Thermal conduction and tribological properties of carbon/carbon composites densified by xylene pyrolysis using La as a catalyst

摘要

Carbon/carbon composites with densities of 1. 72.1. 73 g/cm(3) were fabricated by film boiling chemical vapor infiltra. tion of a needle-pierced preform using xylene as a carbon precursor and LaCl3 as a catalyst, followed by resin impregnation and graphitization. The effects of the catalyst content on the thermal conduction and tribological properties of the composites were investigated by SEM, thermal tests with a laser flash instrument, and friction tests. Results showed that the thermal conductivities in the through thickness and in-plane directions, the friction coefficient, and the wear rate all had maxima at 6 wt% for LaCl3 contents from 0 to 15 wt%. The maximum thermal conductivities were about 58. 5 and 75. 6% higher than those of the composites without a catalyst in the through thickness and in-plane directions, respectively. A smooth friction film was most easily formed on the friction surface of the composite fabricated with a 6 wt% catalyst content, resulting in the lowest coefficient of friction and wear rate as well as the highest braking stability.