Enhancement of the oxidation resistance of interfacial area in C/C composites. Part II: oxidation resistance of B–C, Si–B–C and Si–C coated carbon preforms densified with carbon

Oxidation of carbon–carbon (C/C) composites occurs preferentially at fibre/matrix (FM) interfacial zones. C/deposit/C composites (B–C, Si–B–C and Si–C deposits were obtained) were fabricated in order to protect C/C interfacial zones and the oxidation resistance of these composites was studied. B–C deposits oxidize rapidly and lead to the formation of a B2O3 film that protect carbon from oxidation at interfacial zones. The problem is that a hole is formed all around carbon fibres. It gives an easy access to oxygen to hearth of the material. Silicon-rich Si–B–C and SiC deposits do not protect C/C composites from oxidation. The deposit oxidizes slower than the carbon and oxidation progresses between the fibre and the deposit and between the deposit and the matrix. Boron-rich Si–B–C deposits form at interfacial zones a glassy compound that block efficiently interfacial carbon oxidation.