PROCESSING AND PROPERTIES OF FIBER REINFORCED BARIUM ALUMINOSILICATE COMPOSITES FOR HIGH TEMPERATURE RADOMES

Advanced Cerametrics, Inc. (ACI) has developed celsian (strontium-doped barium aluminosilicate, SBAS) matrix/celsian fiber ceramic composites that meet the needs for clectromagnetic windows on the next generation of hypersonic missiles. The windows have to withstand temperature rises of several thousand degrees in a few seconds, resist impact erosion of Mach 6 raindrops or ice while being electronically transparent to radio-frequencies (RF). Celsian fibers are made using the Viscous Suspension Spinning Process (VSSP), which was developed and patented by ACI. ACI's BAS ceramics have a dielectric constant (K) of about 6.8. A fibrous SBAS composite has K of about 6, which is desirable from an RF standpoint. An additional important feature of the BAS ceramics is their high thermal conductivity and thermal shock resistance. The BAS material is sufficiently strong, but ACI is developing methods to make the BAS stronger and more wear resistant to meet the needs of the next generation of hypersonic missiles. Prototype radomes of BAS-fiber reinforced BAS structures were prepared to characterize the mechanical properties. These radomes are about 1/4 the price of reaction-bonded silicon nitride (RBSN) radomes and are much simpler to produce in volume.