Enhancing the oxidation resistance of TZM alloy by laser-clading MoSi2-TiVAlZrNb composite coating
Weiguo Zhao, Li Wang, Ping Hu, Man Cheng, Jiayi Long, Jiayu Han, Jiao Luo, Qijia Chu, Lili Gao, Junzhou Yang
Abstract
The MoSi 2 coating is an ideal coating system for molybdenum alloys due to the formation of a SiO 2 glass phase and its good oxidation resistance in high-temperature service environments. However, the difference in the thermal expansion coefficient between MoSi 2 and molybdenum alloy results in cracks in the MoSi 2 coating, which has an important effect on the oxidation resistance at high temperature. In this paper, MoSi 2 coatings were optimized by the addition of a multicomponent TiVAlZrNb on a TZM alloy prepared by laser cladding. The results showed that the MoSi 2 -TiVAlZrNb composite coating had a more uniform structure and fewer internal cracks than the single MoSi 2 coating. The mass loss of the MoSi 2 -TiVAlZrNb composite coating was 0.1500–0.8721 g, which was lower than that of the single MoSi 2 coating (0.3885–1.14190 g) at 1000 °C–1400 °C for the 1 h oxidation test. The higher oxidation resistance of the MoSi 2 -TiVAlZrNb composite coating was attributed to the dense oxide film formed by the increase in Ti and Al content on the surface and the decrease in the number of cracks, thus reducing the diffusion of oxygen along the cracks to the matrix. Therefore, the addition of TiVAlZrNb multicomponent alloys could provide a new method for the further development of molybdenum alloys in the field of high-temperature oxidation environments.