The granular shaped refining flux has a good effect on removing slag (oxides, borides, carbides) and impurities (alkali metal elements Na, Ca, Li) in the aluminum melt.
When the solid particle refiner is sprayed into the aluminum melt by inert gas, the solid particles can quickly melt into liquid droplets. Because the density of these droplets is less than that of the aluminum melt, the surface tension of the slag inclusion is smaller. The granular shaped refining flux has a strong ability to wet, adsorb and entrain slag; when the slag inclusions are adsorbed by the flux droplets, they will float and be discharged from the melt. At the same time, after the flux droplets float up, a liquid layer will be formed to cover the surface of the aluminum melt, thereby reducing the oxidation burnout of the aluminum melt.
In the process of aluminum alloy smelting, inclusions and gases are often generated, which greatly affects the quality of ingots and aluminum products. Common inclusions include oxides, carbides, nitrides, borides, etc., among which oxides pollute aluminum alloy melt the most. These inclusions not only provide a carrier for the gas, but also increase the gas content in the melt, and also cause defects such as slag inclusion and looseness in the ingot.
In addition, the impure raw and auxiliary materials used in the smelting of aluminum alloys will also bring some harmful impurities to the melt, such as alkali metals such as sodium, calcium, and lithium, which reduce the physical and chemical properties of the aluminum alloy. The Na element has a high Mg content. Aluminum alloy is easy to cause "sodium embrittlement" and also reduces the fluidity of the melt. Therefore, in the production of aluminum alloy materials, there are strict regulations on the slag content, gas content, and impurity element content in the aluminum alloy melt.
In order to remove the gas and inclusions in the aluminum alloy melt, the aluminum casting industry usually uses a mixture of granular refining agent, inert gas and powder flux to spray in the melting furnace.
Refining purification treatment method, in order to remove harmful impurity elements, the use of chlorine-containing gas refining. However, this traditional refining process has many shortcomings, for example: it produces a large amount of harmful gases and flue gas containing chlorine and fluorine, which pollutes the environment; The granular shaped refining flux of powder mixing exists in the melt in solid form, which is harmful to slag inclusion. The effect of adsorption and dissolution is not obvious, and the effect of degassing and slag removal is limited. If the operation is improper, it is easy to form flux inclusions and pollute the aluminum alloy melt.