Chyrkin A. Thermal degradation processes in high temperature metallic materials

The thesis is devoted to the investigation of the high temperature oxidation effect on chemical and microstructural stability of high alloyed steels, nickel- and cobalt-base superalloys as well as high temperature protective coatings. An extensive experimental program has been performed for a wide spectrum of high temperature alloys and coating ranging from NiCr- and NiCrAl-base single-phase alloys to complex multicomponent multiphase coating systems “coating-substrate”. A pre-oxidation technique was developed for a commercial high-Cr NiCrAl-base alloy 602 CA to improve its oxidation resistance at 1000-1200°C. After pre-oxidation for 100 hours at 800°C, the alloy forms a nanoscale (100 nm thick) a-Al2O3 based oxide film which si able to prevent internal oxidation of Al above 1000°C in air.