The aluminum degassing process in casting can greatly improve the quality and output of aluminum products, thereby increasing the profitability of aluminum melting and casting plants.
In this way, the aluminum degassing unit manufacturer Adtech explained the cause of H in the aluminum melt.
Hydrogen can be burned in a gas furnace, and the condensate on the tool, flux and alloy additives are introduced into the liquid aluminum.
However, most commonly, hydrogen is introduced into molten aluminum through atmospheric humidity. The solubility of hydrogen increases with the relative humidity of the atmosphere.
Due to its light weight, aluminum is a metal and is usually used for its relative strength.
However, when casting aluminum, impurities called inclusions can create weak points in the product.
There are many reasons for these inclusions, but the presence of hydrogen is one of the most common reasons.
Hydrogen is soluble in liquid aluminum, and it can pass through molten aluminum almost like air.
As the liquid metal cools and hardens, hydrogen flows from the high-pressure area to the low-pressure area.
It will coalesce and create air pockets. When the metal solidifies, the air pockets become inclusions and weak points.
The aluminum degassing process in casting is a process used to remove hydrogen from molten aluminum.
Removal process
As the demand for high-quality aluminum products increases, especially in the aerospace industry, the need to reduce inclusions in molded products has also increased.
A popular method of removing hydrogen involves introducing blown nitrogen into liquid aluminum.
Hydrogen is attracted by nitrogen bubbles, then absorbed by aluminum and released to the surface.
Argon is also very effective, but due to the high costs associated with this gas, nitrogen is preferred.
Rotary degassing device
The rotating impeller works by increasing the surface area of the inert gas introduced into the metal.
The smaller nitrogen bubbles produced by the impeller process have a larger total surface area and collect more hydrogen.
The lower surface disturbance of the smaller bubbles also allows less hydrogen to be recaptured into the metal from atmospheric moisture.
In the aluminum degassing process in casting, inert or chemically inert gases (argon, nitrogen) are removed through the rotating shaft and rotor.
The energy of the rotating shaft results in the formation of a large number of small bubbles, thus providing a very high surface area to volume ratio.
The large surface area promotes the rapid and effective diffusion of hydrogen into the bubbles, thereby equalizing the hydrogen activity in the liquid and gas phases.
Compared with flux degassing, the rotary degasser can remove hydrogen more thoroughly.
In addition, the rotary degasser does not use harmful chlorine and fluoride salts.
Rotary degassing machine can also combine degassing and flux introduction functions.
In this case, the inert gas acts as a carrier for the granular flux. This method is called flux injection.
