Developmental tendencies of technology of ultradispersed and nanosized WC–Co hard alloys alloyed with tantalum carbide: Review

Abstract

The main production methods of WC powders, notably, rapid carbothermic reduction (RCR), “calcination–reduction–carburization” (CRC), reduction of tungsten oxide with carbon in rotating furnaces, spray conversion process (SCP), high-energy milling, etc., are considered. The influence of growth inhibitors of the carbide grain on the structure of hard alloys is analyzed. According to the data of some authors, the optimal inhibitor content is 0.5–1.5 wt %, and the alloy embrittles at its higher content due to the formation of complex carbide phases. It is shown that nanosized hard alloys (dWC < 100 nm) cannot be prepared by the traditional liquid-phase sintering the mixtures, and the application of alternative solid-phase consolidation methods is necessary. The structure, properties, and application regions of submicron and nanosized hard alloys fabricated by hot pressing, high-frequency induction pressing, electric discharge sintering under the plasma pressure consolidation (PPC), spark plasma sintering (SPS), etc., are considered.