Rapid Densification of Carbon/Carbon Composites Plate by Pressure‐Gradient Chemical Vapor Infiltration

Carbon/carbon (C/C) composites plate is prepared in the temperature range 1 223–1 373 K by improved pressure‐gradient chemical vapor infiltration (CVI). The bulk densities and pore distributions of C/C composites after different infiltration period are measured and the densification kinetics is investigated. The results show that C/C composites plate with 300 × 300 × 15 mm is able to be densified to 1.52 g cm⁻³ within 60 h by pressure‐gradient CVI. The porosity of pores with a size larger than 60 µm reduces markedly and the large pores are able to be filled more effectively by pressure‐gradient CVI. The densification kinetics depends on the temperature and competition between reaction and convection mass transport. The activation energy is about 366 kJ mol^–1at 1 223–1 313 K and 43.2 kJ mol⁻¹ above 1 313 K.