Research On Preparation And Tribological Property Of Copper Powder Metallurgy Brake Pads For High-speed Train

With the continuous development of science and technology, the speed of highspeed train is higher and higher. At the same time, people pay much more and more attention to the safety of high-speed train, especially have more rigorous requirements of brake pads in braking system, and make further studies on properties of braking pad materials. Based on this background, two different ratio copper-based brake pad materials FA and FB were fabricated by powder metallurgy, and used the brake pad materials for commercial 300km/h high-speed train as reference, named DB. Do comparative study on the brake performance of the three kinds materials.On the MM-1000II-type friction and wear testing machine, we respectively trial the tribology properties of the friction pair formed by three kinds material and25Cr2Mo1 VA steel at different braking speeds and different braking pressure. We also analyze surface organizations and form of paired materials by SEM and EDS. Then we discuss the copper powder brake friction and wear mechanisms.The results show that: With the brake speed increasing, the friction coefficients of FA and DB have shown an decreasing trend when the friction coefficient of FB increase firstly and then decrease; If the braking speed remains constant, with the increment of the braking pressure, the friction coefficient of the three materials increase firstly and then decrease. Compared comprehensively, the friction coefficient and the braking distance under different braking speed have been able to the requirement of the high-speed train braking, and the stability of friction performance is well, but the wear resistance of FA and FB have not been up to DB.The SEM micrograph of the worn surface of the three kinds of materials at different conditions, find that the main wear mechanisms are abrasive wear, adhesive wear, fatigue wear and oxidative wear. Because of the influence of braking load and braking speed, the wear mechanisms of FA and FB are mainly abrasion and oxidation wear,and the main wear mechanisms of DB are abrasion and fatigue wear.