High Temperature Tribological Properties Of Laser Cladding In-Situ Carbide Reinforced Self-Lubricating Wear Resistant Composite Coating

The NiCrBSi-Ti3SiC2-CaF2-WC self-lubricating anti-wear composite coating was fabricated on TC11 alloy substrate by laser cladding. The phase compositions and microstructure were investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Microhardness was measured with a microhardness tester. Tribological properties of the fabricated composite coatings were evaluated under dry sliding condition at room-temperature (25 degrees C), 300 degrees C and 600 degrees C, and the wear mechanism was analyzed. The results show that the microstructure of the composite coatings consists of gamma Ni eutectic phase, M-23 C-6 , TiC, (Ti, W)C, Ti5Si3 hard phase and some Ti3SiC2, CaF2, TiF3 lubricating phase. The microhardness of laser cladding layer is improved greatly. The average microhardness of the laser cladding coating is 863.63HV(0.2), which is 2.46 times of the matrix. The friction coefficient and wear rate are lower than that of the substrate. The lowest friction coefficient and wear rate are 0.275 and 4.8 X 10(-5) mm(3) . N-1 . m(-1) at 300 degrees C, respectively.