Effect of sintering temperature on the phase composition and microhardness of WC-8 wt % co cemented carbide

The effect of sintering temperature (800-1600 degrees C) on the phase composition, density, and microhardness of WC-8 wt % Co cemented carbide has been studied using x-ray diffraction, scanning electron microscopy, optical microscopy, and density measurements. The results indicate that, during sintering of the starting powder mixture, containing not only WC and Co but also the lower carbide W2C and free carbon, W2C reacts with cobalt metal to form Co3W. At sintering temperatures from 900 to 1200 degrees C, the reaction intermediate is the ternary carbide phase Co6W6C. During sintering at 1300 degrees C, this phase reacts with carbon to form Co3W3C. Sintering at 1000 degrees C and higher temperatures is accompanied by the formation of a cubic solid solution of tungsten carbide in cobalt, beta-Co(WC). The density and microhardness of the sintered samples have been measured as functions of sintering temperature, and the optimal sintering temperature has been determined.