CATION CONCENTRATION PROFILES IN FLOAT GLASS SURFACES DURING CORROSION IN AQUEOUS-SOLUTIONS

The chemical composition of the thin surface layer of float glass is n ot homogeneous with respect to the concentration of some cations. This inhomogeneous cation distribution significantly changes if the glass surface comes into contact with aqueous solutions. Using ESCA signific ant changes in the distribution of magnesium and sodium cations were f ound on the ''top'' surface of float glass in static corrosion environ ment. The magnesium concentration increases in the thin surface layer, while sodium concentration decreases almost to zero. The relative amo unts of calcium, silicon and oxygen appear to be nearly the same both in the original and the corroded surface layer. The change of magnesiu m and sodium concentrations as well as an electron micrograph of the g lass surface indicate damage and hydration of the ''top'' surface laye r of float glass. The distribution of the elements does not show any s ignificant change if corrosion proceeds in streaming water. Consequent ly, total dissolution of the basic glass network built by silicon and oxygen atoms appears to be the fundamental process in this case.