Study On The Growth Process Of The Friction Transfer Film Of Nano-SiO₂/POB Modified PTFE Composite

The Stirling engine is an important component of the dish-type solar thermal power generation system.Its unique working principle requires that the piston sealing material has good self-lubricating performance and wear resistance.Therefore,based on the working conditions of the Stirling machine,the friction performance of the corresponding polymer materials is studied according to the use requirements,which provides test basis for the development of sealing materials,and has practical significance for the development of the dish solar thermal power generation technology.In order to better study the friction,wear and failure between the piston ring and the cylinder wall,this paper takes the bolt-disk friction model as the test object.Under dry friction conditions,the synergistic anti-friction effect of polymer POB(Polyphenylester)and Nano-SiO₂ modified PTFE composite material,the evolution of the transfer film of the composite material and the influence of the dual surface morphology on the growth process of the transfer film of the composite material were studied.Two composite materials,Nano-SiO₂/PTFE and Nano-SiO₂/POB-PTFE were prepared by the machine blending-molding molding-sintering method.The experiment was carried out on the LSR-2M reciprocating friction and wear tester to observe the growth process of the transfer film of the two materials on the mirror surface and the square texture dual surface and evaluate the tribological properties of the composite material.Through the above experimental research observations,we can see that:1.The growth process of the transfer film of Nano-SiO₂/PTFE composite material on the mirror surface and the dual surface can be divided into two periods:the running-in period and the steady-state period.The growth process of Nano-SiO₂/POB-PTFE transfer film can be divided into four periods:running-in period,transition period,steady-state phase I,and steady-state phase II;POB and Nano-SiO₂ form a synergistic anti-wear effect during the friction process.It promotes the formation of transfer film and stable adhesion,thereby reducing the wear rate of PTFE.2.The square texture promotes the generation of wear debris to a certain extent,can shorten the time for the PTFE composite material to enter the steady state period,and promote the formation of the transfer film,but it will lead to a higher initial friction coefficient and volume wear.In summary,observing the growth process of the transfer film on the dual surface of the PTFE composite material shows that the filling of POB helps to improve the tribological properties of Nano-SiO₂/PTFE,and the square texture dual surface speeds up the time for the PTFE composite material to enter the steady state period and improves The service life of the piston ring can provide a reference for the sealing design of the Stirling engine,thereby improving the efficiency of the dish-type solar power generation system.