Improvements in electrolytic deposition of nickel

682,173. Electrodeposition of nickel. BOZEL-MALETRA. May 16, 1949 [Oct. 19, 1948], No. 13041/49. Class 41. A method of obtaining thick ductile and very hard nickel deposits on a metal piece which is to be re-metalled or to be hardened superficially, in which the piece is used as cathode in a bath containing nickel sulphate, nickel chloride, boric acid, and an anti-pitting agent, and containing also at least one of the following ductilizing agents in a concentration of from one half gram to five grams per litre: a sulphonated or polysulphonated derivation of naphthalene or of aminotoluene, benzene sulphonamide, toluene or betanaphthalene sulphonamide or saccharin, the temperature of the bath being maintained higher than 35 ‹ C. and the pH value being lower than 5, is characterized in that the current density on the cathode is from 6 to 8 amperes per sq. dm. The polysulphonated naphthalene derivatives may have two or three sulphonated radicals. Either alpha or beta naphthalene monosulphonate may be employed as a sulphonated derivative of naphthalene. The sulphonated aminotoluene derivative is preferably one in which the amino group is in the ortho position. The anti-pitting agent may be an organic product with a heteropolar chain. An example of an anti-pitting agent is a sodium salt of the lauric alcohol sulphate. Specification 525,847 is referred to.