A fused glass coating for oxidation protection of Mo–W–ZrO2 cermet

Mo–W–ZrO2 cermet is suitably used for the liquid steel temperature sensor due to its excellent erosion resistance, good thermal shock resistance and high-temperature strength. However, it is easily oxidized in the firing process of the sensor below 1000°C, which limits its application. In this work, a continuous coating of borosilicate glass was developed to prevent the cermet from oxidizing by a two-step process. Raw materials of borax and potash feldspar were initially fused at 1200°C and ground into powder. Then, the slurry of the powder and ethyl alcohol was applied to the cermet and fused at 1000°C. Results showed that the coating had an amorphous nature and low volatility (0.39% weight loss up to 1000°C), which exhibited good continuity and adhesion to the cermet. Moreover, no matter whether the coating was in a non-molten or molten state (800 or 1000°C), it had good oxidation resistance. According to the application test in the firing, the coating could protect the cermet from oxidation at 400–1000°C. The method of fused glass coating may have important implications for other oxidation resistance in a wide temperature range, especially at low temperatures. •Anti-oxidation coating of borosilicate glass was developed for the Mo–W–ZrO2 cermet.•Compactness, volatility and adhesion of the coating were discussed.•We study the oxidation resistance of the coating for the cermet.•Good anti-oxidation for the cermet at 400–1000°C was verified by the application test.