Effect of transition metal oxide additions on the chemical durability of SrO-MgO-ZrO2-SiO2 glasses

Abstract

SrO-MgO-ZrO2SiO2 quaternary glasses, such as 26SrO, 20MgO, 14ZrO(2),40SiO(2) (wt%,; Zrn glass) have been found to be highly alkaline resistant because of the high ZrO2 and MgO contents of such compositions, However, the presence of 26wt% SrO makes the glass expensive and may degrade the chemical durability. Therefore,, glasses with MnO and/or Fe2O3 partially replacing SrO have been made with the aim of improving the chemical durability and decreasing the cost. Comparison of chemical durability test results performed hi a pH 14 NaOH solution showed that glass compositions with suitable amounts of Fe2O3 or Fe2O3 plus MnO enhanced the alkaline resistance of the reference Zrn glass. The improved durability of glasses containing iron is attributed to the presence of ferric iron as confirmed by the formation of a hydroxide layer with an iowaite-like structure, while the poorer performance of glasses with Mn is related to the possible absene of Mn3+ ions.