STUDY OF ACID-BASE PROPERTIES OF OXIDE, OXIDE GLASS, AND GLASS-CERAMIC SURFACES

The points of zero charge, pH0, of 25 oxides were first calculated from the well-known Parks theory and then in developing a new approach based on the ionization potential of the corresponding metals. The theoretical values were found in good agreement with literature data and with experimental results obtained in using a method of adsorption of colored indicators. Afterward, the study of acid/base properties of glasses and glass-ceramics was undertaken and a simple additive relationship allowing the calculation of their points of zero charge from their compositions was established and experimentally verified with the colored indicator method. The concept of surface molar composition ensues from the theoretical model. The effect of mechanical surface treatments on the acid/base properties of the materials was related to the role of alkaline and alkaline-earth oxides in the silica network and in particular to the weakening of the glass structure by these elements. As a consequence, a mechanical action on glass and glass-ceramic surfaces increases the alkalinity. © 1992.