Electrolysis Production Of Fine Crystal Ingot Microstructure And Electrochemical Behavior

Aluminum alloys have such characteristics as low density, high specific strength and rigidity, so that it is the second widely used metal material, and have found a wide application in aerocraft and automotive industries.It is the crucial for the capabilities of Al alloys that the grain of the Al-based alloy, and titanium is the crucial grain refining element in the Al alloys, therefore which have low titanium contents are produced by direct electrolysis with the existing pure aluminum production facility and electrolytical system, which can refine the grain of the Al alloys and improve the capabilities of Al alloys.Microcosmic structures of Grain-refining aluminum ingot and with different rare earth contents are investigated in order to advance the capabilities of Grain-refining aluminum ingot, finally deoxidization actions of electrochemistry on Ti⁴⁺, La³⁺ in the cathode are investigated by cyclic voltammetry and chronopotentiometry.The results are that:Firstly, the grain refinement efficiency of Grain-refining aluminum ingot with titanium contents is very obvious, and the grain refinement efficiency is improved with Ti contents increasing. When Ti content is 0.20%, there will be the best refinement efficiency.Secondly, the effect of the refinement efficiency on Grain-refining aluminum ingot is obviously improved by the addition of RE into Grain-refining aluminum ingot, at the same Ti content (0.01%). When the content of RE reaches 0.30%, the best refining efficiency can be obtained, but the refining efficiency begins to decrease when the content of RE is in excess of 0.30%. RE is also an effective modifying agent, which makes the acerose Fe phases transform into short stick shape in the grain boundary or sphere shape in the a-Al. With the contents of RE increasing, the quantities of sphere shape Fe phases in the a-Al increase. RE modification mechanism is that RE enters into Fe(Si) impurity phases, forming complex compounds (AlFeSiRE). At the same Ti content (0.01%) in theGrain-refining aluminum ingot,the optimum is 10Ti/B, 0.1%RE which is confirmed by Quad orthogonal test and Mixture design.Thirdly, deoxidization steps of electrochemistry on Ti⁴⁺ in the tungsten filament electrode are two steps in the Na₃AlF₆-AlF₃-TiO₂ melt salt system: the first step is that Ti⁴⁺ is deoxidized into Ti²⁺, the second step is that Ti²⁺ is deoxidized into Ti metal. The deoxidization steps of electrochemistry on La³⁺in the tungsten filament electrode is the simple one step in...