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Frictional losses in ultrasonic gas atomization (USGA) nozzles
POWER P R O D U C T I O N 1,
FRICTIONAL L O S S E S IN ULTRASONIC GAS ATOMIZATION ( U S G A ) NOZZLES
A. lJnal. Imperial College, London, UK, Powder Metallurgy, Vol 33, No 3, 1990, 327-333. Attention was drawn to a recent observation t h a t gas flow rates in USGA are less t h a n t h o s e predicted, by a factor as m u c h as 50%, a n d t h a t t h i s was due to a self-adjusting effect in t h e nozzles. It was shown that this explanation was inappropriate. Calculations are p r e s e n t e d in w h i c h t h e nozzle is t r e a t e d as a n adiabatic pipeline with frictionless losses a n d it is shown t h a t operating conditions correspond to subsonic flowwith choking at t h e exit. A p r e s s u r e loss of 36% was c a l c u l a t e d . S u g g e s t i o n s a r e m a d e for minimization of t h e p r e s s u r e loss.
PRODUCTION AND P R O P E R T I E S OF ATOMIZED ALUMINIUM-CHROMIUM ALLOY POWDERS
L ~ P o z n y a k et al. Poroshkovaya Metallurgiya, No 4, 1991, 7-10. (In Russian). A u n i t for the p r o d u c t i o n of No-Cr-A1 alloy p o w d e r s by m e t a l m e l t i n e r t gas a t o m i z a t i o n i n d e s c r i b e d . R e s u l t s of characterization, composition, particle size a n d size d i s t r i b u t i o n a n d m i c r o s t r u c t u r e are p r e s e n t e d a n d discussed.
PRODUCTION OF ULTRAFINE CARBONYL IRON POWDER BY PLASMA-CHEMICAL DECOMPOSITION
V.D.Parkhomenko et al. Poroshkovaya Metallurgiya, No 4, 1991, 10-14. (In Russian). An analysis of Fe p o w d e r m a d e by decomposition of Fe(CO)5 in a plasmachemical reactor, with respect to s t r u c t u r e a n d particle size a n d size distribution, is presented. Kinetics of p o w d e r nucleation a n d growth are described a n d discussed. It was found t h a t t h e initial particle growth was rapid and that the growth rate d i m i n i s h e d with position in t h e reactor. Applications of t h e d a t a o b t a i n e d were demonstrated. OPTIMIZATION OF COPPER ALLOY MELTING FOR POWDER PRODUCTION BY ATOMIZATION
N.S.Sarkisyan et al. Poroshkovaya Metal-
46 MPR December 1991
lurgiya, No 4, 1991, 64-69. (In Russian). Process v a r i a n t s for t h e melting of Cu a n d its alloys p r i o r to a t o m i z a t i o n are discussed. The effects of t i m e of holding t h e melt on homogeneity were investigated as was t h e o p t i m u m use of d e o x i d a t i o n by a B addition. The effects of i m p u r i t y levels in t h e m e l t were d e t e r m i n e d for a wide r a n g e of e l e m e n t s a n d r e l a t e d t o i m p u r i t y d i s t r i b u t i o n a n d diffusion in t h e m o l t e n metal. ATOMIZATION AS A CHEMICAL E N G I N E E R I N G UNIT P R O C E S S
