ION EXCHANGE HARDENING OF GLASSES OF THE ZnO–MgO–Al2O3–SiO2 SITALL-FORMING SYSTEM WITH AN INCREASED CONTENT OF Na2O

Zinc magnesium aluminosilicate (ZMAS) glasses have been obtained with the addition of Na2O (from 1.1 to 7.0 mol. %). Influence of the Na2O content on glass forming ability and effectiveness of the ion-exchange treatment in molten KNO3 was studied. Dependences of depth and strain of subsurface layer on treatment duration have been also studied, concentration shifts of alkaline cations in result of ion-exchange process have been evaluated. It was showed that glass Vickers hardness increases both with the Na2O content in glass and with the duration of ion-exchange. Vickers hardness of the ion-exchanged glasses with 7 mol. % of Na2O treated duration for 72 h reaches 900 HV. Possibility of ion-exchange process usage with glass-ceramics, obtained from glasses of ZMAS system modified with sodium oxide, has been discussed.