Study of the Performance of Laser Melting Wear-Resistant Coatings on TC4 Titanium Alloy Surfaces

To improve the wear resistance of TC4 titanium alloy, two types of wear-resistant coatings were applied to the surface using laser melting: Ni60 + 50% WC and d22 powder priming. The phase composition and microstructure of the coatings were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy spectroscopy (EDS). The mechanical properties of the coating were tested using an HV-1000 micro-Vickers hardness tester, an HRS-2M high-speed reciprocating friction and wear tester, and a WDW-100D electronic universal testing machine. The results show that Ni60 + 50% WC composite coating and d22 priming + (Ni60 + 50% WC) composite coating mainly consist of W₂C, TiC, Ni₁₇W₃, Ni₃Ti, and Ti_xW_1−x phases. Compared to the TC4 substrate, the microhardness of both coatings is significantly higher, approximately 2.8 times the microhardness of the substrate. In frictional wear experiments, the average friction factors of the two coatings and the TC4 substrate are 0.476, 0.55, and 0.865, respectively, and the wear of the two coatings is only 0.0559–0.0769 that of the TC4 substrate, with a significant increase in wear resistance, nearly 17 times higher than that of the substrate. The coating shows flaking, shallow abrasion marks, and granular debris, dominated by adhesive wear and fatigue wear, while the TC4 substrate shows more furrows on the surface, dominated by abrasive wear. The shear bond strengths of the Ni60 + 50% WC composite coating and the d22 powder primed + (Ni60 + 50% WC) composite coating were 188.19 MPa and 49.11 MPa, respectively. Conclusion: both coatings significantly improve the hardness and wear resistance of the TC4 titanium alloy substrate surface, with the Ni60 + 50% WC composite coating performing better in hardness, wear resistance, and bond strength.