Foundry Chemicals

DEGASSER - for light alloys

Aluminium and aluminium based alloys intensely adsorb gases , largely hydrogen, and reacts readily with carbon dioxide and carbon monoxide in their molten state.

The common source of hydrogen is water vapor in the furnace atmosphere , water present as hydrated oxide film on scrap and water absorbed on or combined in refractories. Water vapor reacts with molten metal to form oxide and liberate Hydrogen :

2Al + 3 H2O -> Al2O3 + 6H
8Al + 3CO2 -> 2Al2O3 + Al4C3

Hydrogen enters into solution and the oxide remains entangled. The product of reaction with other gases from non-metallic inclusions. During the course of crystallization of castings the hydrogen is evolved leading to pinholing & general unsoundness. Ladleadd Degassers prove ideal to overcome the problems.

Benefits

• Removes soluble hydrogen and sweep non-metallics and oxides which go into the slag at the surface.
• Available in degassing plus grain refining grade thereby improving mechanical properties.
• Eliminates the hazard associated with chlorine gas.
• Tablets are large as 1000 gms sizes are available so degassing of larger melts can be done effectively.
• Degasser range of products include magnesium, calcium and sodium removal grades.

Guide to degassing operation

The amount of gas dissolved increase with rising temperature, perform degassing at temp.730°C. to 760oC. Remove the surface dross. Remove the foil (never break the tablets) and introduce required quantity to the bottom of the melt with the help of clean pre-heated box plunger and rotating throughout the melt until reaction ceases. Sprinkle Fluxal evenly on the surface to prevent further oxidation.

Packaging

La-Degassers are available in 50 gms., 100 gms., 250gms., 500 gms. & 1000 gms. Tablet size packed in 5 Kgs, 27 Kgs. cartoons

Grade	Appearance	Applicability	Type of Alloy	Qty. %	Remarks
201	Violet	Degassing	All Al alloys and Al-Mg,alloys	0.15 to 0.20	Excellent Degassing Power
191	Green	Degassing and grain refining	All alloys and Al-Mg alloys	0.15 to 0.20	One-step method to perform two operations
41	Blue	Degassing & Oxide Removal	All al alloys except Al-Mg alloys	0.15 to 0.20	Low fume evolution cheaper version of 201
61	Black	Degassing	All alloys	0.15 to 0.20	Reaction is slow compared to 201 acceptable upto 2% Mg. alloys
301	Dark Yellow	Magnesium removal and degassing	Al. ingots and casting where Mg. is not desired	0.20 to 0.60	Quantity to be used will depend upon the Mg. alloys
401	Dark Pink	Na, Ca removal and degassing	Al-Mg. alloys and hypereu tectic Al-Si Alloys	0.20 to 0.60	Quantity to be used will depend upon the Na. Ca. content