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property relationships of sintered hard materials
PM
conditions. The alloy was fabricated from Zn-22%A1 a n d Zn-22%Al-l%Cu-o.03%Mg prealloyed powders m i x e d with 50% of a s t r o n t i u m ferromagnetic powder w h i c h was h o t p r e s s e d a t 420°C a n d 300 MPa w h i c h yielded a m a t e r i a l with a cold crushing s t r e n g t h of 157 MPa.
A STUDY O F SILVER-NICKEL ELECTRICAL CONTACT MATERIALS L J a n q i o n g et al, (Guilin Research Inst. for Electrical Appliance Science, China.) PM Technology, Vol 9, No 4, 1991, 209-214. (In Chinese.) The production of Ag-Ni contact m a t e r i a l s is discussed. C o m p a c t s were m a d e with Ni a d d e d in t h e form of fibres a n d t h e effects of fibre orientation, parallel or p e r p e n d i c u l a r to t h e contacting surfaces, on t h e properties were determined. The optimum process conditions were established. The m a t e r i a l s were r e p o r t e d to give satisfactory service lives in t h e i n t e n d e d applications, BONDED FERRITE PERMANENT MAGNETS L.Qiren, (University of Science a n d Technology, Shanghai, China.) PM Technology,
Vol 9, No 4, 1991, 228-232. (In Chinese.) The characteristics, applications, p r o d u c t i o n a n d p r o b l e m s in p r o d u c t i o n of b o n d e d ferrite p e r m a n e n t m a g n e t s a r e r e v i e w e d . A t t e n t i o n is d r a w n to t h e v e r s a t i l i t y of t h e m a t e r i a l s for a wide range of applications. EFFECTS OF CHLORIDE ADDITIONS ON R E D U C T I O N - D I F F U S I O N P R O C E S S I N G O F IRON-NEODYMIUMBORON POWDERS C J . C h e n et al.(Industrial Technology Research Ins., Taiwan.) MRL Bull. Research and development, Vol 4, No2, 1990, 29-35. The use of t h e chlorides of Nd a n d Ca i n s t e a d of Nd203 in t h e processing of FeNd-B p o w d e r alloys is evaluated a n d a s t u d y of m e c h a n i s m s reported. It was found t h a t t h e Fe14Nd2B particles were coated with CaC12, Ca0 a n d Ca w h e n t h e chloride c o n t e n t e x c e e d e d 10%. P r o c e s s i n g was r e p o r t e d to reduce t h e Ca c o n t e n t to 400 to 8 0 0 p p m a n t h e 0 c o n t e n t to 2600 to 4000ppm. The m a t e r i a l s were found to have good magnetic properties,
NARD MATERIALS AND TOOL
STEELS
D E N S I F I C A T I O N AND P R O P E R T I E S O F MATERIALS BASED ON SILICON CARBIDE AND SILICON N I T R I D E S.Boskovic et al. (Boris Kidric Institute, Belgrade,Yugoslavia.) Science of Sintering, Vol 23, No 3, 1991, 183-191. The properties of SiC a n d Si3N 4 h a r d
52 MPR April 1992
LITERATURE
REVIEW
materials were discussed in t e r m s of t h e high h a r d n e s s of b o t h c o m p o u n d s a n d t h e high t h e r m a l shock resistance of SiC a n d t h e t o u g h n e s s of Si3N4. The densification of t h e c o m p o u n d s d u r i n g h o t pressing a n d sintering was investigated a n d t h e effect of oxide a n d non-oxide sintering aid a d d i t i o n s s t u d i e d . H i g h d e n s i t i e s of t h e t w o c o m p o u n d s separately was a t t a i n e d by t h e use of sintering aids, oxides of A1, Y a n d Dy, O p t i m u m c o n c e n t r a t i o n s of sintering aids were, for SiC, 1.5% a n d 10% for sintering at 1900 a n d 1950C respectively. A d d i t i o n of Zr02 was found to increase t h e t o u g h n e