Validation of silicon and boron based oxygen-impermeable material systems for protection of continuous fiber reinforced carbon composites

In a continued effort to protect carbon materials such as continuous fiber reinforced carbon composites from oxidation and to improve their service life in high-temperature environment, we have studied both silicate and borate forming materials on '4D' (four enforcement directions) composites. Attempts to solve the problems of 'silica and carbon interaction' have been made by incorporating MoSi2, Al2O3, and B4C to the multilayer coating system. Oxidation studies have been carried out on the following material combinations: C-SiC, C-SiC-MoSi2-Al2O3, and C-SiC-B4C. These were experimented both in dynamic and isothermal heating conditions up to 1473 K. The hardness, surface topography; developed phases and integrity of coatings on the samples at various stages of the experiment have been characterized and analyzed. Under identical experimental condition C-SiC-B4C coating was found to be most effective compared to the other mentioned coating systems.