Sinterable Yttria-Doped Zirconia Powders Chemically Coprecipitated in Non-Aqueous Medium
Yttria-doped zirconia powders were synthesized by coprecipitation, by mixing an alcoholic solution of ZrCl4 and YCl3. 6H2O with an alcoholic solution of NaOH. The purified powders were characterized for physical and chemical properties, pressing behavior and sinterability. The powders are ultrafine, highly pure and presumably chemically homogeneous but strongly agglomerated. TZP (Toughened Zirconia Polycrystals) were pressureless sintered from powders calcined at around 700°C and fired densities around 95–99% were obtained with the appropriate processing. Very uniform microstructures were observed in the sintered samples, with most of the grains in the submicron range. For a 4 w/o Y2O3 composition (2.2 m/o) flexural strengths as high as 1157 MPa (3 point) and fracture toughness values (microindentation method) of 5–6 MPa·m1/2 were measured.
KeywordsMagnesium Hydroxide Azeotropic Distillation Ammonium Hydroxide Solution Ammonium Tartrate Scanning Auger Microscopy
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