Microstructure and frictional properties of copper-tin composites containing graphite and MoS2 by rapid hot-press sintering

Abstract

Rapid hot-press sintering was employed to prepare the self-lubricating composites using Cu-Sn alloy, Cu-coated graphite, and Cu-coated MoS2 powder as raw materials. The effects of the sintering temperature on the microstructure, interfacial characteristics, and friction properties of the composites were primarily examined. The findings demonstrated that as the sintering temperature rose from 680 °C to 780 °C, the copper alloy matrix's grain size grew. The composites' density and hardness increased and subsequently declined as the sintering temperature rose. Moreover, the interfacial bonding between the copper-coating lubricant and the copper alloy matrix was improved by raising the sintering temperature. The average friction coefficient of the composite grew and then fell as the sintering temperature rose, and the wear initially increased, then decreased, and then increased again. The copper-tin composite had good frictional properties because a composite lubricating film made of graphite, MoS2, and metal oxides formed on the worn surface. Among them, the comprehensive friction performance was best at the sintering temperature of 760 °C, with an average friction coefficient of 0.11 and a wear rate of 2.332 × 10−6 mm3N−1·m−1. The wear mechanism was the combined coupling effect of abrasive wear, adhesive wear and oxidative wear.