Silicon and boron containing components for high temperature CMCs

Control of the deposition of SiC, BxC, Si-B-C, BN and Si-B-N layers for making multilayered composites is shown. SiC/B4C/SiC and SiC/Si-B-C/SiC layered materials allow self-healing of the matrix. The microstructure of BN interphase can be controlled to modify its properties and the Si-B-N ternary system can be used as a more oxidation resistant material and also to increase the interfacial bonding with the reinforcement fibers. The oxidation resistance of SiCf/BN/SiC is improved at moderate temperature when compared to SiCf/C/SiC. From the combination of self-healing properties at different temperatures of BxC and Si-B-C used with SiC in multilayered matrices and the ability of the mechanical compliant BN used as interphase to deviate the microcracks farther from the fibers, the preservation of the ceramic matrix composite properties for long duration, in oxidative environments, under high temperature fatigue, thermal and mechanical cycling is discussed.