Mechanical behavior of two-dimensional carbon fiber fabrics reinforced carbon matrix composites

Effects of processing parameters and interfacial carbon layers on the mechanical behavior of two-dimensional carbon fabrics reinforced carbon matrix composites were investigated. Phenolic resin reinforced with two-dimensional plain woven carbon fiber fabrics was used as starting materials for carbon-carbon composites and was prepared using vacuum bag hot pressing technique. They were then carbonized to convert into carbon-carbon composites. The effects of carbonization and graphitization temperatures on the fracture behavior of carbon-carbon composites were evaluated. In order to study the effect of interfacial bonding, a carbon layer was applied to the carbon fabrics in advance. The carbon layers were prepared using petroleum pitch with different concentrations as precursors. The experimental results indicate that the carbon-carbon composites with interfacial carbon layers possess higher fracture energy than that without carbon layers after carbonization greater than 800 degrees C. For a pitch concentration of 0.15 g/ml, the carbon-carbon composites have both higher flexural strength and fracture energy than composites without carbon layers. Both flexural strength and fracture energy were increased for composites with and without carbon coatings after graphitization. The amount of increase in fracture energy was more significant for composites with interfacial carbon layers. Results indicated that a suitable pitch concentration could be used to tailor the fracture behavior.