High Temperature Oxidation Behaviors of SiON Coated AISI 441 in Ar + O2, Ar+H2O, and Ar + CO2 Atmospheres

Abstract Silicon oxynitride (SiON) coated AISI 441 was prepared by pyrolysis of a dip-coated perhydropolysilazane (PHPS) precursor polymer. The high temperature oxidation behaviors of SiON coated AISI 441 substrates were studied in Ar + O2, Ar+H2O, and Ar + CO2 atmospheres at 800 °C for 100 hours. The SiON coated AISI substrates showed better performance in all three atmospheres compared to the uncoated AISI 441 substrate. This improvement was attributed to the dense, crack-free SiON coatings, which provided complete separation between oxidizing species and the steel substrate. A thin oxide scale was observed on top of the SiON coating for all the atmospheres, which was attributed to the reactions between the oxidizing species in the atmosphere and the metallic species (Cr, Mn, and Fe) diffused through the SiON coating from the AISI 441 substrate.