FIBER REINFORCED CERAMIC RADOME MATERIAL WITH IMPROVED RESISTANCE TO THERMAL SHOCK, HIGH TEMPERATURE, AND EROSION

For this research, Advanced Cerametrics, Inc (ACI) proposes to combine its patented viscose suspension spinning process (VSSP) for manufacturing ceramic fiber, with conventional slip casting, to develop a low cost and economically scalable fiber-reinforcedceramic matrix composite (CMC) radome material. The proposed CMC is high-celsian barium aluminosilicate (BAS) matrix reinforced with continuous Si3N4 fibers. Green Si3N4 will be made by VSSP and then made into plate-shaped preforms consisting ofunidirectional fibers. The fiber preforms will be infiltrated with the BAS powders by slip casting. The green composite bodies will then be fired to high densities and will consist of high celsian matrices reinforced with continuous Si3N4 fibers. Thefibers are expected to impart improved mechanical properties (increased toughness, hardness, low and high temperature strength and wear resistance), while still maintaining the good dielectric and thermal shock resistance of celsian. The mechanical,thermal and dielectric properties will be fully characterized as a function of fiber diameter and volume fraction. Flat plates will be made in Phase I, and prototype cone shaped radomes by the end of Phase II. The Phase I goal will be to demonstrateimproved resistance to thermal shock, high temperatures and erosion for the composite versus current monolithic BAS and mainstay ceramic radome materials. ACI intends to apply for the Phase II SBIR Fast Track. In addition to radome applications there areseveral potential commercial applications in which Si3N4 fiber reinforced BAS could find use. For example due to their expected good high temperature mechanical properties and lower density, these composites can be considered as a replacement material formetallic components in the high temperature sections of gas turbine engines (e.g., in land based turbine power generators, high bypass engines and jet engines for commercial aircraft). Additionally, the electronics industry will benefit from the lowerdielectric constant of the proposed composite, which could replace high dielectric alumina in high-heat-load, surface, mount technology electronics.