Hydrothermal corrosion and flexural strength of Si3N4-based ceramics

Mechanisms of dissolution of silicon nitride ceramics prepared with Y2O3 sintering aid, and of SiAlON ceramics in deionized water and in 0.5 M sodium chloride solution tested in the temperature range between 150 °C and 290 °C are discussed with respect to their influence on flexural strength of the corroded materials. The corrosion resulted in deterioration of the flexural strength of silicon nitride, which dropped from ∼700 MPa to ∼290 MPa after 12 days exposure at 290 °C. For SiAlON exposed to deionized water increase of the flexural strength from 190 MPa to ∼300 MPa was observed.