Influence of mixed alkali oxides on some melt properties of TV screen glass

The influence of K2O/R2O (R2O = Na2O + K2O) on some melt properties was stu died in alkali-alkaline earth-silicate TV screen glasses. Viscosity, surfac e tension, electrical resistivity, volatilization and devitrification of gl ass melts were determined. No mixed alkali effect was observed in viscosity , surface tension and liquidus temperature They showed a linear behavior wi th increase of K2O/R2O. On the other hand, electrical resistivity and weigh t loss by volatilization showed a strong mixed alkali effect against relati ve alkali concentration. According to the dependence of viscosity, electric al resistivity and volatilization on K2O/R2O, the slope change of those pro perties took place at K2O/R2O = 0.4 to approximate to 0.5. The compositiona l dependence of viscosity, surface tension and liquidus temperature was dis cussed in terms of field strength, polarizability and material diffusion, r espectively. A correlation was also discussed between the dependence of pro perties on K2O/R2O and the production process of TV screen glass. In conclu sion, from the viewpoint of both production and application of TV glasses i t was suggested that the mole fraction of K2O/R2O should lie between 0.2 an d 0.5.