Chemical reactivity of silicon nitride with steel and oxidised steel between 500 and 1200°C

M. Kalin, J. Vižintin, J. Vleugels, O. Van Der Biest

Materials Science & Engineering 281 (2000) 28–36.

Abstract

The chemical interaction of a Si₃N₄ ceramic with pristine and oxidised 100Cr6 steel was studied by means of static interaction couple experiments between 500 and 1200°C. Si₃N₄ was not chemically stable in contact with oxidised steel at elevated temperatures, and reacts with the formation of N₂, SiO₂ and/or Fe₂SiO₄ at temperatures at and above 1000 °C. At 700 and 500 °C, Si diffusion into the oxide layer indicated the dissociation of the Si3N4 ceramic. Si3N4 also dissociated in contact with pristine steel. In the temperature region between 700 and 1100 °C, the Si dissolves and diffuses into the steel whereas a nitrogen pressure is built-up in the voids of the metal-ceramic interface, limiting the degree of interaction. Above 1100°C, the nitrogen dissolves and diffuses into the steel as well, enhancing the reactivity and resulting in the formation of a strong metal-ceramic interface.

Keywords: silicon nitride, oxidation, reactivity, interaction couple

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