Effect of 1.5TiC/1.5TiC + 0.6 Ce2O3 addition on the oxidation behavior of WC-Cu-10Ni-5Mn-3Sn cemented carbides

Abstract

The oxidation experiments on WC-Cu-10Ni-5Mn-3Sn-1.5TiC and WC-Cu-10Ni-5Mn-3Sn-1.5TiC-0.6Ce₂O₃ materials were carried out for 2 h, 4 h, 6 h, 8 h, and 10 h in the temperature range of 500–800 °C, respectively, to elucidate the effects of oxidation temperatures and times on the properties of cemented carbides. The evolution laws of oxidation products and oxide layer microstructure of WC-Cu-10Ni-5Mn-3Sn-1.5TiC-0.6 Ce₂O₃ cemented carbide material with the change of temperature and time were mainly investigated. The oxidation behavior and oxidation mechanism were analyzed in combination with the oxidation kinetics and thermodynamics of the formation of oxidation products. The results revealed that the addition of Ce₂O₃ improved the oxidation resistance of the cemented carbide material at 500–800 °C after 2–10 h of heat treatment. With the increase of oxidation temperature or the prolongation of oxidation time at the same temperature, the oxidation resistance of the cemented carbide material decreased. The cemented carbides were shown to withstand a long-term oxidation at 500 °C. However, the surface of the material was completely oxidized even after 2 h of oxidation at the temperature of 800 °C. The products of the interaction between O²⁻ and metal ions appeared in the following order: Cu₂O, WO₂, WO₃ + Mn₃O₄ + MnO, CuO, W₁₈O₄₉, and Mn₂O₃ + MnO₂. Moreover, the oxidation products of the same element changed from low to high valence. However, the high-valence oxidation was also reduced to a low-valence state in the complex oxidation process involving many elements. Meanwhile, the oxidation products with greater thermodynamic driving force were not detected in the oxide layer due to the influence of element diffusion, the ionization energy and the competition with O₂ during the formation and growth of oxides.