Papers

Journal of Materials Science

, Volume 13, Issue 6, pp 1319-1328

First online:

Sodium-assisted oxidation of reaction-bonded silicon nitride

  • M. I. MayerAffiliated withDepartment of Ceramics, Houldsworth School of Applied Science, The University of Leeds
  • , F. L. RileyAffiliated withDepartment of Ceramics, Houldsworth School of Applied Science, The University of Leeds

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Abstract

The oxidation of reaction-bonded silicon nitride in air, and with small amounts of sodium carbonate applied to the sample surface, has been studied. The action of the alkali is to cause short-term enhanced oxidation,which is terminated when specific compositions of the product sodium silicate glass are attained. These correspond closely to liquidus compositions in the Na2O-SiO2 system, and it is postulated that the retardation in the oxidation rate at this stage is due to the formation of a stable tridymite film at the silicon nitride-glass interface. The implications for the high temperature stability of reactionbonded silicon nitride components in alkali contaminated atmospheres are discussed.