Fundamental Research On Vehicle Friction Material Fabricated By Fibrous Polygorskite From Dafang, Guizhou Province

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 and health harmlessness. So, 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 constitute in the braking pad or lining.Palygorskite has been widely used in many industrial fields because it possesses its abundance, low price, large surface area, low density, high temperature resistance, good absorption ability and its special mineral structure, no report about the application of palygorskite in the friction material has been founded so far, so some application researches of palygorskite as reinforced component in friction material are presented.This paper studies friction and wear properties and impact strength of the friction materials composed of polygorskite (include dehydrating polygorskite) and phenolic resin modified with NBR using a D-MS wear tester and impact instrument. And polygorskite-reinforced friction materials compare with asbestos, sepiolite, wollastonite, brucite composites. The results are showed below:1. Based on the results of friction and wear test and impact test of the composites with polygorskite and phenolic resin, the best process parameter of pressure 6.5MPa was obtained.2. Both the mean of friction coefficient and the mean of wear rate rise with the increase of palygorskite content, the wear rate increases with the increase of test temperature, and friction materials relatively made from 20 meshes, 81%wt. 40meshes, 87%wt. 60 meshes palygorskite have better anti-heat fading capability above 350℃. In addition, with the increment of polygorskite mesh, impact strength of the friction materials declines; with the increment of polygorskite content, impact strength rises and then falls.3. Palygorskite dehydrates 4 kinds of water respectively at 200℃,500℃,800℃. The test results show that with the increase of friction temperature, the friction coefficient of friction materials with dehydrating palygorskite falls, which is the same with undehdrating palygorskite. PalygorskiteⅠwith dehydrating absorbing water, and zeolite water at 200℃agrees with undehydrating palygorskite on friction coefficient. The more polygorskite dehydration water is, the higher friction coefficients are, especially PalygorskiteⅡand PalygorskiteⅢrespectively with dehydrating crystal water and structure water at 500℃and 800℃. So, it greatly accounts for good high temperature (350℃) resistance of polygorskite. In addition, friction and wear test and impact test shows that with the increase of dehydrating water, wear rate rises, impact strength drops. This mainly relates with polygorskite fiber strength weakening after dehydrating water.4. Compared with asbestos, sepiolite, wollastonite, brucite mineral fibers, friction coefficient, wear rate and impact strength of polygorskite are poor. However, polygorskite represents high temperature resistance, other three mineral fibers show obvious heat fading.Although friction material with palygorskite possesses good high temperature resistance,. palygorskite fiber can't be used as single reinforcement component in friction material due to its relatively lower strength and impact strength, higher wear rate and lower friction coefficient during medium temperature region.