s s of Si3N4. VACUUM TECHNOLOGY FOR DIAMOND TOOLMAKING E.D.Kizikov. (Institute for S u p e r h a r d Materials Ukraine Academy of Sciencs, Kiev, USSR.) Powder Metallurgy Science and Technology, Vol 2, No 4, 1991, 21-29. An outline of t h e principles of v a c u u m s i n t e r i n g of d i a m o n d i m p r e g n a t e d tool materials is presented. As a result of close control t h e process is r e p o r t e d to be more efficient t h a n t h e conventional press-ands i n t e r route. N E W H E A T R E S I S T A N T TOOL MATERIALS P R O D U C E D FROM D E V I T R I F I E D A M O R P H O U S IRON BASE ALLOY POWDERS L.Arnberg et al ( S w e d i s h I n s t i t u t e for Metals Research, Stockholm Sweden.) Materials Science and Engineering A, Vol A133, 1991, 288-291. M a i n l y a m o r p h o u s h i g h alloy s t e e l powders of Fe-16at%Cr-8%Mo-18%C-4%(B or V) were p r o d u c e d by a t o m i s a t i o n with particle sizes less t h a n 25 ~m. The alloys crystallised d u r i n g c o n s o l i d a t i o n by h o t p r e s s i n g a t 1080°C a n d t h e s t r u c t u r e s c o m p r i s e d c a r b i d e s a n d b o r i d e s in a ferritic or m a r t e n s i t i c m a t r i x . Vicker's hardness up to 1250°C at room t e m p e r a t u r e a n d in t h e r a n g e 600 to 950 a t 600°C were measured. The alloys were found to r e s p o n d to h e a t t r e a t m e n t . It is suggested t h a t t h e alloys have p o t e n t i a l for use as h e a t r e s i s t a n t tool m a t e r i a l s or for wear r e s i s t a n t applications, E F F E C T O F BONDING METALS ON S T R E N G T H O F S I N T E R E D SYNTHETIC DIAMOND TOOL MATERIALS T.Fujimori et al. ( C h i b a Ins. of Technology, Chiba, J a p a n . ) J.Japan Soc, Powder and Powder Metallurgy, Vol 38, No 5, 1991, 586590. (In Japanese.) A t t e n t i o n is d r a w n to t h e loss of s t r e n g t h of d i a m o n d p a r t i c l e s a f t e r sintering in m e t a l c e m e n t e d toll materials. The s t r e n g t h of single d i a m o n d particles, before a n d after h e a t i n g to t h e sintering t e m p e r a t u r e a n d t h e t h e r m a l b e h a v i o u r of the diamond were investigated. The deterioration of t h e p r o p e r t i e s is r e p o r t e d to be due to t h e d e v e l o p m e n t of r o u g h surfaces on t h e d i a m o n d by reaction with
t h e m e t a l m a t r i x a n d t h a t t h i s can be m i n i m i s e d by coating t h e d i a m o n d p r i o r to i n c o r p o r a t i o n in t h e m e t a l matrix. FLAKING O F ALUMINA-TITANIUM CARBIDE C U T T I N G TOOL MATERIALS Y.Katsumura et al. (Toshiba Tungaloy Co. Ltd., Kawasaki, Japan.) J.Japan Soc.Powder and Powder Metallurgy,Vol 38, No 5, 1991, 591-596. (In J a p a n e s e . ) A1203-(10 to 50) a t %TiC c o m p a c t were p r e p a r e d from powder by h o t pressing a n d t h e n subjected to t u r n i n g t e s t s to s t u d y t h e incidence of flaking of t h e tools. Low a n d high TiC specimens with coarse TiC grains showed low resistance to failure by flaking and it was established that flaking originated a t surface microcracks. Surface a n d flank wear a n d surface p r e - h o n i n g were investigated as a function of TiC c o n t e n t and theincidenceofflaking. A P P L I C A T I O N S O F QUANTITATIVE I M A G E ANALYSIS TO STUDY O F STRUCTURE/PROPERTY R E L A T I O N S H I P S O F S I N