Impact of B and Al on the initial and residual dissolution rate of alumino-borosilicate glasses. Part I: kinetic data

Nuclear glasses are made of highly soluble (B) and low soluble (Si, Al) glass formers. This paper investigates the influence of these two types of elements on the initial and residual alteration rates of 6-oxide borosilicate glasses with varying B and Al contents. The results show that Al, by strengthening the glass network, leads to a decrease both in the glass matrix hydrolysis and in the gel reorganization. This provides a reduction of the initial dissolution rate and an increase in the residual rate due to a delay in the passivation effect. Regarding B, when its content in the glass is sufficient to form a continuous sub-network of Si‒O‒B bonds, it strongly increases both the initial and residual rates. However, below the threshold (estimated between 5.5 mol% and 9.7 mol% of B), its effect on the initial and residual rate becomes negligible.