Inhomogeneity-Packing Density Relations in Binary Powders—Experimental Studies

The purpose of this investigation was to determine if the bulk specific volume of inhomogeneous binary powder mixtures, with a large size ratio, corresponds to the theoretical values calculated from known compositional inhomogeneity data. The theoretical calculations are based on the assumption that the body packs according to the Furnas model on a local scale. To minimize the effects of particle geometry, experiments were performed with glass microbeads.     

Energy Relations in Binary Alkali Borates

The heats of solution of glasses and devitrified alkali borates in the systems Li₂O–B₂O₃, Na₂O—B₂O₃, and K₂O–B₂O₃ were measured in 2 N nitric acid with a simple vacuum-bottle calorimeter. The standard deviation was 0.35 cal. per gm. for approximately 130 determinations. From these data, together with available thermodynamic data, heats of formation were calculated for alkali borate glasses and devitrified alkali borates from two combinations of possible reactants. All the curves for the heats of solution of glasses showed minima at 20 mole % alkali oxide, but similar curves for devitrified alkali borates showed minima at 20 mole % for potassium and sodium borates only. The curve for devitrified lithium borates showed a minimum at 25 mole % alkali. The conclusion was drawn that there is probably no congruently melting Li₂O.4B₂O₃ compound.     

Packing Density of Binary Mixtures of Wet Spheres

An experimental study of the packing of binary mixtures of coarse spheres with the addition of water has been conducted. The results indicate a similarity between dry and wet packings, either in the relationship between the packing density and the moisture content or in the relationship between the packing density and the particle-size distribution. The Westman equation is used to describe the wet packing after necessary modification. The approach is verified by the good agreement between the calculated and measured packing densities.     

Pervaporation Separation of Methanol-Carbontetrachloride Binary Mixtures Using Low Density Polyethylene Membranes

In this study, the pervaporation behaviour of azeotrope-forming methanol-carbontetrachloride binary mixture at different compositions was investigated at 30°C and 45°C through LDPE membranes with two different melt flow indices for two different thicknesses. Experimental fluxes and selectivities for methanol and carbontetrachloride were determined. Theoretical calculations for fluxes based on a solution-diffusion model as developed by Yeom and Huang using Fujita′s free volume approach and Flory-Huggins thermodynamics showed deviations from the experimental results. Experimental fluxes were decomposed into sorption and diffusion terms to discuss the effects of experimental conditions.     

石英砂二元混合颗粒初始流化过程的研究

在一套Φ300 mm×3000 mm的有机玻璃冷模流化床实验装置上,考察了石英砂二元混合颗粒的初始流化特性。所有二元混合颗粒均由颗粒密度相同但粒径不同的A、B、C、D四类颗粒组分两两按照一定质量分数混合而成。采用FXC-Ⅱ/32型压力巡检仪测得了不同轴向位置床层的压降曲线,得到了不同二元混合颗粒的起始流化过程特性曲线和起始流化速度。实验结果表明,两种颗粒组分平均粒径大小和差异及其组分质量分率对二元混合颗粒的起始流化特性具有显著影响。A类颗粒加入可显著改善B、C和D类颗粒的流化质量;C类颗粒加入量过大会使混合颗粒在流化过程中出现严重的沟流现象;当浮升组分(小颗粒)质量分数为0.4时,组分粒径差异较大的二元混合颗粒在流化过程中最容易发生完全分级现象;对于粒径差别较大的二元颗粒组分,床层最小流化速度随小颗粒组分的增多而下降,而对于具有较强颗粒间作用力组分的二元颗粒组分,床层最小流化速度则随小颗粒组分的增多而增大。根据实验数据对等密度BD二元混合颗粒的起始流化速度预测公式进行了修正,发现实验值与计算值吻合较好。     

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

Density determinations of pure B₂O₃ and binary rubidium and cesium borates have been made in the temperature ranges 450° to 1300°C and 500° to 1100°C respectively. The density of B₂O₃ can be represented between 600° and 1000°C as d = 1.3388 + 228 (1/T) and for temperatures above 1000°C as d = 1.3947 + 157.9 (1/T), where d is in grams per milliliter and T is in °K. The volume expansion (dV/dT) in the alkali borate systems at 800°C increases with an increase of alkali oxide when the alkali concentration is more than 18 mole %. This increase in the volume expansion follows the order Cs > Rb > K > Na > Li. In the range 15 to 20 mole % alkali oxide a break in the volume expansion was observed. This break suggests a possible change in the structural configuration of the alkali borates.     

