CHEMICAL DURABILITY OF THE GLASSES OF SYSTEM LiF-CaO-Al(PO3)3

Chemical durability of the glass 0.8 LiF - 0.2 Al(PO3)3 (designated below as LiF-80) was studied in water and in 0.01 mol dm-3 HCl solution (further 0.01 M). The experiments were carried out at 25, 40 and 60°C with glass discs in unstirred solutions, which have been refreshed daily during a month. The methods used were mass loss measurements and determination of Li, F, and P2O5 concentrations in the solutions. The mean velocities and the apparent activation energies of the glass dissolution were estimated. The time dependencies of mass losses and leaching of the components were apparently linear. The ratios Li F and Li / P2O5 in solutions tend to be twice in water and four times as large in HCl solution in comparison to such ratios in glass itself, i.e. the dissolution of the glass runs with a preferred leaching of Li+. Additions of 2 and 5% CaO (over 100% by weight) increase slightly the chemical durability of the glass in unstirred 0.1 M HCl solution. In comparison with the glass LiF-80 the durability of the glass LiF-85 is much worse.