Nitrogen rotary degassing device can 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.
Advantages of Nitrogen Rotary Degassing Device
- Due to better mixing with the melt, the effectiveness of the flux is high;
- Short flux processing time;
- Controllable flux introduction;
- A more environmentally friendly flux method.
In the rotating degassing method, inert or chemically inert gases (argon, nitrogen) are purged through the rotating shaft and rotor. The energy of the rotating shaft results in the formation of a large number of small bubbles, which provides 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.
When aluminum is cast, impurities known as inclusions can create weak points in the product. One of the most prevalent causes of these impurities is the presence of hydrogen in the molten aluminum due to atmospheric humidity, combustion in gas furnaces, condensation on tools, fluxes, and alloy additives.
Hydrogen gas is soluble in liquid aluminum and can pass through it almost as easy as it passes through air. As the liquid metal cools and becomes hard, the hydrogen flows from areas of high pressure to areas of low pressure which creates pockets of gas. When the metal solidifies, those pockets become inclusions and weak spots in the castings.
Compared with flux degassing, nitrogen rotary degassing device can achieve more thorough dehydrogenation. In addition, the rotary degasser does not use harmful chlorine and fluoride salts. Stainless steel construction enables this unit to withstand the corrosive and abusive high-temperature environment of the foundry. It can be used with argon or dry grade nitrogen gas for a safe working environment.