CHARACTERIZATION OF GLASS-CERAMIC CORROSION AND DURABILITY

The chemical durability of some selected glass-ceramic materials based on the Li2O- (MnO, CaO)MgO-Al2O3-SiO2 glass composition, has been determined by HCl, using the powder test. The leachability of the glass-ceramic was gradually increased by replacing MgO with MnO, while it was decreased by addition of MnO instead of CaO. Calcium oxide had a retarding effect on the durability of the material when it was added instead of MgO and/or MnO. However, on the addition of Al2O3 in replacing Li2O, the durability of the material was markedly improved The leaching data were found to be dependent mainly on the proportion of the glass oxide constituents i.e. MgO/MnO, CaO/MnO and Li2O/Al2O3 ratios present in the glasses. The results were correlated to different views concerning the effect of various ions on the rate of interdiffusion between the crystalline-glass materials and leaching solution, the type, and proportions of the crystalline phases developed in glass-ceramics and residual glass phase.