Laser cladding technology serves as a pivotal technique in industrial production, especially in the realms of additive manufacturing, surface enhancement, coating preparation, and the repair of part surfaces. This study investigates the influence of metal powder composition and processing parameters on laser cladding coatings utilizing the Taguchi orthogonal experimental design method. To optimize the laser cladding parameters, multi-response grey relational analysis (GRA) was employed, aiming to improve both the microhardness and the overall quality of the coatings. The optimal parameter combinations identified through GRA were subsequently validated through experimental tests. The results reveal that the microhardness and quality of the coatings are substantially influenced by several critical factors, including the powder feed rate, laser power, high-entropy alloy (HEA) addition rate, scanning speed, and substrate tilt angle. Specifically, the powder feed rate exerts the most significant effect on the microhardness, dilution rate, and average contact angle. In contrast, laser power primarily impacts the mean contact angle difference. The HEA addition rate notably affects the mean contact angle difference, while the scanning speed affects the microhardness and the substrate tilt angle influences the average contact angle. The results of the validation experiment showed a deviation of only 0.95% from the predicted values, underscoring the efficacy of the grey relational analysis (GRA) in optimizing the laser cladding process parameters. The methodology presented in this paper can be applied to determine the ideal processing parameters for multi-response laser cladding processes, encompassing applications such as surface peening and surface repair.

At present, the common protection technology of power-transmission and transformation equipment is mainly coating protection and hot-dip zinc protection. However, due to the low adhesion of epoxy zinc-rich coating, and the poor compatibility with top paint, environmental pollution, complex processing, high energy consumption and other defects of the hot-dip zinc process, its development is limited. In view of the above deficiencies, new anti-corrosion coating materials and processes were investigated in this study. Zinc coatings and Al-Zn coatings were prepared on the C45 steel matrix by hot-spraying and cold-spraying processes. The macro appearance, micromorphology and phase composition analysis of the coatings were evaluated. The adhesion of the coating to the substrate after the salt-spray test was tested. The results showed that the hot dip zinc coating and hot spray zinc coating had obvious cracking after the salt-spray test. The surface structure of cold-sprayed Al-Zn coating was relatively dense after the salt-spray test. The critical load of the cold-sprayed Al-Zn coating after the salt-spray test was higher than that of the other two coatings. The corrosion resistance to salt spray of cold-sprayed Al-Zn coating was demonstrated to be better than the hot-dip zinc coating, and thus has great application prospects.

Three kinds of Fe₃₀Ni₂₀Co₂₀Cr₂₀Mo_3.5 high entropy alloy (HEA) coatings were prepared on the surface of a Q235 steel plate using plasma cladding and laser cladding. The microstructure, crystal structure, element distribution, microhardness, wear resistance, and corrosion resistance of the coatings were studied. The grain size of the high-speed laser cladding coating (HLC) was the smallest. The crystal structures of the plasma cladding coating (PC) and HLC were single face-centered cubic (FCC), while that of the deep laser cladding coating (DLC) was body-centered cubic (BCC). DLC had the best microhardness and wear resistance. The microhardness of PC, HLC, and DLC increased by 70%, 108%, and 109%, respectively, and the average friction coefficient decreased by 33%, 44%, and 51%, respectively, compared to Q235. HLC had the best corrosion resistance, with an annual corrosion rate of 0.66925 mm/a. The annual corrosion rate of PC and HLC was only 40% of Q235. The polarization curves of PC and HLC had obvious passivation regions with a width of up to 2 V. The corrosion types of PC were pitting corrosion and intergranular corrosion, that of HLC was general corrosion, and that of DLC was severe pitting corrosion.

This work focus on the effect of different contents of Cu on microstructure and properties of Al–Zn composite coatings. The SEM and EDS were used to analyse the microstructure and composition of the coatings, and the deposition efficiency and porosity of the coating were calculated. The results show that the coatings have low porosity and uniform structure. The hardness, electrical conductivity and corrosion resistance of the coating were measured, and the results showed that the addition of Cu can improve the hardness, electrical conductivity and corrosion resistance of the coating but reduce the deposition efficiency of the powder.