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Powder metallurgy titanium alloys
A s t u d y of a l t e r n a t i v e s to Pb, for e n v i r o n m e n t a l reasons, for p r o m o t i o n of machinability, in Cu alloys was reported. The use of MnS, a d d e d d u r i n g powder blending, was investigated. It was r e p o r t e d t h a t t h e a d d i t i o n of less t h a n I%MnS r e s u l t e d in a five-fold i m p r o v e m e n t in machinability, compared with unleaded brass, with only a small effect on m e c h a n i c a l p r o p e r t i e s . O p t i m i z a t i o n of process t e c h n i q u e s was said to lead to increased tool life. MACHINABLE NON-LEADED BRASS POWDERS F.W. Hinger (Zinc Corp of America, Palmerton, USA). The p a p e r r e p o r t e d a comparison of t h e machinability, m e c h a n i c a l properties a n d colour of u n l e a d e d sintered brasses in the range 10 to 30%Zn. The s t r u c t u r e s of t h e alloys and the machining test were described.
Intermetallic materials INTERMETALLIC POWDERS FOR POWDER I N J E C T I O N MOULDING (VIM) S.I( G u h a et al (MER Corp, USA). The applications of NiA1 were discussed with respect to t h e factors which limit its use. PIM was considered to be a m e a n s of increasing t h e use of NiAl but t h e large powder sizes available (40 to 150 m m ) were said to be u n s u i t a b l e for PIM a n d expensive. Plasma initiated selfp r o p a g a t i n g high t e m p e r a t u r e synthesis (PSHS) w a s s h o w n to be c a p a b l e of producing powders below 5 ~m in size, at reduced cost, a n d t h e use of this powder for PIM was discussed. Densities above 96% were reported. Microalloying with t e r n a r y elements to improve m e c h a n i c a l properties was outlined. POWDER P R O C E S S I N G OF NICKEL ALUMINO-SILICIDE INTERMETALLIC COMPOUND N.S. Stoloff et al (Rensselaer Polytechnic Inst, Troy, New York, USA). Properties of Ni~Al b a s e d c o m p o u n d s were discussed with regard to t h e costs. It was r e p o r t e d t h a t Ni3(A1,Si) h a d been produced by Nazby a n d straubli which in the directionally solidified s t a t e e x h i b i t e d good creep properties. The p a p e r e x a m i n e d t h e use of PM processes, including powder extrusion, HIP a n d h o t rolling, or t h e p r o d u c t i o n of t h e alloy. P r o p e r t i e s a t a m b i e n t a n d elevated t e m p e r a t u r e were described. PRODUCTION OF TITANIUM A L U M I N I D E IN E X T R U D E D ELEMENTAL POWDERS ICB. Mfiller et al (Technical University of
Berlin, Germany). The p r o d u c t i o n of TiA1 by e x t r u s i o n of elemental powders at high t e m p e r a t u r e a n d pressure with s u b s e q u e n t h e a t t r e a t m e n t was described a n d discussed with reference to ductility. The influences of e x t r u s i o n p a r a m e t e r s were investigated. Properties a n d m i c r o s t r u c t u r e s of t h e a s - e x t r u d e d a n d h e a t t r e a t e d materials were shown.
