Erosion Properties Of Copper Alloy Electrode In High Current

Reliability of power electronics depends largely on the quality and level of slidingelectric contact. Working conditions is more demanding for electric power equipmentwhich is applied to105A level. To ensure its performance and lifetime, studying onelectrode erosion of electrical contact equipment under the condition of such large currentis meaningful.Special device for electrode erosion, which is called HCED-I, was used in this study.Ablation performance of four different kinds of fixed electrodes, namely, pure copper,La₂O₃/Cu, Al₂O₃/Cu and laser cladding copper, were investigated in different preload andcurrent. The erosion rate and hardness distribution were measured, the contour of erosionsurface and fixed electrodes expansion graph were surveyed and mapped. Macromorphology and microstructure of four kinds of fixed electrodes after ablation wereanalyzed by high-definition camera, OM, XRD, SEM and TEM analysis method. Theexperimental results are as follows:1. The erosion rates of four kinds of fixed electrodes all increase with the increasingcurrent and decrease with the increasing preload. Under the experimental conditions, therange of erosion rates are respectively0.080-0.290g·ms-1（pure copper）,0.018-0.055g·ms-1（La₂O₃/Cu）,0.025-0.061g·ms-1（Al₂O₃/Cu） and0.017-0.157g·ms-1（laser claddingcopper）. Performance of dispersion-strengthened copper is better than that of lasercladding copper, and pure copper is the worst.2. Spatter and plastic deformation in electrodes’ surface is different due to thedifference of hardness, latent heat of fusion, viscosity and structure.Dispersion-strengthened copper and laser cladding copper are better than pure copper.And porosity and cracks are rarely found in dispersion-strengthened copper, but evensome hole cracks and debris in laser cladding copper. The resistance ablation performanceof electrodes is improved by dispersion phase.3. Different organizational structure is found in erosion affected zone of differentelectrodes, a layer of columnar crystal is found in the surface of pure copper and La₂O₃/Cu, but no change in Al₂O₃/Cu. Because of regional segregation, the surface hardness of lasercladding copper electrode is slightly improved. Other electrodes are reduced in differentdegree. According to XRD and TEM analysis, intermediate phase （CuAl） which canreduce the performance and life of electrode is found in pure copper electrode ablativelayer, but not found in La₂O₃/Cu.