INTERACTION OF SI3N4 WITH MN UNDER AR OR N-2 ATMOSPHERE

In relation to the joining of silicon nitride ceramics to metal, the reaction products and reaction mechanism between Si3N4 and Mn have been investigated in Ar or Nz at temperatures from 1073 to 1573 K. Using an Si3N4-Mn powder mixture, the reaction rate was determined thermogravimetrically, and the reaction products were examined by X-ray diffraction. Under an Ar atmosphere, from 1223 to 1423 K, MnSiN2, Mn0.815Si0.185 and Mn3Si were produced, and above 1423 K, MnSiN2 disappeared. At higher temperatures and on prolonged heating, the silicide composition changed in the following order: Mn0.815Si0.185, Mn3Si, Mn5Si3, and MnSi. Under an Nz atmosphere, the reaction between Mn, Si3N4 and N-2 produced Mn nitrides and MnSiN2. Below 1223 K, the reaction products were Mn6N2.58 and Mn4N. At higher temperatures, MnSiN2 appeared, while Mn nitrides disappeared, Above 1423 K, only MnSiN2 was produced. By relating these results to TG measurements, a full understanding of the reaction mechanism between Si3N4 and Mn was acquired.