Isothermal Oxidation of Pt Modified and Ru Modified Aluminide Coating on a Fourth Generation Single Crystal Superalloy
Isothermal oxidation behavior of a 4th generation Ni-base single crystal superalloy with Pt-modified and Ru-modified aluminide coating was examined in a temperature range 1223 to 1373 K in air. Both Pt and Ru modification improve the oxidation resistance of a simple aluminide coating, especially above 1273 K. They allow thin protective and continuous Al2O3 scales to be intact for at least 500 h at temperatures up to 1323 K. However, the Pt modification drastically accelerates the formation of a secondary reaction zone (SRZ). This suggests that Pt promotes the formation of a topologically close-packed phase by lowering the solubility of refractory elements in γ-Ni. In contrast, the Ru modification reduces the SRZ, and is expected to enhance the phase stability under the coating by preventing the depletion of Ru due to its outward diffusion.
Shigeji Taniguchi, Toshio Maruyama, Masayuki Yoshiba, Nobuo Otsuka and Yuuzou Kawahara
Y. Matsuoka et al., "Isothermal Oxidation of Pt Modified and Ru Modified Aluminide Coating on a Fourth Generation Single Crystal Superalloy", Materials Science Forum, Vols. 522-523, pp. 301-308, 2006