RU2248414C1 - Low-concentration electrolyte for nickel plating - Google Patents

Abstract

FIELD: electrochemistry.

SUBSTANCE: electrolyte is composed of, in g/l: 50-100 of nickel chloride, 30-45 of boric acid, 2-5 of sodium sulfate, 0.5-2.5 of saccharin, and 4-8 of potassium glycol. The electrolyte allows applying glare nickel coatings for high-density currents from low-concentration electrolyte without mixing and forced pumping of the solution at a temperature of 18-40^oC .

EFFECT: enhanced quality of nickel coating.

2 dwg

Description

The invention relates to electrolytic nickel plating, in particular to high-performance low-concentration brilliant nickel plating electrolytes.

Known chloride electrolyte nickel composition, g / l: Nickel chloride 200-300, ammonium acetate 50-75, at a temperature of 20-35 ° C, the cathode density is in the range of 3-10 A / DM ² and the deposition rate of Nickel reaches 2.01 μm / min (A.S. 541901 USSR. Nickel plating electrolyte / M. - N.P. Vayilavichene, R.P. Shirvite, A.I. Bodnevas. - Publ. in BI 1977, No. 1).

In the chloride electrolyte of nickel plating, g / l: nickel chloride 200-275, sodium fluoride 1-2, hydrochloric acid 100-140 at a temperature of 20-25 ° C, the cathodic density is in the range of 20-30 A / dm ² , and the deposition rate nickel reaches 4.3 μm / min (Popilov L.Ya. Tips to a factory technologist. - L .: Lenizdat, 1975. - 264 p.).

In the chloride electrolyte of nickel plating, g / l: nickel chloride 50-350, sodium or potassium sulfate 5-25, chloramine B or saccharin 0.5-2.5, Novokor-N 0.15-9.8 at pH 1, 1 and at a temperature of 60 ° C, the maximum permissible current density reaches 26 A / dm ² , and the nickel deposition rate reaches 4.37 μm / min (Patent 2071996 of the Russian Federation. Aqueous electrolyte of brilliant nickel plating, its variant. V.I. Balakai. - Publ. in BI 1997, No. 2).

In the nickel chloride electrolyte composition, g / l: nickel chloride 200-300, boric acid 25-35, saccharin 0.6-1.2, ammonium fluoride 60-80, 1,4-butynediol 0.3-0.8, tetramethyl glycol 0.5-2.0 at a temperature of 21-25 ° C and an electrolyte pH of 1.0, the maximum permissible cathodic current density reaches 42 A / dm ² and the nickel deposition rate reaches 6.8 μm / min (A.S. 1737024 USSR. Brilliant nickel electrolyte. F.I. Kukoz, I. D. Kudryavtseva, V. I. Balakai, V. I. Mikhailov. - Publ. In BI 1992, No. 20).

However, these electrolytes have low rates of deposition of nickel coatings, and are also mainly highly concentrated.

Closest to the proposed invention in technical essence and the achieved result is a nickel electrolyte of the following composition, g / l:

nickel chloride 50-100

boric acid 25-35

sodium sulfate 2-5

saccharin 0.5-1.5

bottoms of 1,4-butynediol 3-8

ammonium fluoride 20-60

β-alanine 20-40

at a temperature of 21-25 ° C and an electrolyte pH of 1.0, the maximum permissible cathodic current density reaches 62 A / dm ² and the nickel deposition rate reaches 6.61 μm / min (Patent No. 2213810. Low-concentration brilliant nickel plating electrolyte. V.I. Balakai, I.D. Kudryavtseva. - Published in BI 2003, No. 28).

However, this electrolyte has a low current efficiency, is more complex in composition, and has an insufficient rate of deposition of nickel coatings.

The objective of the present invention is to increase the rate of deposition of Nickel coatings of low-concentrated electrolytes without mixing and forced pumping of the electrolyte.

This problem is achieved by the fact that potassium glycolate is additionally added to the nickel electrolyte containing nickel chloride, boric acid, sodium sulfate, saccharin in the following ratio of components, g / l:

nickel chloride 50-100

boric acid 30-45

sodium sulfate 2-5

saccharin 0.5-2.5

potassium glycolate 4-8

Electrodeposition of nickel is carried out at a temperature of 18-40 ° C without stirring and pumping the electrolyte, nickel anodes.

No technical solutions are known in which potassium glycolate would be used as an increase in the rate of deposition of nickel coatings in low concentrated electrolytes.

