CONCENTRATION PROFILES OF SODIUM IN THE SURFACE OF DEALKALIZED GLASSES

Concentration profiles of sodium in the surface layer of glasses dealk alized with ammonium sulphate were measured by the stepwise etching me thod and subsequent chemical analysis of the solutions obtained, as we ll as by the ESCA method. The results allow to conclude that the diffe rence in hydrolytical resistance of glass surfaces dealkalized by diff erent procedures can be explained by the parallel effects of the chemi cal dealkalizing reaction, and of the diffusion processes involved. At the lower temperatures (of approx. 400 degrees C) the concentration p rofiles formed are stable in character, whereas at the higher temperat ure (800 degrees C) following exhaustion of the reaction agent, the di fference in the concentration of sodium will be gradually eliminated b y diffusion within the concentration gradient zone formed.