Overview on corrosion in supercritical fluids
Résumé
Whatever the supercritical fluid is, the performance of structural materials is a key issue for industrial applications. An overview is carried out on the corrosion behavior of metallic metals and alloys under pressure and temperature conditions appropriate for supercritical fluids. Steels, including stainless steels, and nickel base alloys are the main alloys investigated in supercritical environments. In supercritical water (SCW), the review highlights how SCW density changes the corrosion mechanisms. Beside the density, temperature and impurities (especially chlorine) play key roles. SCW oxidation is promised to a strong development if corrosion issues are solved, as illustrated with the DELOS process (French acronym for destruction of organic fluids) applied to radioactive organics.
At low temperatures, in supercritical fluids like supercritical CO2, authors observed that no corrosion occurs in pure fluids but the water content is a key parameter. Temperature, water and pollutants are the major factors leading to increase the uniform or localized corrosion rates.