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PM components in process engineering
A1-2.8 wt% Fe in flake f o r m w a s produced by atomization and splat cooling onto a w a t e r cooled Cu roller. The flakes were subjected to Ifigh energy MA with stearic acid as a process control agent. The powder was consolidated by cold pressing, degassed and hot extruded. The structure of the alloy was shown to contain very fine dispersoids and subgrains. The structure was stable on heating up to 400°C. The tensile strength was found to be higher as a result of MA and this is attributed to the fine d i s p e r s i o n o f t h e s t r u c t u r e . The ductility was lower.
India), Powder Metallurgy Science and Technology, Vol 2, No 1, 1990, 52-60. The MA of silver-tin oxide materials by a t t r i t i o n a n d p l a n e t a r y ball milling is e x a m i n e d with the objective of replacing silver-cadmium oxide (toxic) materials. Dispersion of the resultant powders was studied by X-ray diffraction and electron microscopy. Optimum processing conditions with respect to efficiency of milling and p r o d u c t i o n of products, with satisfactory properties, were established.
Metal injection moulding R E A C T I O N S DURING MECHANICAL ALLOYING (MA)
G.B. Schaffer and P.G. McCormick, (Uni versity of Western Australia, Perth, Austra lia), Metallurgical 7~ansactions A, Vol 21A, No 10, 1990, 2789-2794. Solid s t a t e d i s p l a c e m e n t r e a c t i o n s occurring during MA have been studied. Reduction of CuO to Cu by a variety of metallic reducing agents was investigated and the powders characterized by X-ray and electron diffraction and microscopy. The addition of a liquid process control agent was found to be n e c e s s a r y to p r e v e n t combustion of the powders. The as-milled p o w d e r c o n s i s t e d of n a n o m e t r e sized crystallites with a highdefect density.
P R O D U C T I O N OF NANO-CRYSTALLINE Ti-Mg ALLOYS BY M E C H A N I C A L ALLOYING ( M A )
C. Suryanaryana and F.H. Froes, (University of Idaho, USA), J MateriaLs Research, Vol 5, No 9, 1990, 1880-188t~,. The p a p e r draws attention to the very low solid solubility of Mg in Ti. The use of MA to process Mg and Ti resulted in the production of nano-crystalline (10-15 nm) p o w d e r s of Mg-Ti solid s o l u t i o n . The material was shown to have a m e t a s t a b l e FCC structure and it is suggested t h a t this is formed as a result of the very heavy deformation of the hop materials, Ti and Mg, d u r i n g MA. The s o l i d s o l u t i o n d e c o m p o s e s into the elemental p h a s e s on heating.
I N T E G R I T Y OF C O M P L E X S H A P E D P R O D U C T S M A D E BY P O W D E R INJECTION MOULDING (PIM)
K.F. ttens et al, (Rensselaer Polytechnic Institute, New York, USA), Powder Metallurgy International, Vol 23, No 1, 1991, 1521. Metal and ceramic a r t e f a c t s were produced by PIM using different binders. The problems encountered during moulding, debinding and sintering were studied. Volume shrinkage, green s t r e n g t h and stress relaxation in process stages are t h e main factors w h i c h d e t e r m i n e t h e success of the PIM process. The problems are said to be solved by optimization of binder composition, moulding p a r a m e t e r s and debinding practice.
PM parts
No 3/4, 1990, 521-529. The use of Ni carbouyl p o w d e r to f a b r i c a t e l i g h t w e i g h t e l e c t r o d e s for a e r o s p a c e a p p l i c a t i o n s is d i s c u s s e d . Comparison is m a d e with a non-woven m a t electrode made from Ni fibre. PM C O M P O N E N T S IN P R O C E S S ENGINEERING
A.X. Kischer and V. Arnhold, (Sintermetallwerk Krebsoge, Germany), Chem Ing Tech, Vol 62, No 4, 1990, 263-270. In German. The diverse a p p l i c a t i o n s of PM are reviewed. E x a m p l e s are drawn from automotive applications, the electrical and electronic industries and chemical industry. Fully dense, as well as porous materials, are considered. Novel applications mentioned include materials for use as catalysts.
