DYNAMIC FATIGUE OF ALUMINA CERAMICS IN WATER-CONTAINING ENVIRONMENT

Alumina ceramics have found wide application in water-containing media being subjected to delayed failure resulting from the stress-enhanced chemical reactions between environment and ceramics. Effect of compos ition of both the environment and ceramics on delayed fracture of vari ous alumina-base ceramics is investigated. A dynamic fatigue technique was utilised with special emphasis on proper choice of the experiment al conditions for testing procedure. High-alumina ceramic material is revealed to be more resistant to subcritical crack growth than glass-b onded materials. The behaviour of glass-bonded ceramics is dependent o n the composition of glassy grain-boundary phase. The water content in environment affects slightly the crack velocity exponent and influenc es the mean crack-growth velocity. The results are discussed in terms of the chemical reaction rate. (C) 1998 Elsevier Science Limited and T echna S.r.l. All rights reserved.