High‐Temperature Density Determination of Boron Oxide and Binary Rubidium and Cesium Borates

Abstract

Density determinations of pure Bz03 and binary rubidium and cesium borates have been made in the temperature ranges 450" to 13OO0C and 500" to ll0O'C respectively. The density of BZO3 can be represented between 600' and 1000°C as d = 1.3388 + 228 (l/T) and for temperatures above 1000°C as d = 1.3947 + 157.9(l/T), where d is in grams per milliliter and T is in O K . The volume expansion ( d V / d T ) in the alkali borate systems at 800°C increases with an increase of alkali oxide when the alkali concentration is more than 18 mole yo. This increase in the volume expansion follows the order Cs > Rb > K > Na > Li. In the range 15 to 20 mole yo alkali oxide a break in the volume expansion was observed. This break suggests a possible change in the structural configuration of the alkali borates.

Structure‐Property Relations for Pyrolytic Graphite

“…To support this view, residual stresses were obtained by longitudinally splitting rings cut from thin cylindrical shells deposited under a variety of substrate surface conditions. Circumferential stresses determined from the amount of opening or closing of the split rings are compared with those computed from equation (5) (Table I). Figure 14 shows the surfaces obtained for these conditions.…”

Physicochemical model for predicting molten glass density

“…It may be noted that the partial molar volume of tricoordinate boron at 1273 K (46.50 cm 3 mol À1 ) is equal, within the uncertainty limits, to the molar volume of the B 2 O 3 glass (46.8 ± 0.9 cm 3 mol À1 ) reported by Riebling [10] and Li et al [7] at the same temperature. The close fit of the model with boron glass in which the boron is at coordination number 3 shows the relevance of the structural approach.…”

“…The existing models are based on density measurements in simple binary, ternary or quaternary systems to limit the calculations necessary to determine the density (q) or molar volume (m = M/q, where M is the molar mass of the molten glass). Based on data published between 1950 and 1970 [1][2][3][4][5][6][7][8][9][10][11][12][13], Bottinga and Weill [14] were the first to suggest that the density of binary or ternary liquid silicate systems could be used to fit the coefficients of volume models for more complex glass melts. Since Bottinga and Weill [14], the scientific literature [51][52] has provided numerous density measurements and models, many of which concern natural liquid silicates.…”