A unified equation for the viscosity of pure liquid metals

Abstract

A unified equation for the viscosity of pure liquid metalsThe following unified equation has been elaborated in the present paper, to describe the viscosity of all liquid metals as a function of temperature:i being the dynamic viscosity, atomic mass, molar volume and melting point of the given metal i, and T is temperature. The above equation was tested on 101 measured points of 15 selected liquid metals, and the average values of the generally valid parameters were found as: A = (1.80 AE 0.39) · 10 -8 (J/Kmol 1/3 ) 1/2 , B = 2.34 AE 0.20.Based on these parameters, the temperature dependence of viscosity was estimated for 32 liquid metals. The above equation was derived by (i) combining Andrade's equation with the activation energy concept, and (ii) by combining Andrade's equation with the free volume concept. It is shown, that the activation energy and the free volume concepts have identical roots and lead to identical results. The above equation is shown to be valid for liquid semi-metals (Si, Ge, Sb, Bi), if their actual melting points are replaced by their corrected melting points, corresponding to (unstable) metallic solid crystals. The ratio of viscosity to surface tension of pure liquid metals is discussed, as well.

Communication: Simple liquids’ high-density viscosity

“…(9) in non-reduced units. 60 This expression was shown to work well for 18 metals at ambient pressure. 60 Equation (10) is qualitatively different by having (T F /T ) 1/2 instead of T F /T in the exponential.…”

“…60 This expression was shown to work well for 18 metals at ambient pressure. 60 Equation (10) is qualitatively different by having (T F /T ) 1/2 instead of T F /T in the exponential. The new viscosity equation represents data well in the region of the phase diagram studied by Kaptay and others, as well as at much higher temperatures.…”

“…The approximately linear dependence observed close to the freezing line (dotted line) is consistent with Kaptay's expression, Eq. (9), 60 In order to validate Eq. (7) we proceed to identify an expression for the LJ system's freezing temperature as a function of density.…”

Viscosity variation of Cholesteryl oleyl carbonate at various temperature with Acoustic parametres

“…is justified by experimental data mainly at the melting point of liquids [19]. In the present study, we have used the ultrasonic Interferometer (Mittal Enterprises Make) for the observation of ultrasonic velocity (C) and knowing the frequency we can find out various parameters such as adiabatic compressibilitysurface tension , viscosity.…”

“…The calculations of viscosity of cholestryl oleyl carbonate is done according to the statistical calculations [19,20]. statistical mechanics provides a solid scientific basis to calculate viscosity of liquids.One of the useful approximate solutions of the statistical mechanical approach is due to Chapman [20], who characterized the force between the atoms in liquids by a distance parameter (the Goldschmidt atomic diameter, di) and a semi-empirical energy parameter (ei).Chapman showed that the reduced experimental viscosity data can be plotted as a function of the reduced temperature using a unique curve for all liquids.…”