Friction And Wear Properties Of PTFE Matrix Composite

Polymer matrix composites showed well wear-resistant. The matrix was thermoplastic resin or thermosetting resin and the enhanced materials were organic or inorganic components. The polymer matrix composites had excellent property, such as self-lubricating, wear-resistant, corrosion-resistant, reducing the noise, low relative density, high strength and processing simply. The polymer matrix composites were widely used as replacement products or substitute products of other materials. Polytetrafluoroethylene (PTFE) had the lowest friction coefficient, the maximum temperature used space and the lowest surface energy, so PTFE had special status in the field of friction and wear. PTFE had bad wear-resistance, low hardness, bad creep-resistance and bad thermal conductivity. So the disadvantages limited a lot of its application. Over the years, the people used various methods to modify PTFE. Among the methods, packing modification became an effective and convenient way.In this paper, three kinds of inorganic padding—carbon fiber (CF), glass fiber (GF) and wollastonite were selected to be the packing modification to PTFE. Also CF/ wollastonite and GF/ wollastonite were selected to be the packing modification to PTFE. Preparation of composites used dry mixing, molding and sintering.In this paper, the wear properties of inorganic padding reinforced PTFE matrix composites were tested with 45 carbon steel ring on dry sliding condition using MM-200 model friction and wear testing machine. A XHR-250 hardness testing machine was employed to test the surface hardness of the composites. Electron metallographic microscopes, electron probe microscope, scanning electron microscopy were used to observe the worn surface of composites and analyze the mechanism of abrasion.The result indicates that PTFE matrix composites' wear resistance enhanced by adding proper amount of CF, GF and wollastonite padding. When the padding proportion exceeds the proper amount, the wear resistance no longer enhances, and the attrition quantity increases. Moreover, adding CF, GF and wollastonite increases the friction coefficient and the surface hardness of the PTFE matrix composites. PTFE matrix composites' wear resistance enhanced by adding proper amount of CF/ wollastonite, GF/ wollastonite padding.The result shows that adding 40% of GF, 40% of CF and 30% of wollastonite separately can significantly improve the hardness of composites and reduce the wear rate, at the same time, the friction coefficient increases. Adding 20% GF +20% wollastonite and 25% CF +25% wollastonite separately can significantly improve the hardness of composite materials and reduce the wear rate. Compared with the pure PTFE, PTFE matrix composite materials has increased the hardness around 60% and reduced the wear rate about 90%.In this research, we find that the wear mechanism of pure PTFE materials is adhesive wear through observing the specimen's worn surface. The wear mechanism of composite materials which have been modified by inorganic paddings is particle abrasion wear and plow wear.