Effect of Milling Time on Electrical Breakdown Behavior of Al2O3/Cu Composite

In order to clarify the relationship between the microstructure and the arc erosion behavior of metal-matrix composite, Al2O3/Cu composites with different distributions of Al2O3 particles were prepared by high energy ball milling and powder metallurgy. The effect of milling time on microstructure, properties, and arc erosion behavior of Al2O3/Cu composite was investigated. The results show that the distribution of Al2O3 particles improves significantly with increase of milling time, but Al2O3 particles will be aggregated if milling time is too long. The optimal milling time is 24 h in the range of experiments. A uniform distribution of Al2O3 particles in copper matrix can improve the hardness, electrical conductivity, average breakdown strength, chopping level, and arc life. With improvement in the distribution of Al2O3 particles, the erosion area becomes larger, and the erosion pits become shallower and are dispersed more uniformly.