A comparative investigation on the effects of reinforcement phase addition methods on laser melting deposited WC/Co coatings

To unravel the fundamental mechanisms underlying the influence of ceramic phase addition methods on the formation quality and performance enhancement of coatings, the WC/Co-based composite coatings were manufactured on 42CrMo substrate utilizing laser melting deposition technology with different reinforcement phase addition methods grounded in the variable-process alternated overlapping strategy. A comparative analysis was conducted to examine the phase transformations, surface fluctuations, pore defects, microhardness, wear resistance and corrosion behavior. The findings revealed that the in-situ formation of tungsten-carbide phase fell short of the anticipated level due to the physical properties and size constraints of W particles. Notably, the 40 wt% WC particles addition significantly hindered the molten pool fluidity and impeded gas release, leading to pronounced a surface fluctuation of 180.14 μm and a porosity of 31.06 %. In contrast, the direct addition WC particles imparted support, pinning, and strengthening effects, resulting in the optimal microhardness and wear resistance compared to other addition methods, which are 1.46 times and 3.75 times higher than the 42CrMo substrate, respectively. However, an increase in WC particles destabilized the passivation film and promoted the formation of corrosion channels, ultimately exacerbating the corrosion behavior of the WC/Co-based coatings. These insights provide vital theoretical guidance and technical foundations for the adaptive selection of ceramic phase addition methods tailored to the actual working conditions and desired strengthening effects of reinforced coatings for key components.