Microstress in the matrix of a melt-infiltrated SiC/SiC ceramic matrix composite

Microstress in the SiC: Si matrix of a ceramic matrix composite (CMC) has been characterized, using Raman spectroscopy. The matrix of the composite was manufactured using liquid melt infiltration, and has about 20% unreacted free silicon. During the processing of the composite, the unreacted free silicon expands 11 vol % when transforming from liquid to solid. This crystallization expansion creates compressive microstress in the silicon phase of the matrix, which ranges from 2.4 to 3.1 GPa, and tensile microstress in the SiC of the matrix which ranges from 0.24 to 0.75 GPa. The microstress varies significantly with position, following a normal distribution.