Powder production POWDER METALLURGY TITANIUM ALLOYS J.C. Krause de Verney et al (Centro de Tecnologia -- LTM -- UFRGS, Brazil). The use of PM Ti a n d Ti alloys in biomedical applications was described. The p a p e r outlined t h e p r o d u c t i o n of Ti powder and presented data concerning the properties of t h e product. PREPARATION AND C H A ~ C T E R I S T I C S OF M O N O D I S P E R S E UNIFORMLY S H A P E D METAL POWDERS M. Figlarz et al (University of Picardy, France). The need for fine m e t a l powders of high purity a n d uniform s h a p e was discussed. A process to satisfy t h i s need was described. The process consists of polyol reduction of an inorganic precurser u n d e r controlled conditions. Process conditions are used to control characteristics of t h e powders. The m e t h o d was r e p o r t e d to have been used to p r e p a r e monodisperse, n o n - a g g l o m e r a t e d Co, Ni, Cu a n d Ag powders in micron a n d sub-micron sizes for which t h e p r o p e r t i e s were described. PREPARATION O F SILVER-TUNGSTEN C O M P O S I T E POWDERS BY CHEMICAL CO-PRE CIPITATION H. Zhow et al (Zhuzhou C e m e n t e d Carbide Works, Zhuzhou City, Hunan, China). The p r o d u c t i o n of a Ag-W composite powder by H reduction of co-precipitated Ag t u n g s t a t e was d e s c r i b e d . E l e c t r i c a l contacts m a d e from t h e powder were said to be fine in microstructure and h o m o g e n e o u s in c o m p o s i t i o n a n d t o p e r f o r m well in service c o m p a r e d w i t h c o n v e n t i o n a l material. The p o w d e r was characterized with respect to composition a n d particle size a n d shape. The effects of process p a r a m e t e r s were outlined.
A NEW M E T H O D OF P R O D U C I N G STRONGLY MAGNETIC IRON OXIDE POWDER D.M. Kaxikaev et al (Technolgical Inst, Russia). It was reported that explosive d e f o r m a t i o n h a d b e e n used to c o n v e r t
feebly m a g n e t i c Fe20 a ( h e a m a t i t e ) into strongly m a g n e t i c Fe304 ( m a g n e t i t e ) . The raw m a t e r i a l s used, t h e effects of processing conditions a n d a p p l i c a t i o n s were described. P R O D U C T I O N OF SPHERICAL POWDERS BY PLASMA ROTATING ELECTRODE PROCESS V.T. Musienko (NPO VILS, Russia). The p r o d u c t i o n of m e t a l p o w d e r by expulsion of m o l t e n droplets from t h e gap between a rapidly s p i n n i n g c o n s u m a b l e electrode an a m o l t e n m e t a l pool, with a p l a s m a arc between, was described. The v a l u e of t h e t e c h n i q u e for p r o d u c i n g p o w d e r w i t h c o n t r o l l e d size a n d size distribution and minimal contamination was outlined and production of c o m p o n e n t s from t h e p o w d e r was reported.
Novel applications S I N T E R E D I N T E G R A T E D HEAT EXCHANGER/CATALYST FOR FIXED B E D CHEMICAL REACTOR J.W. Geus et al (University of Utrecht, The Netherlands). The use of p o r o u s s i n t e r e d m e t a l bodies as c o m b i n e d h e a t e x c h a n g e r s a n d catalyst carriers in chemical process e q u i p m e n t was discussed. Investigations to develop this concept were described. The study c o n c e n t r a t e d on a) t h e d e v e l o p m e n t of m a t e r i a l s with high porosity to c o n t a i n t h e catalyst in t h e voids, b) m e a s u r e m e n t s of t h e r m a l conductivity a n d c) modelling of the reactor applications for desulphurization and natural gas combustion. Results were p r e s e n t e d a n d discussed in t h e light of t h e p o t e n t i a l of s i n t e r e d reactors. F I X E D B E D CATALYTIC REACTORS B A S E D ON S I N T E R E D METALS J.W. Geus et al (University of Utrecht, The Netherlands). The p r o d u c t i o n of a fixed bed catalyst/ h e a t e x c h a n g e r was described. A m e t a l p o w d e r / p o l y m e r m i x t u r e is placed in a m e t a l tube. The h e a t t r e a t m e n t process a l l o w s r e m o v a l o f t h e p o l y m e r by combustion a n d s i n t e r i n g . T h e r e is s i n t e r i n g of p o w d e r to t h e t u b e wall resulting in good thermal contact c o n d u c t a n c e b e i n g i n c r e a s e d , typically, from 0.4 to 7.5 W/m°C w h i c h p e r m i t s d i s s i p a t i o n of t h e h e a t of t h e chemical reaction. A silica layer s u b s e q u e n t l y applied increases t h e surface a r e a from 0.5 to 10 m2/g. MICROWAVE P R O D U C T I O N OF A S U P E R C O N D U C T O R POWDER T.V. Mani et al (Regional Research Laboratory, Trivandrum, India).
