RU2411308C2 - Nanomodified electrolyte for electrochemical deposition of nickel coating - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: nanomodified electrolyte for electrochemical deposition of nickel coating contains nickel salts - nickel heptahydrate sulfate and nickel hexahydrate chloride, boron-containing additive and water, at the same time it additionally contains carbon nanomaterial with number of graphen layers of not more than 30, diametre of fibres from 10 to 60 nm, length of at least 2 mcm and quantity of structured carbon of at least 95%, at the following ratio of components, g/l: nickel heptahydrate sulfate - 250-400, nickel hexahydrate chloride - 50-70, boric acid 30-40 and nanocarbon material - 0.05-0.08.

EFFECT: production of pore-free nickel coatings with high microhardness with increased speed of nickel coating deposition.

2 cl, 2 ex

Description

The invention relates to the field of electrochemical deposition of metal coatings, in particular nickel, and can be used to obtain a corrosion-resistant, hard, heat- and wear-resistant coating in mechanical engineering, electronics and other industries.

Known electrolyte for electrochemical deposition of multifunctional coatings based on nickel [1], containing nickel salts - nickel sulfate and nickel chloride, saccharin, boron-containing and buffering additives in the form of sodium decahydroborate and malonic acid, sodium fluoride, formaldehyde, paratolum sulfate 102 and water. Such an electrolyte is characterized by the following ratio of components, g / l:

Nickel sulfate heptahydrate - 300-400

Nickel chloride chloride - 20-40

Saccharin - 0.5-1.0

Sodium Decahydroborate - 0.01-0.5

Malonic acid - 25-30

Sodium fluoride - 3.5-4.5

Formaldehyde - 0.5-1.2

Paratoluenesulfamide - 1.0-1.5

Wetting agent SV-102 - 0.01-0.05.

The disadvantages of this electrolyte are:

- a large number of components, which complicates the preparation of the electrolyte and makes it impossible to reinforce it when it is depleted;

- low microhardness of the resulting coating;

- large unevenness of the resulting coating.

These disadvantages are partially eliminated in the electrolyte for electrochemical deposition of the nickel-boron alloy [2]. The electrolyte contains, g / l:

Nickel sulfate heptahydrate - 280-400

Nickel Dichloride - 25-60

Boric acid - 25-60

1.4 Butindiol - 0.2-1.5

Formaldehyde - 0.02-1.5

Sodium saccharin - 0.25-2.0

Sodium borohydride - 0.1-2.0.

This composition allows you to expand the working pH range and increase the deposition rate of coatings, reduce the number of components, however, it is characterized by the following disadvantages:

- low microhardness of the resulting coating;

- large unevenness of the resulting coating.

The technical result of the invention is to obtain non-porous nickel coatings with high microhardness while increasing the deposition rate of the Nickel coating.

The technical result is achieved by the fact that a nanomodified electrolyte for electrochemical deposition of a nickel coating containing nickel salts of heptahydrate nickel and hexavalent nickel chloride, a boron-containing additive and water, according to the invention, additionally contains carbon nanomaterial with no more than 30 graphene layers, fiber diameter from 10 up to 60 nm, a length of at least 2 microns and a structured carbon amount of at least 95%, with the following ratio of components, g / l:

Nickel sulfate heptahydrate - 250-400

Nickel chloride chloride - 50-70

Boric acid 30-40

Nanocarbon material - 0.05-0.08.

A nano-modified electrolyte may contain nanocarbon material introduced into the electrolyte without purification from the nickel catalyst used for its synthesis in an amount of 0.05-0.08 g / l.

Such an electrolyte is characterized by a smaller number of components used, and when using carbon nanomaterial without purification from the nickel catalyst, lower financial costs, since the nanomaterial is not treated with nitric acid to remove the catalyst.

The electrolyte is prepared as follows.

Pre-nickel salts are dissolved separately in distilled water at a temperature of 40-60 ° C. Boric acid is also dissolved separately in distilled water at a temperature of 75-80 ° C.

