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 composition of both the environment and ceramics on delayed fracture of various alumina-base ceramics is investigated. A dynamic fatigue technique was utilised with special emphasis on proper choice of the experimental conditions for testing procedure. High-alumina ceramic material is revealed to be more resistant to subcritical crack growth than glass-bonded materials. The behaviour of glass-bonded ceramics is dependent on the composition of glassy grain-boundary phase. The water content in environment affects slightly the crack velocity exponent and influences the mean crack-growth velocity. The results are discussed in terms of the chemical reaction rate.