Ion Exchange Strengthening of Glasses of the ZnO–MgO–Al2O3–SiO2 Glass-Ceramic-Forming System with an Increased Content of Na2O

Zinc magnesium aluminosilicate (ZMAS) glasses were obtained with the addition of Na₂O (from 1.1 to 7.0 mol.%). The influence of the Na₂O content on glass forming ability and effectiveness of the ion-exchange treatment in molten KNO₃ was studied. The dependencies of depth and stress of subsurface layer on treatment duration were also studied along with an evaluation of the concentration shifts of alkaline cations in result of ion-exchange process. It is shown 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. The possibility of using an ion-exchange process with glass-ceramics obtained from glasses of ZMAS system modified with sodium oxide is discussed.