Densification of two-dimensional carbon/carbon composites by pitch impregnation

Densification of two-dimensional phenolic resin-based C/C composites was performed by melted petroleum pitch impregnation under a uniaxial mechanical pressure followed by recarbonization at atmospheric pressure. With increasing number of densification cycle, decrease in open porosity and increase in bulk density were obtained. However, densification efficiency was found to decline with the densification cycles. In the later stage of the densification cycles, voids closure resulted in a decrease in the apparent density, and much lower densification efficiency was obtained. Results of flexural test indicated that both strength and modulus increased with increasing number of densification cycle. Significant improvement in mechanical performance was found when an intermediate high temperature heat treatment of 2000°C was used between densification cycles.