Study on dual-path friction mechanisms of modified sepiolite (sepiolite-MgSiO3-CaCO3) reinforced copper-based composites

The reinforcement mechanism of modified sepiolite (Sepiolite-MgSiO 3 -CaCO 3 ) in copper-based composites under dual-path loading conditions was investigated. Results demonstrate that the composite exhibits optimal comprehensive performance at 20 % sepiolite content, with relatively moderate degradation in mechanical and thermal properties. In sliding friction tests, each 10 % increase in sepiolite content raises the friction coefficient by 4.1 %, 2.9 %, and 5.7 %, respectively, while also accelerating wear, as evidenced by expanded wear tracks and a transition in debris morphology from flocculent to laminated structures. Braking tests reveal that increasing the speed from 1500 to 6000 rpm at intervals of 1500 rpm, the fluctuation ranges of the average friction coefficient are 12 %, 6 %, and −16 %, respectively, with the friction stability coefficient following a similar trend, though the wear rate remains consistently low. The three components in modified sepiolite demonstrate synergistic anti-wear mechanisms: sepiolite forms a film-like structure through fragmentation, smoothing, and aggregation, while MgSiO 3 and CaCO 3 enhance wear resistance by plowing effects, collectively promoting a transition in the dominant wear mechanism from abrasive to adhesive wear.