Surface Reinforcement and Mechanical Behavior of Aluminum-Alloy Mechanical Arms for Logistics Robots

Abstract

To enhance the hardness and tensile performance of aluminum-alloy mechanical arms used in logistics robots, WC–Ni composite powder was employed to fabricate coatings via single-track laser cladding, and tensile specimens were prepared using multi-track cladding. The experimental results indicate that as the laser power increases, the cladding layer height first increases and then decreases, while the molten pool depth continuously increases and the cladding width gradually expands. Meanwhile, the dilution rate initially decreases and subsequently increases. When the laser power reaches 1.0 kW, the single-track cladding layer exhibits the lowest dilution rate and achieves the most favorable metallurgical bonding with the substrate, indicating optimal coating–substrate compatibility. Phase composition analysis reveals that new phases, including W₂C, NiAl, Ni₃Al, M₇C₃, and M₂₃C₆, are formed within the cladding layer. In terms of microstructural morphology, the top region of the cladding layer is dominated by fine cellular crystals; the middle region is enriched with a large number of WC particles as well as M₇C₃/M₂₃C₆ carbides; and the bonding zone mainly consists of dendritic structures with pronounced directional characteristics. Mechanical property evaluation shows that the maximum microhardness of the single-track cladding layer reaches 960.6 HV, with hardness first increasing and then decreasing as the laser power rises. Regarding tensile performance, the coated specimens exhibit a tensile strength of 313 MPa and an elongation of 1.3%. Compared with the substrate material, the tensile strength is increased by 21.8%, while the elongation is reduced by 27.8%. In addition, multi-track laser cladding effectively improves the tensile fracture morphology and mitigates brittle fracture features at the coating–substrate interface, contributing to enhanced overall mechanical compatibility.