Evaluation of IKTS Transparent Polycrystalline Magnesium Aluminate Spinel (MgAl2O4) for Armor and Infrared Dome/Window Applications

Report No. ARL-SR-262
Authors: James W. McCauley; Parimal Patel
Date/Pages: March 2013; 102 pages
Abstract: This report is the first detailed study attempting to relate the ballistic performance of a transparent armor ceramic material with two significantly different grain sizes to a comprehensive set of material characteristics (phase, microstructure, and defects) and quasi-static and dynamic properties. Two fine-grain polycrystalline spinels (magnesium aluminate) of nomiual size 0.6 µm (205) and 1.6 µm (200), fabricated under the direction of Dr. Andreas Krell of the Fraunhofer Institute for Ceramic Technologies and Sintered Materials in Dresden, Germany, were studied in depth. The key characteristics and properties determined consisted of the following: microstructural analysis, nondestructive ultrasonic evaluation, porosity determined indirectly from density measurements, hardness, bulk plasticity from load/Knoop hardness curves, spherical indentation, quasi-static bend-bar strength, dynamic compressive strength, and quantification of fragmentation in a ballistic impact event at 850 and 1100 m/s. The fine-grain spinel material V50 was determined to be about 60 ft/s (18 m/s) better than the coarser grain material. This is close to a difference that is considered to be significant.
Distribution: Approved for public release
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Last Update / Reviewed: March 1, 2013