Inclusions and gases in the metal will have a significant impact on strength, fatigue resistance, corrosion resistance, and stress corrosion cracking performance. Effective control of oxidized inclusions in the melt can improve the quality of cast rods and rolled plates, which has become a common goal pursued by the metallurgical, foundry and material industries of various countries. Currently, filtration and purification methods are widely used to remove inclusions in aluminum alloy melts. Practice has proved that the foam ceramic filters are the most effective aluminum cast filters for removing oxidized inclusions.
Foam ceramic filter technology came out in the 1970s and has been widely used in the United States, Canada, Japan, France, Australia and Switzerland. This is the most effective way to remove inclusions in aluminum melt. Practice has proved that the ceramic foam filter plate is currently the most effective tool for removing oxidized inclusions in molten aluminum. General fiber filtration can only remove large impurities, while the foam ceramic filter plate can filter both large impurities and fine impurities at the same time.
The ceramic foam filter plate has a multilayer network and multi-dimensional through holes, and these holes communicate with each other. When filtering, the molten aluminum will carry inclusions along the tortuous channels and pores. When the molten aluminum contacts the foam framework of the filter plate, the molten aluminum will be directly intercepted, adsorbed and deposited. When the melt flows in the hole, the filter plate channel will bend, and the melt flowing through the channel will change the flow direction. As a result, the inclusions collide with the hole wall anvil and firmly adhere to the hole wall.
The ceramic follicle has a certain strength network structure, which can bear the influence of the pressure difference on the surface of the metal liquid and the metal flow, but it is brittle and brittle. Due to the precise structure, uniform mass and large surface area of this material, the filtering effect is excellent.
Aluminum cast filters usually use polyurethane foam as a carrier, immersed in a ceramic slurry made of fine powder (such as refractory aggregate sintering aids, binders and water), and then squeeze out the excess slurry. The ceramic material around the foam fiber is dried at high temperature, fired and sintered, and finally the foam ceramic product is left. Because the casting temperature of the casting alloy is different, the foam ceramic filter of refractory material should be selected for casting.
AdTech alumina ceramic foam filter plate is installed in the CFF filter box. The molten aluminum flows out of the furnace port through the filter box, and then enters the distribution plate through the launder. With the extension of the filtration time, the inclusions on the surface of the filter plate and the pore walls increase, and the filtration flow rate decreases. The selection of filter plates must be based on the flow of molten aluminum. Second, consider the cleanliness of the melt, the maximum content of inclusions and the total output of the melt filter plate. It is mainly determined by the size and porosity of the filter plate. The greater the porosity of the filter plate, the worse the slag removal effect. For aluminum castings with very strict requirements, small hole filter plates should be selected.