The Chemical Durability of B_2O_3-SiO_2-Na_2O System Glasses

A disolving phenomenon of alkali in glass for water has been studied in this paper. Ten kinds of glasses in B_2O_3-SiO_2-Na_2O system and twenty kinds of glasses i. e. AlO_<1.5> 5mol or CaO 5mol were added on the composition of these ten kinds of glasses respectively were fused in the electrical furnance. The fused glasses were powdered into particles of 35-60 meshed and 2g of them were immersed in 50cc water of 30,50 and 70℃ under constant agitation of 10,20,40 and 80min respectively. Then the quantity of dissolved into water was measured by 0.01NHCl. The results are as followings. 1) The experimental data is tested by analysis of variance and it is proved that the theory of Douglas is established exactly. 2) The effects of the addition of AlO_<1.5> 5mol. Or CaO 5mol. On the B_2O_3-SiO_2-Na_2O system glasses are examined by the aid of the data. Then it is found that the addition of AlO_<1.5> or CaO are very effective, but their effect are different in all glasses.