Grain size effects in advanced ceramics

Abstract

Advances in particle science and technology is providing a powerful impetus for the growth of advanced ceramics production at an unprecedented rate. The impact of these advances on the novel processing methods as well as enhanced properties of ceramics is reviewed here. The sol-gel route for obtaining submicron particles of great compositional homogeneity and near-net shape fabrication by gel-casting are discussed. The importance of small grain size is illustrated in terms of enhanced strength of glass-ceramics, increased dielectric constant of barium titanate and its reduced sensitivity to temperature, improved fracture toughness of zirconia ceramics by the presence of platelets of metastable tetragonal zirconia, and suppression of microcracking on thermal cycling of ceramics, which exhibit anisotropic axial (but low overall) thermal expansion lowered fatigue of piezoelectric transducers and actuators even after they are cycled electrically a billion times or more.