Wear performance of alumina-reinforced copper–matrix composites prepared by powder metallurgy

Abstract

Copper–alumina composite materials with improved electrical conductivity and tribological properties were developed. The copper–alumina composite materials were prepared by powder metallurgy using nano-Cu/Al₂O₃ powder. The powders were deoxidized from CuO/Al₂O₃ powder synthesized by coprecipitation using NH₄HCO₃ as precipitator and CuSO₄ + NH₄Al(SO₄)₂ as maternal solution. The wear test against 440C stainless steel was performed at room temperature using a ball-on-flat configuration with 300 µm amplitude at various normal loads ranging from 0.1 N to 1 N. The effects of load and mass fraction of Al₂O₃ on the friction coefficient and wear loss were investigated. Results showed that the wear loss first decreased and then increased with an increase in the mass proportion of Al₂O₃ from 1% to 5%. Minimum wear loss was found at 2% proportion, in which the electrical conductivity was 82% of the International Annealed Copper Standard. The friction coefficient of the copper increased slightly with an increase in load. By contrast, it first increased and then decreased for the copper–alumina composite materials. The wear loss of the copper–alumina composite materials is always lower than that of copper. The highest relative wearability is 3.13, indicating better wear resistance. The wear mechanism of copper is oxidation wear, whereas that for the copper–alumina composite materials is adhesive wear.