Microcrystalline Strengthening And Moulding Of Selenium Based Infrared Glass

As a new infrared optical material, chalcogenide glass has attracted considerable attention due to its high flexibility in chemical composition, wide infrared transmission range, low manufacturing cost and could be shaped by molding. However, enlarging the application of chalcogenide glass are limited by weak mechanical properties and homogeneity. Micro-crystallizing process, microstructure and properties in different positions and moulding technology of selenium based infrared glass were studied in this study. The research results are as follows:(1) Different cooling methods have a great influence on the infrared transmittance and impurities absorption of chalcogenide glass. Infrared transmittance of air cooled glass is higher than water cooled glass, for air cooled glass, the infrared transmittance in wavelength 8-12μm range reaches to 70%, while the infrared transmittance of water cooled glass is about 64%; Impurities absorption peak of air cooled glass is stronger than that of water cooled glass, due to the slow cooling rate, the solid solubility of hydrogen in selenium increases with the temperature lowing, finally the Se-H impurity absorption increased.(2) Water cooled chalcogenide glass has a better fracture toughness, and it is more suitable for the preparation of high strength chalcogenide glass. After the thermal treatment at Tg+30℃ for 20h, the fracture toughness of water cooled glass can reach to 0.414 Mpa·m1/2, increased 26% compared with that without thermal treatment, the maximum fracture toughness of air cooled glass is only 0.368 Mpa-m1/2.(3) Top of the chalcogenide glass has a better comprehensive properties than that of bottom. The infrared transmittance of the top glass is up to 64% and the fracture toughness reaches to 0.373 Mpa·m1/2, while the infrared transmittance of bottom glass is about 58% and the fracture toughness is about 0.367Mpa·m1/2. Comprehensive properties of marginal part is superior to the central part of chalcogenide glass, the infrared transmittance of marginal part is up to 65% with good compactness and weak impurity absorption, while the central part of chalcogenide glass has lower infrared transmittance (60%), stronger crystalline ability and Se-H impurity absorption.(4) Flake mould pressing product has good infrared transmittance above 55%, good shaping ability and surface finish, while powder mould pressing product has lower infrared transmittance about 45% and worse amalgamation. Among them, the optimum parameters for molding process is obtained as follows:molding temperature 310℃, molding pressure 10kg, holding time 70-90min and dwell time 60min.