Effect of carbon fiber on the friction and wear behavior of paper-based friction material

A paper-based friction material reinforced by carbon fiber was prepared by dipping of the pulp composed of short cut carbon fiber, friction modifier, fillers, and water, in phenolic resin, and the successive compression of the dipped pulp at elevated temperature. The friction and wear behavior of the resulting paper-based friction material was evaluated using an MQ1000-II friction and wear tester, with the effect of the carbon fiber mass fraction on the friction and wear behavior of the friction material to be focused on. Moreover, the thermal stability and mechanical strength of the paper-based friction material were also examined as the functions of the carbon fiber mass fraction. It was found that the dynamic friction coefficient, static friction coefficient, and wear rate of the friction materials were closely related to the content of the carbon fiber as the reinforcing agent. The dynamic friction coefficient increased with increasing content of the carbon fiber, while the static friction coefficient and wear rate decreased therewith. When the mass fraction of the carbon fiber was greater than 5%, the dynamic friction coefficient reached to about 0.13 and retained almost unchanged with further increase in the carbon fiber mass fraction. When the mass fraction of the carbon fiber rose over 10%, the static friction coefficient and wear rate reached to about 0.15 and 4.5×10^-8 cm³/J, respectively, and assumed little change with further increase of the carbon fiber mass fraction. The improved friction and wear behavior and stability of the friction coefficient of the paper-based friction materials reinforced with the carbon fiber were attributed to the increased thermal stability and mechanical strength and the solid lubricity of the carbon fiber.