The order of preparation of the electrolyte: in distilled water, heated to a temperature of 100 ° C, the required amount of boric acid, and then nickel salts, were introduced. Saccharin and potassium glycolate were introduced into the electrolyte at a temperature of 40-60 ° C and the volume and pH were adjusted to the required value. The pH of the electrolyte is adjusted either with hydrochloric acid or with a solution of sodium or potassium hydroxide (100-150 g / l).

The electrolyte is stable in operation. Components are adjusted based on chemical analysis of the electrolyte.

Examples of the compositions of the proposed electrolyte and electrolyte prototype for the deposition of Nickel coatings and deposition modes are shown in table 1.

Boundary concentrations of electrolyte components are determined experimentally.

1. The increase in the content of Nickel chloride above the upper claimed limit is impractical, which is associated with a decrease in the dissipating ability of the electrolyte, an increase in the entrainment of nickel along with the parts after they are coated.

2. The decrease in the content of Nickel chloride below the lower claimed limit leads to a sharp decrease in the rate of deposition of Nickel coatings, the current output of Nickel.

3. An increase in the content of boric acid above the upper claimed limit is impractical, which is associated with the limiting solubility of boric acid.

Table 1
The composition of the proposed electrolyte and electrolyte prototype and electrolysis modes The composition of electrolytes and modes of electrolysis The concentration of components, g / l 1 2 3 4 5 prot. Nickel chloride 40 fifty 75 100 125 100 Boric acid twenty thirty 38 45 46 35 Sodium sulfate 1 2 3,5 5 7 5 Potassium glycolate 2 4 6 8 10 - Saccharin 0.2 0.5 1,5 2,5 3.0 1,5 Ammonium fluoride - - - - - 60 VAT residues of 1,4-butynediol - - - - - 8 β-alanine - - - - - 40 electrolyte pH 2.7 2,5 1.8 1,2 1,0 1,0 Temperature ° C 16 eighteen 29th 40 45 21

4. A decrease in the content of boric acid below the lower claimed limit leads to a decrease in the rate of deposition of nickel coatings, a decrease in current efficiency, and a deterioration in the quality of the deposited coating.

5. An increase in the content of sodium sulfate above the upper claimed limit is impractical, which leads to a decrease in the rate of deposition of nickel coatings.

6. The decrease in the content of sodium sulfate below the lower claimed limit leads to a decrease in the rate of deposition of Nickel coatings.

7. An increase in the content of saccharin above the upper claimed limit is impractical, which is associated with the limiting solubility of chloramine B.

8. A decrease in the saccharin content below the lower claimed limit leads to a deterioration in the quality of the deposited coating.

9. The increase in the content of potassium glycolate above the upper claimed limit is impractical, which is associated with a decrease in current efficiency, deterioration in the quality of the deposited coating.

10. The decrease in the content of potassium glycolate below the lower claimed limit leads to a decrease in the rate of deposition of Nickel coatings and the deterioration of the quality of the deposited coating.

In the table. 2 shows the comparative operational characteristics of electrolytes and the physicomechanical properties of nickel coatings deposited from a low-concentration electrolyte at a temperature of (18–40 ° C), without stirring and circulation of the electrolyte.

table 2
Properties of electrolytes and coatings Characteristics of electrolyte and nickel coatings Electrolytes 1 2 3 4 5 prot. The maximum deposition rate, microns / min 0.3 1,2 3,7 6.94 6.8 6.61 Current output,% 81 87 89 92 86 52 Microhardness, GPa 3.4 3,5 3,7 4.4 4.7 5.2 Porosity at a thickness of 4-5 μm, pore / cm ² 1 1 2 5 8 0 Adhesion to the core of steel, copper and its alloys Meets GOST 9.302-88 The stability of the electrolyte,% 100 100 100 100 100 100

As can be seen from the table. 2, the deposition rate of nickel coatings from a low concentration of chloride electrolyte at a temperature of 18-40 ° C without mixing and pumping of the electrolyte in comparison with the deposition rate of the prototype electrolyte is 1.1 times higher. Physico-mechanical properties of the deposited coatings of the proposed electrolyte are quite high.

Claims (1)

Low concentrated brilliant nickel plating electrolyte containing nickel chloride, boric acid, sodium sulfate, saccharin, characterized in that it additionally contains potassium glycolate in the following ratio of components, g / l: nickel chloride 50-100, boric acid 30-45, sodium sulfate 2-5, saccharin 0.5-2.5, potassium glycolate 4-8.