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

Surface and Coatings Technology 474 (2023), 130049, DOI: 10.1016/j.surfcoat.2023.130049

Cr and its alloys are interesting materials for applications at temperatures higher than 1000 °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 μm thin SiAlOC sol-gel coating on the oxidation resistance and kinetic of Cr at 950 °C for 50 h and 1050 °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.