Abstract
On the basis of thermodynamic and kinetic considerations, the role played by surface oxide layers in the sintering of metallic powders is evaluated. For metals with stable oxides, the influence of the surface layer is determined by the relative sintering and diffusional fluxes x s/x d to the interparticle neck region. When x s/x d>1 sintering is retarded by the oxide layer. Conversely, unretarded sintering occurs when x s/x d <1. For metals with oxides which are unstable with respect to dissolution in the metal at the sintering temperatures, the sintering process is preceded by an incubation period. Calculated values of the relative neck growth rates and the incubation periods provide the bases for predicting the effects of these surface layers. Predictions of the present analysis are shown to be consistent with experimental observations. PM/0174
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