Low velocity drop weight impact behaviour of Al2O3-Ni-ZrO2 and Al2O3-Ni-Cr2O3 ceramic composites

Particulate Al2O3 matrix nanocomposites containing 1 vol.% Ni were prepared by the heterogeneous precipitation method and the addition of 5 vol.% ZrO2 (ANZ) or 1 vol.% Cr2O3 (ANC). The prepared samples were subjected to the low energy drop weight impact tests to compare the behaviour of the composites under low energy impact and to investigate the damage mechanisms. The pure Al2O3, Al2O3/Ni, Al2O3/ZrO2 and Al2O3/Cr2O3 compositions with the same additive ratios were also produced to make the comparison systematically. Also, the Vickers hardness measurements were carried out and a significant increase in hardness was attained for both ANZ and ANC composites. The average hardness value around 24.8±1.0 GPa was measured for the ANZ and ANC composites which means ∼15% improvement compared to the pure Al2O3. Between all the compositions, the maximum force (Fmax) value was obtained for the ANZ (for 12 J impact energy level Fmax = 26617 N) according to the low energy drop weight impact test results. Tensile radial crack network formation, cone formation, fracture and crushing of the cone structure were observed as damage mechanisms for all compositions. The volume of conical frustum structure was evaluated for each composition and the effect of microstructure on possible ballistic performance was also discussed