- Email: [email protected]
Production of powdered metals and alloys by atomization
POWDER PRODUCTION
PRODUCTION OF POWDERED METALS AND ALLOYS BY ATOMIZATION
GRINDING OF HARD ALLOY MIXTURES IN A Q U E O U S MEDIA
V. Prochazka a n d F. Jakcsi, Strojfrenstvi, Vol 39, No 11, 1989, 696-701. In Czech. The various methods for powder p r o d u c t i o n are reviewed. The a p p l i c a t i o n of atomization with high p r e s s u r e nitrogen to produce high speed steels a n d corrosion r e s i s t a n t alloys is reported t o g e t h e r with a w a t e r atomization method.
Zanozin et al, P o r o s k o v a y a Metallurgiya, No 7, 1990, 98-100. In
V.M.
Russian. The grinding of h a r d alloy m i x t u r e s in a liquid m e d i u m ( e t h a n o l ÷ water) h a s been studied. It is established t h a t t h e a d d i t i o n of a s u r f a c t a n t to t h e liquid m e d i u m p e r m i t s t h e p o w d e r s to b e s i z e d by screening after drying w i t h o u t t h e need for a degassing operation. It is shown t h a t t h e mechanical properties of alloys p r o d u c e d from powders processed in this way are c o m p a r a b l e with those ground in e t h a n o l alone.
VIBRATION GRINDING OF POWDERS
Dabizha et al, P o r o s k o v a y a Metallurgiya, No 8, 1990, 6-9. In Russian. A.A.
The efficiencies of different types of ball mill were c o m p a r e d using A1203 as the working material. Vibratory a n d rotary mills a n d a vortex a p p a r a t u s were studied. It was concluded t h a t t h e vibratory type was m o s t suitable for grinding alumina.
POWDER INTERACTIONS DURING NON-STATIONARY SPRAYING
PULVERIZATION OF MOLTEN Sn AND Sn-Cu ALLOYS BY A BLADED ROTOR METHOD
T. Itoh et al, (Nagoya University, J a p a n ) , Trans Iron and Steel Inst Japan, Vol 28, No 7, 1989, 561-568. M o l t e n Sn a n d S n - C u alloys w e r e pulverized by i m p a c t atomization onto a bladed rotor. The properties of t h e powder, p a r t i c l e size a n d d i s t r i b u t i o n , specific surface and particle shape were determined and correlated with the process p a r a m e t e r s . It was shown to be possible to control t h e properties of t h e powder.
CONTROL O F PARTICLE SIZE AND EFFICIENCY OF ELECTROMAGNETIC ENERGY ON E L E C T R O M A G N E T I C ATOMIZATION OF MOLTEN METALS
N.M. Maslovsky; Poroskovaya Metallurgia, No 8, 1990, 59-62. In Russian. The b e h a v i o u r of Ni, Cu, Mo, A1203 a n d WC-Ni p a r t i c l e s d u r i n g h i g h e n e r g y spraying has been investigated. It issuggested that particle-particle i n t e r a c t i o n s r e s u l t in g r i n d i n g a w a y surface layers a n d t h a t blowing away of t h e m o l t e n surface is one of t h e possible m e c h a n i s m s . The effect is r e p o r t e d to increase with increased particle size. The effect of spraying distance was also studied.
S. Ninagawa et al, Tetsu-to-Hagan, Vol 67, No 6, 1990, 863-869. In Japanese. The effects of electric a n d m a g n e t i c fields on t h e process of atomization have been investigated. Closed circuit television was used to m o n i t o r t h e experiments. The p r o b l e m s of c o n t i n u o u s operation of t h e p r o c e s s were studied. A m a t h e m a t i c a l m o d e l was c o n s t r u c t e d for t h e b e t t e r u n d e r s t a n d i n g of t h e process. The effects of process variables on particle size were e s t a b l i s h e d a n d control of size was found to be possible by a d j u s t m e n t of the nozzle/ electrode distance.
