Premium
Stress‐Enhanced Oxidation of Silicon Nitride Ceramics
Author(s) -
Gogotsi Yury G.,
Grathwohl Georg
Publication year - 1993
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1993.tb06614.x
Subject(s) - materials science , silicon nitride , ceramic , corrosion , stress (linguistics) , creep , composite material , oxide , stress relaxation , nitride , deformation (meteorology) , silicon , ultimate tensile strength , cavitation , cracking , metallurgy , layer (electronics) , linguistics , philosophy , physics , mechanics
Silicon nitride ceramics show an accelerated oxidation rate under load in air. This phenomenon was observed for porous and dense ceramics with and without additives in a wide temperature range (700°–1450°C) and can be interpreted as stress corrosion in oxygen‐containing environments. Stresses cause an alteration of the amount and composition of oxidation products, formation of pits and cracks on stressed parts of specimens, and changes of the surface coloration and oxide scale morphology. Both tensile and compressive stresses can affect the oxidation process. An exponential dependence of mass gain on stress was found. On the other hand, oxidation of silicon nitride‐based ceramics can affect the material response to mechanical stresses as, for example, deformation, cavitation and cracking. Stress‐assisted chemical reaction at lower temperatures and stress‐affected diffusion at higher temperatures seem to be the main reasons for the susceptibility of Si 3 N 4 ceramics to stress corrosion. The effect of stress corrosion on mechanical properties is discussed.