OXIDATION PROTECTION OF 20CR-25NI-NB STAINLESS-STEEL AT 1300-DEGREES-C

Enhanced environmental protection of chromia-forming advanced metallic alloys at normal operating temperature, typically less-than-or-similar-to 900-degrees-C, may be provided by two well-established approaches-incorporation of reactive elements into the protective oxide scale or an amorphous ceramic coating acting as a diffusion barrier. The continued effectiveness of such approaches, namely by cerium and yttrium ion implantation and with a vapor deposited amorphous silica coating, in reducing oxidation of 20Cr-25Ni-Nb stainless steel in a carbon-dioxide-based environment has been examined during 0.5 and 1 hr transients to 1300-degrees-C. The influence of pre-oxidation of the ion-implanted, silica-coated, and uncoated steel for extended periods in the same environment at 825-900-degrees-C has also been established.