The Estimation of Viscosity Coefficient, Self-diffusion Coefficient, and Surface Tension of Molten Metals by the Principle of Corresponding States
1975 Volume 61 Issue 1 Pages 46-53
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1975 Volume 61 Issue 1 Pages 46-53
The principle of corresponding states has been applied to the measurements of viscosity and selfdiffusion of molten metals using the reducing form suggested by Helfand and Rice. In the present work, the parameters were determined by means of the pair potentials directly derived from the experimental structural data. Viscosity coefficient (η) and self-diffusion coefficient (D) data for several molten metals whose melting points are low were examined and the temperature dependence for molten metals are ex-expressed by the following equations.
η=η(V*)2/3×(1.28×10-4)×(TmM)1/2/(Mρ)2/3 (Poise)
log η*(V*)2/3=(-0.11±0.08)+(0.55±0.09) (1/T*)
D=D*/(V*)1/3×(1.28×10-4)×(Tm/M)1/2(M/ρ)1/3 (cm2/sec)
log D*/(V*)1/3=(-0.28±0.03)-(0.91±0.05) (1/T*)
T*=T×(0.71/Tm)
where Tmis the melting point in K M is atomic weight, ρ is density (g/cm3) and T is the absolute temperature. The simple form of surface tension (γ) was also derived from the relationship between viscosity coefficient and surface tension as follows;
γ=η*(V*)2/3×(T·Tm)1/2/(M/ρ)2/3 (dyne/cm)
Using these equations and density data, it is possible to estimate the values of viscosity coefficient, self-diffusion coefficient, and surface tension for any molten metals at any temperatures. The usefulness of these eqations was demonstrated on the molten metals which have high melting points.
