Measurement of High Temperature Thermodynamic Propertiesof Several Binary Alkali Silicate Glasses

The method for continuous measurement of the high temperature heat content, developed by W.Oelsen et al. and applied to the glasses by M.Tashiro, was examined and modified in some points. Relations between the temperature and heat contents referred to the standard temperature 25℃, were determined for the some glasses of R(2)O-SiO(2) system, and the specific heats as well as the entropies were calculated. Comparing the results, some views have been obtained relating to the effect of the species and content of alkali ions on the thermodynamic quantities of such glasses

Potential Sweep Voltammetry of Na(2)O-SiO(2) Glass Melt by Stationary Platinum Electrodes

Potential sweep voltammetries of Na(2)O·SiO(2) and Na(2)O·2SiO(2) at 730-1200°C were performed with the stationary platinum wire electrode and with the sweep rates of 40 and 120mV/sec. Although current-potential relation of Na(2)O . SiO(2) at 1200°C gave stationary S-shape pattern, those of the rest were transient modes with hysteresis. From the voltammetric considerations, a reversible oxygen electrode process where diffuion of free oxygen anion or silicate anion may be a rate-determining stage was tentatively proposed. Approximate estimations of decomposition voltage supported that a sole reaction process such as the decomposition of Na(2)O or indirect decomposition of SiO(2) in the melt was most probable

Solubility of Sulphur in a Cadmium Borate Glass and SomeProperties of the Sulphur Containing Glasses

The glass forming limit by substitution of CdS for CdO in a CdO-B(2)0(3) glass was determined by chemical analysis. When x CdS-(60-x)CdO-40B(2)0(3) nominal mixtures in weight ratio were heated at 1100°C in flowing nitrogen gas for 1/2 hour, about 40~50% of mixed CdS and 10-15% of the mixed CdS were evaporated. The limit of nominal composition for glass forming was 10CdS-50CdO-40B(2)0(3) and the corresponding virtual composition after the above heat treatment was found to be 4.9CdS-46.4CdO-48.7B(2)O(3). Further addition of CdS made the melt devitrefied with CdS precipitation. D.C. conductivity measurements revealed that the current density was not linear with respect to the applied voltage, but the resistivity ranged around 10(12)Ω･cm for 4.1CdS-48.8CdO-47.1B(2)O(3) (virtual composition) glass and around 10(11.5)Ω·cm for 4.9CdS-46.4CdO-48.7B(2)O(3) glass. These sulphur containing glasses did not show photoconduction, although CdS-precipitated materials showed slight photoconductivity when disposed in ultra violet radiation. Apparent dielectric constant and tan 8 were also measured as a function of frequency, revealing a moderate dispersion in the CdS-precipitated glasses

Diffusion Phenomena of Silver Ion in Molten Sodium Borate by Chronopotentiometry

Diffusion phenomena of silver ion in the molten sodium diborate of low silver ion content were investigated at the temperature range from 880℃ to 625℃ by means of chronopotentiometry. From the results, it was shown that the silver ion was reduced reversibly to metallic state at the silver electrode used and silver ion was transported only by diffusion in case that transition time in a potential-time relation was within several seconds. Diffusion coefficients measured at various temperatures satisfied Arrhenius equation. The activation energy of diffusion and diffusion coefficient were respectively 32Kcal/mol and 6.5×10(-7) cm(2)/sec at the liquidous temperature. By comparing these values with those obtained in some molten salts, the difference of structure between the molten glass and molten salts was discussed. Moreover, the consideration for the size of borate anion existing in the molten glass was also tried from the viewpoint of rate process and from Stokes-Einstein's equation

Glass Melting Tanks as Models for the Behavior of Mantle

The authors have attempted to make clear the characteristics of convection current of molten glass in a cross-fired glass tank furnace by model techniques and also obtained some information about flow patterns of natural convection motion in mantle. In this paper we introduce an outline of our study on the model experiments in glass tank furnace and try to obtain some information about their analogy with mantle flow

Diffusion through the Interface between Viscous Liquids in a Laminar Flow (Diffusion in a Laminar Flow)

Studies were carried out in order to know in some detail the transport phenomena through the interface in the viscous liquid moving in laminar flow. Experiments were carried out using ca. 88% glycerin solution, one added with an acid, and the other with alkali together with a small amount of phenolphthalein. Acidic glycerin solution was supplied to a long transparent cuvette of rectangular cross section through which the liquid was made to move slowly enough to establish the laminar flow, thin cords of coloured basic solution were introduced in the direction normal to the axis of flow at regular time intervals. The so obtained patterns of bending cords shortening in regular succession were photographed also at regular time intervals. The authors attribute the origin of the changing patterns of the cords to the velocity gradient existing in the acidic solution which accelerates the diffusion by increasing the concentration gradient near the cords as well as the increase of the interfacial area, and also the decrease of the thickness of the cords. Based on these idea a mathematical analysis was carried out and was obtained an equation which gives the change of the concentration distribution of two dimensional cords. Fair agreement was obtained between the results of mathematical analysis and those of experiments. Furthermore, the influence of the thickness of the cords, and that of the velocity gradient as well as of the diffusion coefficient on the concentration at the center of the cords were discussed

Spectrophotometric Studies on High Iron Content Silicate Glasses

Spectrophotometric investigations were carried out on soda-lime-silica glasses containing iron in high content, corresponding to 4.9 wt.% Fe(2)O(3), and melted under the various reducing conditions, as a part of series of studies on the redox behavior of glass. Absorption measurement was made in the range from 340 mμ to 1000 mμ. Ferric ions could not be reduced to ferrous ions completely even by the amount of carbon of four equivalents. The ratio of the strength of light absorption at 1000 mμ as a typical band of Fe(2+) ions and that at 380mμ of Fe(3+) ions was expressed as E(1000)/E(380), which was examined for glass compositions as well as various carbon amount added to glass batches. The ratio decreases as the carbon amount increases and increases with decreasing content of Na(2)O or CaO. These changes of spectrophotometric properties of glasses were discussed from the view point of state of the the iron ions. Besides, some results on oxidized glasses were also added