Optimization And Performance Research Of Anode Aluminum Foil Corrosion Process Based On Direct Current Galvanic Corrosion And Spontaneous Corrosion

For corrosion pore diameter of the anodic aluminum foil is larger,and it is not easy to block the tunnel hole after forming by DC etching,the capacitors made of anodized aluminum foil are widely used in high-voltage circuit.With the development of miniaturization and integration of capicitors,it is important to guarantee the small size and high static capacitor of the capacitor.Although science and technology workers do a lot of work on DC etching process,there are still exist some problems,such as low quality of aluminum foil,corrosion coefficient less than the limit corrosion coefficient,there can be not meet the market demand for high performance aluminum electrolytic capacitor.High quality and low cost are the core of improving product competitiveness.The research in our team's prophase study found that linking the graphite cathode and anode directly and adjusting the corrosion system,anode aluminum foil erosion can occur spontaneously and produce larger corrosion current rather than needing the power converter.the spontaneous erosion can save energy consumption,reduce product cost,and has a great application prospect.further researching is urgently needed,so as to realize industrialization application at an early date.The article first analysis weight loss rate,reduction rate,specific volume,the cross section and surfacial morphology after DC or spontaneous etching;the dipping acrylic resin,double cathode electrolytic corrosion and the influence of adding metal ions in DC etching were studied,the influence of halogen ions,sodium chloride,electric field and electrophoresis coating in spontaneous etching were discussed,and the optimum process level and corrosion mechanism were researched;then the optimum process level was obtained by orthogonal experiment.The main conlusions are as follows:1.Analysising and ptimizing DC etching process and obtaining optimum condiction by dipping acrylic resin,double cathode electrolytic corrosion and adding metal ions,The main conlusions are as follows:?1?After dipping acrylic resin with the mass fration of 0.6%,the corrosion tunnel holes are dense and long,distribute tidely and extreme corrosion less,its mechanical performance is relatively good,the volume increase relatively,so the better impregnation concentration is about 0.6%.The better corrosion time is 2 min after analysising the reduction rate and weight loss rate of aluminum foil dipped in 0.6%.?2?The double cathode corrosion process was discussed in 3.5mol/LH₂SO₄ and1.0mol/LHCl,the results show that the reduction rate is smaller but the weight loss rate is much more,which shows that the surface area,the volume and bend degree are larger,So the optimum process condition that the temperature of 80?,the corrosion current of 0.1A/cm²,corrosion time of 120s was obtained.?3?After adding metal ions in period of corrosion,because of the balance of occupying active site effect,galvanic cell effect and competition effect,the reduction rate of aluminum foil decreased first,increased later,then decreased again,while the variation of the weight-loss rate is complex relatively with increasing of metal ions or metal oxides concentration.Etching 2min after adding Fe²⁺,the higher specific surface area and specific capacitance were presented,the most about 17.1%was enhanced comparing to blank sample.?4?Proceeding orthogonal experiment in temperature 80?,corrosion time 2min,obtaining the best process parameters are the current density is 0.15A/cm²,the concentration adding Fe²⁺is 120ppm,the mass fraction of acrylic resin is 0.6%.2.Optimizing the spontaineous corrosion process and analysising its mechanism from the influence of halogen ions,sodium chloride,external field and electrophoresis coating,the optimum process parameters of low energy consumption and cost were found.The main conlusions are as follows:?1?With the addition of halogen ion,the corrosion velocity is fast,the density and the pore length of corrosion aluminum foil were increased.The reduction rate is smaller but the weight loss rate is much more in 0.1%,which shows that the more corrosion tunnels were formed,the less extreme etching was occurred and the higher specific surface area and capacitance were obtained.?2?When the NaCl concentration is 0.4mol/L,the reduction rate of aluminum foil began to decrease,the weight loss rate is about to enter rapidly descending area,and a great bend degree was represented.Therefore,a better NaCl concentration of 0.4mol/L was determined.?3?Under the action of applied electric field,the corrosion time is 90s,the distance between the plates is 20cm,and the maximum corrosion currency is 4.56A.?4?The reduction rate is smaller but the weight loss rate is larger when the resin mass is 5×10^-8,which shows that the quatity loss of the aluminum foil is mainly caused by the formation of corrosion tunnel;the surface of corrosion aluminum foil afer coating is more uniform and the extreme etching is less.Therefore,the better resin concentration is 5×10^-8.?5?Proceeding spontaneous corrosion after external applied field,adding Cl^-and electrophoresis coating in NaCl replacing HCl electrolyte with the corrosion temperature of 80?and corrosion time of 120s,by orthogonal test design,the optimum corrosion conditions that the Cl^-concentration of 0.1mol/L,NaCl concentration of0.5mol/L,electric field plate spacing of 25cm and electrophoresis solution solute mass fraction of 0.55×10^-7 were obtained.