Effects of chromia coatings on the high-temperature behavior of F17Ti stainless steel in air. Effect of rare-earth-element oxides

The MOCVD technique was used to form thin films of chromia and/or of a rare-earth-element oxide on the surface of F17Ti stainless-steel samples. These oxides were deposited alone oi together, successively or by codeposition. Coated samples were then subjected to high-temperature oxidation tests, either under isothermal conditions at 1273 K for 50 h, or under cyclic conditions at 1223 K for 40 cycles. An improved oxidation behavior was observed in every case, especially with codeposited Ln(2)O(3)-Cr2O3 Weight gain decreased during oxidation, compared with an uncoated sample, and scale spallation, generally observed under cyclic conditions, disappeared. Longer time experiments were also carried out. Large differences were observed depending on the sample-surface treatment.