Effects of Load‐Induced FeS/Cu Interface Bonding Behaviour on the Tribological Properties of FeS/Cu–Bi Composites

The interfacial bonding between a matrix and a lubricating phase has a considerable effect on the mechanical properties of lead‐free FeS/Cu–Bi self‐lubricating composites, but the effect of the load‐induced interfacial bonding behaviour of heterophases on the composites' tribological properties is unclear. In this study, FeS/Cu–Bi self‐lubricating composites with weak and strong FeS/Cu interface bonding were prepared, and the effects of sliding load on the precipitation characteristics of FeS particles and tribological properties of FeS/Cu–Bi composites were studied through experiments and numerical simulation. Results showed that the interfacial failure of FeS/Cu heterophases and precipitation morphology of FeS particles varied because of the varied strength of FeS/Cu bonds. In FeS/Cu–Bi composites with weak interfacial bonding between FeS and Cu, FeS is prone to detachment and expulsion from the friction interface in the form of wear debris during sliding. Under low‐load conditions, the effect of FeS discharged as wear debris is weak, and the material exhibits a relatively low friction coefficient (0.31) and wear rate (5.7 × 10 −5 mm 3 ·N −1 ·m −1 ). The friction coefficient and wear rate of the material gradually increased with load. Strengthening the interfacial bonding between FeS and Cu impedes the detachment of FeS as wear debris during sliding, promoting its precipitation and deposition on the worn surface and thereby mitigating adhesive wear. The friction coefficient and wear rate of the material decreased initially and then increased with increasing load. The material with strong FeS/Cu interfacial bonding effectively induced the precipitation of FeS towards the worn surface under a moderate‐load condition and formed a complete and continuous lubricating film. The minimum friction coefficient and wear rate were 0.22 and 1.3 × 10 −5 mm 3 ·N −1 ·m −1 , respectively.