Comparison of the oxidation behaviour of WC–Co and WC–Ni–Co–Cr cemented carbides

• Published in: Corrosion science 2011-09, Vol.53 (9), p.2754-2760
• Main Authors: Aristizabal, M., Sanchez, J.M., Rodriguez, N., Ibarreta, F., Martinez, R.
• Format: Article
• Language: English
• Subjects: A. Cobalt; A. Metal matrix composites; A. Nickel; Alloys; Applied sciences; C. Oxidation; Cemented carbides; Cermets; Cobalt; Corrosion; Corrosion environments; Exact sciences and technology; Metals. Metallurgy; Oxidation; Oxidation resistance; Scale (corrosion); Tungsten carbide; Tungsten oxides
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2011.05.006

► We analyze the oxidation resistance of several WC based cemented carbides. ► The oxidation resistance of WC–Co and WC–Ni–Co–Cr alloys increases with their metallic content. ► The calculated activation energies suggest that oxidation is controlled by surface chemical reaction. ► Activation energies increase with temperature between 650 °C and 800 °C for both types of alloys. ► This increment is higher for WC–Co materials due to their tendency to form scales with higher tungstate contents. Thermogravimetric experiments confirm that the oxidation resistance of WC–Co and WC–Ni–Co–Cr alloys increases with their metallic content. This is due to the fact that, as the metallic content increases, the oxide scales present higher MWO 4 to WO 3 ratios and lower porosity. The good correlation found between the activation energies calculated by either the isothermal or the isoconversion method suggests that oxidation is controlled by surface chemical reaction. Activation energies increase with temperature between 650 and 800 °C for both WC–Co and WC–Ni–Co–Cr alloys. This increment is higher for WC–Co materials due to their tendency to form scales with higher tungstate contents.