Nanograin Ceramic for Hypersonic Sensor Windows

Hypersonic vehicles require IR transparent windows to protect sensitive guidance opto-electronics from the aggressive aerothermal environment, which may involve temperatures in excess of 1650°C.  The window material must be able to withstand the extreme thermal, mechanical and chemical environments encountered during high-speed flight so that performance of the window is not degraded and the IR sensor platform is protected and insulated from these extreme aerothermal conditions.  In addition, shock waves and extremely high heat loads can lead to wave-front distortions, which will affect the fidelity and accuracy of the signal detected by the sensor/seeker.  CeraNova is proposing to use a high strength yttrium oxide ceramic window to address the needs of the solicitation.  Transparent yttria is one of the best oxide materials for sensor window applications based on its wide transmission band and its melting point above 2400°C.  Transparent yttria is stable at 1650°C, and has a transmission band from 0.25 µm to 8 µm, meeting the SWIR and MWIR criteria.  In addition, yttria has very low self-emission, so transparency is not degraded at higher temperatures. CeraNova has experience producing an enhanced strength yttria, and in addition, raw materials availability and processing techniques have improved over the last decade.  In the proposed work, we will apply the latest techniques and raw materials along with a proprietary process to produce a high strength transparent yttria that meets the transmission, temperature and mechanical requirements.