Effect of C₂H₂/N₂ ratio on tribological and mechanical behavior of carbon nanotube containing brake lining materials prepared through 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. The commercial friction powder mixed with the same concentration of catalyst sol was fed into the CVD furnace and different ratio of C ₂H₂/N₂ was adopted to fabricate the CNT containing friction powder. The CNT containing brake lining specimens were fabricated by hot pressing these homemade CNT containing friction powders. Experimental results indicate that the CNT containing brake lining specimens prepared through 30% C₂H₂ show the lowest open porosity and the highest bulk density. Significant enhancement in mechanical properties of specimens was obtained when the CNT containing friction powders are adopted. The green 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. Based on the experimental results on friction and wear behavior, although the CNT proves to be beneficial in improving the friction and wear performance of the brake lining materials, too many CNT would result in the higher friction coefficient.