Microstructure and wear resistance of laser cladding WC reinforced Ni based composite coating on TC4 titanium alloy

Abstract:

In order to improve the wear resistance of TC4 titanium alloy, two wear-resistant composite coatings of Ni60+50%WC and d22 powder based +(Ni60+50%WC) were prepared on the surface of TC4 titanium alloy by laser cladding. Microstructure and phase composition of the coating were characterized by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD). The properties of the coating were analyzed by HV-1000 micro Vickers hardness tester, HRS-2M high-speed reciprocating friction and wear tester and WDW-100D electronic universal testing machine. The results show that the two coatings are composed of W₂C, TiC, Ni₁₇W₃, Ni₃Ti and Ti_xW_1-xphases; The two coatings not only exhibit excellent metallurgical bonding with the substrate, but also have uniform and dense microstructure without cracks; Due to the presence of the in-situ synthesized hard phase and fine-grain strengthening make the hardness of the coating significantly increased, which is about 2.8 times that of the TC4 substrate; The friction coefficient (COF) and wear amount of the two coatings are much lower than that of TC4 titanium alloy substrate, and the wear resistance of the two coatings is nearly 17 times higher than that of the substrate; The shear bonding strength of Ni60+50%WC composite coating and d22 powder based + (Ni60+50%WC) composite coating are 188.19 MPa and 49.11 MPa respectively. Conclusion: Both coatings can significantly improve the hardness and wear resistance of the TC4 titanium alloy substrate surface, and Ni60 + 50% WC composite coating performs better in hardness, wear resistance and bonding strength.

Key words:Laser cladding; Titanium alloy; Microstructure; Microhardness; Wear resistance; Bonding strength