Friction and Wear Behavior of Laser Cladding NiAl/hBN Self-Lubricating Composite Coating

Abstract

NiAl/hBN coating was successfully prepared on a Ni-based superalloy substrate by means of laser cladding. The microhardness profile of the composite coating along the depth direction was measured, while its cross-sectional microstructures and phase compositions were analyzed by means of scanning electron microscopy and X-ray diffraction. Moreover, the friction and wear behavior of the composite coatings sliding against Si3N4 from ambient to 1000 °C was evaluated using a ball-on-disc friction and wear tester, and the worn surface morphologies of the composite coatings were observed using a scanning electron microscope. It was found that the laser cladding NiAl/hBN coating on the Ni-based superalloy substrate had high microhardness and good friction-reducing and antiwear abilities at elevated temperatures up to 1000 °C. The friction and wear behavior of the laser cladding NiAl/hBN coating was strongly dependent on test temperatures. The coating had a small friction coefficient and wear rate as it slid against the ceramic counterpart at elevated temperatures up to 1000 °C. The wear mechanism was characterized by mixed adhesion and abrasive wear as it slid against the ceramic ball below 300 °C and mild adhesion wear and plastic deformation up to 400 °C and above.