Estudio del mecanismo de eliminación demagnesio de aleaciones Al-Si en estado líquido mediante inyección de minerales base sílice

Abstract

ResumenSe empleó el método de inyección sumergida de polvos por medio de un gas de arrastre inerte (Ar) con el fin de eliminar el magnesio de la aleación Al-Si A380 a 750°C. Los polvos inyectados al baño de metal fundido fueron zeolita mineral, arena sílice y mezclas de ambas. Las variables de respuesta medidas fueron el contenido de magnesio en el baño metálico respecto al tiempo de inyección y las mermas de metal al final de cada experimento. En el análisis de resultados, la mezcla sílice:zeolita 66:34 % e.p. obtuvo la mayor eficiencia, lográndose una disminución en el contenido de magnesio en el baño metálico de 1 a 0.0066 % e.p. Los productos de reacción se analizaron por difracción de rayos-X, microscopía electrónica de barrido y de transmisión. Los resultados de estos análisis y el empleo del paquete termodinámico FactSage, versión 6, permitieron justificar el mecanismo de reacción entre los minerales y el aluminio líquido. Palabras claveZeolita; Sílice; Aluminio; Magnesio; Minerales. Study of the removal mechanism of magnesium from Al-Si liquid alloys using silica base minerals injection AbstractIn order to eliminate magnesium from an A 380 Al-Si alloy at 750°C, the submerged powder injection method, using an inert carrier gas (Ar), was applied. The injected powders in the liquid aluminum bath were zeolite, silica and mixtures of zeolite-silica minerals. For each experiment the response variables were: eliminated magnesium versus injection time and quantity of drosses produced. Chemical analysis by atomic absorption spectrometry showed that mixtures of silica-zeolite 66:34 wt% have the best results with regarding to the removal magnesium from 1 to 0.0066 wt%. During the elimination of magnesium complex stoichiometry compounds were formed due to the reactions among zeolite, water steam and liquid aluminum. These compounds were analyzed by XRD, SEM and TEM. The results obtained, along with using the FactSage 6 thermodynamic software, allowed to elucidate the reaction mechanism between the minerals used and liquid aluminum.

Magnesium Removal from an Aluminum A-332 Molten Alloy Using Enriched Zeolite with Nanoparticles of SiO2

“…It should be noted that the initial content of Mg in this research work is considerably high (1.6 wt-% Mg) with regard to that in other reports in the literature [4,10] that starts from 1 wt-% of Mg using enriched zeolites with different percentages of SiO 2 as bulk. Likewise, removal times over 60 min in order to reach 0.1 wt-% of Mg in the alloy are as shown by Muñoz-Arroyo et al [11]. This means that the Mg removal method using nanoparticles improves the efficiency of the process and decreases the removal time.…”

“…Additionally, the kinetics of the Mg removal using silica is relatively slow [10]. However, in recent studies Muñoz et al [8,11] have demonstrated the feasibility of Mg removal from aluminum molten alloys by injecting zeolite (containing more than 50 wt-% of SiO 2 ) and silica using an inert carrier gas. On the other hand, nanotechnology has been applied in foundry processes to improve mechanical properties of some materials according to studies in Al alloy treatment with nano-SiC powders in order to improve toughness [12].…”

Use of Chlorine to Remove Magnesium from Molten Aluminum

“…The use of Cl 2(g) flow, electrolysis and reactive powders are the main alternatives to decrease Mg concentrations in Al baths. 2,6,7) Muñoz-Arroyo et al 8) used rich silica based compounds such as Ca(Si 7 Al 2 ) 18 ·6H2O, KAlSi 3 O 8 and SiO 2 . In such cases the goal is to form MgAl 2 O 4 .…”