New generation chemical tempering of soda lime silicate glasses

Since the beginning when glass materials were discovered, their usage areas are increasing over time with the development of technology. There is a big difference between theoretical and practical strength of glasses. This difference occur due to the microscobic defects on the surface of glasses. Therefore, it is important to increase the strength of glasses. Today, thermal and chemical tempering methods are used to increase the strength of glasses. Higher strength increases are achieved in chemical tempering compared to thermal tempering. Additionally, chemical tempering can be applied to thin and complex shaped glasses. In this study, chemical tempering was applied to soda lime silicate glasses by coating them with the paste method. Chemical tempering process was carried out for 4 different mixtures at 450 °C for 3 different periods: 8, 12 and 16 hours. An attempt was made to create compressive stresses on the surface of glass by exchanging of K+-Na+ ions by chemical tempering method. In these mixtures, by adding Mg(OH)2 in addition to the KNO3 salt, the mixed cation effect was investigated with the Mg+2 cation thought to come from Mg(OH)2. Samples chemically tempered for 8 hours with mixture 2, containing Mg(OH)2 increased strength the result of the three-point bending test by 4-5 times. Samples coated with mixture number 4 and chemically tempered for 12 hours with a different method for homogeneous diffusion mechanism has increase strength the result of the three-point bending test by 5-6 times.