OPTIMIZING PROPERTIES OF CEO2 SOL-GEL COATINGS FOR PROTECTION OF METALLIC SUBSTRATES AGAINST HIGH-TEMPERATURE OXIDATION

The application of CeO2 ceramics derived from sol-gel as coatings depo sited on nickel, chromium, and some nickel-base superalloys to improve their oxidation behaviour at high temperatures is presented. The majo r factors affecting the protective properties of CeO2 coatings, relate d to the coating microstructure, the nature of the substrate, and oxid ation parameters are discussed. On the basis of the experimental evide nce, the conditions leading to the optimum performance are selected. T he efficacy of sol-gel technique is compared with results obtained by CeO2 sputtering and Ce ion implantation.