Study On Friction And Wear Properties Of Epoxy Nanocomposites

Polymers and polymer composites are being increasingly used in the filed of tribology because of their better damage tolerance, mechanical properties, erosion resistance and abrasion resistance in comparison with metals. The study on friction and wear properties of polymers and their composites also attracts more and more attention of researchers.As an important member of polymer family, epoxy exhibits outstanding mechanical and adhesive properties, chemical erosion resistance and excellent capacity for bearing load. At present, the reports about the tribological performance of epoxy and its nanocomposites are little. Owing to the large specific surface area and high surface energy, nano-materials might strongly bond with epoxy, and hence improve greatly the physical and mechanical properties of epoxy. The wear resistance of epoxy might also be improved greatly.The friction and wear tests of epoxy and its nanocomposites were conducted on an MM-200 model friction and wear tester under dry sliding friction and water lubricant. The effects of the load and nano-clay/Si on the frictional coefficient and wear mass loss were researched. The microcosmic morphologies of specimen surfaces were analyzed with a JSM-5600 scanning electron microscopy (SEM). At last, the process of the friction and wear was simulated using the software of ANSYS/LS-DYNA, and its changes and influences of the stress, displacement and temperature field were discussed.The friction coefficient and wear mass loss of neat epoxy and its nanocomposites all increase with increasing applying loads under the condition of dry sliding friction. The stability of the friction coefficient becomes bad with increasing applied load. The wear mass losses under 49N and 98N loads are little, but the wear mass losses under 147N and 196N loads increase suddenly. The changes of the frictional coefficient are steady under 49N and 98N loads, but the changes are great under 147N and 196N loads because of high loads. For the wear resistance, epoxy/1.0%clay/Si nanocomposite surpasses the epoxy/0.5%clay/Si, epoxy/2.0%clay/Si nanocomposites and neat epoxy. Because the 1.0% nano-clay/Si content approaches the optimal value, the friction coefficient is small and stable, the wear mass loss is also quite small, and the wear resistance is improved greatly. Especially this kind of situation is more obvious under a high load.The friction coefficient and wear mass loss of neat epoxy and its nanocomposites also increase with increasing applied load under the condition of water lubricant, but they have their characteristics compared with those under the condition of dry sliding friction. The wear mass losses under 49N and 98N loads are as much as those under the condition of dry sliding friction, but under 147N and 196N loads the wear mass losses are more obviously than those under the condition of dry sliding friction. At each load, the changes of the friction coefficient are steadier and the values of the friction coefficient are bigger because of the scour of the water. For the wear resistance, epoxy/1.0%clay/Si nanocomposite also surpasses the epoxy/0.5%clay/Si,epoxy/2.0%clay/Si nanocomposites and neat epoxy, and this is maybe also relative with nano-clay/Si content which approaches the optimal value.The process of the fiction and wear was simulated using the software of ANSYS/LS-DYNA.the stress and displacement of each element of the typical position of epoxy have different rules. On the one hand, the rapider the rotational speed is, the greater the impact is, and the shorter the impact time is because of the impact comes from steel wheel; On the other hand, the distributions of the deformation region are different because of the mutual extrusion of elements. The rotational speed is still the main factor to the temperature under the same friction coefficient. The temperature increases first, and then the stable region appears under low rotational speed; the temperature strides over the stable region and increases quickly under high rotational speed. However, according to the numerical theory, the general trend is that the temperature changes quickly first, and then the temperature grad trends to a constant, and the temperature trends to a constant after the heat exchange arrives to a balance at last. For the relation among the stress, the displacement and the temperature, when the rotational speed is given in a sliding process, the temperature is fluctuant, the stress and deformation are also fluctuant in the contact region, and they are relative with the temperature. These indicate that the contact situation is instable. The instability of the contact situation indicates that the asymmetrical friction and wear can happen simultaneously when the moving pair produces the contact vibration.