MPR January 1993 45
Intermetallic materials INTERMETALLIC POWDERS FOR POWDER I N J E C T I O N MOULDING (VIM) S.I( G u h a et al (MER Corp, USA). The applications of NiA1 were discussed with respect to t h e factors which limit its use. PIM was considered to be a m e a n s of increasing t h e use of NiAl but t h e large powder sizes available (40 to 150 m m ) were said to be u n s u i t a b l e for PIM a n d expensive. Plasma initiated selfp r o p a g a t i n g high t e m p e r a t u r e synthesis (PSHS) w a s s h o w n to be c a p a b l e of producing powders below 5 ~m in size, at reduced cost, a n d t h e use of this powder for PIM was discussed. Densities above 96% were reported. Microalloying with t e r n a r y elements to improve m e c h a n i c a l properties was outlined. POWDER P R O C E S S I N G OF NICKEL ALUMINO-SILICIDE INTERMETALLIC COMPOUND N.S. Stoloff et al (Rensselaer Polytechnic Inst, Troy, New York, USA). Properties of Ni~Al b a s e d c o m p o u n d s were discussed with regard to t h e costs. It was r e p o r t e d t h a t Ni3(A1,Si) h a d been produced by Nazby a n d straubli which in the directionally solidified s t a t e e x h i b i t e d good creep properties. The p a p e r e x a m i n e d t h e use of PM processes, including powder extrusion, HIP a n d h o t rolling, or t h e p r o d u c t i o n of t h e alloy. P r o p e r t i e s a t a m b i e n t a n d elevated t e m p e r a t u r e were described. PRODUCTION OF TITANIUM A L U M I N I D E IN E X T R U D E D ELEMENTAL POWDERS ICB. Mfiller et al (Technical University of
Berlin, Germany). The p r o d u c t i o n of TiA1 by e x t r u s i o n of elemental powders at high t e m p e r a t u r e a n d pressure with s u b s e q u e n t h e a t t r e a t m e n t was described a n d discussed with reference to ductility. The influences of e x t r u s i o n p a r a m e t e r s were investigated. Properties a n d m i c r o s t r u c t u r e s of t h e a s - e x t r u d e d a n d h e a t t r e a t e d materials were shown.
Powder production POWDER METALLURGY TITANIUM ALLOYS J.C. Krause de Verney et al (Centro de Tecnologia -- LTM -- UFRGS, Brazil). The use of PM Ti a n d Ti alloys in biomedical applications was described. The p a p e r outlined t h e p r o d u c t i o n of Ti powder and presented data concerning the properties of t h e product. PREPARATION AND C H A ~ C T E R I S T I C S OF M O N O D I S P E R S E UNIFORMLY S H A P E D METAL POWDERS M. Figlarz et al (University of Picardy, France). The need for fine m e t a l powders of high purity a n d uniform s h a p e was discussed. A process to satisfy t h i s need was described. The process consists of polyol reduction of an inorganic precurser u n d e r controlled conditions. Process conditions are used to control characteristics of t h e powders. The m e t h o d was r e p o r t e d to have been used to p r e p a r e monodisperse, n o n - a g g l o m e r a t e d Co, Ni, Cu a n d Ag powders in micron a n d sub-micron sizes for which t h e p r o p e r t i e s were described. PREPARATION O F SILVER-TUNGSTEN C O M P O S I T E POWDERS BY CHEMICAL CO-PRE CIPITATION H. Zhow et al (Zhuzhou C e m e n t e d Carbide Works, Zhuzhou City, Hunan, China). The p r o d u c t i o n of a Ag-W composite powder by H reduction of co-precipitated Ag t u n g s t a t e was d e s c r i b e d . E l e c t r i c a l contacts m a d e from t h e powder were said to be fine in microstructure and h o m o g e n e o u s in c o m p o s i t i o n a n d t o p e r f o r m well in service c o m p a r e d w i t h c o n v e n t i o n a l material. The p o w d e r was characterized with respect to composition a n d particle size a n d shape. The effects of process p a r a m e t e r s were outlined.
