| Popis: |
An arc-sprayed oxidation protective barrier coating system on austenitic stainless steel is composed of an inner Ni-Cr-Ti alloy layer and a pure aluminum outer layer. The high-temperature oxidation behavior of the coatings on 304N substrate was investigated during isothermal exposures in air at 1100°C. Experiments showed that interdiffusion of alloying elements within the protective coatings occurred, and the elements, Cr,Ni and Al, were also diffusing into the substrate metal. As test time proceeded, aluminum nitrides were generated in situ in the substrate, which had a layer-like distribution. The nitrides generated play the roles as element diffusion barriers, and together with the surface alumina they provide a long-term effective anti-oxidant protection to the steel substrate. The coatings on 304N substrate were not deteriorated and the substrate was protected well, being exposed to 1100°C for 350 hours. The analysis results of oxidation kinetics showed that the specific mass changes of the coated specimens were much smaller than those without coatings. |
