Silicon Carbide/SRBSN Composites

Abstract

Ceramic matrix composites have been produced using unidirectionally aligned Textron SCS-6 fibers in a sintered reaction bonded silicon nitride (SRBSN) matrix. A tape casting technique was used to produce a prepreg sheet that could be cut and stacked to form a lay up. Sintering aids were MgO, Al2O3, and Y2O3 either singly or in combination, final sintering being carried out under pressure at temperatures up to 1750°C. The three-point bend strength of the material vaired between 448 and 513 MPa and showed no variation with oxidation time at 1000°C up to 25 hours. Interfacial shear strength measured by indentation was 4 MPa; some samples had a reaction layer at the interface and a shear strength of >8 MPa. Within sections 6 mm from exposed fiber ends the interfacial carbon layers were partially removed and the interfacial shear strength was reduced with increasing oxidation time.