CONTROL OF B CONTENT IN AMORPHOUS POWDER PRODUCED BY BOROHYDRIDE REDUCTION
PREPARATION OF METALLIC PARTICLES BY HYDROGEN REDUCTION OF CHLORIDE VAPOURS
D.S. Xue et al, (Lanzhou University, China),
H. Ishikawa et al, (Kawasaki Steel, J a p a n ) , Kawasaki Steel Giho, Vol 21, No 4, 1989, 323-328. In Japanese. Powders of Ag, Cu a n d W were p r e p a r e d by H2 reduction of volatile chlorides. The Ag a n d Cu yielded spherical powders. The W powder was ultrafine a n d polyhedral in s h a p e u n d e r some process conditions.
J. Materials Science Letters, Vol 9, No 5, 1990, 506-508. The p a p e r discusses t h e difficulty in controlling t h e B c o n t e n t of a m o r p h o u s powder p r o d u c e d by borohydride reduction. T h e e f f e c t s of p r o c e s s v a r i a b l e s a r e investigated. Aqueous solutions of NaBH4 or KBH4 were m i x e d by vigorous stirring with a solution of a salt of a divalent metal Fe-B, Fe-Co-B or Fe-Ni-B. The precipitate was washed, dried a n d t h e B c o n t e n t determined. The particles were shown to be a m o r p h o u s by m e a n s of X-ray a n d electron diffraction.
48 MPR April 1991
PRODUCTION OF METAL POWDERS BY ULTRASONIC GAS ATOMIZATION
W. Zolkowski et al, (Niezelaznych Metallurgical Institute, Glwicice, Poland), Metalur-
gia Proszkow, Vol 23, No 2, 1990, 49-54. In Polish.. The principles of ultrasonic gas atomization are outlined and an experimental unit is described. Calculations of pressure d i s t r i b u t i o n are given. The m e a s u r e d results of gas p r e s s u r e as a function of distance from t h e gas orifice a n d gas a n d particle velocities are presented. The powder characteristics a n d solidification rates are given.
MANUFACTURE O F A M O R P H O U S AND MICROCRYSTALLINE ALLOY POWDERS L. Berlinska et al, (Niezelaznych Metallurgical Institute, Glwicice, Poland), Metalurgia Proszkow, Vol 23, No 3, 1990, 79-94. In POlish. An outline is given of the characterization of amorphous and m i c r o c r y s t a l l i n e powders. E x a m p l e s of a p p l i c a t i o n s r e l a t e d to p r o p e r t i e s a r e given as well as principles o f m a n u f a c t u r e of t h e s e powders t o g e t h e r w i t h d e s c r i p t i o n s of t h e t e c h n i q u e s used. C h a r a c t e r i z a t i o n of p r o d u c t s m a d e from t h e s e p o w d e r s is described.
PRESSING AND SlNTERING VOLUME CHANGES IN S I N T E R E D P R O D U C E D FROM SPHERICAL POWDERS
H. Yagi et al, J Japan Soc Powder and Powder Metallurgy, Vol 37, No 8, 1990, 1138-1142. In Japanese. T h e s h r i n k a g e d u r i n g s i n t e r i n g of c o m p a c t s f o r m e d f r o m s p h e r i c a l Cu p o w d e r was studied. 45 to 53~m powder was c o m p a c t e d to a specific density of 0.61 a n d sintered at 1000°C for 3 or 6 hours. The total volume reductions were m e a s u r e d a n d volume r e d u c t i o n ratios calculated. The volume r e d u c t i o n ratio was also calculated from t h e neck growth between particles a s s u m i n g t h a t t h e necks grew by a c o n s t a n t radius interpenetration mechanism and t h a t r e a r r a n g e m e n t of a t o m s d i d n o t occur d u r i n g sintering. Good a g r e e m e n t was found between t h e two sets of values. It was shown t h a t t h e volume reduction d u r i n g sintering was in accordance with t h e a s s u m p t i o n s used in t h e calculation of v o l u m e r e d u c t i o n r a t i o a t t h e specific density used. RADIAL ISOSTATIC COMPACTION O F LONG POROUS PM PARTS L.S. Boginsky et al, Poroskovaya MetaUurgiya, No 8, 1990, 10-14. In Russian. A method for the radial-isostatic pressing of long sizeporous c o m p o n e n t s is described. Use is m a d e of static a n d i m p a c t loading. Production of t u b e s a n d bars, as
PRODUCTION OF POWDERED METALS AND ALLOYS BY ATOMIZATION
GRINDING OF HARD ALLOY MIXTURES IN A Q U E O U S MEDIA
V. Prochazka a n d F. Jakcsi, Strojfrenstvi, Vol 39, No 11, 1989, 696-701. In Czech. The various methods for powder p r o d u c t i o n are reviewed. The a p p l i c a t i o n of atomization with high p r e s s u r e nitrogen to produce high speed steels a n d corrosion r e s i s t a n t alloys is reported t o g e t h e r with a w a t e r atomization method.