K.Bauckhage. (Univ of Bremen, Germany). Chem. Ing. Tech. Vol 62, No 8, 1990, 613625. (In G e r m a n ) . The m e c h a n i s m s of liquid a t o m i z a t i o n , d i s i n t e g r a t i o n , flow in t h e s p r a y a n d i m p a c t of t h e droplet on to t h e s u b s t r a t e are discussed w i t h regard to particle size distribution. Size d i s t r i b u t i o n is, said to be a d y n a m i c p a r a m e t e r i n w h i c h local changes occur a n d t h e i m p o r t a n c e of t h e s e local effects is emphasized. The effects are a t t r i b u t e d to coalescence, evaporation or chemical reactions. Use of improved instrum e n t a t i o n for m e a s u r e m e n t of particle size d i s t r i b u t i o n m a k e s it possible to use a differential a p p r o a c h to particle size analysis r a t h e r t h a n a n integral one. PRODUCTION OF POWDER BY ATOMIZATION OF MOLTEN METAL WITH LOW TEMPERATURE LIQUID GAS
J.Backer. (Krupp Pulvermetall GmbH, Essen, Germany). Metall, Vol 25, No 8, 1991, 764-771, (In G e r m a n ) . Atomization of Fe a n d Ni using A at 200 ° C is described. The d e v e l o p m e n t s have c o n c e n t r a t e d on nozzle design a n d liquid gas technology a n d on t h e effects of process parameters on characteristics of the powders. The process uses conventional gas a t o m i z a t i o n w i t h a d d i t i o n a l liquid i n e r t gas supply. The p o w d e r is r e p o r t e d to be of high purity, spherical s h a p e a n d to be in t h e size r a n g e 60 to 150 pm. PREPARATION OF TITANIUM CARBIDE POWDER BY S E L F PROPAGATING HIGH TEMPERATURE SYNTHESIS
D-G.Chang et al, (National Univ, Taejon, Korea). J. Korean Inst. of Metals, Vol 29, No 6, 1991,626-630. (In Korean). The high temperature combustion synthesis of TiC from e l e m e n t a l powders was investigated. It was found t h a t t h e purity of t h e TiC was high. Lattice c o n s t a n t s
were m e a s u r e d a n d were found to increase with C content. Particle sizes were in t h e range 2 to 40 ~m. CHANGES IN PHYSICAL P R O P E R T I E S OF ULTRAFINE NICKEL CARBONYL POWDER ON LONG TERM STORAGE
R.Teng, a n d C.Lu. (Central Iron a n d Steel Research Inst, China). J. Iron and Steel Research, Vol 1, No 1, 1989, 49-54. (In Chinese). C h a n g e s in p a r t i c l e size a n d size d i s t r i b u t i o n i n u l t r a f i n e c a r b o n y l Ni powder on long term storage are described a n d discussed. It was found t h a t small particles ( s m a l l e r t h a n 15 n m ) t e n d to d i s a p p e a r a n d t h a t t h e p r o p o r t i o n of mid-size range particles (30 to 80 n m ) increases. This t e n d e n c y was found to be less for increased m e a n particle size. Thus t h e m e a n particle size increases on long t e r m storage. CHANGES IN SPECIFIC SURFACE OF ULTRAFINE CARBONYL NICKEL POWDER ON LONG TERM STORAGE
R.Teng, (Central Iron a n d Steel Research Inst, China). J. Iron and Steel Research, Vol 1, No 2, 1989, 55-60. (In Chinese). The causes of c h a n g e in t h e specific surface of ultrafine Ni p o w d e r on long t e r m s t o r a g e a r e d i s c u s s e d w i t h r e g a r d to changes in m e a n particle size a n d size distribution. Migration of a t o m s is said to be t h e d o m i n a n t m e c h a n i s m in causing changes in t h e particle surface state.
