| 摘要 |
523,858. Asymmetrically conducting resistances; electro-deposition of metals. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. Jan. 16, 1939, No. 1519. Convention date. June 15, 1938. [Classes 37 and 41] In a rectifier element of the copper-copper oxide type, after producing a compound layer, for example, oxide, on the base metal, a superficial layer of the compound is reduced to the original metal, preferably by electrolytic treatment and then a layer of another metal such as nickel is deposited on the reduced metal. In the case of copper oxide, the outer laver of black oxide need not be removed by a separate operation but may be reduced. Preferably the reduction is effected in a sulphuric acid bath 12 of about .35 grams per litre concentration, current being passed from a graphite anode 13, to the elements A mounted in a masking device C, comprising a central metal washer 3, rubber rings 4, 6 and clamping washers 7 with bolts 8 to protect the outer edges of the elements. The inner edges are protected by clamped rubber washers 9. The elements may have the nickel &c. layer applied while still in the mask and, for this purpose, after rinsing and drying in an air blast, they are made the cathode in a plating solution, e.g., of the following composition: nickel sulphate, ammonium chloride, boric acid and sodium chloride at a pH value of about 5.8 using a current density of about 18 amps. per square foot, for about two minutes. Specification 194,653, [Class 37], is referred to.
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