Effect of cobalt on the synthesis and sintering of WC-Co composite powders

Abstract

With the in-situ addition of cobalt, not only the carbothermal reduction of WC‒Co composite powder, but also its sintering was greatly promoted. It was found that the formation of CoWO4 could reduce the oxygen pressure in the system to 10−20 atm, which significantly accelerates the reduction process. Co3W3C, which was obtained from CoWO4 and WO2, enhanced the carburization reaction of W2C through the dissolution and precipitation of the grains. The sintering of the resulting WC‒Co composite powder was completed within only 360 s by solid state sintering at under 1300 °C. The excellent sinterability of the powder is attributed to a uniform distribution of thin Co film between WC grains.