Investigation of mechanical properties and stored elastic energy-fragmentation of Al2O3-Cr2O3 ceramic system with increasing Cr2O3 content

In the present study, densification, mechanical properties (elastic modulus, hardness, flexural strength) and stored elastic energy-fragmentation of the pure Al2O3 and Al2O3-Cr2O3 ceramics with different Cr2O3 volume content (0.5, 1, 3, 5, 10 and 20 vol.%) were investigated. The fragmentation behaviour was interpreted from the point of armour application as larger fragments are required for higher penetration resistance. The equibiaxial flexural strength test method was used to measure the fracture strength values. A similar densification behaviour was obtained for the pure Al2O3 and the Al2O3-Cr2O3 ceramic specimens with 0.5, 10 and 20 vol.% Cr2O3 with the obtained relative densities of around 97%TD. The elastic modulus of the pure Al2O3 and Al2O3-Cr2O3 ceramic specimens showed consistent values with the densification except for the Al2O3-Cr2O3 ceramics containing 20 vol.% Cr2O3. All Al2O3-Cr2O3 ceramics have lower flexural strength values than the pure Al2O3. The pure Al2O3 had the smallest crack surface area accompanying the largest fragment size for given fracture energy. This indicates that the pure Al2O3 will break into larger pieces in case of a possible impact.