Open AccessEnvironmental microcracking of [NZP] type ceramics
Author(s) -
T. Barrett Jackson,
W.D. Porter
Publication year - 1994
Language(s) - English
Resource type - Reports
DOI - 10.2172/102178
Subject(s) - thermal expansion , materials science , anisotropy , ceramic , sintering , temperature cycling , atmospheric temperature range , composite material , isotropy , thermal , mineralogy , chemistry , thermodynamics , optics , physics
NZP ceramics (sodium zirconium phosphate and its crystal structure analogs) have very low thermal expansion through a large temperature range. Some compositions, with a high degree of thermal expansion anisotropy, are prone to microcracking upon cooling to room temperature. The onset of microcracking is a function of sintering temperature and hence grain size. Subsequent thermal cycling affects the thermal expansion behavior of highly anisotropic compositions due to microcrack healing. Recently it has been determined that this microcracking behavior can be delayed or enhanced by controlling the atmosphere in which the ceramic is heated and cooled. The effects of various atmospheres on the thermal expansion of isotropic and anisotropic [NZP] compositions are presented