Investigation on sintering principle of ultra-fine cemented carbide prepared by WC-6Co composite powder

Abstract

Ultra-fine WC-10Co cemented carbides have been prepared based on WC-6Co composite powder, using the vacuum sintering method. The effect of sintering temperature on morphology and properties of the WC-10Co cemented carbide has been studied. The WC grains got together and the crystal structure becomes completed, at the sintering temperature within 1150 °C−1250 °C that is 50 °C lower than conventional sintering temperature. The eutectic temperature appears to be within 1250 °C−1300 °C, whereas the liquid phase sintering temperature constitutes 1300 °C−1350 °C. The sintering process curve has been determined by combining the TG-DSC curve and properties of the cemented carbide prepared by vacuum sintering at different temperatures. The alloy coercive magnetic force has been found to constitute 29.98 kA m−1, HV30 is equal to 1850 MPa, and TRS 4453 MPa, average grain size of the WC is equal to 0.4 μm when pressurizing in furnace under 5 MPa (low-pressure sintering) in argon atmosphere at 1340 °C. The low-pressure sintering increases the alloy density, strength, hardness, coercive magnetic force and the number of WC/Co grain boundaries as well as decreases porosity and provides a uniform distribution of Co phase.