Development Trends of Technology of Ultrafine and Nanosized Hard Alloys WC–Co The Overlook

Abstract

There were considered the main methods of powders WC production: rapid carbothermal reduction (RCR), «calcination – reduction – carbidization» (CRC), reduction of tungsten oxide by carbon at rotary furnace, method of spray conversion process (SCP), self-propagating high-temperature synthesis (SHS), high energy milling and others. There was made analysis of impact of growth inhibition for carbide grain on structure of hard alloys. According to the data of some authors, optimal content of inhibitor is equal to 0,5–1,5 mas.%; in the case of its large quantity has place brittleness of alloy by means of formation of complex carbide phases. There was demonstrated that is impossible obtain nanosized hard alloys ( d WC < 100 nm) by means of traditional solid-state sintering of mixtures – it is need to use alternative solid phase consolidation. There was considered structure, properties and fields of application submicron and nano sized hard alloys, obtaining by means of hot pressing, high frequency induction pressing, electric discharge sintering during plasma pressure consolidation (PPC), spark plasma sintering (SPS) etc.