Ar雰囲気下でのSi₃N₄とFe-Cr合金との反応機構

抄録

In relation to the joining of silicon nitride ceramics to metal, the reaction products and reaction mechanism between Si₃N₄ and Fe-Cr alloy have been investigated under Ar atmosphere at temperatures from 1223 to 1573K. Using Si₃N₄/Fe-62.5mass%Cr alloy powder mixture, the reaction rates were thermogravimetrically determined, and the reaction products were identified by X-ray diffraction. Cr₂N was produced below 1273K. Above 1273K, the solid solution and silicides were produced, resulting in the mass loss. At higher temperatures and on prolonged heating, the silicides changed in the following order: Cr₃Si, Cr₅Si₃ and CrSi. Two types of Cr₅Si₃ were found; hexagonal crystal above 1323K and tetragonal crystal above 1423K. Iron is considered to form the solid solution with chromium silicides. The initial rate was described by the linear rate law. The activation energy was 264kJ/mol. An interfacial reaction may be the rate-determining step. When the alloy particles were covered with the reaction product layer, the kinetics obeyed the parabolic rate law. The reaction rate is probably controlled by the solid-state diffusion through the reaction layer.