Agglomerate and Particle Size Effects on Sintering Yttria‐Stabilized Zirconia

The initial-, intermediate-, and final-stage sintering of fine crystallite yttria-stabilized zirconia was studied. Experiments were conducted on powder lots of differing agglomerate size and one specially prepared agglomerate-free powder. Initial-stage sintering kinetics were compared with a sintering study on larger crystallite size calcia-stabilized zirconia to access the Herring scaling law. It was found that agglomerates limit attainable green density, interfere with the development of microstructure, impede initial-stage sintering kinetics, and limit the potential benefit of fine crystallites on final-stage sintering. An gglomerate free powder centrifuge-cast to 74% green density was sintered to 99.5% of theoretical density in a 1 h 1100°C cycle, which is ∼300°C lower than necessary for an agglomerated but equal crystallite size powder.