High-Temperature Energy Relations in the Alkali Borates: Binary Alkali Borate Compounds and Their Glasses

The energy relations existing between the congruently melting compounds Li₂O -2B₂O₃, Na₂O–2B₂O₃, Na₂O-4B₂O₃, and K₂O-4B₂O₃ and their glasses have been determined for the temperature range 25° to 1100°C. High-temperature heat-content, entropy, and heat of solution data are given for both the glasses and the corresponding devitrified materials. A comparison of the heats of fusion of the alkali borates on a gram atom of oxygen basis shows that they follow the order Li > Na > K. The entropy differences between the glass and the corresponding crystalline material have been determined at 25°C. The free-energy change at 25°C. for the reaction crystal → glass has been calculated for the four compounds.     

Physical Properties and Structure of Silicate Glasses: I, Additive Relations in Alkali Binary Glasses

Correlations between certain physical properties, P , and all eighteen compositional ratios between the five ionic parameters of the system were studied with a computer for the five alkali silicates. Linear relations were found between P and the alkali/silica, alkali/oxygen, and silica/alkali ratios for certain regions of the glass field when the P's are expressed in proper molar terms. Specific volume and heat of formation data indicate three linear regions with two sharp break points between. The log electrical resistivity and the volatilization loss show two such regions and only the second break point. The break points, while structural in origin, must therefore occur for different reasons. The break points are the same for all P's and coincide with the eutectics. The constants of the linear relations are the partial molar quantities associated with P. Break points are not found in the molar refractivity data, so that no change in ligancy for these systems is indicated.     

Surface Tension, Density, Viscosity, and Electrical Resistivity of Molten Binary Alkaline-Earth Borates

Results of an investigation of some properties of the systems CaO-B₂O₃, SrO-B₂O₃, and BaO-B₂O₃ are reported. The formation of two liquids at low RO concentrations limited the range of compositions which could be measured. The values of surface tension and temperature coefficient of surface tension obtained for compositions where two immiscible liquids exist corresponded closely to those for pure B₂O₃. At RO concentrations above the two–liquid regions the surface tension rose sharply with increasing RO content. The densities in the liquid range as well as at room temperature were in the order Ba > Sr > Ca. The introduction of RO into B₂0₃ caused contractions in the glass network; the order of the contracting effect was Ca > Sr > Ba. Neither the method of Huggins or of Stevels was satisfactory for representing the density behavior of these glasses. The viscosity isotherms of barium borate liquids in the temperature range 850° to 950°C. showed maxima at about 22 to 23 mole yo BaO; the other two systems were too fluid for the counterbalanced sphere apparatus used in this work. The equivalent conductance increased with RO concentration; the order for both specific and equivalent conductance at corresponding concentrations was Ba > Sr > Ca.     

二氧化碳与丙酮,乙醚以及甲醇二元体系饱和液体密度的测定和关联

根据作者建立的一套实验装置,对二氧化碳-丙酮、二氧化碳-乙醚及二氧化碳-甲醇三个含极性混合物二元体系进行了饱和液体密度和泡点压力的测定,测定结果用立方型状态方程进行了关联。     

Binary vapour-liquid equilibria

Vapour-liquid equilibrium data were determined at 75° for three binary systems: benzene-n-heptane, n-heptane-propanol-1 and benzene-propanol-1, using a modified Gillespie still. Log γ values were correlated by a three-constant Redlich-Kister equation.     

