The aluminium degassing method is to reduce the hydrogen (gas content) in the aluminum melt before casting, which is one of the most important components of casting quality control in foundries. The molten aluminium degasser is placed between the holding furnace and the casting machine.
Nitrogen is blown into the molten aluminium alloy, and then the gas is chopped by a rotating graphite rotor in a degassing tank.
Then, a large number of dispersed bubbles are formed so that the liquid aluminum alloy is in complete contact with nitrogen in the processing tank. According to the principle of air pressure difference and surface adsorption, the bubbles absorb hydrogen and oxidation slag.
The bubbles then rise to the surface of the melt to form scum.
Then, the molten aluminum alloy flows from the outlet of the degassing unit to the degassing machine of the casting machine to achieve the purpose of purifying the aluminum alloy.
The process of removing hydrogen is called degassing. One of the most effective degassing methods is to use inert dry gas nitrogen for rotating inert degassing.
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Principle of Degassing
The dissolved hydrogen will move from a high concentration area (in the melt) to a low concentration area (in an inert gas).
Hydrogen will be dispersed in the molten metal, just as it is released in any confined space.
It will maintain a constant concentration throughout the melt.
The migration speed of hydrogen in molten aluminum is almost as fast as in air.
Therefore, it is not necessary to expose every ounce of metal to inert gas.
The efficiency of aluminum degassing depends on two factors, the transfer rate across the metal/gas interface and the total surface area that can be transferred.