Effect of Square Texture on Tribological Properties of Nano-SiO2/POB-PTFE Composites

Abstract

In order to study the seal design problem of piston rings in Stirling engine, on the basis of filling PTFE with Nano-SiO2 and POB and preparing the GCr15 contact surface with square texture by HM20-I laser marking machine, experiments were carried out on LSR-2M wear tester by indirect weighing and in-situ observation methods. Optical microscope (OM) and scanning electron microscope (SEM) were used to observe the evolution of Nano-SiO2/POB-PTFE composites’ transfer film on contact surface. The results showed that the square texture would shorten the running-in and transitionary periods of the composites’ tribological process, accelerate into the stationary period. The formation process of the composites’ transfer film on the square textured contact surface was also different from smooth contact surface. Although the square texture would increase wear rate, its ability to store wear debris is more conducive to the formation of reliable, uniform and continuous transfer film with a same friction direction. Obviously, reasonable design of surface texture can effectively improve the wear resistance of sealing parts made of filling modified PTFE composites, thus providing theoretical guidance for the seal design of Stirling engine piston ring.