Polymer-derived SiAlOC coating to improve the high-temperature resistance of chromium

Cr and its alloys are interesting materials for applications at temperatures higher than 1000(degrees)C. However, challenges such as limited oxidation resistance and nitridation still restrict their usage as high-temperature structural materials. The present work investigates the influence of a 0.6 mu m thin SiAlOC sol-gel coating on the oxidation resistance and kinetic of Cr at 950(degrees)C for 50 h and 1050(degrees)C for up to 100 h of exposure time in dry synthetic air using thermogravimetric analysis. The resulting oxide scale and microstructure were extensively studied by combining different techniques such as EPMA, XRD, SEM, Raman spectroscopy, FT-IR, and STEM. Overall, a reduction in mass gain and an improved scale adhesion was observed. The interaction of coating and substrate causing nanosized Cr2O3 and cristobalite formation in the SiAlOC coating was further supported by investigations of bulk materials.