Process for the oxidation by electrolytic means of the iron, steel, cast iron and copper, as well as other metals previously covered with a layer of iron or copper deposited electrolytically

摘要

164,127. Rondelli, T., Sestini, Q., and Sestron Colour Oxidising Co., Ltd. March 2, 1920. Addition to 106,774. Metallic oxides, obtaining and depositing. - Articles of metals such as copper, copper alloys, and iron are coloured by connecting them exclusively as anodes while immersed in a heated solution of a fixed alkali in which is dissolved, preferably to saturation, a copper compound such as cupric oxide, hydrate, or sulphate. The concentration of alkali is preferably such that the boiling-point is 120-130‹ C. The electrolyte may be heated to 90-130‹ C. for treatment of copper or iron. Current densities of 1-30 amperes per sq. dcm. may be employed; a higher density is allowable for pure copper or bronze rich in copper than for other copper alloys. According to the duration and conditions of treatment, iridescent effects or light green, dark blue, or black coatings can be obtained. The black coatings can be polished and resist corrosion.