Phase transitions during solid-phase sintering of WC-Co(8%)

Abstract

In this study, the hardmetal powder (WC-Co(8%)), consisting of refractory tungsten carbide (WC) and cobalt (Co) powders (8%), is investigated in order to determine its phase transitions under conditions close to traditional solid-phase sintering at 1450 ○C. Quantitative composition of the WC-Co(8%), WC, Co powders was performed using X-ray microanalysis. The powder’s phase analysis and thermal analysis were conducted using X-ray diffraction and thermogravimetric thermal analysis (TGA)/differential thermal analysis (DTA). Thermal analysis was carried out in an inert argon atmosphere on corundum and platinum-rhodium crucibles with a heating rate of 10 ○C / min. It was found that WC-Co (8%) consists of WC as the primary phase, W2C and α, β - phases of Co as impurities. The thermal analysis revealed an exothermic peak within 250-850 ○C with an increasing mass curve. So, thermal and phase analysis of WC-Co (8%), WC-WC and Co powders after heated to 1450○C makes it possible to establish that Co reacts with crucibles during heated WC-Co (8%) powder made of Al2O and PtRh alloys.