Aluminum degassing with nitrogen is usually to degas in the aluminum casting process, because nitrogen does not react with metals. In order to reduce the gas absorption of aluminum alloy liquid, the alloy raw materials should be properly stored to prevent moisture. It is necessary to preheat and dry before use. Before use, the molten crucible and tools should be fully preheated to remove moisture.
In order to remove gas from aluminum alloy liquid, all aluminum alloy liquid must be degassed and refined before pouring molten aluminum. AdTech offers online degassing unit, it is mainly used for the hydrogen (H) and slags removal from molten aluminum. It takes gas flotation principle. The rotor takes nitrogen into molten aluminum and smash the gas into dispersed tiny bubbles, the bubbles rise to molten aluminum surface, and bring the hydrogen and other impurities.
The production practice of aluminum alloy has proved that hydrogen is the only gas that can be dissolved in a large amount in aluminum or aluminum alloy, and it is also the gas with the highest solubility in aluminum alloy.
Moisture: from furnace gas, insufficient charge, refining agent, covering agent, modifier, insufficient drying of furnace lining, crucible and coating on tools, residual water on crucible, tool and charging solvent, which reacts with aluminum to produce hydrogen, and hydrogen enters into liquid aluminum in atomic state.
Aluminum Degassing With Nitrogen
Nitrogen enters the bottom of liquid aluminum through special treatment equipment. Nitrogen floats from the bottom of liquid aluminum in the form of bubbles. Due to the difference of hydrogen partial pressure at the interface between bubble and molten aluminum, the hydrogen partial pressure in bubble is very low.
When the hydrogen partial pressure tends to equilibrium, the hydrogen in the alloy liquid continuously enters the bubble. When the bubble rises to the liquid level, hydrogen will escape into the atmosphere. When the bubble rises, it will simultaneously absorb the oxidized slag and its fixed impurities, and make them float to the surface together. The inert gas should be condensed and dehydrated before use to prevent moisture from entering the liquid aluminum. The quality of degassing refining is good and the pores must be less.