Refractory metals STUDY OF S T R U C T U R A L D E F E C T S IN HIGHLY D I S P E R S E D W A N D Mo
P.V. Arifov et al, F/z Chim Obrab Mater, No 3, 1989, 117-120. In Russian. The structure of fine W and Mo powders, obtained by gas p h a s e reactions, has been studied. Changes in the structure after pressing and sintering were observed. It was found t h a t the m o s t common defects were vacant lattice site/oxygen c o m p l e x e s . P o s s i b l e m e c h a n i s m s for the formation of such defects are considered.
S E R V I C E A B I L I T Y OF BINARY SELFLUBRICATING BEARINGS
Y.I. Pustovoit, Poroskovaya Metallurgiya, No 8, 1990, 72 76. In Russian. The durability of sintered Fe-grapitepolyamide plain bearings has been studied together with the structural factors and technological problems of their production. It was found t h a t plain bearings c o n t a i n i n g microporous polymeric inclusions showed increased lubricant migration and e x t e n d e d duration of the period of self lubrication.
P R O D U C T I O N OF A4~-SnO 2 E L E C T R I C A L C O N T A C T M A T E R I A L S BY MECHANICAL ALLOYING (MA)
U S E OF CARBONYL N i P O W D E R IN P R O D U C T I O N OF L I G H T W E I G H T ELECTRODES
A. Verma, (Thapar R & I) ('.entre, Patiala,
D. Coates et al, J. of Powder Sources, Vol 29,
Miscellaneous
POWDER METALLURGY A T T H E INDIAN INSTITUTE TECHNOLOGY KANPUR
G.S. Upadhyaya, (Indian Institute of Technology, Kanpur, I n d i a ) , Int J Powder Metallurgy, Vol 27, No 1, 59-64. The facilities and PM research activities of the D e p a r t m e n t of Metallurgical E n g i n e e r i n g at tile Indian I n s t i t u t e of Technology, Kanpur, are described with p a r t i c u l a r e m p h a s i s on s i n t e r i n g . Thtj e d u c a t i o n a l work of the I n s t i t u t e and e x a m p l e s o f t e c h n o l o g y t r a n s f e r are discussed.
MPR April 1991 55
India), Powder Metallurgy Science and Technology, Vol 2, No 1, 1990, 52-60. The MA of silver-tin oxide materials by a t t r i t i o n a n d p l a n e t a r y ball milling is e x a m i n e d with the objective of replacing silver-cadmium oxide (toxic) materials. Dispersion of the resultant powders was studied by X-ray diffraction and electron microscopy. Optimum processing conditions with respect to efficiency of milling and p r o d u c t i o n of products, with satisfactory properties, were established.
Metal injection moulding R E A C T I O N S DURING MECHANICAL ALLOYING (MA)
G.B. Schaffer and P.G. McCormick, (Uni versity of Western Australia, Perth, Austra lia), Metallurgical 7~ansactions A, Vol 21A, No 10, 1990, 2789-2794. Solid s t a t e d i s p l a c e m e n t r e a c t i o n s occurring during MA have been studied. Reduction of CuO to Cu by a variety of metallic reducing agents was investigated and the powders characterized by X-ray and electron diffraction and microscopy. The addition of a liquid process control agent was found to be n e c e s s a r y to p r e v e n t combustion of the powders. The as-milled p o w d e r c o n s i s t e d of n a n o m e t r e sized crystallites with a highdefect density.
P R O D U C T I O N OF NANO-CRYSTALLINE Ti-Mg ALLOYS BY M E C H A N I C A L ALLOYING ( M A )
C. Suryanaryana and F.H. Froes, (University of Idaho, USA), J MateriaLs Research, Vol 5, No 9, 1990, 1880-188t~,. The p a p e r draws attention to the very low solid solubility of Mg in Ti. The use of MA to process Mg and Ti resulted in the production of nano-crystalline (10-15 nm) p o w d e r s of Mg-Ti solid s o l u t i o n . The material was shown to have a m e t a s t a b l e FCC structure and it is suggested t h a t this is formed as a result of the very heavy deformation of the hop materials, Ti and Mg, d u r i n g MA. The s o l i d s o l u t i o n d e c o m p o s e s into the elemental p h a s e s on heating.
