High temperature oxidation behavior of silicon carbide-carbon coated nanostructured ferritic alloy composites in air + water vapor environment

Abstract

Oxidation behavior of silicon carbide (SiC) - carbon coated nanostructured ferritic alloy (C@NFA) composites was investigated in an air + 45 vol% H2O atmosphere at 500–1000 °C. All the composites show an oxidation structure with an outer Fe-rich layer and an inner Cr-rich layer, as well as internal oxidation along grain boundaries. Oxidation resistance increases with SiC addition. The corresponding fundamental mechanism is proposed. The improved oxidation resistance for the higher SiC content composites is attributed to a delay in ‘breakaway oxidation’ due to improved kinetics for the formation of dense Cr2O3 and SiO2 protective layers.