| 摘要 |
1,132,833. Electrolytically etched fuel cell electrodes. FARBWERKE HOECHST A.G. 18 Nov., 1965 [18 Nov., 1964], No. 49116/65. Heading H1B. [Also in Division C7] An electrolytic etching process for the preparation of a porous, gas-permeable, gas-solvent, fuel-cell electrode comprises masking the surface of an alloy of a first metal and a second metal with a porous or perforated cover, the cover being in contact with the surface of the alloy, and exposing the alloy as anode in an electrolytic bath at a current density in the range of from 1 to 20 milliamps/sq. cm. based on the area of the exposed surface of the alloy and at a voltage at which the second, but not the first, metal will be dissolved out of the alloy until at least 80% by weight of the second metal has been dissolved from the part of the alloy that is masked by the porous or perforated cover. The " exposed surface of the alloy " is that part which at the beginning of the process lies beneath the pores or perforations of the cover. The first metal may be Ag, Au, Pt, Pd, Ni or an alloy of one of these metals with another or with Hg, e.g. Ag-Au or Au-Hg. The second metal may be Cu, Zn, Cd, Al or Si or an alloy of one of said metals with another. The mask may be a perforated sheet of synthetic plastic or may be a plate of porous carbon. All the second metal may be dissolved in which case the remaining electrode metal becomes entangled by the carbon and supported by it. The electrolyte may be an aqueous solution containing ions of the second metal and the cathode may consist of the second metal. The current may be reduced as electrolysis proceeds and may be reversed for a short interval during dissolution. In Examples 1 and 2, 80% by weight and all the Cu is respectively dissolved from a Cu-Ag alloy using a CuSO 4 electrolyte. The porous electrodes so formed are used as oxygen-electrodes in fuel cells. Fig. 3 shows the fuel cell of Example 2. The oxygenelectrode comprises Ag granules 17 between carbon discs 14, 15. Oxygen is supplied through a Ag tube 12. The anodes comprise Ni nets 18 filled with " Raney " (Registered Trade Mark) nickel 19. The electrolyte 7 is a 6N KOH solution containing 12% by weight of ethylene glycol as fuel. |
