Abstract
The reaction between the silicon-nitride ceramics and nickel was studied in vacuum from 1373 to 1473K for up to 176.4ks. The reaction product was composed of two layers, one formed by the diffusion of silicon into nickel, and the other composed of additive oxides particles and nickel-silicon alloy. The growth of the product layer followed the parabolic law with the following rate constants (Kp): 1.2×10-13m2⋅s-1 at 1373K, 3.6×10-13m2⋅s-1 at 1423K, and 1.7×10-12m2⋅s-1 at 1473K. The interdiffusion coefficents (D) obtained were of the orders of 10-15 to 10-14m2⋅s-1 in the temperatures range studied. These values were found to be one half to one fifth of the interdiffusion coefficients determined with a vapour-solid diffusion couple of a nickel-plate and nickel-silicon alloy powder as diffusion source of silicon vapour. The activation energy for interdiffusion (Q) was about 330kJ⋅mol-1, independent of the Si concentration.
