When selecting aluminum casting refining agent, in addition to considering the physical properties of the refining agent (such as melting point, viscosity, surface tension, density, volatility, etc.), the characteristics of the chemical interaction of the refining agent with metals and gaseous media should also be considered.
Advantages of Aluminum Casting Refining Agent
- It is conducive to the removal of the oxide film on the interface between the molten aluminum and the refining agent, and the removal of inclusions and gases.
- It easily reacts with molten aluminum to promote the destruction of the oxide film, and hydrogen can escape from the surface of the molten aluminum.
- It has the function of dissolving and adsorbing inclusions, which is conducive to removing inclusions and gas.
When the refining flux mainly plays a protective role, the salt-chloride which is inert to the molten aluminum should be selected. When degassing purification is the main task, a refining agent that effectively reacts to molten aluminum to generate gaseous substances should be selected. When the main purpose is to exclude inclusions, the slag discharge capacity of the refining agent should be fully considered.
Commonly used chloride salts in production include zinc chloride, manganese chloride, potassium chloride, sodium chloride, hexachloroethane, carbon tetrachloride, etc., which can be used alone or in combination. If the refining agent is required not only to purify, but also to modify or refine the grains, a composite refining agent composed of adding modification and refiners can be used to achieve the purpose of comprehensive treatment of molten aluminum. When hexachloroethane is used to purify the cast aluminum alloy melt, it is necessary to add appropriate additives to delay the reaction and improve the refining effect.
A good aluminum casting refining agent should have a strong ability to adsorb and dissolve inclusions, a low melting point and good slag-aluminum separation performance, and make certain components of the refining agent change the properties of the furnace gas when heated and melted, forming a certain reduction Atmosphere to reduce the oxidation of aluminum.