Research On The Interfacial Mechanical Behavior And Compensation Mechanism Of High Temperature Self-compensating Lubrication Film

The high temperature self compensating lubricating composite is a kind of composite material with high strength and wear resistance,which is prepared by infiltration of molten composite solid lubricants into pores of microporous matrix by infiltration process.Under the action of ambient temperature and frictional heat-stress,the solid lubricant is continuously diffused to the friction surface to form a lubricating film to realize self-compensation lubrication.The durability and integrity of the lubricating film is the key to the normal operation of self-compensated lubrication composites.In this dissertation,the mechanical behavior of self-compensated lubrication film interface was analyzed by establishing the mechanical model of lubrication film/matrix interface,and the self-compensation lubrication mechanism of high temperature self-lubricating composite was also discussed.The melt infiltrated TiC-M3/2 series high temperature self lubricating composite material is taken as the research object.Based on the mechanism of high temperature solid lubricant precipitation and the formation mechanism of the self compensating lubricating film,the mechanical analysis model of the interface between the lubricating film/matrix interface was established and the stress of the model was analyzed and calculated during the friction process.The influences of external loads,frictional contact stress,and residual thermal stress caused by frictional temperature change on the bearing capacity and stability of the lubricating film interface were discussed.The ABAQUS finite element software was used to analyze the interfacial failure behaviors of the lubricating film surface and the lubricating film/matrix.The influence of external loads and frictional thermal stress on the mechanical behavior of the lubricating film interface were discussed.The results indicated that the initial cracks of the lubricating film formed by the friction interface mainly occur at the bonding surface of the lubricating film and matrix,and the cause of the crack is mainly caused by the tangential stress during the friction process.At the same time,under the combined action of external loads and temperatures,residual stress is generated inside the lubricating film,causing it to undergo plastic deformation.When the residual stress exceeds its yield strength,the crack growth will be promoted,and the part of the lubricating film will fall off.The friction coefficient of the friction pair increases and the self lubrication performance are reduced.The infiltrated TiC-M3/2 high temperature self-compensating lubricating composite materials was prepared by infiltrating the Pb-Sn-Ag-RE composite solid lubricant with microporous sintered body using an electromagnetic induction infiltration process.The friction and wear properties of the MMG-10 high temperature friction and wear tester were investigated.Images and structures of worn surfaces were analyzed by means of scanning electron microscopy(SEM),energy dispersive X-rayanalysis(EDXA)and X-ray diffractometry(XRD).Interface failure and self compensation mechanism of lubricating film at high temperature self compensation were discussed.The results indicated that during elevated temperature friction and wear,the solid lubricants infiltrated in the composite materials spread out to the friction interface to form a composite solid lubricating film composed of oxides and intermetallic compounds of lead,tin,silver and other elements to realize the self lubrication of the composites.When the interface crack of the lubricating film is produced,the silver is diffused and enriched at the crack under the effect of high temperature and friction thermal stress,which presents the self compensation and self compensation lubrication of the self lubricating composite.