PRESSING MANUFACTURE OF POWDER COMPACTS
A.D.Rosato et al, (New J e r s e y I n s t of Technology, Newark, New Jersey USA). Int, Materials Reviews, Vol 36, No 2, 1991, 4561. The relationships between powder c o m p a c t quality a n d uniformity of particle size d i s t r i b u t i o n within t h e c o m p a c t a n d r e t e n t i o n of refined m i c r o s t r u c t u r e are critically reviewed. The p a p e r deals with t h e creation of uniform green c o m p a c t s from powders and dynamics of the c o n s o l i d a t i o n process w i t h reference to p a r t i c l e size s e g r e g a t i o n i n d u c e d by vibrations and occuring during powder flows. The implications of segregation on t h e f o r m a t i o n of g r e e n c o m p a c t s a r e considered and the formation of
FRICTIONAL L O S S E S IN ULTRASONIC GAS ATOMIZATION ( U S G A ) NOZZLES
A. lJnal. Imperial College, London, UK, Powder Metallurgy, Vol 33, No 3, 1990, 327-333. Attention was drawn to a recent observation t h a t gas flow rates in USGA are less t h a n t h o s e predicted, by a factor as m u c h as 50%, a n d t h a t t h i s was due to a self-adjusting effect in t h e nozzles. It was shown that this explanation was inappropriate. Calculations are p r e s e n t e d in w h i c h t h e nozzle is t r e a t e d as a n adiabatic pipeline with frictionless losses a n d it is shown t h a t operating conditions correspond to subsonic flowwith choking at t h e exit. A p r e s s u r e loss of 36% was c a l c u l a t e d . S u g g e s t i o n s a r e m a d e for minimization of t h e p r e s s u r e loss.
PRODUCTION AND P R O P E R T I E S OF ATOMIZED ALUMINIUM-CHROMIUM ALLOY POWDERS
L ~ P o z n y a k et al. Poroshkovaya Metallurgiya, No 4, 1991, 7-10. (In Russian). A u n i t for the p r o d u c t i o n of No-Cr-A1 alloy p o w d e r s by m e t a l m e l t i n e r t gas a t o m i z a t i o n i n d e s c r i b e d . R e s u l t s of characterization, composition, particle size a n d size d i s t r i b u t i o n a n d m i c r o s t r u c t u r e are p r e s e n t e d a n d discussed.
PRODUCTION OF ULTRAFINE CARBONYL IRON POWDER BY PLASMA-CHEMICAL DECOMPOSITION
V.D.Parkhomenko et al. Poroshkovaya Metallurgiya, No 4, 1991, 10-14. (In Russian). An analysis of Fe p o w d e r m a d e by decomposition of Fe(CO)5 in a plasmachemical reactor, with respect to s t r u c t u r e a n d particle size a n d size distribution, is presented. Kinetics of p o w d e r nucleation a n d growth are described a n d discussed. It was found t h a t t h e initial particle growth was rapid and that the growth rate d i m i n i s h e d with position in t h e reactor. Applications of t h e d a t a o b t a i n e d were demonstrated. OPTIMIZATION OF COPPER ALLOY MELTING FOR POWDER PRODUCTION BY ATOMIZATION
N.S.Sarkisyan et al. Poroshkovaya Metal-
46 MPR December 1991
lurgiya, No 4, 1991, 64-69. (In Russian). Process v a r i a n t s for t h e melting of Cu a n d its alloys p r i o r to a t o m i z a t i o n are discussed. The effects of t i m e of holding t h e melt on homogeneity were investigated as was t h e o p t i m u m use of d e o x i d a t i o n by a B addition. The effects of i m p u r i t y levels in t h e m e l t were d e t e r m i n e d for a wide r a n g e of e l e m e n t s a n d r e l a t e d t o i m p u r i t y d i s t r i b u t i o n a n d diffusion in t h e m o l t e n metal. ATOMIZATION AS A CHEMICAL E N G I N E E R I N G UNIT P R O C E S S
