Analysis on Mechanism and Tribological Behavior of Al Alloy Based Graphite Composites

The tribological behaviors of Al graphite composites under low load and low sliding speed were studied with a Falex machine. At the initial stage of sliding, the friction coefficient of the composites was nearly the same as that of matrix alloy. With increasing of friction duration, the coefficient of friction decreased and stabilized at about a half of that of the matrix alloy. The higher the graphite particle content in the composites, the less it takes to reach the stable friction coefficient. The reduction in friction of composites is because of the formation of graphite lubricating film during sliding. When the area of self lubricant film exceeds 85%, the friction coefficient keeps steady. The dynamic equilibrium of graphite film is kept due to the balance of the squeezing out and restricting of graphite particles in the surface and subsurface of composites by the deformation of matrix.