Effect Of TiO₂-Al₂O₃ Composite Oxide Film On The Specific Capacity Of Aluminum Electrolytic Capacitor Anode Foil

In this paper,the Al₂O₃-TiO₂ composite oxide film was prepared by introducing TiO₂ with high dielectric constant on the surface of aluminum anode foil to improve the specific capacitance of aluminum anode foil.The process parameters were to be optimized,according to withstand voltage and the SEM analysis data,the specific capacity of 600V secondary formed foil as the main evaluation index,the main conclusions are as follows:Effects of boiling time and heat treatment time on the formation time,specific capacitance and withstand voltage of anode foil were studied in the process of hydration.The result shows that the hydration treatment of the corroded foil before the anodic oxidation treatment can significantly reduce the formation time and increase the conversion efficiency by about 33%.In addition,it can be seen that the anodic oxide film has a certain thermal stability,the heat treatment at 500?,the CV value between 310×10^-6V·F·cm^-2and 312×10^-6V·F·cm^-2,the effect of heat treatment on the stability of hydrated oxide film can be neglected.The best pre-treatment process is:the corrosive foil was boiled in 90?high purity water for 3 min,then dried and sintered at 500?for 1h,in order to obtain?-Al₂O₃.TiO₂ sol was prepared by sol-gel method,using Ti?OC₄H₉?₄as precursor,ethanol as solvent,acetic acid as inhibitor effects of the ratio of TiO₂ sol,dipping time,dipping temperature on the specific capacitance of the anode foil were studied.It was found that the sol-gel time was shortened with the increase of the ratio of water to titanium.Therefore,according to the state of the sol and the influence of the ratio of sol on the specific capacitance,the best ratio of sol are as follow:Ti?OC₄H₉?₄:H₂O:CH₃CH₂OH:CH₃COOH=1:1:20:4Effects of dipping time,dipping temperature on the specific capacitance of corrosion foil were studied.The results show that,the dipping time is too long may cause corrosion again,the dipping time is so short that deposited on the anode foil surface oxide film is limited,which all will affect the specific capacitance of aluminum foil.When the dipping temperature is too high,can increase the probability of particle collision,change gel time to reduce,effect the size of particle,cause tunnel hole blockage.The optimum dipping conditions were as follows:at 20?,dipping time is 4min,the maximum increase special capacitance of formed foil is 11%.The effects of sol concentration,sol aging time and electrophoretic deposition voltage and time on the properties of TiO₂ film on anode foil were investigated by orthogonal experiment design and single factor method.The optimum conditions were as follows:the sol was 0.06mol/L for 3 days with p H=4 for electrophoretic deposition,the deposition voltage was 15V,the deposition time was 20s,and the specific capacitance of anode foil was increased by 17%.At the same time,the effect of CTAB on the specific capacitance of the oxide film was studied.The results showed that the surfactant could improve the specific capacitance of the anode foil,when the mass less than 1g/L.