Search

A formula is derived to describe the surface tensions of binary and dilute multicomponent alloys such as iron alloys. It was thermodynamically proved that the surface tension can be described by a function of the concentrations of the alloy components in bulk phase through the use of thermodynamic parameters. The formula was applied to the binary alloys, Fe-O-N and Fe-O-S systems. The described surface tensions were found to be in good agreement with the measured values., QC 20100525

The accurate knowledge and high-precision measurements of the thermophysical properties of liquids is necessary for the numerical modeling of industrial processes where the solid-liquid phase transformation plays a crucial role. The reduction of magnetic levitation forces in microgravity leads either to a significant improvement in accuracy or makes the measurement possible in the first place. High-precision measurements on chemically highly reactive melts require containerless processing using non-contact diagnostic tools. Scientific precursor experiments were conducted in the TEMPUS containerless processing facility during the Spacelab IML-2 and MSL-1 missions, also., QC 20141204

QC 20141201

A model is presented to predict the mass transport and heat transfer in a continuous casting mould flux bed. Physically consistent micromodels for carbon burning, evaporation of volatiles and thermophysical properties in the mould flux layer have been combined with a one-dimensional finite-difference model of the continuous casting mould flux bed. The sensitivity of the model to bed height, flux consumption rate, carbon burning and powder particle size is investigated for a mould flux composition corresponding to an industrial casting powder., QC 20100525

Five models to estimate slag viscosity have been compared with the experimental data obtained using the rotating cylinder method. The comparison was made for four ternary silicate systems, viz. FeO-MgO-SiO2, CaO-MnO-SiO2, FeO-MnO-SiO2 and CaO-Feo-SiO2. The KTH model and the model using the Gibbs energy of mixing have been found successful in estimating the slag viscosity. On the other hand, the comparisons of the experimental results with the calculated viscosity using the Riboud, Urbain and NPL models have shown poor agreement. While the limited number of the data points used for parameter optimisation would be one of the reasons for the failure of the Riboud and NPL models when applied for these ternary systems, the description of the slag composition in Urbain's approach could probably explain the disagreement between the estimated and experimental viscosity. Further studies are needed for the KTH model to accommodate fluorides in the model structure., QC 20100525

This article considers the viscous-flow phenomenon in molten silicate melts in the vicinity of their liquidus temperatures. An agglomeration of ionic species occurs in the liquid slag with decreasing temperatures and results in an increase in the viscosity and the activation energy for viscous flow. The latter was found to be nonlinear, increasing rapidly as the temperature is approached wherein a solid phase is likely to separate from the liquid. The second derivative of the activation energy for viscous flow with respect to temperature was found to show a discontinuity in the vicinity of the liquidus temperature. This has been verified in the case of viscous flow for both pure water and CaO-SiO2 melts. Experimental data for the viscosities, of complex silicate melts and mold fluxes have also demonstrated the occurrence of a discontinuity in the second-derivative function, which is in accordance with the liquidus temperature as determined by differential thermal analysis (DTA). Thus, the second derivative offers a useful way of estimating the liquidus temperatures of multicomponent silicates, which are often difficult to determine due to supercooling effects., QC 20100525