Abstract:Formation mechanism of self-repair coating on the worn surfaces of 45 steel pairs were investigated by using MM-200 friction and wear tester under lubricated condition with silicate additives.The surface images of self-repair coatings and their chemical composition were detected by using SEM and EDAX.The experimental results show friction energy has a great effect on the formation of self-repair coating on the worn surface.Self-repair coatings are oxide ceramics which mainly comes from silicate additive.The silicate additive can reduce the friction coefficient of the friction pairs,but can't be transferred onto the worn surface of the friction pairs under lower loads of 300 N.Self-repair coatings form on the worn surface of 45 steel at the load of 600 N,900 N and test time of 30 hours.The surface of the self-repair coatings are very smooth without obvious wear scars and plough compared with that without silicate additive.Silicate additive deforms between the friction pairs under shearing stress and prolongs along the worn surface of the friction pairs.Silicate additive continuously shifts from the lubricating oil into the worn surface in the course of friction and wear,and self-repair coatings are formed.Even though the friction coefficient is higher than that without silicate additive,the self-repair coatings on the surface of 45 steel avoid the direct contact of friction pairs.Friction and wear can only take place between the self-repair coatings instead of metal friction pairs,thus improve the wear resistance of the metals.The components of the self-repair coatings mainly come from the silicate additive.