Microstructural Control of a 70% Silicon Nitride- 30% Barium Aluminum Silicate Self-Reinforced Composite

The processing response of a 70% silicon nitride–30% barium aluminum silicate (70%‐Si3N4–30%‐BAS) ceramic‐matrix composite was studied using pressureless sintering, at temperatures ranging from 1740°C, which is below the melting point of BAS, to 1950°C. The relationship between the processing parameters and the microstructural constituents, such as morphology of the β‐Si3N4 whisker and crystallization of the BAS matrix, was evaluated. The mechanical response of this array of microstructures was characterized for flexural strength, as well as fracture behavior, at test temperatures up to 1300°C. The indentation method was used to estimate the fracture resistance, and R‐curves were obtained from modified compact‐tension samples of selected microstructures at room temperature.