K.Bauckhage. (Univ of Bremen, Germany). Chem. Ing. Tech. Vol 62, No 8, 1990, 613625. (In G e r m a n ) . The m e c h a n i s m s of liquid a t o m i z a t i o n , d i s i n t e g r a t i o n , flow in t h e s p r a y a n d i m p a c t of t h e droplet on to t h e s u b s t r a t e are discussed w i t h regard to particle size distribution. Size d i s t r i b u t i o n is, said to be a d y n a m i c p a r a m e t e r i n w h i c h local changes occur a n d t h e i m p o r t a n c e of t h e s e local effects is emphasized. The effects are a t t r i b u t e d to coalescence, evaporation or chemical reactions. Use of improved instrum e n t a t i o n for m e a s u r e m e n t of particle size d i s t r i b u t i o n m a k e s it possible to use a differential a p p r o a c h to particle size analysis r a t h e r t h a n a n integral one. PRODUCTION OF POWDER BY ATOMIZATION OF MOLTEN METAL WITH LOW TEMPERATURE LIQUID GAS
J.Backer. (Krupp Pulvermetall GmbH, Essen, Germany). Metall, Vol 25, No 8, 1991, 764-771, (In G e r m a n ) . Atomization of Fe a n d Ni using A at 200 ° C is described. The d e v e l o p m e n t s have c o n c e n t r a t e d on nozzle design a n d liquid gas technology a n d on t h e effects of process parameters on characteristics of the powders. The process uses conventional gas a t o m i z a t i o n w i t h a d d i t i o n a l liquid i n e r t gas supply. The p o w d e r is r e p o r t e d to be of high purity, spherical s h a p e a n d to be in t h e size r a n g e 60 to 150 pm. PREPARATION OF TITANIUM CARBIDE POWDER BY S E L F PROPAGATING HIGH TEMPERATURE SYNTHESIS
D-G.Chang et al, (National Univ, Taejon, Korea). J. Korean Inst. of Metals, Vol 29, No 6, 1991,626-630. (In Korean). The high temperature combustion synthesis of TiC from e l e m e n t a l powders was investigated. It was found t h a t t h e purity of t h e TiC was high. Lattice c o n s t a n t s
were m e a s u r e d a n d were found to increase with C content. Particle sizes were in t h e range 2 to 40 ~m. CHANGES IN PHYSICAL P R O P E R T I E S OF ULTRAFINE NICKEL CARBONYL POWDER ON LONG TERM STORAGE
R.Teng, a n d C.Lu. (Central Iron a n d Steel Research Inst, China). J. Iron and Steel Research, Vol 1, No 1, 1989, 49-54. (In Chinese). C h a n g e s in p a r t i c l e size a n d size d i s t r i b u t i o n i n u l t r a f i n e c a r b o n y l Ni powder on long term storage are described a n d discussed. It was found t h a t small particles ( s m a l l e r t h a n 15 n m ) t e n d to d i s a p p e a r a n d t h a t t h e p r o p o r t i o n of mid-size range particles (30 to 80 n m ) increases. This t e n d e n c y was found to be less for increased m e a n particle size. Thus t h e m e a n particle size increases on long t e r m storage. CHANGES IN SPECIFIC SURFACE OF ULTRAFINE CARBONYL NICKEL POWDER ON LONG TERM STORAGE
R.Teng, (Central Iron a n d Steel Research Inst, China). J. Iron and Steel Research, Vol 1, No 2, 1989, 55-60. (In Chinese). The causes of c h a n g e in t h e specific surface of ultrafine Ni p o w d e r on long t e r m s t o r a g e a r e d i s c u s s e d w i t h r e g a r d to changes in m e a n particle size a n d size distribution. Migration of a t o m s is said to be t h e d o m i n a n t m e c h a n i s m in causing changes in t h e particle surface state.
PRESSING MANUFACTURE OF POWDER COMPACTS
A.D.Rosato et al, (New J e r s e y I n s t of Technology, Newark, New Jersey USA). Int, Materials Reviews, Vol 36, No 2, 1991, 4561. The relationships between powder c o m p a c t quality a n d uniformity of particle size d i s t r i b u t i o n within t h e c o m p a c t a n d r e t e n t i o n of refined m i c r o s t r u c t u r e are critically reviewed. The p a p e r deals with t h e creation of uniform green c o m p a c t s from powders and dynamics of the c o n s o l i d a t i o n process w i t h reference to p a r t i c l e size s e g r e g a t i o n i n d u c e d by vibrations and occuring during powder flows. The implications of segregation on t h e f o r m a t i o n of g r e e n c o m p a c t s a r e considered and the formation of