Infrared Transparent Glass Ceramics with Near-Zero Thermal Expansion

The thermal shock resistance of current mid-infrared window and dome materials is insufficient for some high speed flight application due to their relatively large thermal expansion. Leveraging our extensive experience on infrared materials, L2 Tech, Inc and University of California-Santa Cruz propose to develop a new glass ceramic material with high mid-infrared transmission and low emissivity at elevated temperature. The material has 45-60% (in volume) crystals that have negative thermal expansion. It balances with the positive thermal expansion of the surrounding glass to give a combined Near-Zero Thermal Expansion of less than 0.5 ppm/K over a wide temperature range from 0-600 oC, and has superior thermal shock resistance. By specially designing the composition, the material will have very good mechanical properties and high chemical erosion resistance. In Phase I, we will fabricate the glass ceramic, measure its thermal expansion and optical transmission.