CS241666B1 - Fluorescent additive for electrolytic deposition of glossy nickel coatings up to 10 µin thickness - Google Patents

Abstract

A gloss-forming additive for the electrolytic deposition of nickel coatings from galvanic baths based on sulphate, chloride or nickel bromide and boric acid in various proportions, based on a suitable combination of 5 basic groups of organic compounds, ensuring with its catalytic, synergistic and retarding properties a significant reduction in the kinetics of their decomposition, a reduction in their sorption capabilities and at the same time a positive effect on the sorption properties of decomposition products, which enables continuous filtration and periodic replenishment of the bath with a gloss-forming additive and a continuous flow of the galvanic bath. This simultaneously achieves an increase in the stability of galvanic baths, high levelling ability, high gloss of deposited coatings, low porosity and high ductility as well as good adhesion of other coatings. In nickel plating baths, the gloss-forming additive is maintained at a concentration of 20 to 30 ml/ /1000 ml of bath under working conditions of 55 to 70 °C and pH 3.5 to 4.5.

Description

The present invention relates to brighteners for the electrolytic deposition of bright nickel coatings from nickel sulphate, nickel (II) chloride or bromide and boric acid galvanic baths in various proportions.

To date, a wide variety of organic or inorganic additives have been designed and used for the galvanic deposition of shiny nickel coatings, which are usually divided into two classes.

Substances classified as · 1st class contain a sulfur atom in their molecule - these are most often different types of inorganic sulfo acids and its esters, sulfonamides, sulfoimides, sulfones, etc.

Class 2 includes salts of certain metals (Zn, Cd, Pb, etc.) and a number of organic compounds such as aldehydes, ketones, acids, amines, pyrazole, imidazoles, quinoline or their derivatives, azo compounds, etc. Most of these organic substances themselves during plating under working conditions of the nickel-plating bath, ie pH 3.5 to 4.5 and temperatures of 55 to 70 ° C, it decomposes rapidly into decomposition products with a negative effect on the operation of the bath and can therefore be used alone. The gloss-forming effect of the substances themselves is little or no. It is noticeable only in their certain combinations, in which the stability and the decomposition rate are considerably slowed down. The decomposition products formed in the galvanic bath accumulate, leading to a decrease in the quality of the coatings and manifesting itself in a reduction in the bath's buffering ability, loss of gloss, increased porosity of the coatings, brittleness, reduced adhesion of other coatings due to surface passivation. The deterioration of the quality of the coatings can reach the limit of unusability.

For these reasons, it is necessary to remove the reaction products from the galvanic bath. Strong oxidizing agents (hydrogen peroxide or potassium permanganate) are most commonly used for decomposition of the reaction products, followed by absorption of the decomposition products on activated carbon, resulting in considerable economic losses (loss of part of the electrolyte, decomposition of virtually the total amount of pollutants and cost of oxidizers). The removal of the reaction products is incomplete and must be repeated periodically.

The above-mentioned deficiencies are eliminated by the inventive brightener composition

It consists of 10 to 30 wt. % of aromatic compounds having an unsaturated bond between the carbons adjacent to the sulfone group, from 3 to 50 wt. % of salts of unsaturated aliphatic sulfonates, 0.1 to 5 wt.% salts of aliphatic sulfosuccinic esters, 0.05 to 5 wt. % unsaturated alcohols and derivatives thereof optionally ethoxylated to one or more stages, 0.01 to 5 wt. % of substituted sulfobetaine pyridine and its derivatives, from 75 to 88 wt. water and is added to the nickel-plating bath in an amount of 0.5 to 5% by volume.

A suitable combination of the above-mentioned substances and their relative proportions by their catalytic, synergistic and retarding properties ensures a substantial reduction of their decay kinetics, decreases the sorption properties of the basic components of the brightening agent on activated carbon, while favorably affecting the sorption properties of Coal and periodic replenishment of the bath with a gloss-forming additive and thus the continuous operation of the bath, which is positively manifested also by increasing the stability of galvanic baths, high leveling ability and gloss, low porosity and high ductility.

The following is an example of a brightener for the galvanic deposition of shiny nickel coatings.

Example 1

115 g of benzenesulfoimide, 45 g of sodium vinylsulphonate, 2.5 g of disodium isodecylsulfosuccinate, 0.8 g of propargyl alcohol and 13.5 g of phenylpyridine sulfobetaine are mixed with 870 g of water at room temperature in a mixer to obtain 1000 ml of a brightener suitable for shiny nickel coatings up to 10 μΐη. This additive is dispensed into a galvanic bath containing, per 1000 ml, 300 g of nickel sulfate, 60 g of nickel chloride and 40 g of boric acid in an amount of 20 ml / l. The specimens were metallized at a current density of 5 A / dm ² , a voltage of 4.5 V and a temperature of 60 ° C for 10 minutes. The nickel bath had a pH of 4.1. The deposited coatings had an average thickness of 10 µm and these properties - 74% alignment, 4% ductility.

Claims (3)

SUBJECT Gloss-forming additive for electrolytic deposition of shiny nickel coatings up to 10 µm thick from galvanic baths based on nickel sulphate, nickel chloride or bromide and boric acid in various proportions of pH 3,5 to 5 at temperatures of 50 to 80 ° C, voltage 3, 8 to 5.3 V and current densities 2 to 10 A / dm ² , characterized in that it consists of 10 to 30 wt. % of aromatic compounds with an unsaturated bond between the carbons adjacent to the sulfone group, VYNALEZU 3 to 50 wt. % salts of unsaturated aliphatic sulfonates, 0.1 to 5 wt. % salts of aliphatic esters of sulfosuccinic acid, 0.05 to 5 wt. % of unsaturated alcohols and their derivatives, optionally ethoxylated to one or more stages, 0.01 to 5 wt. % of substituted sulfobetaine pyridine and its derivatives, 75 to 88 wt. % Water and added to the electroplating nickel bath in an amount of 0.5 to 5 vol.%.