Wear study on polymer matrix composite materials for brake shoe applications

Abstract

A polymer based automotive brake shoe lining material manufactured in Bangladesh has been compared with those of three imported brake shoes sold in the local market. X-ray diffraction, infrared spectroscopy, and optical microscopic techniques of the four materials were used upon to identify the constituents. Relevant physical properties of Materials viz. density, water absorption and swelling characteristics were also determined using standard analyzed methods. The friction and wear behaviour of the materials were tested in a pin-on-disc type apparatus IlIlder ambient conditions. Linear speed and load employed were 2.97 and L88m"j and ISN respectively. During the tests, friction force was measured with an on-line load cell. II has been observed that all of the four friction materials contain phenol fonnaldehyde as the matrix. Other major ingredients were also the same in all the samples. These include asbestos as fiber reinforcement, barium sulphate as filler, brass particles and cashew nut shell/pre cured resin as friction modifiers. It was found that the swell resistance of the friction material manufactured in Bangladesh compares favourably with that of the improved materials, but the bulk density of the Bangladeshi material was the lowest and its water absorption the highest. The room temperature friction coefficient of the Bangladeshi material was found to be about 0.4 which lies well with in the acceptable range. Among the four materials tested the Bangladeshi material waS found to rank third in respect of wear resistance. Besides the above, a wear testing machine based on SAE J661a has been developed to correspond closely to the wear and frictional condition of an actual automobile.