Gas Filtration in Binary Fluidized Beds

Abstract

A systematic experimental study of aerosol filtration in a binary fluidized bed of dielectric material is carried out. Measurements of the collection efficiency when such parameters as gas velocity, bed height, collecting mixture, and column diameter are varied over a wide range have been made. Experimental evidence is given to show that charges generated naturally by triboelectrification of the bed dielectric particles can considerably increase the efficiency of such beds. Furthermore, it is demonstrated that a proper choice of the fluidized mixture can significantly improve the performance of such filters.     

Film Formation in Binary Sol-Gel Systems

The film-forming capacity of binary systems containing Sb₂O₃, SnO₂, CeO₂, Y₂O₃, Nd₂O₃, Bi₂O₃, V₂O₅, ZnO, CuO, CdO, and Al₂O₃ are investigated. The best film-formers are Sb₂O₃ and SnO₂, whereas ZnO, CuO, CdO, and Al₂O₃ cannot produce films of optical quality. The rest of considered oxides do not impair the clarity of coatings when their molding content is 20 – 50%. A proportional dependence is established between the refractive index and the reflection coefficient of a film and the refractive indexes of oxides making parts of this film, as well as between the concentration of deposited FFS, the film-forming capacity of oxides, and the film thickness.     

Mass-Transfer Coefficients in Dense Binary Mixtures

A modified elementary kinetic theory of gases is generalized to arbitrary densities of mixtures (from the gaseous to the solid state). Derived expressions for the mass-transfer coefficients are based on the lattice gas model, which is applicable to all the three aggregation states. For a rarefied gas, the expression for the mutual diffusion coefficient that is derived in terms of the modified theory is consistent with that obtained in terms of the rigorous kinetic theory of gases. The migration of particles is described in terms of transition state theory. The theory takes into account the role of thermal fluctuations in surmounting the activation barrier in dense phases. The label diffusion coefficient, pressure diffusion coefficient, thermal diffusion coefficient, and forced diffusion coefficient are discussed.     

Subliquidus Immiscibility in Binary Alkali Borates

The phase boundaries of subliquidus immiscibility in the lithium, sodium, potassium, rubidium, and cesium borate systems were determined. Two-phase structures were developed in thermal gradients and examined by direct-transmission electron microscopy. No opalescence was observed. Microstructures were of the order of a few hundred angstroms. The extent of immiscibility in each system was determined by the approximate intersection of the immiscible phase boundary with the glass transition region.     

Binary systems with monoglycerides

A number of binary systems have been studied, each involving a 1-monoglyceride. Included was the binary system of 1-monopalmitin (1P)-1-monostearin (1S). Other systems involved 2-monoglycerides, 1,3-diglycerides and triglycerides as follows: 2P-1P, 2S-1S, PP-1P, SS-1S, PPP-1P, SSS-1S. A general principle running through the observed behavior is that the more chemically similar the components, the greater is the interaction or solid solution formation. Thus 1P-1S showed continuous solid solution in both stable and metastable states with “compound formation” in the stable state. The systems 2P-1P and 2S-1S showed α (sub α) stability in a single solid solution phase for the range 20–80% 1-monoglyceride. The system PP-1P and SS-1S showed extensive solid solution formation in an α state but little or none in the stable state. There was essentially no solid solution formation observed for stable states of PPP-1P and SSS-1S; experimental limitations made it difficult to draw certain conclusions about the metastable state, but here, too, it is believed, solid solution formation was negligible.     

Marangoni Instability in Evaporation of Binary Mixtures

The Marangoni instability is considered, which emerges in evaporation of binary mixtures and is related to the dependence of the surface tension on the composition of a mixture. The dispersion equation, which describes the development of hydrodynamic perturbations in the supercritical region, is derived in a linear approximation with respect to perturbations and with an exact undisturbed profile of the composition of the mixture in the surface region.     

Effective Transformation Strain in Binary Elastic Composites

This communication concerns the strain in a binary elastic composite when one component undergoes a transformation such as a martensitic phase change. The results are significant when the transforming phase has elastic properties which are different from those of the matrix material. The estimates are pertinent to transformation toughening of ceramic composites. Experimental data for transformation toughening are reviewed in the context of the theoretical results.