Analytical TEM study of a yttria stabilized zirconia/glass composite

Abstract

Yttria stabilized zirconia is a versatile ceramic material. It can be used for structural components or as a solid electrolyte. Its properties (such as high toughness) are strongly affected by the microstructure. In partially stabilized zirconia, the high toughness is mainly due to the toughening effect of a tetragonal (t) to monoclinic (m) phase transformation in the vicinity of a crack. Retention of tetragonal zirconia at room temperature is important for fabricating transformation toughened materials. To completely retain tetragonal zirconia at room temperature the grain size of the material must be less than a critical size. In yttria stabilized zirconia this critical grain size depends on the yttria concentration. Grain growth of yttria stabilized zirconia is also influenced by the amount of yttria in the grains. These previous studies, however, have focused on the behavior of materials with minimal glassy grain boundary phases. In contrast, in commercial polycrystalline zirconia often a significant amount of glassy grain boundary phase is present. This current research seeks to elucidate the effects of these grain boundary phases on the grain growth in yttria stabilized zirconia ceramics.