The oxidation performance of a single-phase Pt-modified aluminide coating was assessed in oxidation test at 980 °C in comparison with the single crystal superalloy. The results suggested that the Pt-modified aluminide coating exhibited superior oxidation resistance. During oxidation, the oxide scale formed on bare alloy changed constantly followed by the constitution of the multi-layer scale structure: An outer scale mainly consisted of Cr₂O₃ + NiCr₂O₄ + TiO₂ with scarce protection, and an internal scale mainly consisted of Al₂O₃. The thickness of the outer oxide scale increased with time, where the scale became looser and more porous. Meanwhile, the internal scale was discontinuous. Oxygen and nitrogen inwardly diffused into substrate, forming Ta₂O₅ and TiN particles. In contrast to the complex constitution of oxide scale, a uniform and continuous Al₂O₃ scale formed on Pt-modified aluminide-coated samples after oxidation at 980 °C for 1500 h, which showed no spallation and cracking. Interestingly, θ-Al₂O₃ and α-Al₂O₃ phases remained after such a long oxidation time. It is the relatively lower temperature and the presence of Pt retarded θ-α transformation. The degradation rate from β-NiAl to γ′-Ni₃Al was very slow in the coating. The various development of oxide scale on the coating and substrate was individually studied.

With the development of industry, the operating temperature of aero engines and gas turbines continues to increase; developing thermal barrier coatings (TBCs) with superior resistance to CaO-MgO-Al₂O₃-SiO₂ (CMAS) corrosion has become a prominent research focus. In this study, atmospheric plasma spraying (APS) was used to prepare yttria-stabilized zirconia (YSZ), nanostructured yttria-stabilized zirconia (n-YSZ), and Gd-Yb-Y-stabilized zirconia (GYYSZ) coatings. The effects of CMAS exposure on the microstructure, chemical composition, phase transition, and microhardness of the coatings were investigated. Comparative analysis revealed that both phase transition and exfoliation occurred in corroded YSZ and n-YSZ coatings, with n-YSZ exhibiting more pronounced changes. In contrast, GYYSZ coatings remained stable without phase transition and exhibited a smaller increase in microhardness (270 HV0.3). Consequently, doping Gd/Yb/Y elements into ZrO₂ can improve the performance of TBCs.