Experimental study of the ballistic resistance of transparent spinel against tungsten carbide core projectiles

Transparent materials are some of the most critical components in the protection of light armored vehicles. It has been demonstrated that significant weight reductions can be achieved in the defeat of steel core projectiles, compared to conventional glass-based armor, when a transparent ceramic is used as the strike face on a glass-polymer laminate. In order to assess the efficiency of spinel types of different microstructures, against projectiles with tungsten carbide core, Depth of Penetration (DoP) tests were conducted. In these tests, spinel plates were glued either directly on a thick polycarbonate backing, or on a soda-lime glass plate, placed between the spinel and the polycarbonate backing. All impact tests were performed using 7.62 mm AP projectiles with tungsten carbide core at a nominal impact velocity of 930 m/s. One commercial grade of transparent spinel ceramic and four distinct spinel grades with defined microstructures, manufactured by the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), were tested. The test results demonstrated an increase of the ballistic resistance with increasing spinel thickness. For spinel plate thicknesses of 8 mm and more, significant differences in the performance were observed, depending on the microstructure. Target and projectile fragments were extracted from the target chamber and analyzed. The DoP-results indicate that coarser-grained spinel variants have a higher ballistic resistance against tungsten carbide core projectiles.