“…Alumina disks produced using the PSD technology had a sintered density above 99.7% TD, but very large voids several millimetres long severely limited the mechanical properties of the samples [220]. Alumina tiles manufactured by PSD had a density of 3.89 g cm −3 , corresponding to ~98% TD, a flexural strength (ASTM C1684 [221]) of 130 ± 38 MPa, and a Knoop hardness (ASTM C1326 [222]) of 17.7 ± 1.0 GPa [223]. These tiles were tested for ballistic impact and were compared to both commercially available tiles manufactured by die pressing [224].…”