The High-Temperature Oxidation Behavior of Al Coating on Nickel-Based Single Crystal Superalloy

Al coating was fabricated by chemical vapor deposition on the nickel-based single crystal superalloy. The high-temperature oxidation behavior at 900 ℃ and 1000 ℃ for 200 h were detected by scanning electron microscopy, energy disperse spectroscopy and X-ray diffraction. Results indicated that the oxidation kinetics of the alloy substrate and Al coating were all in accord with the parabolic rule. Compared with the alloy substrate, the Al coating manifested lowest oxidation rate and highest activation energy. After oxidation at 900 ℃, the alloy substrate and Al coating formed Al2O3 protective film, represented some high-temperature oxidation resistance. After oxidation at 1000 ℃, the alloy substrate emerged lots of microcracks and holes in the surface layer with serious internal oxidation and nitridation phenomena, resulted in a poor oxidation resistance. The Al2O3 protective film of Al coating took on the less surface spallation, more pure and continue, exhibited more excellent high-temperature oxidation resistance.