Synthesis and thermodynamic functions of barium cerate co-doped with erbium and indium

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Liquid-liquid equilibrium in the-<Emphasis Type="Italic">n</Emphasis>-heptane-<Emphasis Type="Italic">n</Emphasis>-perfluorohexane system

The shape of the liquid-liquid coexistence curve in the C₇H₁₆-C₆F₁₄ system in the molar concentration-temperature coordinates close to the critical solution point was studied by narrow-beam gamma-raying of two-phase samples. The molar volumes of the coexisting liquid phases and critical point coordinates (critical temperature T _c = 316.266 ± 0.03 K and critical concentration x _c = 39.0 ± 0.4 mol % C₆F₁₄) were determined. The critical index β of the coexistence curve was found to be 0.322 ± 0.005. The diameter of the coexistence curve did not obey the classic “rectilinear diameter rule.”     

The density and the binary diffusion coefficients of silver-tin melts

Temperature dependences of the density of liquid silver-tin melts containing 61.6 and 96.5 wt. % Sn (59.3 and 96.15 at. % Sn) have been determined using gamma-ray attenuation technique over the temperature range from liquidus line to 950 K. The density changes during solid-liquid transition have been directly measured for the first time for eutectic alloy (96.5 wt. % Sn). The temperature and concentration dependences of the thermal properties for Ag-Sn system have been constructed. Kinetics of homogenization of the melts with mean composition of 61.6 wt. % Sn has been investigated in the temperature range from 770 to 950 K. The coefficients of binary diffusion have been derived from these experiments.     

Laser flash method for measurement of liquid metals heat transfer coefficients

New laser flash technique for the measurement of heat transfer coefficients of liquid metals is presented. The thermal diffusivity of the liquid mercury has been studied experimentally over the room temperature range. The thermal conductivity coefficient has been calculated with the use of the reference data on density and heat capacity. Analysis of systematic errors of the measurements has shown that the data error is about 3%. Comparison of the obtained results with data available in publications has proved their reliability.     

Thermal conductivity of refrigerant R-415A in the vapor phase

Thermal conductivity of refrigerant R-415A in the vapor phase has been studied by the steady-state method of coaxial cylinders in the range of temperatures 308–415 K and pressures 0.12–1.68 MPa. The approximation dependence of thermal conductivity on pressure and temperature was determined. Thermal conductivity on the dew line and in the ideal gas state was calculated.     

Speed of sound in the gaseous refrigerant R-409A

Speed of sound in the gaseous refrigerant R-409A has been measured by ultrasonic interferometer in the temperature range from 293 to 373 K and at pressures from 0.05 to 0.58 MPa. The experimental uncertainties of the temperature, pressure, and speed of sound measurements were estimated to be within 20 mK, 4 kPa, and 0.1–0.2 %, respectively. On the basis of the obtained data, the isobaric molar heat capacity was calculated for the ideal-gas state. A comparison of the obtained results with the calculated speed of sound on the basis of REFPROP program was carried out.     

Experimental study of the density of aqueous solutions of lithium bromide at temperature of up to 250°C in the range of mass concentrations from 30 to 65 %

The density of aqueous solutions of lithium bromide was studied by the monochromatic gamma-ray attenuation method at the saturation line from the liquidus temperature of up to 250 °C for five samples with initial concentration of 30,927, 39.706, 50,936, 59.322, and 65.148 mass % of LiBr. The errors of temperature and density measurements were ±0.02÷0.05 °C and ±0.05%, correspondingly. Approximating equations and tables of reference data were obtained for density dependencies on temperature and concentration. Measurement results were compared with published data. The work was financially supported by the Russian Foundation for Basic Research (Grant No. 04-02-16302).     

Determination of the density of Pb-Sn melts and segregation phenomena on their crystallization

The density of liquid lead-tin alloys (17.64, 25.34, 25.61, 26.07, and 33.88 at % Pb) has been determined using an γ-ray attenuation technique over the temperature range from the liquidus line to 750–1040 K. The experimental uncertainty of the density measurements is estimated to be within the range of ±0.20–0.25%. It has been shown that the temperature hysteresis of the melt density and thermal expansion, which was observed previously in several studies, disappears after stirring the melts. The distribution of the components through the height of the liquid and solid samples and its variation with time and during melting-crystallization has been investigated. The study shows that the melts do not segregate on long standing (about 4 hours) near the liquidus temperature. However, crystallization and melting of homogeneous Pb-Sn alloys is accompanied by liquation phenomenon, which is enhanced as the sample composition deviates from the eutectic one. The text was submitted by the authors in English.