Initiation of Degradation in Polycrystalline Sodium-beta Alumina Electrolytes

Download or read book Initiation of Degradation in Polycrystalline Sodium-beta Alumina Electrolytes written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sodium-beta alumina solid electrolytes degrade during use in sodium sulfur cells. The degradation can take two forms: Mode I degradation involving the rapid propagation of macroscopic cracks driven by cathodic deposition of sodium in them; and Mode II degradation involving a slow degradation due to electron injection from the Na/.beta. alumina contact. The initiation stage of Mode I is the most important one since cracks propagate rapidly once they are formed. The significance of the local microstructure on the Mode I initiation is discussed. It appears that grain boundaries can be favorable sites for Mode I failure initiation.