RU2362843C1 - Electrolyte for sedimentation of composition coating nickel-cobalt-diamond - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to electrolytic metallurgy field and can be used in different fields of industry. Electrolyte contains, g/l: nickel chloride 200-350, cobalt sulphate 8-12, boric acid 25-40, chloramine "Б" 1.5-4.5, superdispersed adamantine suspension 0.1-2.3.

EFFECT: increasing of coatings microhardness.

2 tbl, 1 ex

Description

The invention relates to the field of electroplating, in particular to the deposition of a composite coating of Nickel-cobalt-diamond, with the aim of using them in various industries as coatings with high microhardness. The higher the microhardness, the higher the reliability and durability of products and the wider the scope of their application.

Known electrolytes for applying alloys and composite coatings based on nickel in order to obtain coatings with increased microhardness of the following composition, g / l:

1. Nickel or cobalt sulfate or sulfamate 100-250, nickel chloride 15-20, boric acid 15-20, anionic polyhedral borate salt of the general formula M _z C _n B _m H _x (where M is sodium, potassium or ammonium, z = 1, n = 0, 2, m = 3, 9, 10, 12, x = 8, 10, 12) 0.03-0.45 (AS USSR No. 1129974, 1981);

2. nickel or cobalt chloride 10-20, nickel or cobalt sulfamate 50-200, boric acid 25-30, an alkyl derivative of borate of the general formula C ₂ B ₉ H ₁₂ NH _n R _m (where R is alkyl, n = 0, 1, 2, 3, m = 1, 2, 3, 4) 0.5-4.0 (A.S. USSR No. 527488, 1974);

3. Nickel chloride 60, nickel sulfate 300, boric acid 30, Cr ₂ O ₃ 100 (TiO ₂ 25, TiC 50) (Sayfullin RS Composite coatings and materials. - M .: Chemistry, 1977. - 272 p. );

4. Nickel chloride 200-300, boric acid 20-30, salt of anionic polyhedral borate (in terms of C ₂ B ₉ H ₁₂ ^2- , B ₁₀ H ₁₀ ^2- , B ₁₂ H ₁₂ ^2- ) 0.5-1 , 0, alcohols of the series 2,2,6,6-tetramethylpiperidine 0.2-0.9, hydrochloric acid or ammonium hydroxide (35%) to pH 1-5 (Kukoz F.I., Kudryavtseva I.D., Kudimov Yu.I., Sysoev G.I., Svitsyn R.A., Balakai V.I. Electrolyte for coating deposition with nickel-boron alloy - A.S. 1387528 USSR, MKI C25D 3/56. - No. 4001609 / 31- 02; claimed 02.01.86; publ. 08.12.87).

However, coatings deposited from these electrolytes have insufficient wear resistance.

Closest to the proposed invention relates to an electrolyte for the deposition of an alloy of Nickel-boron-diamond of the following composition, g / l:

nickel chloride hexahydrate 200-300 boric acid 20-25 ammonium sulfate 10-40 saccharin 0.6-1.5 decahydrodecaborane sodium (TU 6-02-01-513-86) 0.3-3.6 ultrafine diamond suspension (UDA-V TU 84.1124-87) 0.05-1.2.

The cathodic current density is 1-5 A / dm ² , pH 1.0-4.5, temperature 18-25 ° С (Degtyar L.A., Kudryavtseva I.D., Kukoz F.I., Sysoev G.N. Composite electrochemical coating. - AS USSR 2048573, MKI C22C 19/03, 26/00, C25D 15/00. - No. 5020525/02; decl. 03.01.92; publ. 11.02.95, Bull. No. 32. - 3 p.).

Coatings deposited from this electrolyte have insufficient microhardness.

The task of the invention is to increase microhardness.

This object is achieved by the fact that cobalt sulfate is additionally introduced into the electrolyte containing nickel chloride, ultrafine diamond suspension, boric acid, chloramine B in the following ratio of components, g / l:

nickel chloride hexahydrate 200-350 cobalt sulfate 8-12 boric acid 25-40 chloramine B 1,5-4,5 ultrafine diamond suspension (UDA-V TU 84.1124-87) 0.1-2.3.

Electrolysis modes: pH 1.1-5.0, temperature 18-40 ° C, cathodic current density 0.5-14.0 A / dm ² with stirring.

The presence of cobalt sulfate in the electrolyte makes it possible to electrodeposit a nickel-cobalt-diamond composite coating with high microhardness.

Example 1. The electrolyte was prepared as follows. In an electrolytic bath filled to 3/4 of the required volume with tap water, at a temperature of 60-70 ° C, 25 g / l of boric acid, 1.5 g / l of chloramine B, 150 g / l of nickel chloride hexahydrate and 8 g / l were dissolved cobalt seven-water sulfate, after the electrolyte level was adjusted to the required volume, 7 g / l of ultrafine diamond suspension was introduced. The pH of the electrolyte was adjusted either with hydrochloric acid or with sodium or potassium hydroxide (100-150 g / l).