Zanozin et al, P o r o s k o v a y a Metallurgiya, No 7, 1990, 98-100. In
V.M.
Russian. The grinding of h a r d alloy m i x t u r e s in a liquid m e d i u m ( e t h a n o l ÷ water) h a s been studied. It is established t h a t t h e a d d i t i o n of a s u r f a c t a n t to t h e liquid m e d i u m p e r m i t s t h e p o w d e r s to b e s i z e d by screening after drying w i t h o u t t h e need for a degassing operation. It is shown t h a t t h e mechanical properties of alloys p r o d u c e d from powders processed in this way are c o m p a r a b l e with those ground in e t h a n o l alone.
VIBRATION GRINDING OF POWDERS
Dabizha et al, P o r o s k o v a y a Metallurgiya, No 8, 1990, 6-9. In Russian. A.A.
The efficiencies of different types of ball mill were c o m p a r e d using A1203 as the working material. Vibratory a n d rotary mills a n d a vortex a p p a r a t u s were studied. It was concluded t h a t t h e vibratory type was m o s t suitable for grinding alumina.
POWDER INTERACTIONS DURING NON-STATIONARY SPRAYING
PULVERIZATION OF MOLTEN Sn AND Sn-Cu ALLOYS BY A BLADED ROTOR METHOD
T. Itoh et al, (Nagoya University, J a p a n ) , Trans Iron and Steel Inst Japan, Vol 28, No 7, 1989, 561-568. M o l t e n Sn a n d S n - C u alloys w e r e pulverized by i m p a c t atomization onto a bladed rotor. The properties of t h e powder, p a r t i c l e size a n d d i s t r i b u t i o n , specific surface and particle shape were determined and correlated with the process p a r a m e t e r s . It was shown to be possible to control t h e properties of t h e powder.
CONTROL O F PARTICLE SIZE AND EFFICIENCY OF ELECTROMAGNETIC ENERGY ON E L E C T R O M A G N E T I C ATOMIZATION OF MOLTEN METALS
N.M. Maslovsky; Poroskovaya Metallurgia, No 8, 1990, 59-62. In Russian. The b e h a v i o u r of Ni, Cu, Mo, A1203 a n d WC-Ni p a r t i c l e s d u r i n g h i g h e n e r g y spraying has been investigated. It issuggested that particle-particle i n t e r a c t i o n s r e s u l t in g r i n d i n g a w a y surface layers a n d t h a t blowing away of t h e m o l t e n surface is one of t h e possible m e c h a n i s m s . The effect is r e p o r t e d to increase with increased particle size. The effect of spraying distance was also studied.
S. Ninagawa et al, Tetsu-to-Hagan, Vol 67, No 6, 1990, 863-869. In Japanese. The effects of electric a n d m a g n e t i c fields on t h e process of atomization have been investigated. Closed circuit television was used to m o n i t o r t h e experiments. The p r o b l e m s of c o n t i n u o u s operation of t h e p r o c e s s were studied. A m a t h e m a t i c a l m o d e l was c o n s t r u c t e d for t h e b e t t e r u n d e r s t a n d i n g of t h e process. The effects of process variables on particle size were e s t a b l i s h e d a n d control of size was found to be possible by a d j u s t m e n t of the nozzle/ electrode distance.
