ES368186A1 - Improvements in or relating to high-rate electrolytic nickel-plating methods, and installations - Google Patents

Abstract

A continuous, automatic process for electrodepositing mator bright nickel using insoluble anodes (e.g. of lead) and a bath of an aqueous solution comprising NiSO4 (e.g. providing 70-110 g/l Ni ion) buffered by H3BO3 (e.g. 30-50 g/l) at a pH of 2À8-4À8 and containing one or more stable organic additions, such as sodium lauryl sulphate as wetting agent and optionally (for bright deposits) sodium naphthalene 1, 3, 6-trisulphonate, sodium benzoyl sulphimide, 2-propyne 1-ol and coumarin as brighteners and levelling agents, is carried out at a cathode current density of 5-40 amp/sq dm and a temperature of 50-85 C, the plating bath being recycled and filtered continuously, and regenerated automatically by adding before filtration an aqueous dispersion of Ni (OH)2 or NiCO3 containing the organic additive(s), monitored by the variation in pH outside the above range. As shown, an installation for carrying out the process comprises: at least one Ni-plating tank 1 having insoluble lead anodes and cathode-forming articles to be plated suspended from bars supplied with rectified D.C. a recycling circuit 18, 7, 16 for the Ni-plating bath including a heat transfer device 2 for maintaining the temperature, a pump 3 and a valve 4 in a duct 7, connected to which is a pH recording meter 17 an automatic electrolyte regenerating circuit 19, 21, 15 branched off the recycling circuit, including a Wurtz pump 6 for drawing up the NiCOH)2 or NiCO3 in container 8 via a regulating valve 9, a Raschig dissolution column 10 (optionally with a gas extraction column 13 for NiCO3 ), a filtration pump 11 with a filter 12 at the outlet and an automatic regulation line connecting the pH recording meter 17 to the regulating valve 9 by electromechanical means 20. Specification 1, 80, 119 is referred to.