In order to ensure the reliable operation of all-ceramic bearings under dry friction conditions,tetrafluoroethylene (PTFE) cage was selected to provide lubrication for all-ceramic bearings.The friction and wear properties of Si3N4/PTFE under different load and rotating speed were studied by using Rtec pin/disk friction and wear tester and taking PTFE disk and silicon nitride (Si3N4) pin as friction pairs.The morphology of the transfer film on the surface of Si3N4 was observed by SEM,and the formation reason of the transfer film was analyzed.It is found that the range of test parameters,the friction coefficient first decreases and then increases with the increase of load,and increases with the increase of rotating speed.The wear rate first increases,then decreases and then increases with the increase of load,and increases with the increase of rotating speed.PTFE transfer film will be produced in the friction process of PTFE/Si3N4 friction pair.The surface morphology of the transfer film is different under different load and speed,among which the filament-like transfer film has the best anti-wear and lubrication effect.The increase of frictional heat between the friction pairs causes the change of wear form from abrasive wear to adhesive wear,in which adhesive wear has a greater impact on the wear rate of PTFE.The transfer film produced by PTFE in the process of dry friction can play a role of anti-wear and lubrication,so PTFE can be used as a lubricating material for all-ceramic bearings under dry friction conditions.