(1) The characteristics of ordinary aluminum alloy flux
It does not chemically react with molten aluminum, nor dissolve each other. It is lower than the melting temperature, and has good fluidity, which can form a good coating on the surface of molten aluminum. It also has good refining ability which can dissolve the oxidation in the molten aluminum at the same time and form easily volatile gas.
(2) Use of ordinary aluminum alloy flux
All aluminum alloys except high-magnesium alloys are used for refining and covering.
(1) Features of covering flux for aluminum alloy flux
The viscosity of the covering flux for aluminum alloy flux is small, and the surface tension is greater than that of the molten aluminum. It also can be separated from the molten aluminum well, and it is not easy to form flux inclusions.
(2) Use of covering flux for aluminum alloy flux
In addition to high-magnesium alloys, it is used for gas furnaces, high-frequency furnaces, and natural gas furnaces to cover smelting finished alloys and complex materials.
(1) The characteristics of the refining agent of aluminum alloy flux
It can increase the surface tension of aluminum and slag, because the separation of aluminum liquid is good, and the slag is dry, loose and easy to remove. It does not contain sodium, and sodium is almost insoluble in aluminum. When sodium is present in the alloy, sodium is adsorbed on the surface of dendrites or grain boundaries during solidification. During thermal processing, the sodium on the grain boundary forms a liquid adsorption layer and sodium cracking, which is the so-called "sodium brittleness". If magnesium and silicon exist at the same time, magnesium will deprive silicon and release free sodium, resulting in sodium brittleness.
(2) Use of refining agent for aluminum alloy flux
It is used for the smelting of pure aluminum and aluminum alloys that avoid sodium, remove scum on the surface of aluminum liquid, and absorb slag near the surface.