Patent GB-1415913-A (GB)
Title: Electrodeposition of metal foil
IPC: C25D1/04
Filed: 1973-01-08
Abstract: 1415913 Electro-depositing on moving foil ELECTRICITY COUNCIL 8 April 1974 [8 Jan 1973] 995/73 Heading C7B Metal foil is produced by electro-depositing in a primary cell metal e.g. Fe onto a cathode 1, the surface of which moves continuously through an electrolyte e.g. FeCl 2  at a uniform rate past a non- consumable anode 4 uniformly spaced from the cathode with the electrolyte flowing at uniform speed between the cathode and anode, stripping deposited metal as foil 47 from the cathode and passing it to increase its thickness through one or more secondary electro-deposition cells 49 1 -49 7  past respective non-consumable anode(s) 58 uniformly spaced from the foil, e.g. via rollers 40, 48, 50, 51, with the electrolyte flowing at uniform speed between the foil and respective anode, the foil being electrically connected to a current source by contacting means 54 on the foil face remote from the anode such that substantially all of the current passes through the foil substantially perpendicular to its plane. The contacting means may include a conductive solid and/or liquid e.g. Hg or molten metal (mixture) e.g. two or more of Sn, Pb, Bi, Cd, Te, As, Ga, Zn. A conductive solid e.g. support 54 is preferably provided with a contacting surface of complementary shape to that of the anode; the foil may be pressed against this surface by suction applied from a vacuum source 55 via passages 57 and interconnecting pipe 56 (as shown), or by providing a pre-selected hydrostatic pressure in the adjacent electrolyte or a magnetically derived force; and electrical contact may be enhanced by supplying a conductive liquid e.g. Hg permeated in a porous sheet of sintered metal (77) to the surface via further passages in the contacting means (block 76, Fig. 9). The contacting means may also include a conductive belt which travels around the conductive solid about an axis of rotation transverse to the length of the foil and at a speed equal to that of the foil. The foil edge may be bent up to form side walls which with end walls provided form a trough for containing electrolyte or conductive liquid e.g. Hg (73, Figs. 7 and 8). The contacting means may be provided below, Figs.2 to 4 and 10) or above (Figs. 5 to 9), the foil. The primary cathode 1 may be cylindrical comprising a sleeve with Al inner and Ti outer parts. The anodes may be of graphite. The contacting means and/or anode(s) may be thermally insulated and/or heated. The electrolyte in all the cells may be a FeCl 2  solution of molarity between 1.5 and 3.5, and have a pH between 0.3 and 2.0 and temperature between 92 and 108 C, the electrolyte being made to flow at speed between 2 and 10 cm/sec; the cathode and foil is preferably maintained between 92 and 110‹C and the anodes at between 50 and 108‹C, the CD being between 0.2 and 1.0 A/cm<SP>2</SP>. Heaters may be disposed inside the primary cathode. An iron alloy may be produced by electro-depositing the or each constituent of the alloy from the secondary cell(s) onto Fe foil produced in a primary cell, and sintering the resultant foil to interfuse the whole or only a surface region of the foil; e.g. to produce 18% Cr-8% Ni steel. Coated foil may be passed through an additional secondary cell to electro-deposit the same or a different metal onto the uncoated foil surface; e.g. Fe foil coated on both surfaces with Cu. The foil surface may be activated e.g. by passing it through a hot HCl bath prior to entering any secondary cell.