Design of surface oxide film structure that maintain corrosion resistance under high temperature sulfuric acid environment

Hirota, Noriaki   

In the Iodine Sulfur process (IS process) for a thermochemical hydrogen production method, sulfuric acid's high-temperature corrosion is a problematic. To solve this problem, the sulfuric acid decomposer utilizes on silicon carbide (SiC), which is a heat-resistant and corrosion resistant ceramic. However, using brittle SiC in practical plants remains a challenge due to difficulties in predicting decomposer lifespan caused by sudden impact-induced cracks and restrictions on upscaling component size due to furnace limitations in SiC production. This paper discusses the development of corrosion resistant metallic materials using two kinds of surface oxide films on metals, achieving sufficient corrosion resistance and long-term durability in high-temperature sulfuric acid environments through formation of a dense oxide film using a chemical densified coating and alloy compositional improvements with added aluminum, ultimately involving -AlO