Microstructure and mechanical properties of surface coating prepared on grade 2 titanium by Ni-B composite electroplating and laser cladding

To improve the mechanical properties of TA2 (grade 2 titanium), a Ni-B-Ti composite coating was prepared on the surface of TA2 by a two-step surface modification method with composite electroplating and laser cladding. Using plating instead of powder feeding or powder pressing as the preset layers of laser cladding can effectively improve the coating quality, save materials and alleviate the agglomeration or splashing of powder under laser beam irradiation. The results of the microstructure analysis show that excellent metallurgical bonding is obtained between the coating and substrate, and cracks or pores are not found in the coating. The coating is mainly composed of TiNi/Ti2Ni intermetallic compounds and TiB/TiB2 ceramic phases, which can effectively increase the hardness and wear resistance of the TA2 surface. The mechanical property test results showed that the maximum hardness of the composite-modified layer was 10.695 GPa, which is 377% higher than that of the TA2 matrix. In addition, although the coating has higher friction coefficients than that of the TA2 substrate, the wear rate of the composite coating is 93.17% lower than that of TA2, which indicates that the wear resistance of the coating has been effectively improved.