Investigation of the mechanical properties and ballistic performance of alümina based composites with sandwich laminated structure prepared with rare earth oxide and zirconia additives

Advanced ceramics are important in armour applications due to their high mechanical properties and low specific gravity and the most widely used are Al2O3, SiC and B4C. Although Al2O3 offers a high benefit/price opportunity, it cannot show superior performance in multiple hit conditions due to its low toughness and low flexural strength. In this study, it is aimed to produce an Al2O3-based sandwich composite at a low cost with Sm2O3 and ZrO2 additives with high toughness and/or bending Strength and superior ballistic performance. Three-layered sandwich composites containing 0.8vol% Sm2O3 and 5vol% ZrO2 in different compositions were produced (Al2O3-Sm2O3 for surfaces, either Al2O3-Sm2O3-ZrO2 or Al2O3-ZrO2 for center) and densification, thermal expansion, residual stress, microstructure, mechanical properties (elastic modulus, hardness, flexural strength, toughness), ballistic performance with depth of penetration test were investigated comparatively. In general, no improvement in mechanical properties was achieved in the sandwiches except toughness compared to the pure Al2O3. A lower residual DOP was provided for the sandwich composites than all other comparison samples and the pure Al2O3. In sandwich structures, more energy can be absorbed by forcing the layers to fracture, due to the large difference in the grain sizes of the compositions forming the layers and the different fracture characteristics. This study showed that the sandwich composites produced with Al2O3-based Sm2O3 and ZrO2 additives are alternative materials that can generally show better ballistic performance compared to the pure Al2O3.