All solutions are mixed and settled for 7 days. The prepared solution is decanted into an intermediate container. From the intermediate container, the solution is filtered under vacuum through filter paper. To remove organic compounds, 10 g / L of 6% hydrogen peroxide is added to the electrolyte heated to 30 ° C. The electrolyte is stirred vigorously for 10 minutes. At the same temperature and vigorous stirring, 3 g / L of activated carbon is added to the electrolyte. The electrolyte is left to stand for 12 hours, then decanted and filtered under vacuum through filter paper. After that, a nanocarbon material with a number of graphene layers of not more than 30, a fiber diameter of 10 to 60 nm, a length of at least 2 μm and a quantity of structured carbon of at least 95% is added to the electrolyte solution, and the electrolyte is processed on an ultrasonic unit with a frequency of 22 kHz to reduce sizes of agglomerates from nanocarbon tubes and their more uniform distribution in the electrolyte. As a carbon material, it is preferable to use carbon nanomaterial “Taunit”, a manufacturer of carbon nanomaterial LLC “NanoTechCenter”, Russia, Tambov.

The surface preparation of the parts before plating is carried out by standard methods using known solutions.

Precipitation is carried out at a pH of 3.0-5.0, a current density of 1.0-4.0 A / dm ² and a temperature of 45-60 ° C.

Example 1

The electrochemical deposition of the coating on a previously prepared surface of the base from a steel St3 material is carried out in an electrolyte containing (in g / l)

Nickel sulfate seven-water - 254.6

Nickel chloride chloride - 67.5

Boric acid 32.33

Nanocarbon material - 0.065.

Precipitation is carried out at a pH of 3.5, a current density of 4 A / DM ² and a temperature of 52 ° C.

Within 50 min receive a coating of an average thickness of 16 microns.

The resulting coating is non-porous and fairly evenly distributed over the surface of the part. The microhardness measured on the PMT-3 microhardness meter is 1123 kg / mm ² . The characteristics of the resulting coating - microhardness and porosity - correspond to the characteristics of chromium coatings, and the uniformity of the resulting coating is significantly superior to chromium. This allows you to use the proposed electrolyte in mechanical engineering instead of chromium electrolyte, which is more expensive, highly toxic and has low dissipation ability and current efficiency.

Example 2

The electrochemical deposition of the coating on a previously prepared surface of the base from a steel St3 material is carried out in an electrolyte containing (in g / l)

Nickel sulfate seven-water - 254.6

Nickel chloride chloride - 67.5

Boric acid 32.33

Nanocarbon material “Taunit” with the following characteristics:

the number of graphene layers is not more than 30,

fiber diameter - from 15 to 40 nm,

length - not less than 2 microns,

the amount of structured carbon is not less than 95%,

crude nickel catalyst - 0.07.

Precipitation is carried out at a pH of 3.5, a current density of 4 A / DM ² and a temperature of 52 ° C.

Within 50 min receive a coating of an average thickness of 43 microns.

The resulting coating is non-porous and fairly evenly distributed over the surface of the part. The microhardness measured on the PMT-3 microhardness meter is 1009 kg / mm ² . The characteristics of the resulting coating - microhardness and porosity - correspond to the characteristics of chromium coatings, and the uniformity of the resulting coating is significantly superior to chromium. This allows you to use the proposed electrolyte in mechanical engineering instead of chromium electrolyte, which is more expensive, highly toxic and has low dissipation ability and current efficiency. In addition, the use of Taunit nano-carbon material, which is not purified from a nickel catalyst, leads to a significant (2.6-fold) increase in the deposition rate of the coating, which increases the productivity of galvanic equipment.

Literature

1. RF patent No. 2149927, IPC C25D 3/56, 2000

2. RF patent No. 2265086, IPC C25D 3/56, 2005

Claims (2)

1. Nanomodified electrolyte for electrochemical deposition of a nickel coating containing nickel salts - nickel sulfate and nickel chloride, boron-containing additive and water, characterized in that it additionally contains carbon nanomaterial with no more than 30 graphene layers, fiber diameter from 10 to 60 nm, a length of at least 2 microns and a structured carbon amount of at least 95% in the following ratio of components, g / l:
Nickel sulfate 250-400 Nickel chloride chloride 50-70 Boric acid 30-40 Nanocarbon material 0.05-0.08 2. The nano-modified electrolyte according to claim 1, characterized in that the nanocarbon material is introduced into the electrolyte without purification from the nickel catalyst used for its synthesis in an amount of 0.05-0.08 g / l.