The effects of Z-stitching density on thermophysical properties of plain woven carbon fiber reinforced silicon carbide composites

Three types of plain woven carbon fiber reinforced silicon carbide composites (C/SiCs) with 4, 9, and 16 Z-stitching/cm² densities (S4, S9 and S16) were fabricated by chemical vapor infiltration. The results indicated that the activation energies for thermal diffusive mechanism transition of S9 and S16 increased by 151 and 192% compared with that of S4, respectively. With the increase of Z-stitching density, the positive effects of "pore" phase, in-plane fibers and Z-yarns on thermal conductivity were enhanced. Compared with that of S4, the through-thickness thermal conductivities of S9 and S16 increased by approximately 0.3 and 0.5 W/m °C in the temperature range 200-1400 °C, respectively. The thermal expansions of these composites were mainly determined by SiC matrix. The increase of structural integrity and decrease of SiC amount reduced the in-plane coefficient of thermal expansion (CTE) with the increase of Z-stitching. Compared with that of S4, the in-plane CTEs of S9 and S16 decreased by about 0.4 and 0.7 × 10^-6 °C^-1 in the same temperature range, respectively.