A NEW M E T H O D OF P R O D U C I N G STRONGLY MAGNETIC IRON OXIDE POWDER D.M. Kaxikaev et al (Technolgical Inst, Russia). It was reported that explosive d e f o r m a t i o n h a d b e e n used to c o n v e r t
feebly m a g n e t i c Fe20 a ( h e a m a t i t e ) into strongly m a g n e t i c Fe304 ( m a g n e t i t e ) . The raw m a t e r i a l s used, t h e effects of processing conditions a n d a p p l i c a t i o n s were described. P R O D U C T I O N OF SPHERICAL POWDERS BY PLASMA ROTATING ELECTRODE PROCESS V.T. Musienko (NPO VILS, Russia). The p r o d u c t i o n of m e t a l p o w d e r by expulsion of m o l t e n droplets from t h e gap between a rapidly s p i n n i n g c o n s u m a b l e electrode an a m o l t e n m e t a l pool, with a p l a s m a arc between, was described. The v a l u e of t h e t e c h n i q u e for p r o d u c i n g p o w d e r w i t h c o n t r o l l e d size a n d size distribution and minimal contamination was outlined and production of c o m p o n e n t s from t h e p o w d e r was reported.
Novel applications S I N T E R E D I N T E G R A T E D HEAT EXCHANGER/CATALYST FOR FIXED B E D CHEMICAL REACTOR J.W. Geus et al (University of Utrecht, The Netherlands). The use of p o r o u s s i n t e r e d m e t a l bodies as c o m b i n e d h e a t e x c h a n g e r s a n d catalyst carriers in chemical process e q u i p m e n t was discussed. Investigations to develop this concept were described. The study c o n c e n t r a t e d on a) t h e d e v e l o p m e n t of m a t e r i a l s with high porosity to c o n t a i n t h e catalyst in t h e voids, b) m e a s u r e m e n t s of t h e r m a l conductivity a n d c) modelling of the reactor applications for desulphurization and natural gas combustion. Results were p r e s e n t e d a n d discussed in t h e light of t h e p o t e n t i a l of s i n t e r e d reactors. F I X E D B E D CATALYTIC REACTORS B A S E D ON S I N T E R E D METALS J.W. Geus et al (University of Utrecht, The Netherlands). The p r o d u c t i o n of a fixed bed catalyst/ h e a t e x c h a n g e r was described. A m e t a l p o w d e r / p o l y m e r m i x t u r e is placed in a m e t a l tube. The h e a t t r e a t m e n t process a l l o w s r e m o v a l o f t h e p o l y m e r by combustion a n d s i n t e r i n g . T h e r e is s i n t e r i n g of p o w d e r to t h e t u b e wall resulting in good thermal contact c o n d u c t a n c e b e i n g i n c r e a s e d , typically, from 0.4 to 7.5 W/m°C w h i c h p e r m i t s d i s s i p a t i o n of t h e h e a t of t h e chemical reaction. A silica layer s u b s e q u e n t l y applied increases t h e surface a r e a from 0.5 to 10 m2/g. MICROWAVE P R O D U C T I O N OF A S U P E R C O N D U C T O R POWDER T.V. Mani et al (Regional Research Laboratory, Trivandrum, India).
MPR January 1993 45