Q235B is widely used in marine engineering materials; however, its wear resistance and corrosion resistance are poor. To improve wear and corrosion resistance, a CoCrFeNi high-entropy alloy (HEA) composite coating was cladded using laser cladding (LC) technology. Different proportions of tungsten carbide (WC) and Nb elements were added to the CoCrFeNi HEA coating, and the microstructure, phase, hardness, wear, and corrosion resistance of three different composite coatings were analyzed. The results show that the in situ synthetic phase is composed of Face central cubic (FCC) (Cr₃C₂) and strengthening phases such as W, WC, and NbC. In the process of LC, Nb will react with WC in situ, which not only reduces the morphology of the CoCrFeNi HEA cladding coating changed by adding WC, but also generates NbC, which leads to the dissolution of WC particles and improves the uniformity of particle distribution of the coating. The hardness of the coating with Nb is increased by 1.40 times, the wear resistance is enhanced, and the peeling of the hard phase is reduced during wear. The corrosion resistance of the coating with only WC particles is the best. Nb reduces the morphology of CoCrFeNi HEA cladding coating changed by WC particles. Although the coating with Nb is not as strong as that with WC particles only, it has outstanding hardness and wear resistance.

In this paper, the preparation of Ni60 + WC/NbC composite coating by laser cladding technology was studied. The coating properties were analyzed by a scanning electron microscope (SEM), an energy dispersion spectroscope (EDS), X-ray diffraction (XRD), a hardness tester, and a friction and wear tester. The results show that WC and NbC, as two typical ceramic reinforcing phases, play a positive role in improving the wear resistance and hardness of the coating. Under the action of a high-temperature (about 2500 °C) laser beam, some complex compounds, such as Ni₃Fe and M₂₃C₆ (M=Fe, Cr) are formed in the coating, which leads to the left deviation of XRD peak position. With the decrease in WC and the increase in Nb particles, the wear mechanism of the coating changes from abrasive wear to adhesive wear. When adding 10% WC, the microhardness of the coating reaches 809.5 HV, the coefficient of friction is 0.496, and the wear rate is 1.1804 × 10⁻⁷ mm³ N⁻¹·m⁻¹, which shows the best wear resistance.

HfC possesses high hardness, high melting point, and excellent thermal stability, and is regarded as an important wear-resistant reinforcing phase material. In this study, the laser cladding technique was employed to fabricate CoCrFeNiTi and CoCrFeNiTi/HfC composite coatings on the surface of Q235 substrate. The influence of HfC addition on the phase structure evolution, microstructure, and wear resistance of the coatings was systematically investigated. The results showed that the addition of HfC did not alter the phase structure of the coating, which remained dominated by an FCC solid solution. However, they induced the formation of an in situ TiC strengthening phase and reduced the brittle Laves phase content, thereby optimizing the coating’s toughness. At the same time, the coating transformed from columnar to equiaxed crystals, with significantly finer grains and further improved structural uniformity. Compared with the CoCrFeNiTi coating, the CoCrFeNiTi/HfC composite coating exhibited a more stable friction coefficient, a significantly lower wear rate, and improved wear resistance by approximately 2.4 times. The performance improvement was mainly attributed to the load-bearing strengthening and crack-pinning effect of the in situ TiC, the inhibitory effect of the reduction in the Laves brittle phase on adhesive wear, and the synergistic effect of Hf, which forms a stable oxidation-protective film during friction.