The rapid development of aerospace technology has led to the development of high-performance aero engine alloys as a hot topic of global attention. Compared with traditional nickel-based superalloys, niobium alloys have been considered one of the most promising high-temperature structural materials in metallurgy, aerospace and nuclear energy due to their moderate density, high melting point and excellent high-temperature strength. But the lethal oxidation of niobium in an oxygenated environment severely limits its use at high temperatures. In contrast, surface coating is an effective way to protect niobium alloys. Therefore, how to obtain high-temperature anti-oxidation coatings with high density, no defects and high bonding by adjusting the composition and structure of the coating system has become the core of research.

  In order to solve the problem of high-temperature anti-oxidation coating on the surface of refractory metal niobium, we used waste silicon-molybdenum rods and refractory metal silicide as raw materials to prepare silicide anti-oxidation coating by SPS. By introducing refractory metal silicide and silicon carbide, the penetration cracks inside the coating can be effectively reduced, and the Zr-Si-O complex phase oxide glass film with low oxygen permeability can be formed in the high temperature environment of 1700°C, which plays an excellent role as an oxygen barrier layer in the high temperature environment. In addition, advanced thermodynamic calculations and other methods were used to assist in explaining the oxidation process, and the oxidation kinetic model was established.

This research work was published in Composites Part B: Engineering.

Link to paper: https://doi.org/10.1016/j.compositesb.2024.111281

Fig.1 Surface morphology and WDS analysis of MoSi2(a-c) and MoSi2-ZrSi2-SiC(d-f) coatings after SPS sintering 

Fig. 2 Surface morphology and corresponding EDS analysis of MoSi2(a,c) and MoSi2-ZrSi2-SiC(b,d) coatings after 30 and 120 min oxidation at 1700 °C