Effect of ZrB2 and Polyvinyl Butyral Content on the Oxidation Resistance of ZrB2–SiC Coatings Produced by Slurry Brushing Method

ZrB 2 –SiC coatings are prepared on the surface of graphite by slurry brushing method to improve the oxidation resistance. Effects of ZrB 2 content and polyvinyl butyral (PVB)–ethanol solution concentration on microstructure and static oxidation behavior of the ZrB 2 –SiC coatings are investigated at 1200 °C in air. The results indicate that increasing ZrB 2 content improves the oxidation resistance of the coatings. When ZrB 2 content increases from 30 to 45 wt%, weight loss rates of the coated samples after oxidation at 1200 °C for 120 min decrease from −0.92% to −1.67%. Increasing binder solution concentration raises component content in the coatings. As PVB–ethanol binder concentration increases from 0.025 to 0.075 g mL −1 , weight loss rates of the coated samples after oxidation at 1200 °C for 120 min decrease from 0.32% to −0.38%. Excellent oxidation resistance of ZrB 2 –SiC coating is attributed to self‐sealing ability of B 2 O 3 and borosilicate glass. The composite glass can inhibit oxygen diffusion by filling defects in the coating promptly. The borosilicate glass phase can enhance the fluidity of the composite glass. ZrO 2 and ZrSiO 4 particles restrict the growth of the microcrack, which improves the oxidation resistance of ZrB 2 –SiC coating.