Aluminium Treatment — Sodium-Free Flux

Sodium-Free Flux

Sodium-free flux for aluminium is a covering and drossing flux formulated without sodium chloride or sodium fluoride compounds, eliminating sodium pick-up in alloys where dissolved sodium is harmful — principally Al-Mg alloys and sodium-modified Al-Si alloys where flux sodium would interfere with controlled modification levels.

Standard aluminium flux formulations use sodium salts as key active ingredients. In most Al-Si applications this causes no problem, but for Al-Mg alloys (5xxx wrought, marine casting alloys) and for alloy-sensitive recycling streams, sodium transferred from the flux into the melt degrades corrosion resistance, ductility, and solidification behaviour. CFC Egypt's EGYFLUX 700 series — available in powder and granular form — provides the same covering and drossing performance as standard flux without contributing sodium to the bath. It is a drop-in alternative requiring no change to furnace equipment or treatment procedure.

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When Sodium-Free Flux Is Required

Sodium exclusion from flux is required wherever sodium in the melt would affect alloy specification, casting quality, or downstream product performance.

Al-Mg Alloys (5xxx Series & Marine Casting Grades)

Magnesium-bearing aluminium alloys are particularly sensitive to sodium contamination. Sodium in an Al-Mg melt segregates to grain boundaries and can cause inter-granular corrosion in marine and structural applications. Alloy specifications for 5xxx wrought and EN AB-51xxx casting grades typically require sodium below a few parts per million, making sodium-free flux the only acceptable option for melt surface protection.

Sodium-Modified Al-Si Alloys — Precise Control

Where sodium modification of the Al-Si eutectic is deliberate and controlled by a separate modifier addition, any sodium contributed by the covering flux adds to the sodium budget unpredictably. Using sodium-free flux eliminates this variable, giving the metallurgist full control over the sodium level used for modification and avoiding over-modification that causes coarse eutectic and reduced ductility.

Secondary Remelting — Mixed Alloy Streams

Remelters processing mixed-alloy scrap that includes Al-Mg components often use sodium-free flux across all furnaces to avoid accidental sodium pick-up in heats destined for sodium-sensitive applications. A single universal sodium-free flux product simplifies material management and avoids the risk of using the wrong flux grade on a sodium-sensitive heat.

High-Purity & Wrought Aluminium Production

Wrought aluminium producers casting rolling slab or extrusion billet to tightly controlled alloy specifications must minimise all unintended elemental pick-up. Sodium-free flux is part of the melt chemistry discipline that keeps sodium at the lowest achievable level, along with sodium-free degassing agents and careful scrap selection.

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CFC Sodium-Free Aluminium Flux Products

EGYFLUX 700 (powder) and EGYFLUX G 700 (granular) — covering and drossing fluxes free of sodium compounds, for sodium-sensitive aluminium alloy melting and holding operations.

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Perguntas mais frequentes

Technical questions on sodium-free aluminium flux selection and the metallurgical reasons for sodium exclusion.

Standard aluminium fluxes often contain sodium chloride or sodium fluoride as active flux components. When these sodium compounds contact an Al-Mg melt, dissolved sodium can transfer into the aluminium. Sodium in Al-Mg alloys promotes inter-granular corrosion susceptibility and reduces ductility in the final casting. For Al-Mg alloys such as 5xxx series wrought alloys and marine-grade casting alloys, flux sodium must be excluded entirely from the treatment chemistry.

In Al-Si alloys, sodium modifies the silicon eutectic — changing flake silicon morphology to a finer fibrous form that improves ductility. However, if sodium from flux residues persists in a batch not intended to be modified, the residual sodium causes unpredictable modification levels and inconsistent mechanical properties. Using sodium-free flux eliminates this source of unintended sodium pickup and gives tighter control over modification level across heats.

Yes, sodium-free flux provides the same covering, drossing, and surface-protection functions as standard flux without the sodium compounds. The application method, dosing rate, and furnace compatibility are broadly the same. The flux melting point and viscosity may differ slightly from the sodium-containing equivalent, so a brief application trial is recommended when switching grades to confirm spreading behaviour and drossing performance at your operating temperature.

CFC Egypt supplies EGYFLUX 700 (powder) and EGYFLUX G 700 (granular) as sodium-free covering and drossing fluxes for aluminium. Both are formulated without sodium chloride or sodium fluoride and are suited to Al-Mg alloys, 5xxx series wrought alloys, and any application where sodium contamination from flux must be avoided. Contact CFC for dosing guidance and compatibility confirmation for your specific alloy grade and furnace type.

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Processing sodium-sensitive aluminium alloys?

Tell us your alloy grade, furnace type, and current sodium control requirements. Our technical team will confirm whether EGYFLUX 700 or EGYFLUX G 700 is the right grade and advise on dosing rate and application method for your operation.

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