Effect of Cold Isostatic Pressing and VC Grain Growth Inhibitor Addition on WC Grain Size and Mechanical Properties of WC-8Co Cemented Carbide

Abstract

In this study, sub-micron WC-Co cemented carbides were fabricated by cold isostatic pressing using recycled WC powder, Co powder, and VC grain growth inhibitor as the initial composite powders. The raw WC-8Co and WC-8Co-0.3VC compositions were prepared according to conventional technology. After that, part of the green compacts was CIP-ed under pressure of 200 MPa. Sintering was carried out in an industrial vacuum sintering furnace at a temperature of 1420 ºC simultaneously for all samples. The microstructures and properties, including density, coercivity, transverse rupture strength, A-type Rockwell hardness and fracture toughness were investigated, characterized and compared systematically. The experimental results showed that the action of cold isostatic pressing in combination with grain growth inhibitor addition promoted ultrafine grains with the finest WC grain size of 0.68 μm and an increase in the fracture toughness up to 15.4 MPa·m1/2 ± 0.2 compared to rest cemented carbides, showing the techniquehas potential to fabricate cermets with both small average WC grain size and high fracture toughness, which is key in providing excellent performance.