Pseudopartial wetting of WC/WC grain boundaries in cemented carbides

WC-Co cemented carbides are metal-ceramic composites consisting of a ceramic phase, tungsten carbide, and a cobalt binder. The key to the exceptional properties of cemented carbides is the optimal combination of hardness and wear-resistance of WC grains, and toughness and ductility of the Co-based matrix. However, only the minority of WC/WC GBs are completely wetted by Co melt during the liquid phase sintering. We observed for the first time that other WC/WC GBs are not partially wetted and, therefore, “dry”. They are pseudopartially wetted, namely they have the high contact angle with cobalt binder and, nevertheless, contain the 2-3 nm thin uniform Co-rich layer.