The Chemical Durability of P_2O_5-Na_2O System and P_2O_5-Na_2O-Al_2O_3 System Glasses

The chemical durability of seven glasses I, e. (60+x)PO_<25-> (40-x)Na_2O system (x, 0,5,10,15) and (70-x)PO_<25>-(25+x) Na_2O-5AlO_<1.5> system (x, 0,5,10) glasses were examined. The fused glasses were powdered into particles of 35-60 meshes 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 amounts of P and Al dissolved into the water were measured by chelatometric titration. The conclusions are as following. 1) The relation between Log of the amounts P and Al dissolved into the water and square root of stirring time are linear by the theory, it is found that the theory is established approximately, though some results are not accord with it. 2) The relation between Log of the amounts of P and Al dissolved into the water and the reciprocal of their dissolute temperature (°K) are linear by the theory, it is found that the theory is not established. 3) Much amounts of P dissolve from PO_<25>-Na_2O-AlO_<1.5> system in the water PO_<2.5>-Na_2O system under same condition. The chemical durabilities of P_2O_5-Na_2O system glass do not increased on the addition of a little amount of Al_2O_3.