Interaction of Si3N4 with Ni-Cr alloy under N-2 or Ar atmosphere

In relation to the joining of silicon nitride ceramics to metal, the intera ction of Si3N4 with Ni-Cr alloy was investigated at temperatures from 1073 to 1573 K under N-2 or Ar atmosphere. Reaction rates were determined by the rmogravimetry and reaction products were examined by X-ray diffraction. CrN , Ni3Si, Ni5Si2, Ni2Si and (Cr, Si)(3)Ni2Si were produced under N2 atmosphe re. In addition to these products, Ni3Si2, Cr3Si and Cr5Si3 also were produ ced under Ar atmosphere. The reaction products were considered from the sta ndpoint of thermodynamics. While the incubation period was observed under A r atmosphere, it was not observed under Ng atmosphere. The initial rates ob eyed a linear rate equation. The rates at the later stage of reaction descr ibed a parabolic rate equation. The reaction mechanism model was proposed. (C) 1998 Kluwer Academic Publishers.