Interface characteristics and performance of laser-cladded Ni-based composite coatings on ductile cast iron

Ni-based composite coatings were fabricated on ductile cast iron via laser cladding to simultaneously regulate interfacial cracking and enhance surface wear resistance. Multilayer and multi-track coatings composed of Fe- based, Ni-based, and composite powders were prepared and compared in terms of crack formation, phase composition, microstructure, and mechanical performance. With appropriate processing parameters, the incorporation of WC ceramic particles into Ni-based coatings maintains their inherent interfacial crack-controlling capability while markedly improving surface hardness and wear resistance, thereby offering an effective strategy for surface repair and reinforcement of ductile cast iron. The coating prepared using Ni625 + 10% WC exhibited well-distributed ledeburite at the interface and was free of cracks. The average hardness of the coating was approximately 2.49 times that of the substrate, while the average friction coefficient and wear rate were reduced by approximately 4.20% and 37.52%, respectively. The tensile and impact properties, as well as the fracture mechanisms, were comparable to those of the Ni-based coating without WC. Elemental diffusion and thermal effects occurred between the coating and substrate as well as among adjacent coating layers, resulting in higher hardness in the bottom layer and relatively softer upper layers. Nevertheless, the overall mechanical properties across all coating layers remained similar.