Views:8 Author:Site Editor Publish Time: 2019-08-29 Origin:Site
Whether it is aseamless aluminum pipe produced manually or naturally, pollution is always inevitable. When people hear pollutants, they think the pollutants are immediately harmful, but how does this affect the production of aluminum tubes? How to improve the purity of aluminum? Pipeline has become an important topic in the industry.
What Are Impurities In Aluminum Tube?
What Can Impurity Do To Aluminum Tube?
How To Improve Purity Of Aluminum Tube?
The oxidized impurity elements in the aluminum tube mainly include Fe2O3, SiO2 and GaO3, etc. The reduction effect can be obtained through the electrolysis process, so that the electrolytic aluminum solution is polluted.
In bauxite, the most obvious impurity is iron ore, so it can be said that bauxite has a direct impact on the impurity of aluminum pipe. If the iron and aluminum minerals are finely granular, wrapped and bonded together, and Al3+ and Fe3+ appear in a crystalline state, then the dissociation of impurities in the aluminum tube will be very low, and even the pretreatment method will not be able to separate impurities from the aluminum tube.
Alumina production is usually carried out by sintering method. During the production of bauxite sintering maturation material, sodium aluminate is converted, which is characterized by being soluble in water, and calcium silicate is converted from silicon, which is characterized by insoluble in water and strong stability. During the electrolysis process of aluminum pipe, the calcium oxide decomposes and reacts with AlF3 to form SiF4 gases.
Calcium impurity are produced with the production of bauxite, which usually accounts for about 0.01% of bauxite. In the dissolution of bauxite, calcium will also occur in the state of dissolution, mainly concentrated in sodium chlorate solution. Calcium and aluminum have roughly the same chemical properties, and the separation is difficult. Therefore, the presence of impurity calcium element can be found in the metallurgical alumina. In the production process of aluminum tubes, the solid solubility of calcium ions can reach up to 20%.
The bauxite also contains sulfur impurity element. When the content is above 0.7%, the corrosion reaction of evaporation and decomposition will occur in the production of aluminum tube, thus damaging the product.
In the production of aluminum tube, silicon and iron are common impurity elements, which have obvious influence on the properties of the alloy. They mainly exist in FeAl3 and free silicon. When the proportion of iron and silicon is not the same, the aluminum tube will crack, and when the iron content in cast aluminum is too high, the aluminum tube will be brittle.
Chromium forms intermetallic compounds such as ferrochrome and chromium-manganese in aluminum, hindering the formation and growth of recrystallization, strengthening aluminum pipes to a certain extent, improving ductility of aluminum pipes and reducing corrosion sensitivity, but increasing quenching sensitivity.
When the iron content is greater than 0.25%, it cannot get a very normal tone. As the iron content increases, the glossiness decreases, and the color is bluish. When the silicon content in aluminum tube is low, the influence of iron is more obvious. When the silicon content is high, the harmful influence of iron can be reduced to a certain extent. At this time, iron and silicon form AlFeSi metal compound, and part of excess silicon is also consumed. The main reason for the influence of iron coloring is that iron and aluminum form pointed or rod-like structure, ranging from several microns to tens of microns, which affects the uniformity and continuity of oxidation coloring, and also reduces the luster and transparency of aluminum tube oxidation film, affecting the coloring effect.
A small amount of copper is beneficial to the mechanical properties and surface brightness of the aluminum tube without reducing the corrosion resistance. However, when the copper content of aluminum tube oxide film is too high, the film will appear black that the naked eye can see.
When the zinc content is high, it increases the extrusion difficulty of the aluminum tube, resulting in large grain size, large mold loss, opacification of the oxide film, and the accumulation of zinc ions in the alkaline solution. Zinc is inverted on the aluminum tube, resulting in shiny pear-shaped spots.
When the titanium content is more than 0.1%, it has a great influence on the tinting tone and color difference of aluminum tube, which is caused by the inhomogeneity of titanium.
Therefore, in order to ensure the surface quality of aluminum tube, the iron content should be controlled below 0.25%, and the content of other impurities should be less than 0.1%.
The active gas chlorine is used as the aluminum pipe purifier. In this process, when the chlorine gas is injected into the aluminum solution, a lot of extremely small AlCl3 bubbles are generated and fully mixed in the aluminum solution. The hydrogen dissolved in the aluminum solution, along with some mechanical inclusions, is then adsorbed on the AlCl3 bubbles and expelled as the AlCl3 bubbles rise to the surface of the aluminum solution.
Chlorine gas can also make some elements more electronegative than aluminum chloride, aluminum pipe impurities such as calcium, sodium, magnesium and so on are generated by chlorine gas corresponding chloride to be separated. So, chlorination is a very effective primary aluminum purification method.
This method uses alumina tubes as the filtration medium. N2 gas is directly added to the aluminum liquid, which is continuously fed into the purification furnace through the alumina ball filtration layer and washed by nitrogen gas.
As a result, the non-metallic inclusions and dissolved hydrogen in the aluminum solution are removed, the fine nitrogen bubbles are evenly distributed in the treated aluminum solution to play the role of purification for aluminum pipe production.
The above is about the identification and treatment of aluminum pipe impurities, I hope to help you. Our company strictly controls the content of impurities, so that the aluminum pipe to the highest quality. If you want to buy high quality aluminum tubes, please feel free to contact us.