Improving physical and mechanical properties of foil for anodes of high-voltage electrolytic capacitors by introducing an intermediate annealing

Abstract

The results of studies of influence of intermediate and final annealing on the level of physical and mechanical properties of foil for anodes of highvoltage capacitors made of high-purity aluminum (99.99%) are presented. A comparative analytical analysis of efficiency of introduction of the intermediate annealing stage in the thermo-deformation processing mode in comparison with its absence in the scheme was performed. The starting material for the research is a strip with a thickness of 0.45 mm, obtained from hot-rolled strip with a thickness of 8 mm by cold rolling (deformation degree is 0.9437). The chemical composition of the strip corresponds to the A99 aluminum grade according to GOST 11069–2019. Content of basic impurities in the initial strip by the actual chemical composition,%: 0,0018 Si; 0.0012 Fe; 0.0020 Cu. A set of studies of physical and mechanical properties, which allowed to determine the dependence of the maximum value of specific capacity of high-voltage anode foil on the average grain size and crystallographic orientation (in this case - the maximum value of cubic texture, with allowable values of foil ultimate strength). It is shown that with an increase in the intensity of the cubic texture from 90 to 95%, the specific capacitance increases from 29 to 32 μF/dm2. This is achieved through the use of intermediate annealing at 380 оC and further final annealing at 550 оC. The hereditary character of the average grain size of samples with a thickness of 0.45 mm during intermediate annealing and the grain size of the foil with a thickness of 0.100 mm after the final annealing is shown.