Evaluation of Interfacial Tension in The Liquid Aluminum Alloy – Liquid Slag System

Abstract

In the present paper, the results from investigations regarding interfacial tensions present at the borders of a liquid aluminum alloy and two selected melted fluxes (mixtures of salts) are presented. The fluxes feature solidification characteristic curves that are very close to each other as well as differentiated chemical compositions. For the comparative investigations, the so-called surface property index (WS) is calculated for both fluxes with the use of the ion theory of slags. The investigations of the interfacial tensions were conducted on a stand that enabled the measurement of the force values accompanying the tearing-off of the probe from the interfacial surface. A very clear relationship between the interfacial tension values and the WS index values that characterize both fluxes was found. An increase in the WS index value resulted in an increase in the investigated interfacial tension values. It was also found that, in both cases under investigation, an increase in the system temperature value resulted in an increase of the values of the interfacial tensions present within. In the conclusion, we state that the metallurgical treatments (for instance, the recycling of the cast metal composite materials by way of component separation) should be conducted with the use of salt mixtures (fluxes) characterized with WS index and melting temperature values as low as possible.

Calculations of contaminants removal from liquid aluminium to top slag

“…In industrial practice, several refining steps are usually combined, such as blowing of inert gas, refining powders and filtration. The aluminium refining methods involve techniques making us of refining powders, such as aluminium fluoride (AlF 3 ) or magnesium chloride (MgCl 2 ) added to melted aluminium [3][4][5][6][7] , salt -a mixture of sodium chloride (NaCl) or potassium chloride (KCl) and calcium fluoride or aluminium fluoride or cryolite applied to liquid metal surface [8][9][10][11][12][13] . When the liquid metal bath is stirred with inert gas, the liquid aluminium, gas bubbles and contaminants are moved toward the surface.…”

“…The parameters determining the removal of precipitation efficiency will be the viscosity of the layer on top of liquid metal, densities of the contaminant and fluid, as well as the interfacial tensions at the interface of three phases 4,[15][16][17][18][19][20][21][22] . One of the most important parameters determining the effectiveness of contaminants removal into the slag is its viscosity.…”

“…Special importance is this case is presented for the Na 3 AlF 4 − NaCl system, where the viscosity decreases with the addition of NaCl 11 . These results were used to select the slag parameters for computer simulation of the process of removal selected particles 11,21 .…”

Calculations of contaminants removal from liquid aluminium to top slag

“…In the course of this process, a number of phenomena relating to the behaviour of the contaminant may take place, e.g. flowing out, repulsion, absorption and oscillation at the liquid metal/coating layer interface [10,[13][14][15][16].…”

“…The parameters determining the removal of precipitation efficiency will be the viscosity of the layer on top of liquid metal, densities of the contaminant and fluid, as well as the interfacial tensions at the interface of three phases [4,[15][16][17][18][19][20][21][22]. One of the most important parameters determining the effectiveness of contaminants removal into the slag is its viscosity.…”