Study On The Performance Of Piston Rings Formed By M-PTFE Composite Filled With Modified Nanomaterials

Polytetrafluoroethylene(PTFE)based composites are widely used as piston ring materials for small oil-free air compressors due to their excellent tribological properties.Currently,the piston rings molded from PTFE based composites still have insufficient sealing and mechanical strength during operation,which to some extent affects their performance and lifespan.In order to further improve the service life of piston rings,under the premise of considering the working conditions of piston rings,the thesis introduces nanoparticles into the PTFE composite material formula(M-PTFE)previously studied by the research group.Composite material formula were modified continuously to obtain composite materials with better mechanical properties,friction and wear properties and thermal stability.Piston ring products are formed using superior composite material formulations,and appropriate molding process parameters were determined through experiments.Finally,piston ring products with improved performance were formed,providing a theoretical basis and practical application plan for subsequent research on piston ring materials and forming for small oil-free air compressors.Focusing on the above issues,the research content and conclusion of this thesis is as follows:(1)Two kinds of nano particles with good effect are introduced into M-PTFE composites to improve PTFE composites:nano silicon dioxide(Nano-SiO2)and nano silicon carbide(Nano-SiC).By testing the mechanical properties,friction and wear properties and thermal stability of the composite,the influence of the content of two kinds of nano particles on the properties of the composite was studied.Through the comparison of the experimental results,it was concluded that the properties of the composite were improved by filling two kinds of nanoparticles respectively.After comprehensive consideration,the appropriate content value of two kinds of nano particle filling to improve the performance of M-PTFE was determined,and further modification treatment was carried out.(2)Unmodified nanoparticles are easy to agglomerate,and the effect of improving the performance of composite materials is not obvious.This negative impact can be mitigated by modifying nanoparticles with coupling agents.Study the effect of different concentrations of coupling agents KH-550 and KH-570 on the properties of filled composite materials when surface grafting modification of Nano-SiO2 and Nano-SiC was carried out,such as in terms of the dispersion degree of the modified nanoparticles and the various properties of the filled composite.The dispersion degree and surface properties of the nanoparticles were characterized by scanning electron microscopy(SEM)and infrared spectroscopy(FT-IR)to determine the optimal concentration values of the two coupling agents modified nano-SiO2 and nano-SiC respectively.By comparing the modification effects of the four obtained formulations,two groups of composite formulations with better performance were determined for the hot pressing process research of forming piston ring.(3)Forming piston ring products with two groups of composite materials with better performance improvement effect.The experiment compared the effects of different mold temperature and pressure values on the internal and external diameter deviation and thickness deviation of the workpiece.To determine the optimal process parameters for composite hot pressing piston rings with two formulations,the effect of two forming process parameters on the comprehensive quality of piston ring products was considered.Finally,a piston ring product with good assembly relationship,better sealing performance,meeting service requirements,and longer service life is obtained.In this thesis,the application performance of piston ring products was improved by improving the properties of formed piston ring composite materials.A series of studies have been conducted from the powder of each component to forming the ideal product,which has certain reference and promoting significance for the deepening research and practical application in this field.