Studies On Spinel-Based Inert Anodes For Aluminium Electrolysis And Oxide Membrane Inert Anodes On The Ni-plate

The literature survey was made. Several kinds of inert anode were tested and the most serious difficulty for inert anode encountered was the problem of corrosion.ZnFe204 was chose as inert anode materials for the special microstructure.ZnFeA powder was synthesized with ZnO, Fe20:, at 1210 for 20 hours. Theinert anode samples were prepared by cold-pressing and sintering method.Selected additives were used to improve the sintering behavior, electricconductivity and corrosion resistance of the anodes. Several anodesamples got very good conductivity, even high than carbon anode at thesame temperature of aluminum electrolysis. Under the condition of moltensalt electrolysis, the anode was with high electrochemical stability.Under the condition of aluminum electrolysis, the principle of corrosionof anode materials is sophisticated, including the corrosion of the anodein high temperature electrolyte, the reduction of liquid aluminum, thecorrosion of the scour of anode gaseous fluid and the flow of theelectrolyte.Electrochemical tests proved that the anode is static in long term open-circuit working. The potential fluctuates little and several repetitions of testing are doing well. Static open-circuit potential is practicable for metallic oxide anode stability.The corrosion behavior of the anode used in aluminum electrolysis were examined, the conclusion is as follow: when Al20:i-content in the electrolyte was not saturated, the corrosion rate of the anode would be reduced by increasing the A1203 content in the bath, increasing the anodiccurrent density and decreasing in the bath ratio; when the electrolyte was saturated with A120.). the corrosion rate of the anode will be reduced by increasing the anode current. The corrosion rate of anode would be increased obviously, if the electrolyte containing aluminum.The NiO membranes firstly were prepared on the Ni-plate by the magnetron sputtering technique. The samples mentioned above were used as inert anodes in aluminum electrolysis experiments. The composition and structures of the membranes (before and after the experiment) were analyzed by X~ray diffraction and SEM. The results show that the minute particles of the membrane distribute tightly and the testing anodes are well corrosion-resistant in melt salt electrolyte at 960癈.The corrosion rate of anode is 3. 2X10Hg/h ?cm2. Compared with the ZnFe204-based anode, it has a smooth surface and corrosion-resistant. From this, we can obtain valuable experience and use for reference. There are reference price for scientific research and investigation of this sort of anode.