Effect of the content of ball-milled expanded graphite on the bending and tribological properties of copper–graphite composites

Copper–graphite composites with different amounts of ball-milled expanded graphite (EG) were prepared through powder metallurgy. The composites were consolidated at 400 MPa for 60 s and then sintered for 2 h at 850 °C under vacuum condition. The bending and tribological properties of the composites were investigated. The bending strength of the composites decreases from 226.31 MPa at 3 wt.% ball-milled EG content to 85.61 MPa at 12 wt.% ball-milled EG content. The friction coefficient of the composites decreases from 0.3012 at 3 wt.% ball-milled EG content to 0.0973 at 6 wt.% ball-milled EG content, above which the friction coefficient increases slightly. The wear rate of the composites decreases with increasing ball-milled EG content and reaches a minimum value of 2.1 × 10−3 mm3/m at 6 wt.% ball-milled EG content, above which the wear rate of the composites also increases slightly.

► Ball-milled expanded graphite is used as lubricant in copper–graphite composites.
► Ball-milled expanded graphite can be produced easily.
► Ball-milled expanded graphite is an effective solid lubricant.
► Ball-milled expanded is benefital for the bending strength of the composites.