A New Strategy on Designing Fluxes for Aluminum Alloy Melt Refinement

Abstract

With the aim of obtaining a refining flux that is stable and provides effective refining of aluminum melt, a new strategy of designing the flux composition has been proposed. Ten fluxes were designed, by selecting ten molten salt compounds according to their thermophysical parameters, physical properties, and thermodynamic analysis. The melting points of the ten fluxes, and the phases transformation of the fluxes after melting, were studied by DSC and XRD, respectively. The contact angles between four groups of fluxes and alumina at refinement temperatures were studied, and the effect of refinement was characterized by a metallographic microscope. The process of the fluxes removing inclusions and degassing was analyzed thermodynamically. The research findings indicate that flux #10 (11.0 wt.%NaF, 29.5 wt.%NaCl, 46.5 wt.%Na2CO3, 3.0 wt.%CaF2, 10.0 wt.%Na3AlF6) has a melting point (562.2 °C) below the refining temperature. At the refining temperature (760 °C), flux #10 has the lowest contact angle, of 12.78°. In addition, compared to that of flux STJ–A3, currently used in practice, flux #10 has a better refining effectiveness, with the pores and inclusions content of the sample being reduced to 1.11% from 2.96%.

The Impact of Heating Temperature and Flux Ratio on the In-Situ Casting Technique as a Direct Recycling of AlSi7Mg Machining Chips

“…The existence of γ-Al2O3 indicates the presence of a thin oxide layer that enveloped the AlSi7Mg alloy during the in-situ casting process. Furthermore, Saleh et al [20] found that the observed phenomenon may be attributed to the elimination or detachment of the oxide layer present on the surface of the aluminium alloy chips. This occurrence results from the impact of the NaCl-KCl flux during the heating procedure, as seen under the specified conditions.…”

A comprehensive analysis of cooling curves, fluidity, inclusions, porosity, and microstructure of NaCl-KCl-NaF flux treated Al-12Si alloy

“…Their results showed the KF treatment effectively removed inclusion compared to the equimolar NaCl +KCl mixture, however, the addition of KF increased the porosity. Zhang et al [21] conducted a study on the effectiveness of different Na-based flux compositions on inclusion removal and porosity reduction in A6111 aluminum alloy and found that flux containing NaF showed the highest refining efficiency.…”