The preparation of the remaining electrolytes, including the average, upper and foreign concentrations of the components, which are given in table 1, was carried out according to the method described above. And the microhardness values of the coatings deposited from each electrolyte are given in Table 2, respectively.

Comparative operational characteristics of electrolytes and physicomechanical properties of composite coatings nickel-cobalt-diamond and nickel-boron-diamond are given in Table 2.

The boundary concentrations of the electrolyte components are selected for the following reasons:

1. an increase in the nickel content in the electrolyte above the upper claimed limit is impractical due to the limiting solubility of nickel chloride, a decrease in the dissipation ability and stability of the electrolyte, deterioration in the quality of coatings, an increase in nickel consumption due to entrainment of the electrolyte together with parts;

Table 1 Electrolyte Compositions and Electrolysis Modes The composition of electrolytes and modes of electrolysis The concentration of components, g / l one 2 3 four 5 prototype Nickel chloride hexahydrate 150 200 280 350 370 250 Cobalt sulfate 6 8 10 12 fifteen - Boric acid twenty 25 32 40 45 thirty Chloramine B 1,0 1,5 3.0 4,5 5,0 - Saccharin - - - - - one Ammonium sulfate - - - - - 25 Decahydrodecaborane sodium (TU 6-02-01-513-86) - - - - - 1.9 Ultrafine diamond suspension (UDA-V TU 84.1124-87) 0.05 0.1 1.7 2,3 2.5 0.6 pH electrolyte 5.7 5.5 3.0 1,1 1,0 2.7 Temperature ° C 16 eighteen thirty 40 45 21 Cathode current density, A / dm ² four 6 9 fourteen 13 3

table 2 Physico-mechanical properties of coatings Nickel-cobalt-diamond and nickel-boron-diamond electrolyte and composite coating characteristics Electrolytes one 2 3 four 5 prototype Microhardness, GPa 22 25 29th 27 23 23 Internal stress, MPa 58.3 59.0 61.2 64,4 69.3 - Porosity at a thickness of 4-5 μm, pore / cm ² 0 one one 2 four - Adhesion to the core of steel, copper and its alloys Meets GOST 9.302-84 The content of boron, wt.% - - - - - 1,6 The cobalt content, wt.% one, 2.1 5.7 7.3 7.6 - The content of ultrafine diamond powder, wt.% 0.1 0.4 1.8 3.2 3.6 1.3 Stability% one hundred one hundred one hundred one hundred one hundred one hundred

2. a decrease in the nickel content in the electrolyte below the lower claimed limit leads to a decrease in the process speed, a decrease in current efficiency, and a deterioration in the quality of the deposited coating;

3. an increase in the cobalt content in the electrolyte above the upper claimed limit leads to a decrease in the wear resistance of the coatings;

4. a decrease in the nickel content in the electrolyte below the lower claimed limit leads to a decrease in the wear resistance of the coatings;

5. an increase in the content of boric acid in the electrolyte above the upper claimed limit is impractical. This is due to the solubility limit of boric acid and the deterioration of the quality of the coatings and a decrease in the wear resistance of the coatings;

6. a decrease in the content of boric acid below the lower limit of the indicated concentration leads to a decrease in the buffer capacity of the electrolyte, a decrease in current efficiency, electrolyte operation intervals, deterioration in the quality of coatings and a decrease in the wear resistance of coatings;

7. an increase in the content of chloramine B above the upper claimed limit leads to a deterioration in the quality of coatings, an increase in internal voltages, a decrease in current efficiency and the maximum allowable cathodic current density;

8. a decrease in the content of chloramine B below the lower claimed limit leads to a deterioration in the quality of coatings, an increase in internal stresses;

9. an increase in the content of ultrafine diamond suspension above the upper claimed limit leads to a deterioration in the quality of coatings and a decrease in the wear resistance of coatings, an increase in internal stresses, a decrease in current efficiency, and a maximum permissible cathodic current density;

10. The decrease in the content of ultrafine diamond suspension below the lower claimed limit leads to a decrease in the wear resistance of the coatings.

As can be seen from table 2, the wear resistance of the composite coating of Nickel-cobalt-diamond deposited from the inventive electrolyte exceeds the wear resistance of the Nickel-boron-diamond alloy deposited from the prototype, 1.2-1.3 times while maintaining the basic physical and mechanical properties coatings.

This allows you to expand the scope of the Nickel-cobalt-diamond composite coating as a wear-resistant coating in mechanical engineering.

Claims (1)

The electrolyte for the deposition of a composite coating of Nickel-cobalt-diamond containing Nickel chloride, boric acid, ultrafine diamond suspension and water, characterized in that it additionally contains cobalt sulfate and chloramine B in the following ratio, g / l:
nickel chloride hexahydrate 200-350 cobalt sulfate 8-12 boric acid 25-40 chloramine B 1,5-4,5 ultrafine diamond suspension 0.1-2.3