Enhanced-Performance Radome Materials for High-Speed Missiles

BNNT-reinforced ceramic matrix composites are the solution to otherwise intractable challenges to the DOD priority of supersonic and hypersonic flight.  Hypersonic flight requires significant innovation to radar domes (radomes) and other windows/apertures to maintain essential radio-frequency (RF) communications and sensing amid the compressed engagement timelines, severe aerodynamic heating, and thermal shocks that such speed brings.  Known ceramics and fiber reinforcement techniques do not allow the required combination of RF transparency, strength, or high-temperature endurance, nor allow tailoring compatible layers.  The boron nitride in these nanotubes is a known high-temperature dielectric, but not previously in a structurally strong form as now brought by these boron nitride nanotubes (BNNTs).  Conversely, previously known reinforcements do not meet the combined requirements of high-temperature strength, controllable thermal conductivity, and dielectric RF transparency.   BNNT can improve both thermo-structural capability and electrical performance.  BNNTs will reinforce composites by displacing the matrix to lower a composite’s overall relative permittivity, countering effects of higher porosity, and decreasing matrix shrinkage during heating stages of fabrication, further enabling hybrids of dual matrices by bridging dispersoids via the super strong covalent bonds of the nanotubes.  These ceramic matrix composites (CMCs) will be used to develop coupons to test architecture concepts, then prototypes, for new radome architectures to enable multiple future air platforms to fly longer and faster (supersonic and hypersonic) through all weather.  Optimization of ceramics explored is expected to improve strength above 1500 şC, and potentially to 2100 şC for newer matrix systems.