Graded hardmetals and cermets

Application of physical vapour deposition

to 1 5 0 0 ° C to d e t e r m i n e t h e u p t a k e o f N and structures developed. Four struc-

T.Hornig eral, (RWTH, Aachen. Germany.)

t u r e s w e r e f o u n d in T i . W ( C , N ) , a sin glc p h a s e in s a m p l e s o f h i g h T i N a n d t o w \'~'C, a c o r e / r i m s t r u c t u r e in a t medium WC and high TiN:TiC ratio, a sub-micron lamellar structure and a s t r u c t u r e w i t h W C in t h e o u t e r case.

Wide a p p l i c a t i o n o f c o a t i n g s a p p l i e d by physical vapour deposmon

were n o t e d .

The paper described an advanccd PVD hardcoating which allowed machining of a r a n g e of h a r d e n e d steels, h a r d m e t a l s and composites, with envh-onmentatly compatible lubricants. The coatings had g o o d r e s i s t a n c e to o x i d a t i o n a n d a b r a sive weal'.

Submicron and ultrafine grained hardmetals for microdrills and metal cutting inserts

GoGilleetal. (H.C,Starck GrnbH, Gosla~ Germany,) R e c e n t d e v e l o p m e n t s {p u l t r a [ i n e g r a i n hardmetals were

for m i c r o d r i l l

dcscribcd.

Based

applications

on

optimised

processing and properties a new generau o n o f drills w a s d e s c r i b e d It w a s shown that the faihn'e rate was conside r a b l y r e d u c e d a n d drill life i n c r e a s e d . A new material, WC-10%Co, with lwt% mixed VC-Cr3C2.

doped 0.1ram

W C i n t e r c e p t a n d Vicker's h a r d n e s s o f 2050 w a s p r e s e n t e d .

K.Drever etal, {Widia GmbH, Essen, GermanyJ of graded structures m during sintering, were

investigated. Factors studied were sintering time, temperature and profile and p r c s s u r e o f N. T h e e f f e c t s o f t h e s e fact o r s w e r e d e s c r i b e d . It w a s f o u n d t h a t a s u b s t a n t i a l c a r b o n i t r i d e layer is f o r m e d o n s i n t e r e d c e m e n t e d c a r b i d e s . T h e labo r a t o r y e x p e r i m e n t s were s c a l e d u p to industrial conditions. Cutting rests showed that the graded tools had good performance.

Near surface microstructural modification of titanium-tungsten carb0nitrides with nitrogen

W,Lengauer et at, [Vienna University of Technology, Vienna, Austria,) It

was

reported

that

hot

pressed

Ti,W C.N compacts and sintered (Ti,W C.N-Co compacts had been h e a r t r e a t e d in N at 3 0 b a r a n d 1 2 0 0 ° C

~6

~

d u e ~o t h e in d i f f u s i o n o f N. S a m p l e s w i t h C o were h e a t e d a b o v e a n d b e l o w t h e eutect~c t e m p e r a t u r e . T h e s t r u c t u r e s depended on composition and cont a i n e d Yi C , N ) .

Gradient structures in hardmetals

April 2003

PM steels end stai~{ess stee[s Corrosion resistant gears for water hydraulic pumps

C.Bonjour etal. (University of Applied Sciences of Western Switzerland. Sion, Switzerland,) T m p o r r a m p r o p e r t i e s o f alloys for w a t e r p u m p s were o u t l i n e d as h i g h c o r r o s i o n

VoRichter, M,von RuthendorL (fraunhofer lust, IKTS, Dresden, Germany,)

resistance and good strength, wear and c a v i t a t i o n r e s i s t a n c e . Finite e l e m e n t a n a l y s i s w a s u s e d to c a l c u l a t e f o r m s a n d

G r a d e d s t r u c t u r e s in c e m e n t e d c a r b i d e s were reviewed w i t h r e g a r d to m e t h o d s o f p r o d u c i n g these. G r a d i e n t f o r m a t i o n w a s

sizes a n d to m o d e l w e a r a n d c a v i t a t i o n zones. P a r t s were m a d e by P M f r o m a r a n g e o f s t a i n l e s s steel p o w d e r s w i t h

m v e s u g a t e d for s a m p l e s o f W C - C o - c a r bon black of various composition-and W C g r a m size. H o m o g e n e o u s a n d twol a y e r f r a c t u r e b a r s were p r o d u c e d .

a d d i t i o n o f s i n t e r i n g aids a n d Ni a n d C u to reduce porosity. Effccts o f l u b r i c a n t o n green density were invesngated.

Densification, mechanical properties and c o m p o s m o n profiles were i n v e s t i g a t e d . . L a r g e C o g r a d i e n t s , up co 1 0 m m thick.

Graded hardmetals and cermets

Production hardmetals,

The case contained compressive stresses

P r o p e r t i e s o f p a r t s were m e a s u r e d .

Effects of porosity and thermal diffusivity on hardenability of PM steels

c o u l d be o b t a i n e d by differences in W C particle size w i t h differences m Vicker's h a r d n e s s o f u p to 500 p o i n t s .

S~Saritas etal, (Gazi University, Ankara, Turkey,)

Mass spectroscopic study of decarburisation of cemented carbonitrides during sintering

c u s s e d . Pores r e d u c e t h e r m a l c o n d u c t i v i t y a n d t h u s a n d lowers c o o l i n g rare a n d

Effects o f p o r e s in sintered steels o n t h e r m a l r e s p o n s e a n d h a r d e n a b i t i t y were dis

It w a s r e p o r t e d t h a t m a s s s p c c t r o s c o p y h a d been u s e d to s t u d y t h e e v o l u t i o n o f

decreases t h e a m o u n t o f h e a t r e m o v e d . A n c x p c r i m c n t a l a n d m o d e l l i n g study, of t h r e e steels, was described. J o m i n y e n d q u e n c h b a r s w e r e cold i s o s t a t i c a l l y p r e s s e d a n d sintered. C o o l i n g d u r i n g endq u e n c h i n g w a s m o n i t o r e d by a n a r r a y of

g a s e s , as f u n c t i o n s of t i m e a n d t e m p e r a t u r e , m t h e r a n g e 4 9 0 o C co 1 4 8 0 o C , from cemented carbonitrides during vacuum sinterlng. De-gassing rates

thermocouples along the length. E x p e r i m e n t a l d a t a were c o m p a r e d w i t h m o d e l p r e d i c t i o n s . D i f f e r e n c e s were f o u n d w h i c h were a t t r i b u t e d to w a t e r

c o u l d be i n t e g r a t e d t o y i c l d d a t a c o n c o m i n g l o s s e s o f C a n d N. T h e r e was

a b s o r p t i o n into i n t e r c o n n e c t i n g p o r e s .

g r e a t e r toss f r o m ( T i , \ V ) ( C . N d u e t o i n c r e a s e d activity of N c a u s e d by W. T i N s h o w e d loss onl) in p r e s e n c e o f

Sinterlng alloy homogenisation and microstructurai deve|opment in PM nickebchromium-manganese steels

j,Garcia. W.Lengauer, Nienna University 0 f Techn010gg. Vienna. Austria.)

b i n d e r . For p o w d e r

mixtures

t h e loss

on CO, CO2 and N increased with addition of Co. N containing cermets

ECastro etal, (University of Navarra. San Sebastian, Spain,)

s h o w e d g r e a t e r loss of C t h a n materials.

A r a n g e o f F e - N i - C r - M n - C stecls were cold pressed f r o m p o w d e r a n d sintered in

(Ti,W)C

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