Aqueous Colloidal Processing of ZTA Composites

Two different zirconia‐alumina composites, ZTA‐30 (70 wt% Al 2 O 3 +30 wt% ZrO 2 ) and ZTA‐60 (40 wt% Al 2 O 3 +60 wt% ZrO 2 ), with potential for orthopedic applications, were processed in aqueous media and consolidated by slip casting (SC), hydrolysis‐assisted solidification (HAS), and gelcasting (GC) from suspensions containing 50 vol% solids loading. For comparison purposes, the same ceramic compositions were also consolidated by die pressing of freeze‐dried granules (FG). In the HAS process, 5 wt% of Al 2 O 3 in the precursor mixture was replaced by equivalent amounts of AlN to promote the consolidation of the suspensions. Ceramics consolidated via GC exhibited higher green (three‐point bend) strengths (∼17 MPa) than those consolidated by other techniques. Further, these ceramics also exhibited superior fracture toughness and flexural strength properties after sintering for 1 h at 1600°C in comparison with those consolidated by other techniques, including conventional die pressing (FG).