Evaluation of mechanical properties of Al2O3-Cr2O3 ceramic system prepared in different Cr2O3 ratios for ceramic armour components

The aim of the present study was to introduce Al2O3 Cr2O3 ceramic system as an armour material by evaluating its performance with static mechanical tests. Cr2O3 was used as an additive to the pure Al2O3 owing to the character of substitutional solid solution formation that would provide increases in mechanical properties. The effect of Cr2O3 addition in different volume ratios (0.5, 1, 5 vol%) on the microstructure and the mechanical properties (elastic modulus, equibiaxial flexural strength, hardness, fracture toughness) of Al2O3 were investigated. Densification behavior and grain size of Al2O3 changed with the amount of Cr2O3, the highest relative density and grain size were obtained for 1 vol% Cr2O3 added Al2O3 Cr2O3 system. A 44% increase in flexural strength was achieved by 0.5 vol% Cr2O3 addition and attributed to the localized compressive stresses because of the grain boundary modification of the larger size of the Cr3+ ions. 1 vol % Cr2O3 addition increased the hardness 13% while the effect of Cr2O3 on toughness was negligible. The fragmentation behavior was discussed as a function of the stored energy at failure and total crack surface area. A shorter crack length for a given stored energy was observed for 0.5 vol% Cr2O3 composition compared to other compositions indicating its fragments would be larger in identical impact conditions increasing the erosion of the projectile.