For aluminum alloy castings, inclusions and gas are the most important factors that affect their performance and even cause castings to be scrapped. To reduce the scrap rate of aluminum castings, produce high-quality aluminum castings, and meet the needs of actual production, it is difficult to solve the problem by only relying on traditional purification processes. Therefore, research and development of new, more effective and practical purification processes has become a top priority. Through hard work and repeated experiments, the majority of foundry workers finally researched and formed aluminum alloy filtration technology.
Aluminum alloy filtration technology is a technology that performs secondary purification before the aluminum alloy liquid enters the molding compound. The degassing and slag removal capabilities are very significant. This kind of filtration technology is gradually becoming mature. At present, aluminum alloy filtration technology can be successfully applied to casting production such as sand mold, metal mold casting, low pressure casting, precision casting, and lost foam casting.
Aluminum melt filtration technology can reduce the impurities and inclusions in the melt. The quality of aluminum melt treatment will affect the product quality of the ingot, and then affect the product quality of subsequent processed materials. Therefore, the aluminum melt filtration technology is an important part of the production technology of aluminum processing materials.
Aluminum melt filtering device is an application of this technology. The commonly used aluminum melt filter device is the CFF foam ceramic filter box. The CFF ceramic foam filter box is composed of a filter box body and a CFF filter plate. The filter box body is composed of multiple layers of refractory materials and steel structure. The refractory material in contact with the melt is generally made by one-time casting with non-stick aluminum castable. Some filter boxes are also equipped with heating devices, which are generally arranged at the top or bottom to keep the melt in warm.
The foam ceramic filter plate is injected into the sponge plastic with a mixture of AI2O3 and phosphate, and then dried and sintered to volatilize the sponge plastic, thereby forming tortuous channels and pores in the filter plate. When filtering, the aluminum melt is blocked by the filter plate and flows along the tortuous channels and pores in the filter plate. The impurities and inclusions in the aluminum melt are in contact with the inner surface of the filter plate pores under the effects of deposition, inertia, interception, etc., and stay in the gaps, shrinkage holes, caves and other places in the filter plate, and are affected by the aluminum melt fluid axially. Under pressure, friction, surface adsorption, etc., the impurities and inclusions in the aluminum melt are firmly left in the filter plate and separated from the aluminum liquid.