There are many types of fluxes used for aluminum alloy smelting, which can be divided into two categories: covering agent and refining agent. The covering flux can prevent melt oxidation and gas absorption. Refining flux is used for degassing and removing inclusions.
All Fluxes for Aluminum Alloy Smelting must meet the following conditions:
- The melting point should be lower than the melting temperature of aluminum alloy.
- The specific gravity should be less than that of aluminum alloy.
- It can absorb and dissolve the inclusions in the melt, and can remove the gas from the melt.
- It should not be chemically reacted with metal and furnace lining. If it reacts with metal, it should only produce inert gas that is insoluble in metal, and the flux should be insoluble in molten metal.
- Hygroscopicity should be small, and evaporation pressure should be low.
- It should not contain or produce harmful impurities and gases.
- It must have proper viscosity and fluidity.
- Easy to manufacture and low price.
Foundry Fluxes are widely used in the production of primary aluminum and secondary aluminum to improve the quality of the melt and the recovery rate of metal aluminum.
Changing the wettability of the aluminum melt to the oxides, makes the aluminum melt easy to separate from the oxides, so that most of the oxides enter the flux and reduce the oxide content in the melt.
The flux can change the state of the surface oxide film on the melt. This is because it can break the solid and dense oxide film on the surface of the melt into fine particles, which is beneficial for the hydrogen in the melt to permeate and escape from the particle gaps of the oxide film and enter the atmosphere.
The presence of the flux layer can prevent the contact of water vapor in the atmosphere with the aluminum melt, make it difficult for hydrogen to enter the aluminum melt, and prevent the melt from oxidizing and burning.
The flux can absorb the oxides in the aluminum melt, so that the melt can be purified.