Ternary systems thermal conductivity

The first comprehensive study of the ternary system was conducted by [1932Koel] and later reviewed by [1949Jae]. Thermal analysis and metallographic techniques were employed to determine the liquidus surface, isothermal sections at 1300 and 20°C and 2 vertical sections. However, the versions of the Co-Mo and Fe-Mo binary phase diagrams they used in their analysis were somewhat different from those accepted in later work. This will be dealt with later. 

In the inter-alkali alloys, eutectic equilibria have been observed in a number of systems very low melting points have been determined for instance in the Rb-Na system (L (Rb) + (Na), at 82.5 at.% Rb and —4.5°C) and even lower melting temperatures have been observed in ternary systems. Binary sodium-potassium alloys, liquid at room temperature (at 25°C in a composition range of about 15-70 at.% Na, about 7-57 mass% Na), have a good thermal conductivity and a wide temperature range where they are liquid they may be used in heat-exchange systems. Their extremely high chemical reactivity must of course be taken into account. 

The ideal behavior in the case of electric conductivity is not defined physically, as we deal with scalar quantities, for which the total derivative does not exist and the simple additivity rule may thus not be used. However, the electrical conductivity is thermally activated and the additivity of activation energies of pure components is enabled. Based on this idea the additivity of logarithms of the electrical conductivity may be accepted as the ideal behavior. It should be, however, emphasized that there are two kinds of electrical conductivities, i.e. the conductivity, k, and the molar conductivity, X. The concept of the additivity of logarithms is recommended to apply to the molar conductivity, as the concentration course of the molar conductivity is smoothed by multiplying the conductivity with the molar volume. The ideal course of the electrical conductivity in the ternary system can be then expressed in the form... 

Cr-Fe-Zr is one of the ternary systems relevant to Zircaloys, which arc widely used as fuel cladding material in nuclear industry due to their low neutron-capture cross-section, high mechanical strength, high thermal conductivity and good corrosion resistance. In fliese alloys Fe and Cr, which are essentially insoluble in Zr at temperatures lower than about 600°C, are present in flie form of Zr(Fe,Cr)2 precipitates. This is one of the reasons why several studies have been performed on properties and characteristics of the Zr(Fe, Cr)2 phase. 

Methods to estimate the thermal conductivity of liquid mixtures have been reviewed by Reid et al. (1977, 1987) and Rowley et al. (1988). Five methods are summarized by Reid et al. (1987), but three of these can be used only for binary mixtures. The two that can be extended to multicomponent mixtures are the Li method (Li 1976), and Rowley s method (Rowley et al. 1988). According to the latter the Li method does not accurately describe ternary behavior. Furthermore, it was indicated that the power law method (Reid et al. 1977 Rowley et al. 1988) successfully characterizes ternary mixture behavior when none of the pure component thermal conductivities differ by more than a factor of 2. But, the power law method should not be used when water is present in the mixture. Rowley s method is based on a local composition concept, and it uses NRTL parameters from vapor-liquid equilibrium data as part of the model. These parameters are available for a number of binary mixtures (Gmehling Onken 1977). When tested for 18 ternary systems, Rowley s method gave an average absolute deviation of 1.86%. 

Chapter 2 is devoted to properties of solid citric acid and aqueous and orgartic solutions of it. Detailed phase equilibria in the citric acid + water system (melting, freezing, boiling, solubilities and vapour pressures curves) are presented, correlated and thermodynamically analyzed. Dynamic and other physical properties (viscosities, diffusion coefficients, thermal and electrical conductivities, surface tensions and indices of refraction) are examined. Solubihties of citric acid in organic solvents and ternary citric acid + aliphatic alcohol + water and citric add + tertiary amine + water systems are also discussed. 

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