Alüminyum Dökümde Gaz Giderme

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Degassing in aluminum casting is used to reduce dissolved hydrogen in molten aluminum before casting. AdTech aluminum degassing units use a high-speed rotating graphite rotor to disperse nitrogen or argon into fine bubbles. These bubbles provide a large gas-metal contact area, allowing dissolved hydrogen to transfer from the molten aluminum into the purge gas and escape from the melt.

AdTech offers fixed aluminum melt refining units and lifting degassing systems. The equipment can be configured according to the furnace height, melt volume, treatment requirements, and casting-line layout.

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How Does Degassing Work in Aluminum Casting?

During melting and holding, molten aluminum can absorb hydrogen from moisture in the charge materials, furnace atmosphere, tools, and refractories. Excess dissolved hydrogen can contribute to gas porosity when the aluminum solidifies.

The degassing unit introduces an inert gas into the molten aluminum through a rotating graphite rotor. The rotor breaks the incoming gas into fine bubbles and distributes them throughout the melt.

As the bubbles move through the molten aluminum:

Fine bubbles provide a large gas-metal contact area.
Dissolved hydrogen transfers from the molten aluminum into the bubbles.
The hydrogen-containing bubbles rise toward the melt surface.
Hydrogen is removed from the molten aluminum with the escaping gas.

The efficiency of this process depends on bubble size, gas flow, rotor speed, treatment time, melt temperature, and the initial hydrogen concentration.

How Does Degassing Work in Aluminum Casting

Why Is a Rotating Graphite Rotor Used?

A rotating rotor is designed to disperse the purge gas more evenly than a simple gas lance.

The rotor breaks larger gas bubbles into finer bubbles and promotes circulation within the molten aluminum. Better gas dispersion increases the contact area between the purge gas and the melt, supporting more effective hydrogen removal.

This makes rotary degassing suitable for aluminum casting applications where consistent molten metal quality is required.

What Gases Are Used for Aluminum Degassing?

Nitrogen and argon are commonly used as purge gases.

Nitrogen is widely used for its availability and cost-effectiveness, while argon can be selected when a high-purity inert gas is preferred.

The appropriate gas depends on the alloy, melt-quality requirements, gas purity, equipment configuration, and production conditions.

Does Degassing Also Remove Inclusions?

Degassing and filtration have different primary functions.

The main purpose of gas-injection degassing is to reduce dissolved hydrogen. Rotary treatment can also improve melt circulation and may promote the flotation of some inclusions, but it should not replace a dedicated filtration system.

For demanding aluminum casting applications, degassing is commonly combined with ceramic foam filtration or other molten-metal filtration methods.

Degassing → Filtration → Casting

The actual process sequence can be adjusted according to the casting line and melt-treatment system.

Aluminum Degassing Unit

The aluminum degassing unit is auxiliary equipment used for molten aluminum refining before casting.

AdTech provides two main configurations:

Fixed aluminum degassing unit
Lifting degassing system

The lifting system can be adjusted to suit different furnace heights and equipment layouts.

The unit can be configured according to the customer’s furnace dimensions, molten aluminum volume, treatment capacity, and casting process.

Explore Our Degassing Unit

aluminum Degassing Equipment

Graphite Rotor for Aluminum Degassing

The graphite rotor is a key component of a rotary degassing system. It operates directly in contact with molten aluminum and must withstand high temperature, thermal cycling, chemical attack, and mechanical rotation.

Under specified operating conditions, the graphite rotor can operate continuously at approximately 200–400 rpm in molten aluminum around 750°C.

Rotor service life depends on graphite quality, operating temperature, rotor speed, immersion depth, gas flow, treatment frequency, and operating practices.

An appropriate anti-oxidation coating can help reduce oxidation of the graphite and extend rotor service life. Under suitable operating conditions, the service life may reach approximately 2–3 months.

How Can Aluminum Degassing Performance Be Improved?

Stable operating conditions are important for consistent degassing results.

Key factors include:

Appropriate gas flow rate
Suitable rotor speed
Proper rotor immersion depth
Fine and uniform bubble dispersion
Adequate treatment time
Suitable molten aluminum temperature
Dry and clean purge gas
Clean charge materials and equipment

Increasing gas flow or rotor speed without proper control does not necessarily improve degassing. Excessive turbulence can increase oxidation and dross formation.

Degassing-of-Molten-Aluminum

Başvurular

AdTech aluminum degassing units are suitable for molten aluminum treatment in applications including:

Alüminyum alaşımlı döküm
Aluminum billet casting
Aluminum slab casting
Sürekli döküm
Aluminum strip casting
Other aluminum melt treatment processes

Sonuç

Degassing in aluminum casting is primarily used to reduce dissolved hydrogen before the molten aluminum solidifies. A rotating graphite rotor disperses nitrogen or argon into fine bubbles, increasing gas-metal contact and promoting hydrogen transfer from the melt into the purge gas.

For industrial aluminum casting, a properly configured rotary or lifting degassing unit provides more controlled melt treatment than simple manual gas injection. Combining degassing with effective filtration and good temperature and melt-handling practices helps achieve more consistent molten aluminum quality.