High temperature oxidation behavior of Ni-Cr-Al based powder porous metal

This study investigated the high temperature oxidation behavior of newly developed Ni-Cr-Al powder porous metal. High temperature isothermal oxidation tests were conducted at 900, 1000 and 1100 °C temperatures for 24 h under an atmosphere of 79% N₂ + 21% O₂ gas. Oxidation weight gain vs. time curves represented typical oxidation behavior of parabolic shape. Weight gain increased with increasing oxidation temperature. Ni-Cr-Al porous metal mainly created oxides such as α-Al₂0₃, Cr₂O₃, NiCr₂O₄. The α-Al₂0₃ oxide could be still maintained up to 1100 °C oxidation temperature as a thick and stable protective layer. It was noted that Ni-Cr-Al porous metal had better high temperature oxidation resistance than those of other Ni-based and Fe-based porous metals. The catastrophic degradation of oxidation resistance especially at very high temperature was not observed up to 1100 °C in this porous metal. The micro-mechanism of high temperature oxidation of Ni-Cr-Al porous metal was also discussed.