Friction and wear behaviors of steel/ bronze tribopairs lubricated by oil with serpentine natural mineral additive

The effect of serpentine natural mineral powder as additive on the friction and wear of tin bronze against steel under oil lubrication was investigated by four-factor and three-level orthogonal experiments using SRV4 sliding wear tester. Results show that the tribological properties of tin bronze were remarkably improved by the addition of serpentine powder into the oil. The importance order that affects the friction reducing performance was load, serpentine content, reciprocating frequency, and sliding time. The order of the antiwear property was frequency, content, load, and time. During the friction process, a non-conductive tribofilm consisting of metal oxides, oxide ceramic particles, graphite, and organics was formed on the tin bronze worn surface by serpentine mineral. The nanohardness and elastic modulus of the film demonstrated the gradient variation that low in the surface and high in the sub-surface, which is favorable for the improvement of the tribological behaviors. •Tribological behavior of serpentine as additive was studied by orthogonal tests.•Friction and wear of steel/bronze pair in oil lubrication was improved.•Chemical state and mechanical behaviors of the tribofilm was studied.•The wear mechanism of serpentine additive to bronze was revealed.