UN PROCEDIMIENTO PARA PREPARAR UNA SUPERFICIE DE NIQUEL.

摘要

1,195,874. Electro-depositing nickel and chromium. M & T CHEMICALS Inc. Oct. 25, 1967, [Oct. 26, 1966], No.48524/67. Heading C7B. A duplex Ni plate is prepared on a basis metal, e.g. Fe, Cu, Ni, Zn, or alloys thereof including steel or brass, to receive a Cr plate, by first electro-depositing on to the basis metal a S-containing bright Ni plate, and then electro-depositing to a thickness of at least 0À6 micron (e.g. 0À6-3 microns) an outer micro-cracked Ni plate from an aqueous bath containing 120-187 g/l Ni++, 110- 225 g/l NiCl 2 .6H 2 O and 150-900 g/l Ni (BF 4 ) 2 . For Zn die castings, a base Cu plate e.g. 7À5-15 micron thick is preferably electro-deposited, e.g. from a plating bath containing 45-60 g/l Cu (as Cu CN) and 15-22 g/l free NaCN or KCN, prior to Ni plating. Prior to the first electro-deposition, a preliminary S-free semi-bright Ni plate may be electro-deposited from a conventional Watts, sulphamate, fluoborate or chloride-free bath containing 0.2-3 g/l of a semi-bright additive, such as coumarin, (diethoxylated) butyne diol, chloral or bromal hydrate, formaldehyde or piperonal, to a thickness of 5-40 microns. The bright Ni plate may be electro-deposited from similar baths containing nickel sulphate, chloride with or without fluoborate or sulphamate, or boric acid, and a primary and secondary brighteners, to a thickness of 7-12 microns. Examples of primary brighteners, e.g. in amount of 0À002-0À2 g/l, are (diethoxylated) butyne diol, phenyl propiolamide, propargyl alcohol, 3-butyne 1-ol, 2-methyl-3- butyne-2-ol, and α, a'bis (pyridinium iodide) 2, 6-lutidine. Secondary brightners, e.g. in amount of 1-30 g/l, include saccharin, Na benzene monosulphonate, Na vinyl sulphonate and Na metabenzene disulphonate; secondary auxiliary brighteners, e.g. in amount of 0À5-3 g/l, include Na allyl suphonate and Na 3-chloro butene 1-suphonate. The plating bath for electro-depositing the outer micro-cracked Ni plate preferably further contains 0À002-0À4 g/l primary brightener and 0À1-1 g/l secondary brightener, as above, and 0À1-0À8 g/l an additive heterocyclic having at least 2 N atoms in the ring structure, preferably hexamethylene tetramine, piperazine, pyrazine, 2, 6-dimethyl pyrazine, or 1:11 ethylene 2:21 dipyridinium dichloride; other examples are specified. The final Cr plate may be electro-deposited on the bright Ni plate from a bath containing CrO 3 and SO 4 -(added as Na 2 SO 4 or H 2 SO 4 ), with or without SrCl 2 or SrSO 4 or K 2 SiF 6 , to a thickness of 0À1-1 micron.