SU594214A1 - Palladium-plating electrolyte - Google Patents

Abstract

ELECTROLLT: PALLADIUM containing complex palladium salt, ethanolamine, ammonium sulfate and an organic additive, due to the fact that, with the purpose of increasing the adhesion of the coating to the base, the stability, dispersion and corbel capacity of the electrolyte when palladating brass parts in baths drum and cabol types, as an organic additive it contains Trilon B, with the following ratio of components, g / l: Complex palladium salt (in terms of metal) 10-30 Stanolamine (97%) 50-160 Ammonium sulfate 20- 30 Trilon B0,5-2,0 And \ c

Description

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with

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WITH

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The invention relates to electroplating, in particular to the electrolytic palladating of brass products in drum baths.

Palladium electrolyte containing calcium chloride and ethylenediamine are known.

Glitter coatings are obtained from this electrolyte, but the scattering power of the electrolyte is 15-20%,

The palladium electrolyte containing palladium, polyethylene lenpolyamine, ammonium chloride, ammonium sulfate, and hexamine is known.

However, the current efficiency in this electrolyte is 63%, the precipitates are semi-bright.

The known electrolytes contain toxic substances, ethylenediamine and polyethylene polyamine.

Closest to the composition of components proposed is a palladium electrolyte containing palladium complex salt. Ethanolamine, ammonium sulfate and organic additive (saccharin).

When palladating in such an electrolyte in baths of drum and bell types of brass parts of complex configuration, the base metal of parts is inevitably dissolved from surfaces not coated with palladium (ethanolamine dissolves brass in an alkaline medium), which causes zinc ions to accumulate in the electrolyte, 03 g / l impairs palladium adhesion to the base. To eliminate the effect of zinc ions, it is necessary to carry out a regular study of the electrolyte for an hour, which significantly reduces the useful life of the electrolyte before its regeneration, as well as increases the loss of palladium and process time.

In addition, the stability of the electrolyte is 60-100 Ah-1, and the scattering and covering power are 26 and 83%, respectively.

The proposed electrolyte is different in that, in order to increase the luminosity of the coating with the base, the stability, the scattering and covering power of the electrolyte when palladating brass parts in baths of the drum and bell types.

942142

as an organic supplement he

contains Trilon B in the following ratio of components, g / l:

Complex salt 5 palladium (in terms of metal) 10-30 Ethanolamine (97%) 50-160 Ammonium sulfate 2P-30

Tridon B0.5-2.0

The electrolyte is prepared as follows.

in a way. A solution of the complex salt of the ladie salt, then ammonium sulfate and Trilon B are gradually added to the ethanolamine solution. After the complete dissolution, the solution is filtered, adjusted to the required pH, and the resulting electrolyte of a bright yellow-palladium color is obtained. The electrolyte is stable in operation (230 a-h / l) and has a current efficiency of 90-95%, the scattering capacity of the electrolyte is 33-40%, and covering 90-93%, 25 bonds due to the fact that the electrolyte works with insoluble anodes, the correction is carried out by adding (according to the results of chemical analysis) a concentrate of palladium chloride in ethanolamine (about 100 g of palladium chloride mixed with 170 cm of ethanolamine and 170 cm of water). Trilon B is injected into the electrolyte at a rate of 1 g / l after each correction for palladium, as well as in the case of peeling of the precipitate.

The freshly prepared electrolyte is worked out on a stepped cathode at a current density of 0 A / dm to obtain a quality precipitate. Then, the previously prepared parts are immersed in a drum and palladating is carried out at a current density of 1-0.3 A / dm, a temperature of 20-30 ° C and a pH of 8.0-8.5 to obtain the required coating thickness (3 µm). After palladating, the parts are washed thoroughly with running and distilled water and dried.

50 The palladium concentration in the electrolyte and the current density during deposition are interrelated. Their boundary values are governed by the deposition rate and the quality of the resulting

55 of the coating, so when the current density (Dk) is greater than 0.3 A / dm, the heating of the coating occurs, and when Dk is equal to O, 1 A / dm, the quality deteriorates.

coating and decreases the deposition rate.

The minimum concentration of palladium is 10 g / l, at lower concentrations, the quality of the osaka deteriorates and the deposition rate decreases. At a palladium concentration of more than 30 g / l, the quality of the precipitate does not improve and the deposition time does not decrease, but the loss of palladium due to electrolyte entrainment is increased, as well as the electrolyte viscosity increases.

The ethanolamine concentration in the electrolyte is limited by the amount of ethanolamine stoichiometrically needed to create the complex (for the concentration of palladium 10-ЗП g / you need 35-105 g / l of ethanolamine and to bring the electrolyte to a pH of 8-8.5 10-30. G / l ethanololine ).

Ammonium sulfate is added to the electrolyte in order to obtain shiny coatings. The introduction of more than 30 g / l is impractical because it does not affect the quality of the sediment.

The introduction of Trilon B into the electrolyte allows to obtain well-coupled palladium deposits in the presence of an impurity of zinc ions (do not peel off at bending to fracture), eliminating their influence on the palladium electroplating process by bonding to the complex more stable than with palladium ions at pH 8- 8.5.

In order to obtain qualitatively coherent precipitation in the presence of zinc impurity in the electrolyte, 0.03 g / l of zinc impurity (the amount of zinc ions at which coatings with low-quality

clutch) requires 0.5 g / l of Trilon B (minimum quantity); 2.0 g / l is the amount of Trilon B, which guarantees high-quality coating.

at the maximum possible contamination of the electrolyte with zinc ions between the corrections, while observing the deposition technology. The introduction of Trilon B in a more significant concentration is impractical due to the increase in the cost of the electrolyte and the change in the electrochemical parameters of the deposition of palladium.

Table 1 shows several

compositions of the proposed electrolyte, in table 2 - their properties.

Thus, by replacing saccharin with trilon B, non- disappears. The study of electrolyte processing increases the duration of the disease, the scattering and the ability of the electrolyte.

Table 1

table 2

electrolyte pH

2

Current density A / dm

Duration, min

Current output,%

8.2

0.3

40

94

Total reflectivity,%

Microhardness, kg / mm

Osa deni speed,

µm / min

594214,

Continuation of table 2

70 70 165 165

4.5

4.5

Claims (1)

PALLADIROV ELECTROLYTE - NII, containing the complex salt of palladium, ethanolamine, ammonium sulfate and an organic additive, characterized in that, in order to increase the adhesion of the coating to the base, stability, dissipation and hiding power of the electrolyte when palladium-plating brass parts in tubs of drum and bell types, in as an organo-organic supplement, it contains Trilon B, in the following ratio of components, g / l: Complex salt of palladium (in terms of metal) 10-30 Ethanolamine (97%) Ammonium Sulfate Trilon B 50-160 20-30 0.5-2.0 <594214 2