Corrosion assessment of non-asbestos organic friction material by immersion method

This study addresses the challenge of material degradation due to environmental impact. Brake pads can suffer mechanical damages when they are exposed to a corrosive environment. The study focus here is on Non-asbestos organic (NAO) friction material (FM) which is known as a cocktail of several ingredients, which includes various fillers and reinforcing fibres held together by a thermosetting resin, mostly phenolic. Palm Kernel Shell (PKS) based friction material formulated with varying grain size particles (0.300, 0.425 and 0.850 mm) of PKS. A traditional corrosion testing method, the salt water solution immersion is used. After 7 days of immersion, localized corrosive film is noticeable on samples with 0.850 mm size while there is no noticeable change on the surfaces of samples with 0.300 and 0.425 mm grain sizes. The observed localized corrosive film is typical to pitting type of corrosion. Meanwhile, weight measurement of the samples before and after corrosion test shows and increment in weight (2.1220%, 1.7850% and 2.8774% respectively) after the test and this can be attributed to the diffusion of water into the friction lining within the immersion period. This result is in agreement with what is found in literature as well as suggested by the Turkish standard for corrosion test of passenger vehicles on highways (TS 9075).