Microwave assisted ion exchange in silicate glass

Distribution of electrical field gradients developing upon microwave heating glass parts immersed in an alkaline salt melt is analyzed by simulation. It is assumed that such gradients influence the process of ion exchange between the molten salt and the silicate glass immersed in it. It is shown that strong E-field gradients exist between the melt and the solid glass which could enhance ion transport due to an electro-migration effect superimposing the concentration gradient. In addition, interaction of the solid glass with microwave radiation could facilitate stress relaxation in the glass, which upon thermally induced ion exchange is retarding diffusion of alkali ions. A special microwave applicator has been developed which enables equilibration of inhomogeneous electromagnetic field distribution by mechanical movement of the samples subjected to ion exchange in order to analyze the overall effect of electromagnetic filed influence on ion exchange phenomena.