N_2及びAr雰囲気下でのSi_3N_4とカーボニル鉄との反応

概要

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In relation to the joining of silicon nitride ceramics to metal, the reaction products and reaction mechanism between Si_3N_4 and iron were investigated at temperatures from 1173 to 1573 K under both introgen and argon atmospheres. Using an Si_3N_4-Carbonyl iron powder mixture, the reaction kinetics were determined through thermogravimetry, and the reaction products were examined by X-ray diffraction. An Fe-Si solid solution was formed both in nitrogen below 1323 K and in argon below 1223 K. With an increase in temperature, the product was changed to iron silicides in the following order of occurrence : Fe_3Si, Fe_5Si_3 and FeSi. The lattice constant of the bcc crystal structure successively changed throughout the α-Fe, Fe-Si solid solution and Fe_3Si phase of the transformation. The incubation period was long at low temperatures, but shortened markedly at higher temperatures. The initial stage of the reaction obeyed a linear rate of reaction. This has two possible controlling mechanisms :(1)by a chemical process below 1373 K and(2)by gas-phase diffusion governed by interparticle-pore size above 1373 K. Iron silicides were produced in argon as the reaction rate increased to obey a parabolic rate law during the secondary stage. Thus, the kinetics are probably determined by solid-state diffusion through the reaction layer.
社団法人日本セラミックス協会の論文
1997-09-01