Effect of ceria coatings on growth stresses in wustite scales at 800°C

Abstract

This paper discusses the influence of CeO2 surface modification on the stress developed during pure iron oxidation (oxygen partial pressure = 2 × 10−3 Pa, T = 800°C). Dn blank and coated specimens, the compressive stress varies from −400 ± 80 to −150 ± 100 MPa during the 30 h oxidation test. The in situ XRD compressive stress level determined from the FeO scale is not strongly dependent on the presence of a ceria coating under conditions where no strong epitaxial relationships exist between FeO and an uncoated specimen. Surface modification with low pressure starting conditions induces epitaxial relationships between the FeO scale and iron. This leads to a high in situ compressive stress in the oxide scale, indicating that epitaxial relationships can be a source of stress in an oxide scale. Compressive stress in the scale can be reduced by the use of a ceria coating, known to prevent epitaxial relationships.