RU2410474C2 - Electrolyte for deposition of bismuth-gallium alloy - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to electroplating, in particular, to electrolytic deposition of bismuth-gallium alloy. Proposed electrolyte comprises, in g/l: bismuth chloride - 30-40, gallium chloride - 1-5, ammonium chloride - 20-30, trilon B 35-45, equaliser A 1.5-2.5.

EFFECT: uniform and smooth coats with high micro hardness and corrosion resistance.

1 tbl, 3 ex

Description

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

Known electrolyte for the deposition of a bismuth-gallium alloy containing bismuth and gallium salts, tartaric acid, ammonium chloride and gelatin [1]. However, loose, thin coatings with low microhardness (30-35 MPa) and low corrosion resistance (2.5-2.9 g / m ² · h) of 0.1 N are deposited from the indicated electrolyte. sulfuric acid solution.

The objective of the claimed invention is to increase the microhardness and corrosion resistance of the resulting coatings.

The proposed electrolyte differs from the known one in that, in addition to the chloride salts of bismuth, gallium and ammonium, it contains Trilon B (disodium salt of ethylenediaminetetraacetic acid), and as an additive to surfactants, it is equalizer A (benzenesulfatemethyldiethylaminomethyl polyglycol ether of alkylphenol) in the following ratio of components, g / l

- bismuth chloride - 30-40;

- gallium chloride - 1-5

- ammonium chloride - 20-30;

- Trilon B - 35-45

- equalizer A - 1.5-2.5.

Trilon B binds bismuth and gallium ions into very strong trilonate complexes (logβ _Bi-EDTA = 27.9 and logβ _Ga-EDTA = 20.27), which prevents the hydrolysis of salts and improves the stability of the electrolyte.

Surfactant - equalizer A, adsorbed on the cathode, inhibits the recovery of metal ions, while improving the wettability of precipitation.

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

The electrodeposition of the coatings is carried out at a cathodic current density of 1-3 A / dm ² , at a temperature of 20-25 ° C, pH 1.5-2.5, with stirring using a bismuth anode.

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

Table 1 The electrolyte compositions and properties of the resulting coatings Electrolyte components (g / l) and research results The composition of the examples one 2 3 Bismuth chloride thirty 35 40 Gallium chloride one 3 5 Ammonium chloride twenty 25 thirty Trilon B 35 40 45 Leveler A 1,5 2.0 2.5 The current density, A / DM ² one 2 3 Temperature ° C 20,0 22.5 25.0 Mixing, rpm 60 60 60 pH 1,5 2.0 2.5 Current output,% 98 97 95 The gallium content in the alloy,% 0.6 1,1 2.1 Microhardness, MPa 41 45 48 The corrosion rate, g / (m ² · h) 2.0 1.8 1,6 Appearance of coatings Gray matte Light gray, semi-shiny Light, smooth, shiny

The corrosion rate of coatings obtained from the proposed electrolyte is 1.2-1.7 times less than coatings from a known electrolyte. In addition, the use of the proposed electrolyte by 15-20% strengthens the resulting coatings compared with coatings deposited from a known solution.

Using the proposed electrolyte allows you to precipitate light, shiny, non-porous coatings at higher current densities. Precipitation has good adhesion to the copper base and does not exfoliate from the base after heating at 250 ° C for one hour and subsequent sudden cooling.

Information sources

1. Cooper V.V. and others. Results of science and technology. Electrochemistry, v.16. - M.: VINITI, 1980, p. 49.

Claims (1)

An electrolyte for the deposition of a bismuth-gallium alloy containing bismuth, gallium, ammonium chloride salts, a complexing agent and a surfactant additive, characterized in that it contains trilon B as a complexing agent and equalizer A as a surfactant in the following ratio of components g / l:
bismuth chloride 30-40 gallium chloride 1-5 ammonium chloride 20-30 Trilon B 35-45 equalizer A 1.5-2.5