Optimizing Wear Resistance and Tensile Strength of Nickel-Based Coatings through Tungsten Carbide Reinforcement

While the addition of WC increases the hardness and wear resistance of coatings, an excessive WC content can also induce crack initiation and propagation, increasing brittleness and leading to premature failure. Therefore, in this study, WC particles were incorporated into nickel-based coatings by plasma-arc surfacing to optimize their content and distribution, balancing their tensile properties and wear resistance. The coatings were comprehensively evaluated through microstructural analysis, hardness testing, wear resistance assessment, and tensile testing. The results show that as the mass fraction of WC increased from 45% to 65%, the increase in carbon significantly promoted the formation of M7C3, M6C, and M23C6 carbides and suppressed the formation of the γ-phase. The microstructural analysis showed that the content of massive carbides increased significantly with the increasing WC content, and the XPS analysis further confirmed that the changes in the WC and Cr7C3 phases were particularly pronounced in the high-WC coating. The 65% WC coating showed higher hardness (a 232 increase in HV1.0), a lower and more stable coefficient of friction (0.42), and better wear resistance than the 45% WC coating, with a wear rate of 3.329 × 10−6 mm3/(N·m)−1, which was 3.709 × 10−6 mm3/(N·m)−1 lower than that of the 45% WC coating. The conventional tensile test results show that the maximum stress and strain of the 45% WC coating were 71% and 36% higher than those of the 65% WC coating, respectively. In addition, the 45% WC coating exhibited better ductility and quasi-cleavage characteristics, whereas the 65% WC coating showed typical brittle cracking behavior. The results of the field tensile tests also showed that the fracture time of the 65% WC coating was 27 s shorter than that of the 45% WC coating. Overall, the 45% WC coating had a good combination of strength and toughness.