T E R E D HARD MATERIALS M.Komai et al. (Toyo K o n a n Co.Ltd., Kudamatsu, J a p a n . ) J.Japan Soc. Powder and Powder Metallurgy, Vol 38, No 5, 1991, 614-620. (In J a p a n e s e . ) An investigation into the fracture b e h a v i o u r of TiC d u r i n g b a l l m i l l i n g is described. It is r e p o r t e d t h a t t h e particles f r a c t u r e p r e f e r e n t i a l l y a l o n g t h e (602) p l a n e s w h i c h r e s u l t e d in TiC-Mo2C-Ni alloy containing p l a t e s h a p e d TiC particles. A reaction between t h e carbide particles a n d t h e m a t r i x is also noted. MORPHOLOGY O F T I T A N I U M C A R B I D E S IN N I C K E L C E M E N T E D CERMETS O.Terada et al. (Fuji Die Co. Ltd., tokyo, J a p a n . ) J.Japan Soc. Powder and Powder Metallurgy, Vol 38, No 5, 1991, 610-613. (In Japanese.) The a p p l i c a t i o n of q u a n t i t a t i v e image analysis to electron microscopy of h a r d materials, scattered electron images, i m p r o v e s t h e d e t e r m i n a t i o n of m e a n p a r t i c l e size, c o n t i g u i t y , a n d p a r t i c l e a s p e c t r a t i o h a s b e e n d e v e l o p e d . Itis s h o w n t h a t t h e o b s e r v e d r e d u c t i o n in transverse rupture strength of the m a t e r i a l a t tow sintering t e m p e r a t u r e s can be a t t r i b u t e d to t h e coalescence of h a r d particles. SLIDING WEAR C H A R A C T E R I S T I C S O F IRON-BEARING B O R I D E BASE C E R M E T S AGAINST ALLOY S T E E L S T.Watanabel et al, (Tokyo Kohan Co. Ltd., Kudamatus, J a p a n . ) J.Japan Soc.Powder and Powder Metallurgy, Vol 38, No 5, 1991, 621-626. (In J a p a n e s e . ) A block-on-ring dry wear test was carried o u t to assess t h e wear p r o p e r t i e s
conditions. The alloy was fabricated from Zn-22%A1 a n d Zn-22%Al-l%Cu-o.03%Mg prealloyed powders m i x e d with 50% of a s t r o n t i u m ferromagnetic powder w h i c h was h o t p r e s s e d a t 420°C a n d 300 MPa w h i c h yielded a m a t e r i a l with a cold crushing s t r e n g t h of 157 MPa.
A STUDY O F SILVER-NICKEL ELECTRICAL CONTACT MATERIALS L J a n q i o n g et al, (Guilin Research Inst. for Electrical Appliance Science, China.) PM Technology, Vol 9, No 4, 1991, 209-214. (In Chinese.) The production of Ag-Ni contact m a t e r i a l s is discussed. C o m p a c t s were m a d e with Ni a d d e d in t h e form of fibres a n d t h e effects of fibre orientation, parallel or p e r p e n d i c u l a r to t h e contacting surfaces, on t h e properties were determined. The optimum process conditions were established. The m a t e r i a l s were r e p o r t e d to give satisfactory service lives in t h e i n t e n d e d applications, BONDED FERRITE PERMANENT MAGNETS L.Qiren, (University of Science a n d Technology, Shanghai, China.) PM Technology,
Vol 9, No 4, 1991, 228-232. (In Chinese.) The characteristics, applications, p r o d u c t i o n a n d p r o b l e m s in p r o d u c t i o n of b o n d e d ferrite p e r m a n e n t m a g n e t s a r e r e v i e w e d . A t t e n t i o n is d r a w n to t h e v e r s a t i l i t y of t h e m a t e r i a l s for a wide range of applications. EFFECTS OF CHLORIDE ADDITIONS ON R E D U C T I O N - D I F F U S I O N P R O C E S S I N G O F IRON-NEODYMIUMBORON POWDERS C J . C h e n et al.