Research On The Friction And Wear Performance Of SiCp Reinforced Al-matrix-composites

For the brake disc material used in railway vehicles, cast iron has been the first choice for years. However, with the higher speed the railway vehicle run recently, it's necessary to lighten down the weight of vehicles, especially the weight of brake system. Iron materials traditionally used as brake disc are unable to help to fulfill this task, while the Al-MMC/SiCp(Al based metal matrix composite reinforced by SiC-particles) has the advantages of good wear resistance, low heat-dilated coefficient, high heat conductivity and good erode-resisting ability, and naturally has much lower density than iron materials. Thereby, the weight of brake system would be decreased evidently by using Al-MMC/SiCp material as its brake disc, and consequently, the railway vehicles will has the opportunity to run more safely and with higher efficiency.By using the self-made brake-simulating tester model MM 1000, experiments were performed to acquaint the friction and wear characteristics of Al-MMC/SiCp in brake system, based on the purpose to made Al-MMC/SiCp brake disc for high-speed railway vehicles. And the phenomena occurred in the experiments were primarily analyzed.The results in the experiments showed that, the Al-MMC/SiCp with 20% Si in its matrix had more preferable performance than the Al-MMC/SiCp with 9% and 12% Si. The heat-treated Al-20%Si MMC/SiCp had better performance in the experiments than the original Al-20%Si MMC/SiCp, while the pressed Al-20%Si MMC/SiCp had the best performance in all the Al-20%Si MMC/SiCp used in this research.When considering the effects of brake velocity and pressure, the results suggested that, with the increasing of brake speed, friction coefficient of the pressed Al-20%Si MMC/SiCp decrease appreciably, while the wear rate of it increased. With the increasing of brake pressure, the friction coefficient decreased and the wear rate had almost no changes.Compared with the cast iron HT250 traditionally used as brake disc material, the pressed Al-20%Si MMC/SiCp had better performance whatever referred to friction coefficient or wear rate. And the other Al-MMC/SiCp had also the similar performance of the cast iron. So it can be concluded that in the field of high-speed vehicles' brake disc, the Al-MMC/SiCp has plenty of potential to be substitute of cast iron.In this article, assited by the method of SEM and EDX, it was primarily analyzed that the wear mechanism of the Al-MMC/SiCp coupled with the semi-metal brake pad,...