The whole course friction characteristic curves, friction coefficient μ versus friction distance n , which consisted
of three stages, i.e., d μ /d n <0(initial self lubricating stage), d μ /d n →+0(stable self lubricating stage) and d μ /d n →∞(failure stage,
self lubrication giving way to dry friction), were obtained for the oily self lubricating materials. The self lubricating mechanism in
sliding friction was founded by studying the physical changes during friction course and analysing the properties of material and lubrication oil, and it may be given as follows: under the compressing action of normal load and friction heat, and based upon the fluidity of oil, compressibility of pores and heated expansibility of oil, the oil stored in the pores of material is compelled to flow to the friction surface to lubricate. During friction process, there are self feedback adjusting functions, i.e., HD mechanism, among friction heat, oil quantity and friction coefficient; and it is that which maintains the friction coefficient low and steady. It is unavoidable for oil to waste during friction process, but the wasted oil is able to supply under the HD mechanism by increasing the friction surface temperature. As soon as the friction surface temperature is near or beyond the flash point of oil, the oil between friction surfaces will volatilize greatly, and this makes the friction type transform from self lubrication friction to dry friction and the self lubrication fails.