(Industrial Technology Research Ins., Taiwan.) MRL Bull. Research and development, Vol 4, No2, 1990, 29-35. The use of t h e chlorides of Nd a n d Ca i n s t e a d of Nd203 in t h e processing of FeNd-B p o w d e r alloys is evaluated a n d a s t u d y of m e c h a n i s m s reported. It was found t h a t t h e Fe14Nd2B particles were coated with CaC12, Ca0 a n d Ca w h e n t h e chloride c o n t e n t e x c e e d e d 10%. P r o c e s s i n g was r e p o r t e d to reduce t h e Ca c o n t e n t to 400 to 8 0 0 p p m a n t h e 0 c o n t e n t to 2600 to 4000ppm. The m a t e r i a l s were found to have good magnetic properties,
NARD MATERIALS AND TOOL
STEELS
D E N S I F I C A T I O N AND P R O P E R T I E S O F MATERIALS BASED ON SILICON CARBIDE AND SILICON N I T R I D E S.Boskovic et al. (Boris Kidric Institute, Belgrade,Yugoslavia.) Science of Sintering, Vol 23, No 3, 1991, 183-191. The properties of SiC a n d Si3N 4 h a r d
52 MPR April 1992
LITERATURE
REVIEW
materials were discussed in t e r m s of t h e high h a r d n e s s of b o t h c o m p o u n d s a n d t h e high t h e r m a l shock resistance of SiC a n d t h e t o u g h n e s s of Si3N4. The densification of t h e c o m p o u n d s d u r i n g h o t pressing a n d sintering was investigated a n d t h e effect of oxide a n d non-oxide sintering aid a d d i t i o n s s t u d i e d . H i g h d e n s i t i e s of t h e t w o c o m p o u n d s separately was a t t a i n e d by t h e use of sintering aids, oxides of A1, Y a n d Dy, O p t i m u m c o n c e n t r a t i o n s of sintering aids were, for SiC, 1.5% a n d 10% for sintering at 1900 a n d 1950C respectively. A d d i t i o n of Zr02 was found to increase t h e t o u g h n e s s of Si3N4. VACUUM TECHNOLOGY FOR DIAMOND TOOLMAKING E.D.Kizikov. (Institute for S u p e r h a r d Materials Ukraine Academy of Sciencs, Kiev, USSR.) Powder Metallurgy Science and Technology, Vol 2, No 4, 1991, 21-29. An outline of t h e principles of v a c u u m s i n t e r i n g of d i a m o n d i m p r e g n a t e d tool materials is presented. As a result of close control t h e process is r e p o r t e d to be more efficient t h a n t h e conventional press-ands i n t e r route. N E W H E A T R E S I S T A N T TOOL MATERIALS P R O D U C E D FROM D E V I T R I F I E D A M O R P H O U S IRON BASE ALLOY POWDERS L.Arnberg et al ( S w e d i s h I n s t i t u t e for Metals Research, Stockholm Sweden.) Materials Science and Engineering A, Vol A133, 1991, 288-291. M a i n l y a m o r p h o u s h i g h alloy s t e e l powders of Fe-16at%Cr-8%Mo-18%C-4%(B or V) were p r o d u c e d by a t o m i s a t i o n with particle sizes less t h a n 25 ~m. The alloys crystallised d u r i n g c o n s o l i d a t i o n by h o t p r e s s i n g a t 1080°C a n d t h e s t r u c t u r e s c o m p r i s e d c a r b i d e s a n d b o r i d e s in a ferritic or m a r t e n s i t i c m a t r i x . Vicker's hardness up to 1250°C at room t e m p e r a t u r e a n d in t h e r a n g e 600 to 950 a t 600°C were measured. The alloys were found to r e s p o n d to h e a t t r e a t m e n t . It is suggested t h a t t h e alloys have p o t e n t i a l for use as h e a t r e s i s t a n t tool m a t e r i a l s or for wear r e s i s t a n t applications, E F F E C T O F BONDING METALS ON S T R E N G T H O F S I N T E R E D SYNTHETIC DIAMOND TOOL MATERIALS T.Fujimori et al. ( C h i b a Ins. of Technology, Chiba, J a p a n . ) J.Japan Soc, Powder