The slag removal ability of the Aluminum Drossing Flux is determined by the adsorption and dissolution of the oxidized inclusions in the melt by the flux and the chemical interaction between the flux and the melt.
Because the oxide inclusions are not wetted by the molten aluminum, the interfacial tension between the two is very large. While the Aluminum Drossing Flux is wetted by the oxide inclusions, the interfacial tension between the two is relatively small. After the flux absorbs the oxidized inclusions in the melt, it can reduce the surface free energy of the system. Therefore, the flux has the ability to automatically adsorb oxidized inclusions, which is called the refining property of the flux. This adsorption is the main reason for flux slag removal. Obviously, the lower the interfacial tension between the flux and the non-metallic inclusions, the greater the interfacial tension between the flux and the molten aluminum and the greater the interfacial tension between the molten aluminum and the non-metallic inclusions, the better the adsorption of the flux and the greater the slag removal effect.
The dissolving effect of the fluxes on the oxide is determined by the nature of the flux. Generally, when the molecular structure of the flux is similar to the molecular structure of some oxides or the chemical properties are similar, mutual dissolution can occur at a certain temperature. For example, A1203 and Na3AIF6, Mg0 and MgCl2 with the same cation have a certain mutual solubility.
The gaseous products AlF and AlCl do not dissolve in aluminum. When bubbles are deposited on the boundary of the metal oxide, they promote the separation of the oxide film from the metal and transfer the oxide film to the flux. At the same time, the bubbles also have flotation and slag removal effect. In addition, the bubbles formed during the dissociation of the flux can also remove some inclusions through flotation.