Tribological Properties Of PMMA Based Composites With Microspheres Embedded On The Surface

Polymer materials are widely used in bearing,transmission,sealing and other mechanical parts due to their excellent self-lubricating properties,high chemical stability and strong performance design.At present,the increasingly harsh environment poses severe challenges to the friction materials and surface properties of mechanical moving parts.Seeking high-performance friction materials and surface is the key to improve the service performance and life of mechanical moving parts.Filling modification and surface texture are effective ways to improve the friction reduction and wear resistance of polymer.A new method of microspheres embedded on surface was used to achieve the dual effects of filling modification and surface texture of PMMA based composites,which provided a reference for the surface strengthening and tribological properties improvement of polymer based composites,as well as the research and development of new materials.The PTFE/PMMA with 304 stainless steel spheres and PEEK/PMMA composite materials were prepared by using self-lubricating excellent PTFE and PEEK,and the PMMA based composites with 304 stainless steel spheres,brass spheres,PA66 spheres and POM spheres were also prepared by self-curing at room temperature.The effects of microsphere type,microsphere diameter and lubrication type on the friction and wear behavior and mechanism of PMMA based composites with microspheres embedded on the surface are investigated.The research indicates:(1)Compared with PMMA composites with steel spheres embedded on the surface,the friction properties of PTFE/PMMA and PEEK/PMMA composites with steel spheres embedded on the surface are both improved.When the filling mass ratio of PTFE is 7wt%,the steel sphere/PTFE/PMMA composites show better friction coefficient and wear-resistance.PTFE is easier to form a transfer film than PEEK,and the presence of a transfer film can significantly reduce friction.(2)The tribological properties of steel sphere/PMMA composite materials can be better when comes to the same diameter microspheres.When the sphere diameters are different,the sphere diameters are 2mm,which can form a larger surface texture pit area density,so that the steel sphere /PMMA composites show a lower friction coefficient and wear rate.Proper reduction of diameter will further reduce the wear rate of PMMA composites.The change of diameter does not improve the high wear of POM sphere/PMMA composites,but the decrease of diameter can reduce the friction coefficient.(3)When the diameter of the steel sphere is 2mm and the filling mass ratio of PTFE is 7wt%,the friction reduction and wear resistance of the steel sphere /PTFE/PMMA composite is the best.When the diameter of steel sphere is 2mm and the diameter of POM sphere is 1.588 mm,the friction coefficient of steel sphere/POM sphere /PMMA composite material increases greatly.(4)The steel sphere/PMMA,brass sphere/PMMA and POM sphere /PMMA composites with the same diameter show better friction coefficient with the liquid paraffin lubrication,and better wear rate with the synthetic oil lubrication.The phenomenon is related to the plastic deformation degree of the composite and the stability degree of the lubrication film.When the diameter of POM sphere is 2.381 mm,POM sphere /PMMA composites show the lower friction coefficient with the liquid paraffin lubrication and lower wear rate with the synthetic oil lubrication.With the increase of load,the friction coefficient of POM sphere /PMMA composites increases first and then decreases.The increase of load will produce elastoplastic deformation,and the increase of oil film fluidity will be enhanced.With the increase of velocity,the friction coefficient of composites decreases,and the lubrication form changes from mixed lubrication to fluid lubrication.The wear rate of POM sphere /PMMA composites increases with the increase of load and velocity.