The Research On The Modification Of Palygorskite And Its Effects On The Properties Of Automotive Friction Material

Braking lining and pad are the key parts in the automotive braking system and play an important role on the stopping of vehicle. The traditional friction material fiber-reinforced by asbestos has been gone out due to harm to human health. Much more friction materials are needed to meet requirements of high-speed, heavy duty, comfortable performance and health harmlessness. Most important work in the research field of automotive friction materials is to find the fibers to replace the asbestos, which has good comprehensive performance as the reinforced material in the braking pad or lining. Some fibers, such as glass fiber, the steel fiber, the aramid fiber(Kevlar),mineral fiber etc. have been developed, but any can't replace asbestos, so two or more fibers are mixed in the friction material commonly. Palygorskite has been widely used in many industrial fields because it possesses high temperature resistance, good absorption ability, large surface area and its special mineral structure, no report about the application of palygorskite in the friction material has been founded so far. Main researches of this paper are as following:1. The optimal modification process parameters are obtained by the drop height method employed to evaluate the effects of surface modification. XD-792 coupling agent: agent ratio in wt. is 2%, modification temperature 60℃, modification time 10Min.; XD-172 coupling agent: agent ratio in wt. is 3%, modification temperature 90℃, modification time 10Min.;ND-42 coupling agent: agent ratio in wt. is 2%, modification temperature 90℃,modification time 30 Min.; Al-Zr coupling agent: agent ratio in wt. is 2%, modification temperature 90℃,modification time 10 Min.2. IR-spectrometry analysis of the modified palygorskite fabricated in above optimal process show that stronger chemical combination exists between Al-Zr coupling agent and fiber-like palygorskite.3. IR-spectrometry analysis of mixed products of four kinds of coupling agent and phenolic resin show that the chemical combination between Al-Zr coupling agent and phenolic resin is the strongest relative to the other three coupling agents.4. The braking pads (linings) were fabricated by mixture of modified palygorskite or unmodified palygorskite, and phenolic resin, the results show the material modified by Al-Zr coupling agent can improve the friction coefficient stability and decrease the wear rate in high temperature. The bake pad fabricated by Al-Zr coupling agent-modified palygorskite posseses better high temperature performance.