High-temperature mechanical characterization of single-crystal sapphire using laser-based ultrasonics

Of current interest in the missile community is the high- temperature mechanical behavior of single-crystal sapphire. For endo-atmospheric IR transparent windows, single crystal sapphire is the material of choice. However, sapphire has been found to undergo a significant change in the mechanical properties, leading to a potential fracture of the window at the high temperatures encountered during typical flight conditions. A critical figure of merit used in considering a material's usefulness as a dome material is its thermal shock resistance.