I N T E G R I T Y OF C O M P L E X S H A P E D P R O D U C T S M A D E BY P O W D E R INJECTION MOULDING (PIM)
K.F. ttens et al, (Rensselaer Polytechnic Institute, New York, USA), Powder Metallurgy International, Vol 23, No 1, 1991, 1521. Metal and ceramic a r t e f a c t s were produced by PIM using different binders. The problems encountered during moulding, debinding and sintering were studied. Volume shrinkage, green s t r e n g t h and stress relaxation in process stages are t h e main factors w h i c h d e t e r m i n e t h e success of the PIM process. The problems are said to be solved by optimization of binder composition, moulding p a r a m e t e r s and debinding practice.
PM parts
No 3/4, 1990, 521-529. The use of Ni carbouyl p o w d e r to f a b r i c a t e l i g h t w e i g h t e l e c t r o d e s for a e r o s p a c e a p p l i c a t i o n s is d i s c u s s e d . Comparison is m a d e with a non-woven m a t electrode made from Ni fibre. PM C O M P O N E N T S IN P R O C E S S ENGINEERING
A.X. Kischer and V. Arnhold, (Sintermetallwerk Krebsoge, Germany), Chem Ing Tech, Vol 62, No 4, 1990, 263-270. In German. The diverse a p p l i c a t i o n s of PM are reviewed. E x a m p l e s are drawn from automotive applications, the electrical and electronic industries and chemical industry. Fully dense, as well as porous materials, are considered. Novel applications mentioned include materials for use as catalysts.
Refractory metals STUDY OF S T R U C T U R A L D E F E C T S IN HIGHLY D I S P E R S E D W A N D Mo
P.V. Arifov et al, F/z Chim Obrab Mater, No 3, 1989, 117-120. In Russian. The structure of fine W and Mo powders, obtained by gas p h a s e reactions, has been studied. Changes in the structure after pressing and sintering were observed. It was found t h a t the m o s t common defects were vacant lattice site/oxygen c o m p l e x e s . P o s s i b l e m e c h a n i s m s for the formation of such defects are considered.
S E R V I C E A B I L I T Y OF BINARY SELFLUBRICATING BEARINGS
Y.I. Pustovoit, Poroskovaya Metallurgiya, No 8, 1990, 72 76. In Russian. The durability of sintered Fe-grapitepolyamide plain bearings has been studied together with the structural factors and technological problems of their production. It was found t h a t plain bearings c o n t a i n i n g microporous polymeric inclusions showed increased lubricant migration and e x t e n d e d duration of the period of self lubrication.
P R O D U C T I O N OF A4~-SnO 2 E L E C T R I C A L C O N T A C T M A T E R I A L S BY MECHANICAL ALLOYING (MA)
U S E OF CARBONYL N i P O W D E R IN P R O D U C T I O N OF L I G H T W E I G H T ELECTRODES
A. Verma, (Thapar R & I) ('.entre, Patiala,
D. Coates et al, J. of Powder Sources, Vol 29,
Miscellaneous
POWDER METALLURGY A T T H E INDIAN INSTITUTE TECHNOLOGY KANPUR
G.S. Upadhyaya, (Indian Institute of Technology, Kanpur, I n d i a ) , Int J Powder Metallurgy, Vol 27, No 1, 59-64. The facilities and PM research activities of the D e p a r t m e n t of Metallurgical E n g i n e e r i n g at tile Indian I n s t i t u t e of Technology, Kanpur, are described with p a r t i c u l a r e m p h a s i s on s i n t e r i n g . Thtj e d u c a t i o n a l work of the I n s t i t u t e and e x a m p l e s o f t e c h n o l o g y t r a n s f e r are discussed.
MPR April 1991 55