CONTROL OF B CONTENT IN AMORPHOUS POWDER PRODUCED BY BOROHYDRIDE REDUCTION
PREPARATION OF METALLIC PARTICLES BY HYDROGEN REDUCTION OF CHLORIDE VAPOURS
D.S. Xue et al, (Lanzhou University, China),
H. Ishikawa et al, (Kawasaki Steel, J a p a n ) , Kawasaki Steel Giho, Vol 21, No 4, 1989, 323-328. In Japanese. Powders of Ag, Cu a n d W were p r e p a r e d by H2 reduction of volatile chlorides. The Ag a n d Cu yielded spherical powders. The W powder was ultrafine a n d polyhedral in s h a p e u n d e r some process conditions.
J. Materials Science Letters, Vol 9, No 5, 1990, 506-508. The p a p e r discusses t h e difficulty in controlling t h e B c o n t e n t of a m o r p h o u s powder p r o d u c e d by borohydride reduction. T h e e f f e c t s of p r o c e s s v a r i a b l e s a r e investigated. Aqueous solutions of NaBH4 or KBH4 were m i x e d by vigorous stirring with a solution of a salt of a divalent metal Fe-B, Fe-Co-B or Fe-Ni-B. The precipitate was washed, dried a n d t h e B c o n t e n t determined. The particles were shown to be a m o r p h o u s by m e a n s of X-ray a n d electron diffraction.
48 MPR April 1991
PRODUCTION OF METAL POWDERS BY ULTRASONIC GAS ATOMIZATION
W. Zolkowski et al, (Niezelaznych Metallurgical Institute, Glwicice, Poland), Metalur-
gia Proszkow, Vol 23, No 2, 1990, 49-54. In Polish.. The principles of ultrasonic gas atomization are outlined and an experimental unit is described. Calculations of pressure d i s t r i b u t i o n are given. The m e a s u r e d results of gas p r e s s u r e as a function of distance from t h e gas orifice a n d gas a n d particle velocities are presented. The powder characteristics a n d solidification rates are given.
MANUFACTURE O F A M O R P H O U S AND MICROCRYSTALLINE ALLOY POWDERS L. Berlinska et al, (Niezelaznych Metallurgical Institute, Glwicice, Poland), Metalurgia Proszkow, Vol 23, No 3, 1990, 79-94. In POlish. An outline is given of the characterization of amorphous and m i c r o c r y s t a l l i n e powders. E x a m p l e s of a p p l i c a t i o n s r e l a t e d to p r o p e r t i e s a r e given as well as principles o f m a n u f a c t u r e of t h e s e powders t o g e t h e r w i t h d e s c r i p t i o n s of t h e t e c h n i q u e s used. C h a r a c t e r i z a t i o n of p r o d u c t s m a d e from t h e s e p o w d e r s is described.
PRESSING AND SlNTERING VOLUME CHANGES IN S I N T E R E D P R O D U C E D FROM SPHERICAL POWDERS
H. Yagi et al, J Japan Soc Powder and Powder Metallurgy, Vol 37, No 8, 1990, 1138-1142. In Japanese. T h e s h r i n k a g e d u r i n g s i n t e r i n g of c o m p a c t s f o r m e d f r o m s p h e r i c a l Cu p o w d e r was studied. 45 to 53~m powder was c o m p a c t e d to a specific density of 0.61 a n d sintered at 1000°C for 3 or 6 hours. The total volume reductions were m e a s u r e d a n d volume r e d u c t i o n ratios calculated. The volume r e d u c t i o n ratio was also calculated from t h e neck growth between particles a s s u m i n g t h a t t h e necks grew by a c o n s t a n t radius interpenetration mechanism and t h a t r e a r r a n g e m e n t of a t o m s d i d n o t occur d u r i n g sintering. Good a g r e e m e n t was found between t h e two sets of values. It was shown t h a t t h e volume reduction d u r i n g sintering was in accordance with t h e a s s u m p t i o n s used in t h e calculation of v o l u m e r e d u c t i o n r a t i o a t t h e specific density used. RADIAL ISOSTATIC COMPACTION O F LONG POROUS PM PARTS L.S. Boginsky et al, Poroskovaya MetaUurgiya, No 8, 1990, 10-14. In Russian. A method for the radial-isostatic pressing of long sizeporous c o m p o n e n t s is described. Use is m a d e of static a n d i m p a c t loading. Production of t u b e s a n d bars, as