Microstructure With The Performance Of 3003 Aluminum Alloy Cathode Foil For Electrolytic Capacitor

The effect of the microstructures of the AA3003 aluminum cathode foil on the performance was investigated. It showed that the microstructures, the composition, the geometry shape and distribution of the intermetallic particles had strong influence on the etching performance and the specific capacitance of AA3003 cathode foils. The foils with fine and dispersed intermetallic particles had high specific capacitance and less etching remnants. While in the foils with coarse particles, the matrix adjacent to coarse intermetallic particles would be preferentially dissolved when being etched, which resulted in heterogeneous etching morphology, serious remnant metal powders on the foil surface and decrease of specific capacitance. It also showed that the density of intermetallic particles had strong influence on the specific capacitance of the cathode foils.The quenching and aging of the AA3003, which is not available in the literature, was proposed to increase the specific capacitance of the foils by improving the microstructures, composition, and the geometrical shape and distribution of intermetallic particles. The coarse (MnFe)Al6 particles will be dissolved in high temperature annealing, which would result in the less etching remnants. The cooling mode after annealing also had strong influence on the performance of the AA3003 cathode foils. Cooling in the furnance, which resulted in coarse intermetallic paricles, would lead to the decrease of specific capacitance and increase of etching remnants. The etching performance would be improved by high temperature annealing and quenching, but there was no substantial increase of specific capacitance. After aging of the quenched foils, there were high density of fine and dispersed MnAle intermetallic particles, which would resulted in the homogeneous distribution of dislocations and etching pits, i.e. the spone-like etching morphology, and the specific capacitance was also improved substantially. It is showed that the annealing at 630 C for 6 hours, then quenching and aging at 60 C for 11 hours was the best one.