Corrosion of silicate glasses by alkaline solutions Communication 3. Inhibitors of the alkaline corrosion of glasses

Summary

• 1. Some anions, in very low concentrations (about 0.01 g-equiv/liter), are able to effect a great reduction in the corrosion of glasses by alkaline solutions. Beryllate aluminate, and zincate ions are particularly effective, and it is proposed to refer to them as “strong inhibi tors” of the alkaline corrosion of silicate glasses. These anions act as inhibitors of the alkaline corrosion of all silicate glasses except the very readily destroyed binary sodium and potassium glasses. The action of strong inhibitors is maintained in alkaline solutions over a wide range of concentrations and temperature, and also when sodium hydroxide solution is replaced by sodium carbonate solution. Other anions are much less effective than the strong inhibitors in retarding alkaline corrosion.

• 2. The experimental results are in accord with the views of Berger and Geffcken concerning the mechanism of the inhibition effect. This effect is due not to the formation of thick layers that render interaction between glass and solution mechanically difficult, but to the action of the inhibitor on the elementary processes of which the corrosion is made up.