Vacancy Engineered Rare Earth Oxide Coatings for High Temperature Applications

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Steels are often used as structural alloys in a wide variety of applications including household appliances, cutlery, and components in power generation and oil and gas pipelines. However, select steels are not as corrosion and failure resistant in the high temperature regime, due to scale spallation. Addition of rare earths in the steel can increase the oxidation resistance, resulting high production cost. However, the application of superficial rare earth oxide coatings might provide a particular solution to the problem. The research would allow us to develop vacancy engineered cerium oxide coatings for high temperature protection of steel substrates. The main objectives of the proposal are: (1) Preparation of cerium oxides, (2) Compare the effectiveness of nanocrystalline ceria and titania to compare the effect of mixed valence states in the oxidation kinetics, (3) Prepare and study the effect of La and Nd doped ceria as a function of oxygen vacancy concentration on the efficacy of the high temperature protection, (4) Explain the oxidation kinetics as a function of vacancy concentration in the formation of early chromia healing layer.A more fundamental understanding of the true nature of cerium oxide with or without doping will be investigated. Comparative studies of two mixed valence states materials (cerium oxide and titanium oxide nanoparticles) on the protective nature of the steel from high temperature oxidation will be conducted as part of this program. This basic consideration and study of these rare earth coatings will also lead to the understanding of the oxidation kinetics as a function of oxygen vacancies and mixed valence states. Thus, these results will lead to the design of better and cost effective oxidation resistant coatings for steel materials.