Experimental Research on Sliding Friction of Dense Dry Particles Lubricated Between Parallel Plates

Particle flow lubrication is a promising choice for extreme working conditions. Lubricated by dense dry particles between parallel plates, clarifying the sliding friction characteristics are significant to the design and parameter selection of particle-lubricated warm forming die, which is not well studied yet through the experimental methods. A self-developed testing apparatus was used to study the sliding tribological characteristics of parallel plates under dense particle lubrication. The experimental results showed that the dry particle lubrication between parallel-plates behaves excellent lubrication characteristics on sliding friction. The average coefficient of friction between the upper palate and particles increases rapidly with the increase of pressure load while corresponding to the change of average coefficient of friction, the average friction force increases linearly with the increase of pressure load. The force chain line between the upper plate and the particle lubrication media becomes thicker with the increase of pressure load, indicating that the contact force and contact stress are increasing. The average coefficient of friction and average friction force decrease with the increase of sliding velocity. The force chain line between the upper plate and the particle lubrication media becomes thinner with the increase of the sliding velocity, indicating that the contact force and contact stress are decreasing. The greater the contact stress is, the greater the average coefficient of friction will be. This study provides a deep understanding of the sliding tribological behaviors of the warm-forming die lubricated by the particle media.