Tribological and mechanical behavior of carbon nanotube containing brake lining materials prepared through sol-gel catalyst dispersion and CVD process

Focus of this study has been placed on the influences of carbon nanotube (CNT) on the mechanical and tribological behavior of CNT containing brake lining materials. Different concentration of catalyst for growing CNT was dispersed into the commercial friction powder by sol-gel method before fed into the CVD process to fabricate the CNT friction powder. The CNT containing brake lining specimens were fabricated by hot pressing these homemade CNT containing friction powders. Experimental results indicate that the open porosity decreases and the bulk density of CNT containing brake lining specimens increases with the concentration of catalyst. Significant enhancement of specimen's hardness was obtained when the CNT containing friction powders are adopted by sol-gel catalyst dispersion and CVD process. The green (0 M concentration of catalyst) specimen which was fabricated by hot pressing commercial friction powders shows less stable, higher friction coefficient and larger mass loss during the wear test. On the contrary, the CNT containing brake lining specimens exhibit better performance, lower friction coefficients and lower mass loss. Morphological observations show that smooth, adherent lubricating films are formed on the sliding surface of CNT containing brake lining specimens, especially for specimens with high concentration of catalyst. Based on the experimental results, the CNT proves to be beneficial in improving the friction and wear performance of the brake lining materials.