Thermal expansion of binary alkali silicate glasses

Abstract

The thermal expansions of a number of binary lithium, sodium, and potassium silicate glasses are reported over the tempcrature range from room temperature to thcir deformation points. The expans ivities of the glasses increased with increasing alkali oxide concentration. These expansivities were used to calculate density values, which were correlated with density measurements in the liquid range. At room temperature the density of each series incrcased with increasing alkali oxide concentration. vVith increasing temperatmc, t he dcnsity-temperature cur vcs for eac ll binary series crossed each othcr and thc density-concentration order was reversed. This reversal occnrrecl in the lowest tempcratuTc range for t he lith ium si licatcs, in an intermediate temperature rangc for the potassium silicates, and in the highest te mpcratnI'e range for thc sodium silicates.