High-Temperature Oxidation Resistance Performance of Si-Ti-Cr Silicide Coating on Nb-Hf Alloy Surface in Constant Oxidation and Thermal Shock

To improve the high-temperature oxidation resistance performance of Nb-Hf alloys, Si-Ti-Cr silicide coatings were prepared on Nb-Hf alloy by slurry sintering and high-temperature permeation methods. The high-temperature oxidation resistance performance of Si-Ti-Cr silicide coating on Nb-Hf alloys in high-temperature constant oxidation and high-temperature thermal shock was analyzed, and the failure mechanism of Si-Ti-Cr coating in high-temperature constant oxidation and high-temperature thermal shock was determined. The results show that the mass gain of the coating is 7 mg/cm² after constant oxidation at 1800 °C for 5 h. The mass gain of the coating in atmosphere is less than 1.8 mg/cm² after thermal shock cycles for 50 cycles followed by constant oxidation at 1700 °C for 5 h. Therefore, the silicide coating exhibits excellent oxidation resistance at 1800 °C in constant oxidation and at 1700 °C in thermal shock/constant oxidation.