Role of Y4Al2O9 in High Temperature Oxidation Resistance of NiCoCrAlY-ZrO2 Y2O3 Coatings
Role of Y4Al2O9 in High Temperature Oxidation Resistance of NiCoCrAlY-ZrO2.Y2O3 Coatings

NiCoCrAlY-ZrO2·Y2O3 coatings were deposited on the substrates by using a technology of combining electron,atom and ion beams (three beams). Isothermal oxidation for these samples was performed at 1100℃ for 100-300 h. The results show that a thermally grown oxide (TGO) layer was formed between NiCoCrAlY layer and oxidation. The TGO contains α-Al2O3 and Y4Al2O9 etc. oxides. The intensity ratio of α-Al2O3/Y4Al2O9 was monotonously decreased with increasing oxidation time based on XRD (X-ray diffraction) analysis. The Y4Al2O9 phase plays the most important role in high temperature oxidation resistance at 1100℃. The related mechanism was also discussed.