Tribological and electrical properties of laser-clad W–Cu coatings on 7075 aluminum alloy

Enhancing the ablation and wear resistance of aluminum-based armature is essential for improving the durability and operational stability of the electromagnetic launcher (EML). In this study, W–40 wt% Cu coatings were deposited on 7075 aluminum alloy (AA 7075) via a strategy combining dual-layer laser cladding with laser remelting to improve wear resistance while retaining electrical conductivity. The effects of laser parameters on the transient formation process, phase distribution, hardness, relative density and electrical conductivity of coatings were investigated. The results indicate that Al diffusion improved W–Cu wettability and may promote the formation of an interpenetrating transition layer at the interface between the two immiscible phases. Nevertheless, low thermal input was required to suppress excessive Al diffusion, which would lead to the formation of brittle intermetallic compounds (IMCs) and a consequent reduction in conductivity. Laser remelting alleviated lack-of-fusion defects, redistributed Al to prevent enrichment and cracks in the overlapping zones, and thus improved the surface relative density. The fabricated coating exhibited an average hardness of 259.5 HV1 and an electrical conductivity of up to 32.1 % IACS. Its wear rate (9.3 × 10−5 mm3/N·m) was 64 % lower than that of AA 7075, with adhesive wear as the dominant wear mechanism. At 300 °C, the wear rate further decreased to 8.5 × 10−5 mm3/N⋅m due to the formation of lubricating WO3. This work offers a potential approach to improve the wear performance of aluminum-based armatures.