First investigations of the influence of IVB elements (Ti, Zr, and Hf) on the chemical durability of soda-lime borosilicate glasses

Abstract

The influence of IVB elements (Zr, Ti, and Hf) on the glass structure and on the alteration kinetics of soda-lime borosilicate glasses has been studied at various stages of glass leaching corresponding to the initial dissolution rate, rate drop, and residual rate regimes. The effect of these elements on the limiting mechanisms of the glass durability as well as the chemistry of both solution and alteration layer are inter-related, depending on the reaction progress. The effect of IVB elements on the glass structure was investigated using 11B MAS NMR. The IVB elements are compensated primarily by Na rather than Ca, at the expense of tetracoordinated boron. The addition of HfO 2 or ZrO 2 decreases the initial dissolution rate in a similar way. Moreover, adding ZrO 2 limits the rate drop in saturated media. The initial dissolution rate decrease is less significant when Ti is added, and a quick drop of the dissolution rate is observed up to 4 mol% TiO 2. At low IVB element concentration, glasses containing Ti and Zr show different residual rates arising from the precipitation of magadiite (Na 2Si 14O 29·11H 2O), at the surface of Ti-bearing glasses. The influence of IVB elements on glass alteration indicates that, unlike Ti, Zr and Hf plays a similar role in the structure of borosilicate glasses.