Chemical interaction between Fe and silicon nitride ceramic

Chemical reaction between silico nitride ceramic and iron metal was studied experimentally with diffusion couples at 1100-1150 degrees C in order to clarify mechanisms in direct bonding of Si3N4 to Fe-based alloys. The reaction products have been characterized and related to the thermodynamic data available. The extent of reaction is controlled by the nitrogen gas pressure build-up at the metal-ceramic interface and the rate by silicon diffusion into the metal. Under the experimental conditions, only the metal. Under the experimental conditions, only an Fe(Si) solid solution was formed with maximum silicon content of about 12 at%. No silicides were found at the metal-ceramic interface. Nitrogen gas evolved at the interface is removed by permeation through the metal and/or through pores. Annealing atmosphere and sintering aid materials in the ceramic may play a role in the interaction. (C) 1996 Elsevier Science Limited.