RU2457287C1 - Electrolyte for deposition of nickel-bismuth alloy - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: electrolyte for deposition of coatings by nickel-bismuth alloy contains, g/l: nickelous chloride 40-60, nickelous bismuth 5-15, trilon B 50-60, boric acid 20-30, leveller A 2-4, distilled water to get the working volume.

EFFECT: increase of electrolyte dissipating ability and increase of coating corrosion resistance.

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Description

The invention relates to the field of electroplating, in particular to electrolytic deposition of a nickel-bismuth alloy.

Known electrolyte for the deposition of an alloy of Nickel-bismuth, containing Nickel sulfate, bismuth chloride and Trilon B [1].

The scattering capacity of this electrolyte, measured in the Field cell, is 45-50%, and the corrosion rate of the resulting coatings in a 0.1 n sulfuric acid solution is 2.6-4.59 g / m ² · h.

The task to which the claimed technical solution is directed is to develop an electrolyte composition with improved properties.

When implementing a technical solution, the problem is solved by achieving a technical result, which consists in increasing the dissipating ability of the electrolyte and increasing the corrosion resistance of the resulting precipitation.

The proposed electrolyte differs from the known one in that, in addition to the salts of nickel and bismuth and trilon B, it contains boric acid and an equalizer A (benzenesulfate methyldiethylaminomethyl alkyl phenol polyglycol ether) in the following ratio of components, g / l:

- nickel chloride 40-60; - bismuth chloride 5-15; - trilon B 50-60; - boric acid 20-30; - equalizer A 2-4.

An additional introduction of boric acid contributes to an increase in the electrical conductivity of the solution and its buffering properties, and also improves the uniformity of the distribution of metal at the cathode. The surface-active non-ionic substance equalizer A, adsorbed on the cathode, inhibits the recovery of metal ions, while improving the wettability of the surface of the sediment. Trilon B binds bismuth and nickel ions to very strong trilonate complexes (log β _{Bi EDTA} = 27.90 and log β _{Ni EDTA} = 18.64), which prevents the hydrolysis of salts and improves the stability of the electrolyte.

The electrolyte is prepared by dissolving bismuth salts, nickel salts and trilon B in separate portions of water. A portion of trilon B is added with stirring to the bismuth salt solution, and the other half of the complexon is added to the nickel salt solution. The mixture of solutions is left for 10-15 minutes for complete complexation, and then slowly (with vigorous stirring) a nickel complexonate solution is added to the bismuth complexonate solution. Boric acid and equalizer A are added to the resulting mixture and the electrolyte volume is adjusted to the working water.

The electrodeposition of the coatings is carried out at a cathodic current density of 1.0-5.0 A / dm ² , a temperature of 20-25 ° C and a solution pH of 1.5-2.5 with stirring using a bismuth anode.

Specific examples of the use of electrolyte and some properties of the coatings are shown in table 1.

The dissipating ability of the proposed electrolyte with the introduction of boric acid and equalizer A is increased by 15-20% compared with the known electrolyte. The corrosion rate of coatings deposited from the proposed electrolyte is 1.5-2.0 times less than coatings deposited from a known electrolyte.

The use of the proposed electrolyte allows the deposition of coatings firmly adhered to the steel substrate, which do not peel off from the substrate after heating at 250 ° C for 1 hour and subsequent rapid cooling.

Table 1 No. p / p Electrolyte components, g / l and research results The composition of the examples one 2 3 one Nickel chloride 40,0 50,0 60.0 2 Bismuth chloride 5,0 10.0 15.0 3 Trilon B 50,0 55.0 60.0 four Boric acid 20,0 25.0 30,0 5 Leveler A 2.0 3.0 4.0 6 The current density, A / DM ² 1,0 3.0 5,0 7 Temperature ° C 20,0 22.0 25.0 8 pH 1,5 2.0 2.5 9 Stirring rpm 60.0 60.0 60.0 10 Current output,% 54.0 58.0 64.0 eleven The content of bismuth,% 16,0 19.0 23.0 12 PC electrolyte (by Field),% 55.0 60.0 62.0 13 The corrosion rate, g / (m ² · h) 2.2 1.7 1,5 fourteen Appearance of coatings light gray, matte light, semi-shiny light, smooth, shiny

Literature

1. Povetkin V.V., Ermakova N.A. // Protection of metals. 1985.Vol. 21, No. 4, pp. 643-645.

Claims (1)

The electrolyte for the deposition of the Nickel-bismuth alloy containing Nickel chloride, bismuth chloride, Trilon B, characterized in that it additionally contains boric acid and equalizer A in the following ratio of components, g / l:
nickel chloride 40-60 bismuth chloride 5-15 Trilon B 50-60 boric acid 20-30 equalizer A 2-4 distilled water to working volume