Luoyang Judian Metal Hot Processing Equipment Co., LTD is mainly engaged in the manufacture of complete sets of equipment in the metal thermal processing industry and the integration of the entire production line.
Adsorption: Salt can adsorb oxides, hydrogen and other impurities in the aluminum liquid in a molten state, causing them to aggregate and float on the surface of the aluminum liquid, making it easier to remove them later. For example, salts such as sodium chloride (salt) can combine with impurities such as aluminum oxide in the aluminum liquid to form a substance with a lighter specific gravity, making it easier to separate from the aluminum liquid.
Refining effect: By adding specific salts, the purity of the aluminum liquid can be improved and the quality of aluminum can be improved. For example, some refining agents contain fluoride salts and other ingredients that can react chemically with impurities in the aluminum liquid to further remove impurities.
Covering protection
Prevent oxidation: Salt forms a covering layer on the surface of the aluminum liquid, which can reduce the contact between the aluminum liquid and oxygen in the air, thereby reducing the degree of oxidation of the aluminum liquid. This helps to maintain the quality of the aluminum liquid and reduce the generation of oxidized slag.
Reduce heat loss: The covering layer can also play a certain role in heat preservation, reduce the heat loss of the aluminum liquid, and reduce energy consumption during the smelting process.
Adjusting the properties of the molten metal
Improving fluidity: The addition of certain salts can adjust the fluidity of the aluminum liquid, making it easier to fill the mold or perform other process operations during casting or processing.
Affecting the solidification characteristics: The presence of salt may have a certain impact on the solidification process of the aluminum liquid, changing the crystal morphology and grain size of the aluminum, thereby affecting the properties of the aluminum material.
In the aluminum melting process, salt is mainly used for the following purposes:
Lower melting point: There is a difference in the melting points of salt (especially sodium chloride) and aluminum. Adding salt can form a low melting point salt aluminum alloy or molten salt, thereby lowering the melting point of aluminum, which not only saves energy, but also improves melting efficiency.
Removal of oxides: Aluminum easily forms an aluminum oxide layer in the air, and this oxide will adversely affect the melting and casting process of aluminum. The addition of salt can effectively remove these oxides. After the molten aluminum reacts with the salt, the resulting salt slag floats on the surface of the molten aluminum, thereby removing oxides and other impurities.
Improve casting quality: By removing oxides and impurities, salt can improve the purity of aluminum liquid and casting quality. This helps reduce casting defects and improves the quality of the final product.
In industrial applications, the use of salt can significantly improve the efficiency of the aluminum melting process and the quality of the final product. However, in specific operations, the appropriate salt and its addition amount need to be selected based on the actual situation.
Salt is added during the melting of aluminum alloys for the following reasons:
Lowering the melting point: The addition of salt can change the crystal structure of aluminum alloys, making them easier to melt, thereby lowering the melting point. This is because salt substances can react with certain components in aluminum alloys, thereby changing the phase transition temperature and melting characteristics of the alloy.
Destroying the oxide layer: A dense oxide film often forms on the surface of aluminum alloys, which hinders the further melting and homogenization of aluminum alloys at high temperatures. Adding salt can effectively destroy this oxide film, making aluminum alloys easier to melt, and also helps to float and remove gases and inclusions, thereby improving the purity of the melt.
Promoting melt flow: An appropriate amount of salt can reduce the viscosity of the melt, enhance the fluidity and uniformity of the melt, and facilitate the uniform distribution of alloying elements in the melt, thereby improving the performance of the alloy.
Preventing burning: Under high temperature conditions, certain elements in aluminum alloys (such as magnesium) are prone to burning, affecting the composition and performance of the alloy. Adding salt can slow down the burning rate of these elements to a certain extent and maintain the stability of the alloy composition.
However, the amount of added salt must be strictly controlled. Excessive salt will introduce impurities and affect the performance and quality of aluminum alloys. In addition, different types of aluminum alloys and smelting conditions may require the use of different types of salts or additives to achieve the best smelting effect.
In summary, adding salt has multiple effects in the melting process of aluminum alloys, such as lowering the melting point, destroying the oxide layer, promoting melt flow and preventing burning. However, in specific applications, factors such as the type of aluminum alloy, smelting conditions and required performance should be comprehensively considered.
