Wear Mechanism, Tribological and Anti-Oxidation Properties of Al Doped WC-Co Hardmetals under High Temperature

Combining high energy ball milling and spark plasma sintering (SPS) technologies, (x%Al-WC)-6%Co (x=0.2 or 0.33, atomic fraction) ternary composites were successfully prepared. The tribological properties of Al doped WC-Co at 500, 600 and 700 ℃ in air environment were studied. The matrix of the prepared Al doped WC-Co was coupled by WC and Co, and Al oxidized during the sintering process. Numerous fine Cr₃C₂ and Al₂O₃, as hard phases, dispersed in the matrix. The hardness and fracture toughness of the (0.2Al-WC-6Co) were higher than that of WC-6Co. (0.33Al-WC)-6Co showed low fracture toughness. The formation of brittle tungsten oxides was the main reason of wear loss of Al-WC-Co at high temperature. With the increasing contents of Al, both the high temperature softening resistance and oxidation resistance of the Al-WC-Co were improved, and the spalling and breaking behaviors on the worn surface were reduced. The addition of Al could led to the improvement of the tribological properties of WC hard alloy.