Mechanical behavior of two-dimensional carbon/carbon composites with interfacial carbon layers

Effect of interfacial carbon layers on the mechanical properties and fractu re behavior of two-dimensional carbon fiber fabrics reinforced carbon matri x composites were investigated. Phenolic resin reinforced with two-dimensio nal plain woven carbon fiber fabrics was used as starting materials for car bon/carbon composites and was prepared using vacuum bag hot pressing techni que. In order to study the effect of interfacial bonding, a carbon layer wa s applied to the carbon fabrics in advance. The carbon layers were prepared using petroleum pitch with different concentrations as precursors. The exp erimental results indicate that the carbon/carbon composites with interfaci al carbon layers possess higher fracture energy than that without carbon la yers after carbonization at 1000 degrees C. For a pitch concentration of 0. 15 g/ml, the carbon/carbon composites have both higher flexural strength an d fracture energy than composites without carbon layers. Both flexural stre ngth and fracture energy increased for composites with and without carbon l ayers after graphitization. The amount of increase in fracture energy was m ore significant for composites with interfacial carbon layers. Results indi cate that a suitable pitch concentration should be used in order to tailor the mechanical behavior of carbon/carbon composites with interfacial carbon layers. (C) 1999 Elsevier Science Ltd. All rights reserved.