Effect of the near-surface pore volume evolution on graphite migration of copper-based graphite composite during friction

The discrete element method was used to simulate the friction process of copper-based graphite composite materials in order to analyze the influence of pore structure on the solid lubricants migration in metal-based self-lubricating materials. And the near-surface pore volume evolution was considered in the simulation. The simulation results showed that the graphite particle motion depth and the migration channel increased gradually and tended to stable during friction. The near-surface pore structure has an important influence on the graphite migration and the tribological properties of the composite: the larger the migration channel was, the greater the graphite migration speed was; with the increase in migration channel, the graphite average critical migration depth decreased first then increased, the number of the film-forming particles first increased and then decreased; the greater the migration channel volume was, the more worn particles number were. The numerical simulation was confirmed by experimental analysis on a self-made in-situ observation tribometer, the experimental results were consistent with the numerical simulation results.