The effects of air and sodium salts on the strength of silicon-nitride-based ceramics

AbstractThe effects of oxidation and hot corrosion on the high-temperature strength of reaction-sintered and hot-pressed silicon-nitride-based ceramics have been investigated. A strength reduction and static- fatigue sensitivity in the temperature range 700–900 °C were observed in the tests in air and in the presence of salts. Silicon-nitride-based ceramics were found to be stress-corrosion sensitive over a specified temperature interval. Sample failure at lower loads was shown to result from both corrosion-induced flaws in the ceramic's surface layer and stress-corrosion cracking. Some methods for ceramic protection against stress corrosion are proposed.Keywords: silicon nitridestrengthoxidationstress corrosionstructural ceramics Additional informationNotes on contributorsG.A. GogotsiAuthorsDr Sci G.A. Gogotsi, Dr V.P. Zavada and Dr V.V. Traskovsky are with the Institute for Problems of Strength, Ukrainian Academy of Sciences, Kiev 252014, Ukraine, USSR.Yu. G. GogotsiDr Yu.G. Gogotsi is with the Institut für Keramik im Maschinenbau, Universität Karlsruhe, W-7500 Karlsruhe 1, Germany.V.P. ZavadaAuthorsDr Sci G.A. Gogotsi, Dr V.P. Zavada and Dr V.V. Traskovsky are with the Institute for Problems of Strength, Ukrainian Academy of Sciences, Kiev 252014, Ukraine, USSR.V.V. TraskovskyAuthorsDr Sci G.A. Gogotsi, Dr V.P. Zavada and Dr V.V. Traskovsky are with the Institute for Problems of Strength, Ukrainian Academy of Sciences, Kiev 252014, Ukraine, USSR.