Microstructure and High Temperature Wear Resistance of Laser Cladding NiCoCrAlY/ZrB2 Coating

NiCoCrAlY and NiCoCrAlY/ZrB2 coatings were prepared on pure Ti substrates by the laser cladding technique. The compositions and the microstructure of the prepared coatings were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The tribological properties were tested through sliding against Si3N4 balls at the temperatures of 20, 100, 300 and 500 °C. Besides, the morphologies of the worn surfaces and wear debris were analyzed by scanning electron microscopy (SEM) and three dimensional (3D) non-contact surface mapping. The results show that the NiCoCrAlY/ZrB2 composite coating has higher microhardness and excellent high-temperature wear resistance than NiCoCrAlY coating. The wear mechanism for NiCoCrAlY and NiCoCrAlY/ZrB2 coatings versus silicon nitride at elevated temperatures is abrasive and adhesive wear.