Kinetics of evaporation of beaded Ag film on sapphire and on alumina scale

Morphological changes of beaded Ag film on sapphire and on alumina scale were investigated by means of scanning electron microscopy and Auger spectroscopy in the temperature range of 822–973 K. It was found that the decrease of the effective thickness and the shift of the boundary of the layer can be attributed to the evaporation of silver into the gas phase. Experimental results were analyzed in terms of the model developed by Kaganovskii and Beke. Our results show that the process is controlled by surface diffusion and temperature dependence of the surface mass transport coefficients is deduced from the experimental data.