Ceramic foam filters for molten metal are the most widely used in the area of aluminum melt filtration. The advantage of ceramic foam filter is a high porosity, high filtration efficiency, easy to replace, low cost, adaptability, which can also be isolated by filtration of solid inclusions portion of the liquid inclusions.
Inclusion formation and ingredients, lining and chute material, furnace gas composition, refining and casting technology, and other related.
The presence of a small amount of the fine inclusions can play a lower crystallinity degree of supercooling, promote nucleation. But the intensity of excessive presence of inclusions would ingot or products, plastic, corrosion resistance, anodic oxidation, and appearance adversely affect the quality.
At the same time, the inclusion of parasitic gases (mainly hydrogen), will cause pinholes products, loose, cracks, and other defects. Thus, cleaning is the key process of aluminum and aluminum smelting. Common filtering method for molten aluminum Modern aluminum melt purification process, the filter is close to the end of the last one cast purification processes.
Prior to this, after the furnace refining flux, standing way, the media and non-media adsorption, though already removed 60% to 80% of the inclusions and gas, but the melt still dispersed with more subtle (the grain diameter is generally <15μm) inclusions (including chute and intermediate production contract secondary raw inclusions).
Glass cloth and mesh filter mainly by mechanical separation of inclusions interception, simple structure, low cost, suitable for inclusion filter out large particles, but the inclusion of micro filtration little effect, coupled with low heat intensity filter, life is short, filter unstable, it can only be used once, it is mainly used for pre-filtering the melt.
In order to obtain high-performance aluminum products, we must make those fine inclusions gathering and adsorptive separation. Compared to other purification methods, the alumina ceramic foam filters for molten metal filtration method because of its low energy consumption, easy operation, high cleaning efficiency, less secondary pollution, has become the molten aluminum terminal purification treatment process of choice.