Microstructure and oxidation behaviour of Pt modified NiCrAlYSi coating on a Ni-based single crystal superalloy

In this study, the N + NiCrAlYSi coating and NiCrAlYSi + N coating were produced onto the Ni-based single crystal superalloy by using the arc ion plating (AIP) and electroplating. For the N + NiCrAlYSi coating, the N mainly distributed in substrate and the bottom of coating, while the N primarily located at the outer part of NiCrAlYSi + N coating. After isothermal oxidation at 1100 degrees C, the weight gains for the NiCrAlYSi coating, N + NiCrAlYSi coating and NiCrAlYSi + N coating were 1.81 mg/cm(2), 1.68 mg/cm(2) and 1.37 mg/cm(2), respectively. The parabolic rate constant of the NiCrAlYSi +N coating was 6.2 x 10(-3) mg(2) cm(-4) h(-1), which was the smallest among three kinds of coatings. The mass of spalled oxides for the NiCrAlYSi coating, N + NiCrAlYSi coating and NiCrAlYSi + N coating were 2.07 mg/cm(2), 0.937 mg/cm(2) and 0.801 mg/cm(2) after cyclic oxidation at 1150 degrees C. So, the addition of N in the NiCrA1YSi coating can significantly improve the adhesion of alumina scale. The oxidation WA results indicated that the NiCrAlYSi + N coating showed the best oxidation resistance. Some Pt-rich particles were observed on the surface of the NiCrAlYSi + N coating after 1 cycle at 1150 degrees C. The enrichment of N on the outer part of NiCrAlYSi + N coating can increase the out diffusion flux of Al and promote the fast formation of pure Al2O3 at the early stage of oxidation.