Laser-cladded hBN/Ni-based composite coatings for enhanced wear and corrosion resistance of HT250 cast iron

HT250 cast iron is widely used for its excellent castability and cost-effectiveness, but its corrosion and wear resistance are insufficient. This study fabricated Ni-based composite coatings (Ni625+Ni50+hBN) on HT250 via laser cladding and systematically investigated the effects of laser power (1100 W, 1300 W, 1500 W) on the coating's microstructure, wear resistance, and corrosion resistance. XRD analysis showed the coating matrix is γ-Ni, with borides (Ni₂B), carbides (Cr₂₃C₆), and undecomposed hBN. SEM and EDS revealed that at 1300 W, hBN decomposes appropriately, forming a dispersion-strengthened structure with moderately sized hard phases. Mechanically, the 1300 W sample exhibited the highest microhardness (552.16 HV), lowest friction coefficient, and minimal wear loss. Electrochemical tests confirmed the 1300 W coating has optimal pitting corrosion resistance, with the highest breakdown potential, most noble repassivation potential, and significantly higher charge transfer resistance than other samples. Thus, 1300 W is the optimal laser power, achieving synergistic optimization of hard phase size, distribution, and corrosion resistance. • A Ni625/Ni50+BN coating was fabricated on HT250 using laser cladding. • The BN in laser cladding powder can significantly improve the hardness and wear resistance of the cladding layer and enhance the self-lubrication property. • The laser cladding test with different power showed that the best performance was obtained at 1300 W.