| 摘要 |
1,169,234. Electrolytic etching of aluminium. H-W. PAEHR. Jan. 16, 1967 [Jan.21, 1966], No. 2198/67. Heading C7B. In a process for the extension of the effective surface area of aluminium electrodes or aluminium foil for electrolytic capacitors by anodic corrosion in a bath containing an electrolyte and a counterelectrode, there is applied across the electrode or foil to be corroded and the counter-electrode a direct voltage and superimposed periodic voltage pulses, e.g. at a frequency of 10-100 cycles/sec, which interrupt the substantially constant corrosion current due to said direct voltage and have a halfwidth of less than 10% of the pulse repetition period. The pulsating voltage may be provided by supplying negative voltage pulses to the part to be corroded and/or positive voltage pulses to the counterelectrode. Pulse shapes which may be used (see Fig.2, not shown) include rectangular and trapezoid pulses, and the pulses are preferably of such height that the voltage difference between the electrodes is equal to the polarization of aluminium with respect to the electrolyte. An aqueous solution of sodium chloride may be used as electrolyte. |
