High temperature wear behavior of NiCoCrAlY-Cr₂O₃-AgMo coating on GH4169 superalloy

In order to determine the possible application of NiCoCrAlY-Cr2O3-AgMo (NCA) coating for the finger seal used in aeroengine, the microstructure and wear behavior against GH605 counterbody of NCA coating at 400 degrees C, 500 degrees C and 600 degrees C were studied. The experimental results indicate that NCA coating exhibited low coefficient of friction (COF) and good wear resistance at high temperatures. The COF of NCA coating decreased with raising temperature and the average COF was 0.268 at 600 degrees C. Wear rates of both GH605 pin and NCA coating at 600 degrees C were much lower compared to those at 400 degrees C and 500 degrees C. It was found that NiMoO4 and MoO3 as effective lubricants formed a lubricant film on the worn surface of the coating at 600 degrees C, which improved the tribological properties of NCA coating. In view of the excellent tribological properties of NCA coating at high temperatures, especially at 600 degrees C which is the most common operating temperature of the finger seal used in aeroengine, it is preliminarily determined that NCA coating has a possible application for the finger seal of aeroengine.