Compositional Factors Affecting the Oxidation Behavior of Pt-Modified γ-Ni+γ’-Ni3Al-Based Alloys and Coatings
Many high-temperature coatings rely on the formation of a continuous and adherent thermally grown oxide (TGO) scale of α-Al2O3 for extended resistance to degradation. For instance, the durability and reliability of thermal barrier coating (TBC) systems in gas turbines are critically linked to the oxidation behavior and stability of an alumina-forming β-NiAl-based bond coat. This study focuses primarily on the development of unique Pt+Hf-modified γ′-Ni3Al+γ-Ni coating compositions that form highly adherent, slow-growing TGO scales during both isothermal and cyclic oxidation at high temperature. Recent findings on the isothermal and cyclic oxidation behavior of γ′+γ alloys and coatings will be discussed, with particular emphasis on the effects of Pt, Al and Hf contents and distributions. Inferred reasons for the observed “Pt effect” will also be presented.
Pierre Steinmetz, Ian G. Wright, Alain Galerie, Daniel Monceau and Stéphane Mathieu
N. Mu et al., "Compositional Factors Affecting the Oxidation Behavior of Pt-Modified γ-Ni+γ’-Ni3Al-Based Alloys and Coatings", Materials Science Forum, Vols. 595-598, pp. 239-247, 2008