| 摘要 |
1,245,286. Phosphatisation of iron; electrolytically producing iron ions. INSTITUT DE RECHERCHES DE LA SIDERURGIE FRANCAISE. Nov. 22, 1968 [Dec.4, 1967], No. 55526/68. Headings C7B and C7U. Protective phosphate coatings are formed on the surface of iron or iron alloy articles by a process in which the articles are immersed in a phosphatizing bath containing zinc in solution, the first stage of the process consisting in enriching the metal/solution interface with iron ions by surface dissolution by means of a direct potential difference applied between a counterelectrode and the articles constituting respectively the cathode and the anode of an electrolytic cell, and the second stage of the process consisting in cancelling the said potential difference to bring about the formation on the surface of said articles of a layer of phosphates rich in iron from iron ions localized at the metal/solution interface and of a layer of zinc phosphate from the zinc introduced initially into the phosphatization bath. The phosphatization bath may contain zinc phosphate, accelerated with zinc nitrate, and the potential difference is maintained for a time sufficient for 1À8 to 5 coulombs per square cm. to pass through the electrolytic cell. |
