Silicon nitride (SN or Si3N4) fiber is a material of interest for high temperature CMC applications, especially for electromagnetically transparent hypersonic radomes and windows. Domestic sources of the SN fibers do not exist. A few universities in China produce it for China, but their fibers show significant performance degradation at elevated temperatures because their fibers are amorphous. UES SN fiber will not show such degradation because it is polycrystalline. UES has fabricated polycrystalline YAG fibers with a diameter of 31 µm and conducted the first reported lasing demonstration with the fiber. The technology used to fabricate defect-free YAG fibers was adopted to produce polycrystalline SN fibers. UES recently produced dense and continuous polycrystalline SN fiber via powder processing route with lab scale equipment. In this program, UES will produce the fiber with a diameter smaller than 20 µm and measure its tensile strength. UES will continue to leverage our network within the aerospace industry to engage with potential defense and commercial customers to define the minimal viable product capabilities/characteristics, refine potential market projections, identify and characterize risks, document processes/quality measures, and pursue insertion windows of opportunity.
