev et al, Poroshkovaya Metallurgiya, No 5, 1992, 100-101. (In Russian). The d e s i g n of a p r e s s for b i l a t e r a l c o m p a c t i o n of p o w d e r is d e s c r i b e d . Bilateral c o m p a c t i o n is realized by m e a n s of m u l t i p l e p r e s s u r e c y l i n d e r s a n d a m e c h a n i c a l cross h e a d on t h e m a c h i n e frame. The design is said to allow s m o o t h s y n c h r o n i z a t i o n of b o t h p a r t s of t h e bilateral c o m p a c t i o n process. USE OF REPETITIVE COMPACTION FOR PRODUCTION OF HIGH S P E E D S T E E L PARTS
H. Tsuru a n d T. Nakagawa (University of Tokyo, Tokyo, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 40, No 1, 1993, 8-11. (In J a p a n e s e ) . Repetitive compaction in which additional p o w d e r is charged to a die on t o p of previously c o m p a c t e d powder w i t h up to four increments, is described. The uniformity of green density a n d t h e effects on s h r i n k a g e during v a c u u m sintering were investigated. It is shown t h a t use of a c o m p u t e r controlled press can minimize variation in green density. The process is said to have p o t e n t i a l for p r o d u c t i o n of p a r t s with a large height. HOT P R E S S I N G OF TITANIUM CARBIDE AND TITANIUM CARBIDEALUMINA CERAMICS
T. Nishida et al (Kyoto Inst of Technology, Kyoto, J a p a n ) , J Japan Soc Powder and Powder Metallurgy, Vol 40 No 1, 1993, 2428. (In J a p a n e s e ) . E q u i a t o m i c p r o p o r t i o n s of Ti a n d C powders were m i x e d with 0 to 40% A1203 were consolidated in a p r e s s u r e r e s i s t a n t die w i t h a C liner for insulation. The powder m i x t u r e was ignited a n d p r e s s u r e of 1 GPa applied. The microstructure of the p r o d u c t s , f o r m e d by t h e h e a t of self-