SU1076499A1 - Sulphate zinc-plating electrolyte - Google Patents

Abstract

SULPHATE ELECTROLYTE GALVANIZING, containing zinc sulphate, sodium sulphate and aluminum sulphate, characterized in that, in order to increase the scattering and leveling capacity of the electrolyte, as well as to increase the plasticity of the resulting zinc coatings, it also contains water-soluble metal nitrate selected from the group including nitrate chromium, thallium nitrate, nickel nitrate and cerium nitrate, in the following ratio of solution components, g / l: Zinc sulfate 230-250 Sodium sulfate .70-80 Aluminum sulfate 25-30 Metal nitrate, with $ 9 you ranny said gruppy0,5-1,0 Io (L

Description

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The invention relates to the galvanic deposition of zinc coatings on a steel base and can be used in the aviation, engineering, radio and other industries.

A zinc sulphate electrolyte containing zinc sulphate, sodium sulphate, aluminum-potassium alum dextrin and brightener U2 and DCU ll is known.

The disadvantages of this electrolyte are low dispersion, increased precipitation strength due to the inclusion of organic additives in zinc coatings, as well as the formation of dark spongy coatings due to decomposition of dextrin.

Closest to the proposed composition is a zinc sulphate electrolyte containing zinc sulphate, sodium sulphate, sulphate, aluminum and dextrin C2.

The disadvantages of the known electrolyte are low scattering and leveling properties, low ductility of the coating, as well as the formation of dark spongy sediments due to decomposition of the organic additive.

The purpose of the invention is to increase the dissipative and leveling ability of the electrolyte, as well as to increase the plasticity of the resulting zinc coatings.

The above objective is achieved in that zinc sulphate electrolyte containing zinc sulphate, sodium sulphate and aluminum sulphate further contains a water-soluble metal nitrate selected from the group including chromium nitrate, thallium nitrate, nickel nitrate and cerium nitrate, at the following component ratio, g / l:

Zinc sulfate 230-250 Sodium sulfate 70-80 Aluminum sulfate 25-30 Metal nitrate selected from the indicated group 0.5-1.0

Electrodeposition of zinc is recommended at a current density of 1-5 A / dm and at room temperature.

The preparation of the electrolyte consists in the sequential dissolution of the components of the solution in distilled water. Metal nitrates are introduced into the prepared electrolyte ..

In tab. 1 shows the chemical compositions of seven electrolytes and their properties.

Table

Cerium nitrate 3.82.5, PI b, A / dm 1-51-5 Deposition rate, µm / hour 14-648-60 Microhardness, CGS / MNf 82,556.3 Porosity, cm 2 Effect of metal nitrates on zinc current (concentration up to. 0.5 g / l, pH 4) are given in table. 2, 4,0 4,02,52,54,2 1-5 1-51-51-51-5 8-56 10-6012-709,6-5612-60 45.9 40.1 - 3- - The zinc current output is determined by the gravimetric method using a copper-20 coulometer.

Known electrolyte (additive dextrin)

table 2

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4.0 The effect of metal nitrates on the dissolving ability (additive concentration 0.5 g / l, pH 4) is given in Table 3 T a l and c - 3

Alignment criterion K; equal to the ratio of the thickness of the cathode sediment in the cavity and on a flat surface. Kg is determined metallographically on thin sections with specially applied grooves D 3 A / dm. The K values shown in the table are an arithmetic average of 5-8 measurements.

The effect of metal nitrates on the stability of the electrolyte is given in Table. five .

iT a. b l and c a 5

Continued table. five

Nickel nitrate

- Cerium Nitrate | Dextrin

(known electrolyte)

The stability test is carried out in a 5 liter bath at a cathode current density of 3 A / dm and 25 ° C. The magnitude of the electrolyte stability is determined by the deterioration of the appearance of cathode deposits. The concentration of metal NIPLETS is 0.5 g / l, dextrin 10 g / l. The acidity index of electrolytes pH 4,

The effect of metal nitrates on the brilliance of cathode precipitates. From galvanized sulfate electrolyte 3 (additive concentration 0.5 g / l, pH 4) is given in Table B.

Table 6

Claims (1)

ZINC SULPHATE ELECTROLYTE, containing zinc sulfate, sodium sulfate and aluminum sulfate, characterized in that, in order to increase the dissipating and leveling ability of the electrolyte, as well as increase the ductility of the obtained zinc coatings, it additionally contains a water-soluble metal nitrate selected from the group including chromium nitrate, thallium nitrate, nickel nitrate and cerium nitrate, in the following ratio of solution components, g / l: Zinc sulfate Sodium sulfate Aluminum sulfate Metal nitrate selected by Hj of said group 230-250 70-80 25-30 s 0.5-1.0 L