| 摘要 |
1,252,691. Electro-machining. HOOKER CHEMICAL CORP. Jan.2, 1969 [Jan.15, 1968], No. 400/69. Heading C7B. [Also in Division C1] In electro-chemical machining processes, in which metal is removed electro-chemically from a chromium-containing workpiece by the application of electrical current from a cathode die to the workpiece anode, there is used as electrolyte an aqueous alkali metal chlorate or ammonium chlorate solution from which trace amounts of hexavalent chromium ion that derive from the anode are removed by introducing into it a soluble salt of divalent Fe, Sn, Ba, Co, Pb, Zn, Cu, an alkali metal sulphide or (NH 4 ) 2 S, and then removing the resulting precipitate. |
