Ceramics have been widely used for personnel and vehicle armour because of their
desirable properties such as high hardness and low density. However the brittle
nature associated with the ceramic materials, i.e. low toughness, reduces their ability
to withstand multiple ballistic hits. The present work is focused on ceramic armour
materials made from alumina and zirconia toughened alumina (ZTA). The effects of
grain size and zirconia phase transformation toughening on the mechanical and high
strain rate properties in both materials were investigated in detail.
Alumina, 10%, 15% and 20% nano ZTA with 1.5 mol% yttria stabiliser were
produced with various grain sizes. The processing of the materials started from
suspension preparation, spray freeze drying of the suspension and die pressing to
produce homogeneous green bodies with densities above 54%. Then, the green
bodies were sintered using conventional single stage and/or two-stage sintering to
produce the samples with full density and a range of grain sizes (0.5 to 1.5 μm
alumina grains and 60 to 300 nm zirconia grains). The effects of the processing
conditions on the microstructures were studied and the optimum processing route for
each sample was determined. [Continues.]
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.
EPSRC. Defence Science and Technology Laboratory (DSTL). Morgan Advanced Materials plc (provision of materials).