| With the booming development of aviation and military industry,the service performance and service life of high-end self-lubricating plain bearings under extreme working conditions have become the focus of attention.Self-lubricating bearing joints with inside and outside the sphere of the friction pair of outer ring and inner ring,paste within the outer sphere of the self-lubricating material in the process of friction on the surface of the deputy form polymer transfer film,the interface evolution from "inner ring-selflubricating material" to "self-lubricating material-transfer film" has taken place,and good lubrication performance can be achieved without lubricating oil..Therefore,the performance of transfer film is very important to the service performance and life of bearings.Self-lubricating materials mainly include PTFE based self-lubricating composite material and PTFE fiber as friction reducing phase self-lubricating liner in two forms.In this paper,the mechanism of the transfer film of pure PTFE,polymer and liner were studied.For the first time,the image information of the whole process of PTFE transfer film formation was recorded and combined with the coverage rate.PTFE/ epoxy self-lubricating composites and PTFE/ Arlene self-lubricating composites were prepared,and the effect of transfer film of the two materials on tribological properties was studied.The formation mechanism and evolution mechanism of PTFE/Kevlar self-lubricating liner transfer film under heavy load condition were studied.In order to improve the performance of the transfer film,the influence of laser surface texture on the formation mechanism and tribological properties of the transfer film was further studied.Two kinds of pre-filled lubricating films(TLFs)with graphite and PTFE textures were prepared using the edge of heat affected zone as anchor points.In order to improve the performance and life of bearings,a self-compensating and selflubricating motion pair was developed.Lubrication film was formed on the friction interface by intervening self-compensating lubricant to solve the stability and failure problems of transfer film.The main conclusions are as follows:It is proved that the coverage rate of pure PTFE transfer film is concentrated in 10-25%,and the higher load and speed are favorable to the formation of transfer film.After the friction stops,the transfer film still has a certain life of friction reduction.The prepared PTFE/ epoxy self-lubricating composite has excellent tribological properties,which proves that the test speed,load and reciprocating stroke catalyzed the physical and chemical reaction of the friction interface and promoted the formation of transfer film.The oxidation reaction during the interface evolution resulted in the formation of carbon-rich zone which inhibited the formation of transfer film.The prepared PTFE/ Arlene self-lubricating composite has good mechanical properties and low friction coefficient.It is proved that the smaller the load and reciprocating stroke is,the better the formation of transfer film.The discontinuity of the transfer film is related to the increased oxidation reaction at high frequency and the uneven distribution of fluorine on the worn surface.The double layer structure transfer film generated by PTFE/Kevlar self-lubricating liner under heavy load condition was found and its formation mechanism was studied.It is proved that the surface texture can effectively improve the tribological properties.The two surface textures pre-filled lubrication film has good tribological properties,strong adhesion,complete and continuous transfer film,which solves the problem of severe wear at the initial stage of friction and shortenes the run-in period significantly.The self-compensation and self-lubrication motion pair developed effectively solves the stability and failure problems of the transfer film,and the initial prototype passes the functional verification,providing a new idea for improving the service performance and life of the self-lubrication joint bearing. |
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