Reaction of Si3N4 with 25%Cr-20%Ni austenitic stainless steel under nitrogen or argon atmosphere

In relation to joining of silicon nitride ceramics to metal, an extensive e xperimental study of the reaction between Si3N4 and 25%Cr-20%Ni austenitic stainless steel was conducted. Reaction rates were determined by thermograv imetry (TG) and reaction products were examined by X-ray diffraction. Cr2N, CrN, Cr3Ni5Si2 and Fe3Si were produced under a nitrogen atmosphere. Fe5Si3 and FeSi also were produced under an argon atmosphere. The reaction produc ts were analyzed according to thermodynamic considerations. The incubation period was found in TG curves and it was much shorter under a nitrogen atmo sphere than under an argon atmosphere. The rates at early stages and late s tages of reaction were given by linear and parabolic rate laws, respectivel y. Possible reaction mechanisms were proposed based on the results of the T G analysis. (C) 2000 Kluwer Academic Publishers.