Patent ID: RE40962

Claim:
A method of making a coated cemented carbide body having a gamma phase-free and binder rich surface zone comprising the steps of: (i) forming a powder mixture comprising WC, 5-12 wt. % Co, 3-11 wt. % cubic carbides of Ta and Ti, where the ratio of Ta/Ti is 1.0-4.0; (ii) adding N in an amount of 0.6-2.0% of the weight of Ta and Ti; (iii) milling and spray drying the mixture to form a powder material with the desired properties; (iv) compacting and sintering the powder material at a temperature of 1300-1500° C., in a controlled atmosphere of about 50 mbar followed by cooling, whereby a body having a binder phase enriched and essentially gamma phase free surface zone of 5-50 μm in thickness is obtained; (v) applying a pre-coating treatment to the body; and (vi) applying a hard, wear resistant coating.