Ceramics constitute an integral part of highly efficient armours due to their low density, high
hardness, strength and stiffness. However, they lack toughness and multi-hit capability. Therefore,
zirconia toughened alumina is investigated. The hardness is evaluated using Vickers, Knoop and
instrumented indentations, while the fracture toughness is evaluated using the indentation technique
and Charpy tests. The strength is evaluated using ring-on-ring, four point bend and drop
weight tests. The Young’s modulus is evaluated using the unloading instrumented indentation
curves. Microstructure, porosity and density are characterised using ultrasonic scanning, Archimedes
principle, optical and scanning electron microscopy. Results show an indentation size effect
on all mechanical properties. A substantial improvement in toughness is achieved through retardation
of crack initiation by tetragonal-to-monoclinic phase transformation in zirconia particles,
crack deviation thanks to appropriate grain structure, as well as energy absorption by densification
due to remaining porosity. This improved toughness is expected to promote multi-hit capability.
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