Behavior of Infrared Window Materials Exposed to Rain Drop Environments at Velocities to 2000 FPS (610 M/S).

摘要

The work described in this report builds on, and extends, that performed in the previous investigation. The objectives were to determine the erosion behavior of current infrared window materials; describe the mechanisms and modes of degradation of material properties; and identify suitable techniques for development of more erosion resistant materials for future infrared window requirements. In addition to zinc selenide and zinc sulfide, the materials studied included silicon, magnesium fluoride, spinel, and sapphire. These additional four materials are of interest for applications at velocities between Mach 1 and Mach 2. Single drop experiments were performed to determine the damage threshold velocity for all the materials; the effect of impact angle for zinc selenide; the improvement to be gained by reducing the grain size of zinc selenide; the response of antireflection coatings on zinc selenide and gallium arsenides; the performance of bilayered zinc sulfide/zinc selenide specimens; and the feasibility of a bimedia protective layer concept.