FORFARANDE FOR FRAMSTELLNING AV ETT KROMSKIKT MED MIKROSPRICKOR OVER ETT MELLANSKIKT AV NICKEL, KOBOLT, NICKEL-JERN, NICKEL-KOBOLT ELLER JERN-KOBOLT SAMT BAD FOR AVSKILJNING AV MELLANSKIKTET

摘要

1371172 Electrolytically producing microfissured chromium LANGBEIN-PFANHAUSER WERKE A G 7 Jan 1972 [11 Jan 1971] 837/72 Heading C7B A micro-fissured Cr layer is produced on an intermediate layer of Ni, Co, Ni-Fe, Ni-Co or Fe- Co by electrolytically depositing at 35 to 70‹C the intermediate layer from a bath of electrolyte which includes the metallic ions, NH 4 ions, Cl ions and at least one aromatic carboxylic acid or a salt of this, and on to this intermediate layer electrolytically applying the Cr layer from a Cr deposition bath. Examples of materials which can be used in preparing the bath for producing the intermediate layer are benzoic acid, "o", "m" or "p" terephthalic acid, benzyl-acetic acid; Ni, Co and Fe sulphate, sulphamate, chloride, fluoborate, fluoride and acetate, NH 4 Cl, MgCl 2 , alkali metal chloride and R 3 BO 3 . The intermediate layer may be electro-deposited at 3-20 A/dm2, a pH of 2À5-6 and operating temperature of 35-70‹C for 1-10 mins. The Cr may be electrodeposited at 3-12 A/dm2 from a bath at a temperature of 25-35‹C. In the Example, the bath contains chromic and sulphuric acids and aluminium fluosilicate.