and Powder Metallurgy, Vol 38, No 5, 1991, 586590. (In Japanese.) A t t e n t i o n is d r a w n to t h e loss of s t r e n g t h of d i a m o n d p a r t i c l e s a f t e r sintering in m e t a l c e m e n t e d toll materials. The s t r e n g t h of single d i a m o n d particles, before a n d after h e a t i n g to t h e sintering t e m p e r a t u r e a n d t h e t h e r m a l b e h a v i o u r of the diamond were investigated. The deterioration of t h e p r o p e r t i e s is r e p o r t e d to be due to t h e d e v e l o p m e n t of r o u g h surfaces on t h e d i a m o n d by reaction with
t h e m e t a l m a t r i x a n d t h a t t h i s can be m i n i m i s e d by coating t h e d i a m o n d p r i o r to i n c o r p o r a t i o n in t h e m e t a l matrix. FLAKING O F ALUMINA-TITANIUM CARBIDE C U T T I N G TOOL MATERIALS Y.Katsumura et al. (Toshiba Tungaloy Co. Ltd., Kawasaki, Japan.) J.Japan Soc.Powder and Powder Metallurgy,Vol 38, No 5, 1991, 591-596. (In J a p a n e s e . ) A1203-(10 to 50) a t %TiC c o m p a c t were p r e p a r e d from powder by h o t pressing a n d t h e n subjected to t u r n i n g t e s t s to s t u d y t h e incidence of flaking of t h e tools. Low a n d high TiC specimens with coarse TiC grains showed low resistance to failure by flaking and it was established that flaking originated a t surface microcracks. Surface a n d flank wear a n d surface p r e - h o n i n g were investigated as a function of TiC c o n t e n t and theincidenceofflaking. A P P L I C A T I O N S O F QUANTITATIVE I M A G E ANALYSIS TO STUDY O F STRUCTURE/PROPERTY R E L A T I O N S H I P S O F S I N T E R E D HARD MATERIALS M.Komai et al. (Toyo K o n a n Co.Ltd., Kudamatsu, J a p a n . ) J.Japan Soc. Powder and Powder Metallurgy, Vol 38, No 5, 1991, 614-620. (In J a p a n e s e . ) An investigation into the fracture b e h a v i o u r of TiC d u r i n g b a l l m i l l i n g is described. It is r e p o r t e d t h a t t h e particles f r a c t u r e p r e f e r e n t i a l l y a l o n g t h e (602) p l a n e s w h i c h r e s u l t e d in TiC-Mo2C-Ni alloy containing p l a t e s h a p e d TiC particles. A reaction between t h e carbide particles a n d t h e m a t r i x is also noted. MORPHOLOGY O F T I T A N I U M C A R B I D E S IN N I C K E L C E M E N T E D CERMETS O.Terada et al. (Fuji Die Co. Ltd., tokyo, J a p a n . ) J.Japan Soc. Powder and Powder Metallurgy, Vol 38, No 5, 1991, 610-613. (In Japanese.) The a p p l i c a t i o n of q u a n t i t a t i v e image analysis to electron microscopy of h a r d materials, scattered electron images, i m p r o v e s t h e d e t e r m i n a t i o n of m e a n p a r t i c l e size, c o n t i g u i t y , a n d p a r t i c l e a s p e c t r a t i o h a s b e e n d e v e l o p e d . Itis s h o w n t h a t t h e o b s e r v e d r e d u c t i o n in transverse rupture strength of the m a t e r i a l a t tow sintering t e m p e r a t u r e s can be a t t r i b u t e d to t h e coalescence of h a r d particles. SLIDING WEAR C H A R A C T E R I S T I C S O F IRON-BEARING B O R I D E BASE C E R M E T S AGAINST ALLOY S T E E L S T.Watanabel et al, (Tokyo Kohan Co. Ltd., Kudamatus, J a p a n . ) J.Japan Soc.Powder and Powder Metallurgy, Vol 38, No 5, 1991, 621-626. (In J a p a n e s e . ) A block-on-ring dry wear test was carried o u t to assess t h e wear p r o p e r t i e s