The purifying molten aluminum plays an important role in improving the mechanical properties of castings. At present, the filtering device used to purify the molten metal is mainly a ceramic foam filter, which can effectively intercept harmful impurities in the molten metal, and convert the metal liquid from turbulent flow to laminar flow, and completely remove large impurities. As well as removing small inclusions from molten metal, improving the structure of the organization, effectively reducing the gas and harmful elements in the metal liquid, and purifying and homogenizing the metal liquid.
In fact, molten aluminum usually contains entrained solids, which are harmful to the final cast metal product. These entrained solids usually come from three sources. Some are alumina particles, the floating oxide layer on the surface sucks them into the liquid stream, and some of the entrained particles are fragments of the furnace lining, conveying trough, and other parts of the molten aluminum processing equipment, which are eroded and entrained. In the flowing aluminum stream, some particles are precipitates of insoluble impurities, such as intermetallic compounds, borides, carbides, or other aluminum compounds. When these impurities appear in the final cast product after the molten aluminum is solidified, they can cause the ductility of such final product to decrease or the trimming characteristics of the final product to be poor. Therefore, it is desirable to remove entrained solids from the molten aluminum stream before casting the molten aluminum stream into a solid.
Generally, before casting, ceramic foam filter purifying molten aluminum method is used to remove entrained solids from the molten aluminum alloy.
The ceramic foam filter has good high-temperature performance, and can filter aluminum metal liquid without polluting the alloy, and has a good through porosity, so it has good filtration and adsorption. The capacity of oxide inclusions and flux inclusions in the metal solution is obtained. It has good filtering and purification effects, and has excellent strength at high temperatures, thermal shock stability and chemical resistance. At the same time, the ceramic foam filter has a simple manufacturing process, and can prepare larger-size filter products.
