Thermal shock resistance and adhesion strength of plasma-sprayed alumina coating on cast iron

A thermal cycling test has been conducted for alumina-coated cast iron as well as alumina-coated steel for comparison. The samples were prepared by plasma spraying alumina on flake graphite cast iron and spheroidal graphite cast iron without an undercoat and with an undercoat of nickel-based self-fluxing alloy or nickel-chromium alloy. The thermal cycling test revealed that the coating on the flake graphite cast iron has good thermal shock resistance and that the undercoating improves the thermal shock resistance appreciably by preventing oxide film formation on the surface of the cast iron substrates.