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 dcnsitytemperature 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.

Density formula for alkali silicate glasses from annealing to glass-processing temperatures

“…Whi te shows that his r esults a t 1400° C are in fair agreem en t with those by Heidtka~p and Endell [9 ] and those by Shartsis, Spinner, and Capps [10]. The " observed " values f<?r compact ed glasses at room tempera ture and at t.h~lr critical t emperatures are b ased on th e d enSitIes publish ed by Young, Glaze, Fai ck , and Finn [11 ] and on thermal coefficients tabula ted by Shermer [7] and by Schmid, Finn, and Young [12].…”

“…The right-face brackets represent data by H eidtkamp and Ende]] [9] for 20-to 50-mole percent of Na.Q (except at 1,100° 0 where their modifier range is only 30 to 50 percent). Shermer's [7] diagram suggests minimum spread in crossings just below] ,350° O. Comparison of computed and observed densities of binary silicate glasses at 1,400 0 C.…”

“…Dotted lines lead to densities computed by form ula at tbe annealing temperatures. Filled circles represen t densities compu ted for annealing temperatures by use of room temperatllre densities and expansivities as measured by Schmid et al [l2] and by Shermer [7]. The total ranges in White's -------…”

“…(1) A bond-angle theory of annealing [4] ; (2) Known linear variations of densities of glasses at equilibrium in the annealing ranges [4] ; (3) Shermer's [7] curves for densities of molten glasses as functions of composition, showing (quali tatively 4) the marked increases in expansivities as cation is added to silica ; (4) White's [8] finding that densities of molten alkali silicates vary nearly linearly with temperature over a 400 0 C range ; (5) White's report that the silicon-oxygen structure in molten silicates is not only similar to that in vitreous silica but is independent of the kind of cations present; and (6) White's report that the partial molar volumes of silica are identical for the alkali silicates and decrease as cation is added.…”

Determination of Refractive Indices and Linear Coefficients of Thermal Expansion of Silicate Glasses Containing Titanium Oxides

“…Figure 4 shows the linear coefficients of thermal expansion for SiO 2 -Na 2 O glasses along with reported values. [8][9][10][11][12][13][14] The present data lie roughly in the middle of the reported values; thus, the present method is considered to be suitable for measurement of linear coefficients of thermal expansion for silicate glasses. Figure 5 shows the length in pixel for a 60SiO 2 -25TiO 2 -15Na 2 O glass as a function of temperature as an example from the SiO 2 -TiO 2 -Na 2 O system, where the uncertainty range represents the maximum and minimum data at each temperature.…”