Hot isostatic pressing of ultrafine tungsten carbide-cobalt hardmetals

Hot Isostatic Pressing (HIP) has been successfully used to consolidate tungsten carbide-10 weight% cobalt (WC-10 wt% Co) powders mixtures with WC powder particle sizes in the range of 100 nanometers. Fully dense specimens of this composition have been obtained by HIP at 1000°C, a temperature well below those usually required for reaching the closed porosity stage in the WC-Co system. Conventional processing by vacuum sintering has also been carried out to study the individual effects of high isostatic pressure and vanadium carbide additions on densification and WC grain growth control of these hardmetals. The finest WC mean grain size after sintering has been obtained for the combined action of applied isostatic pressure and vanadium carbide (VC) additions. These results show that VC additions are effective in controlling WC grain growth even at temperatures as low as 1000°C.