Silicon Carbide-Silicon Carbide Composites

Ceramic composites of silicon carbide fibers in a silicon carbide matrix are currently produced via CVD infiltration (CVI), but the requisite high temperature for CVI can partially degrade the fibers. Infiltrating a SiC precursor polymer into a fiber preform and subsequently converting the polymer at low temperature (<900 C) to SiC can form a composite with improved mechanical properties. A supercritical fluid (SCF) solvent exhibiting high transport properties and no surface tension limitation is used to infiltrate and deposit the polymer uniformly in a SiC fiber preform or tape; the precursor is pyrolyzed to monolithic SiC with no adverse interaction on the fiber surface, thereby achieving full advantage of the SiC fibers in the composite. Improved mechanical properties will be measured and compared with conventionally produced silicon carbide composites. The program is another example of the application of the company's technology to achieving improved performance of materials such as carbon/carbon composites, high performance polymers, space lubricants, and energetic materials.