Corrosion of silicate glasses by alkaline solutions Communication 4. Corrosion of glasses by solutions of various hydroxides

Abstract

1. The hydroxides examined in the present investigation may be arranged in the following order with respect to corrosive action on glasses: KOH > LiOH > NH4OH > Ba(OH)2 > Sr(OH)2 > Ca(OH)2. 2. Sodium hydroxide corrodes silicate glasses of all compositions to a greater extent than all the other hydroxides. It is proposed to call this phenomenon the “sodium anomaly.” The sodium anomaly probably arises from peculiarities in the peptization of silicon acids by hydroxyl ions in presence of sodium ions. 3. The action of hot water (90°) on silicate glasses of low stability consists not only in leaching, but also to a considerable extent in dissolution. The thickness of the layer of glass dissolved is sometimes commensurate with that dissolved by the hydroxides. 4. As the result of the formation of alkali-stable calcium silicates on the surface of the glass, the corrosive effect of solutions of calcium hydroxide is generally less than that of water.