The effects of normal load on the friction and wear characteristics of impregnated graphite under different friction systems were investigated.The surface wear morphology and wear profile were characterized by scanning electron microscope and laser confocal microscope,respectively,and the friction and wear mechanism between impregnated graphite and dual balls (GCr15 steel ball and Si3N4 ceramic ball) were evaluated.The results show that the wear marks deepen and widen with the increase of normal load.The wear rate is negatively correlated with the normal load,while the friction coefficient and wear volume is positively correlated with the normal load.The wear mechanism of graphite under small load is adhesive wear and abrasive wear,while the main wear mechanism under large load is adhesive wear,oxidation wear and fatigue wear.Compared to the friction pairs of Si3N4/graphite,the friction pairs of GCr15/graphite have lower wear rates and form a complete and more continuous "third body" lubricating film during the friction process,which reduces wear and protects the graphite matrix.