Evaluation of ALON for Cannon Window Application.

Report No. ARL-TR-2358
Authors: Beyer, Richard A.; Kerwien, Henry
Date/Pages: October 2000; 26 pages
Abstract: In applying laser ignition to large-caliber cannons, a critical element is the window into the cannon chamber to admit the laser energy. This window must repeatedly withstand a particularly harsh environment of highly reactive, high temperature combustion products from the gun propellant at pressures up to 440 MPa (65,000 psi). Failure of the window can be caused by either thermal gradients in the window, mechanical force, or a combination. Previous successes with single-crystal sapphire have sometimes been limited by window deterioration modes suggestive of crystalline behavior. Samples of aluminum oxynitride spinel (ALON) have been fabricated in the same design as the standard sapphire windows and were qualified for gun testing. This process involves a series of experiments in a closed chamber, where gun propellant is burned to generate an environment similar to that inside the gun. Windows mounted in two methods have been tested. One of these windows has survived the full pregun test series with no visible damage.
Distribution: Approved for public release
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Last Update / Reviewed: October 1, 2000