According to the cause of porosity in cast aluminum alloy, in order to prevent porosity in the aluminium alloy casting and refining process, it is possible to reduce the porosity in aluminum alloy castings by degassing and removing impurities. Granular flux is widely used to degas and remove inclusions.
Aluminium Alloy Refining Process
- Prevent water molecules from entering the aluminum alloy smelting solution and prevent the aluminum alloy from absorbing hydrogen.
- Eliminate the hydrogen and oxides entering the aluminum alloy melt.
- Try to make the hydrogen in the aluminum alloy melt dissolve into the aluminum alloy matrix during the metal crystallization process.
During the molten aluminium alloy refining process, the dissolved hydrogen atoms in the molten aluminum are migrating to the refining bubbles. After being adsorbed, they combine with hydrogen molecules to enter the bubbles, and float up to escape the molten aluminum. This is also the change in the diffusion of hydrogen in the molten aluminum and the adsorption by the bubbles.
Combining the diffusion of hydrogen in molten aluminum and the kinetic process of being adsorbed by bubbles, in order to improve the conditions of dynamic changes and speed up the refining of molten aluminum, it is not only necessary to increase the number of bubbles in the molten aluminum, but also to increase the contact area of the molten aluminum and the bubbles. At the same time, it is necessary to reduce the diameter of the bubbles as much as possible, so as not to cause splashing on the surface of the molten aluminum, and increase the speed of movement of the bubbles in the molten aluminum, thereby enhancing the renewal rate of the gas-liquid surface.
In addition, it is also possible to realize the refining of the molten aluminum by evenly distributing the bubbles in the molten aluminum, or extending the floating distance of the bubbles in the molten aluminum, using high-purity inert gas, and performing the refining of the molten aluminum under vacuum conditions. The improvement of the process can reduce the occurrence of pores in aluminum alloy castings. The online degassing unit can improve the degassing effect.