Tribological Study On PTFE Composite Reinforced With Nano-SiC

The rapid development of science and technologies has drawn tremendous attentionsto polymers, mainly due to the special performances of these materials. The demand frommodem space industry, automobile industry, electronic and national defense industries ontribological, mechanical, thermal-proof as well as chemical stable properties of material isbecoming increasingly higher and higher. Among the highly-rated plastics, PTFE is onewith excellent composite properties, such as chemical stability, high- and low-temperaturedurability, and self-lubricability, and thus has widely found its way in tribological areas.Despite this, the anti-wear property of PTFE is poor. Thereby the demand from certainareas of application can not be satisfied. To counteract this problem, solid lubricant, powdermetal, powder oxidized metal etc. have been used as additives in PTFE, the addition ofthese powders can largely improve the performances of the material. Inorganicnano-materials acquire unique behaviors, such as mini-scale effect, volumetric effect,surface effect along with cooperative effect, and therefore the presence of nano-materials inparent composite materials can lead to many unexpected performances. One of the popularareas in tribological studies in recent years is to use nano-particles as additives to improvetribological performances of materials. Yet, the introduction of composite additives intoparent materials to improve its performance has seldom been reported.Systematic research on tribological properties of treated PTFE composite by additivesof nano- and several other materials has been conducted in this work, which include thestudy on the tribological and mechanical effect from varied load and the addition ofnano-SiC into PTFE, and the analysis of changes on material micro-scale structures. Inaddition to this, the reinforced PTFE by additions of nano-SiC and graphite, MoS₂, glassfiber, nano-Al₂O₃ have also been studied to illustrate the effects from the introduction ofcompound additives into parent materials. Furthermore, the effect of surface-treating oninorganic nano-particle/plastic composite has also been studied, in whichnano-SiC/graphite/PTFE, nano-SiC/MoS₂/PTFE have been applied and the dosage, types ofthese chemicals have been tested to evaluate their influence on tribological performances ofcomposite.The experiment gives the following results: the addition of nano-SiC improves the hardness of PTFE, largely reduces its wear rate, while the coefficient of friction of thePTFE composite is increased; the wear loss is the lowest as the addition of nano-SiC fallsin a range of 5-7%; as the addition of nano-SiC further increases, the wear loss of PTFEcomposite also increases. Nano-SiC effectively improves the load-bearing capacities ofPTFE, while graphite and MoS₂ reduce the friction effect. Under the proposed experimentalconditions, excellent tribological performances can be reached for composite PTFEmaterial with 5% SiC and 3% MoS₂, or 5% SiC and 5% glass fiber. Surface-treatednano-SiC can be evenly dispersed in PTFE, the thus processed composite acquires ananti-wear property 5 times higher than that without treatment, yet its coefficient of frictionis reduced, the recommended dosage of couplings in this case is 1%. Additives haveimportant implications for the improvement of wear-resistance of PTFE composite andhence enlarge the area of application for such materials.The data from the experiment is analyzed and the main results were reached: thecurves of the wear loss, coefficient of friction and hardness of PTFE composite werederived by varying the dosage, types of additives and couplings, so that importanttheoretical as well as experimental basis of importance is proposed for the searching of thebest conditions of addition and modification on PTFE composite.