SBIR-STTR Award

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-reinforced ceramic 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 of unidirectional 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. The fibers 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 demonstrate improved 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. Benefits In addition to radome applications there are several 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 for metallic 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 lower dielectric constant of the proposed composite, which could replace high dielectric alumina in high-heat-load, surface, mount technology electronics. Keywords Radome, Composite, Fiber, Silicon Nitride, Ceramic, CMC, Celsian, Barium Aluminosilicate

For this research, Advanced Cerametrics, (ACI)will combine its patented fiber forming technology with conventional ceramic forming methods including slip casting, injection molding and isostatic pressing to develop a low cost and economically scalable method to make ceramic fiber reinforced ceramic matrix composite missile radomes for hypersonic flight. The matrix material is high-celsian barium aluminosilicate (BAS) and various fiber chemistries will be created to act as composite reinforcement. Examples of these are Si3N4 or ALON. The fibers will impart improved mechanical properties (increased toughness, hardness, low and high temperature strength and wear resistance) while maintaining good thermal shock and dielectric properties. The BAS will also be made into fiber and assembled into a fibrous monolith and backfilled with the low dielectric CeraBlack material. Tooling will be made and sample radomes will be produced by the above forming methods. The various materials will be characterized for electrical and mechanical properties.

Keywords:
Radome,Composite,Fiber,Silicon Nitride,Ceramic,Cmc,Celsian,Barium Aluminosilicate