Brake characteristics of 2D carbon/carbon composites prepared by rapid direction diffused CVI technology

Three kinds of carbon/carbon (C/C) composites are prepared using rapid direction diffused chemical vapor infiltration (RDD CVI) processes, after the composites are densified and their density is up to 1.76 g/cm3, they are separated into three groups, one group in which its matrix carbon belongs to the rough laminar microstructure is heat treated under 2300 °C (sample 3#), and another two groups are treated at 2500 °C (samples l# and 2#, respectively) whose matrix carbon has the smooth and rough laminar microstructure, respectively. The curves of relationships between brake moment and velocity and the effect of factors on the relationships for the three C/C composites are investigated under simulated conditions of aeroplane practical braking. The results indicate that there are the initial brake moment peak values (IPV) on their brake moment–velocity curves in the process of braking. The microstructures of the matrix carbon, heat treatment technology, and braking conditions have strong effect on their IPV and the initial brake moment peak ratio values (IPRV). Those values can be reduced by increasing heat treatment temperatures (higher than 2500 °C) of the brake discs, controlling the formation of the rough laminar matrix carbon in the preparation process of the C/C composites, or decreasing the exerted rate of specific pressure on the brake discs as braking. IPV and IPRV do not vary basically with the brake specific pressure under the constant brake kinetic energy and velocity; however, they increase with a simultaneous increase in the brake kinetic energy, velocity, and specific pressure.