Ultra-high-speed laser cladding process and properties of copper-based micro-multi-electrodes

Abstract To enhance the ablation resistance of cathodes in high-power arc heaters, this study pioneered an innovative methodology through synergistic integration of ultra-high-speed laser cladding with micro-multi-electrodes technology. Capitalizing on the matched emissivity characteristics between LaB 6 and copper matrix, in situ fabrication of arc dielectric coating was achieved on the copper matrix. LaB 6 has strong electron emission and tolerance to cation bombardment. It can attract and disperse the arc, forming separated arc spots that reduce electrode erosion. Analysis revealed the influence of laser cladding process parameters and LaB 6 particle size on the performance of the coating and the distribution of LaB 6 , with the coating’s microhardness being evaluated. Subsequently, a discharge ablation test was conducted to assess the cladding coating’s performance. Laser power was systematically set at 5.4 kW and 4.8 kW, with powder feeding rates of 48.4–24.2 g min −1 . LaB 6 particle sizes were precisely controlled at 1 μ m and 48 μ m. The results demonstrated that at the laser power of 5.4 kW, powder feeding rate exhibited significant control over coating thickness. A reduction in feeding rate from 48.4 to 24.2 g min −1 resulted in a linear thickness decrease from 2.37 to 1.75 mm; At a powder feed rate of 24.2 g min −1 , laser power dominantly controlled LaB 6 melting behavior, with a laser power of 5.4 kW, there is a higher quantity of LaB 6 precipitate in the coating; The microhardness of the coating ranged from 80.4 to 82.9 HV under varying processing conditions, corresponding to a 60% increase relative to the bare copper matrix. The coating generates separated arc spots during discharge, which contributes to minimizing electrode erosion. Notably, 48 μ m LaB 6 shows a broader spotted arc spot region and a more obvious arc spot dispersion effect. The reduction in electrode erosion is mainly attributed to the formation of separated arc spots by adding LaB 6 , which diminishes the heat concentration in the arc spot region.