In addition to gas, there are inclusions in the aluminum melt. When impurities enter the ingot casting process, they not only reduce the purity of the metal, destroy the continuity of the metal, but also reduce the mechanical properties of the product and the stress corrosion resistance of the alloy. Inclusions are generally 1-30um. If they are not removed, it is impossible to produce high-quality products. In the on-line degassing process, through the bubble flotation process, some inclusions are carried to the surface of the molten aluminum, and the remaining inclusions need to be removed by a filter device. Ceramic foundry filters purification is the most effective method to remove non-metallic inclusions in aluminum and aluminum alloy melts.
The filtration of aluminum alloy melt includes surface filtration and internal filtration. Surface filtration mainly refers to the deposition of solid impurities on the surface of the filter medium. Internal filtration refers to that the molten aluminum in the filter medium flows along the tortuous channels and pores, the impurities collide with the pore wall and firmly adhere to the filter. As the filtering progresses, the effective filtering part of the channel is gradually reduced, and the filtering accuracy is improved by decreasing the capacity. Ceramic foundry filters, deep bed filter belongs to internal filtration, tubular filter belongs to surface and internal double filtration.
In order to save production costs, ceramic filter devices are used for those products, such as casting slabs for rolling or round ingots for extrusion. Ceramic filters have been widely used at home and abroad.
Since the successful research of ceramic foam filters in the 1970s, the technology of ceramic foam filters has developed rapidly and is the most widely used in aluminum processing plants. The ceramic foundry filters grade (pore size) ranges from 20 to 80 PPI, but the most commonly used are 30 PPI and 50 PPI. The arrangement of ceramic foam filters includes single-layer filtration and double-layer filtration.
Advantages of Ceramic Foundry Filters
- Low cost;
- Alloy varieties are easy to replace;
- Easy to install;
- Small footprint and easy operation;
- For impurities above 10 um, the filtering effect is> 95%.