RU2248415C1 - Electrolyte for sedimentation of ferro-chrome alloy - Google Patents

Abstract

FIELD: electrometallurgy.

SUBSTANCE: electrolyte is composed of , in g/l: 30-50 of ferrous sulfate, 60-80 of chromous sulfate, 50-60 of ammonium acetate, 40-50 of complexing versene agent, 40-50 of aluminum sulfate, 20-30 of ascorbic acid, 3-5 of sorbite, and distilled water.

EFFECT: enhanced quality and corrosion protection of coating.

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Description

The invention relates to the field of electroplating, in particular to electrolytic deposition of an alloy of iron-chromium.

Known electrolyte for the deposition of an iron-chromium alloy containing sulfate salts of chromium, iron and ammonium, Trilon B and boric acid [Efimov EA, Chernykh VV // Protection of metals. - 1992. - T.28. No. 3. - S. 481-485]. However, coatings with a low current yield of the alloy (6-24%) and with low corrosion resistance (0.15-0.20 g / m ² · h) are deposited from this electrolyte.

The problem to which the invention is directed, is to obtain galvanic coatings with improved properties.

The problem is solved by achieving a technical result, which consists in improving the quality of coatings by increasing the current yield of the alloy and increasing the corrosion resistance of the coatings.

The specified technical result is achieved by the fact that in the known electrolyte for the deposition of an iron-chromium alloy containing iron sulfate, chromium sulfate, an ammonium compound, complexing agent Trilon B (disodium salt of ethylenediaminetetraacetic acid) and distilled water, the peculiarity is that it additionally contains aluminum sulfate , ascorbic acid and sorbitol, and as an ammonium compound it contains ammonium acetate in the following ratio of components, g / l: iron sulfate - 30-50, sulfur isly Cr - 60-80, ammonium acetate - 50-60, Trilon B - 40-50 aluminum sulphate - 40-50, ascorbic acid - 20-30 Sorbitol - 3-5, distilled water - up to the working volume.

An additional introduction of aluminum sulfate contributes to an increase in the electrical conductivity of the electrolyte solution and its buffering properties, and also improves the uniform distribution of the metal at the cathode.

Ascorbic acid inhibits the oxidation of ferrous ions by oxygen and prevents the accumulation of ferric iron and its hydrolysis products in the electrolyte, which degrade the quality of coatings and reduce the current yield of the alloy. The addition of this acid stabilizes the composition of the electrolyte and increases its stability during electrolysis.

Sorbitol, adsorbed on the cathode, increases the cathodic polarization during iron evolution, grinds the structure and improves the quality of the coatings, reducing the level of internal stresses in them.

Replacing ammonium sulfate with acetic acid increases the buffer properties and stability of the electrolyte, as well as the uniform distribution of the metal at the cathode.

The electrolyte is prepared by dissolving in separate portions of distilled water iron sulfate, chromium sulfate and trilon B. One part of the solution of trilon B is added with stirring to a solution of ferrous sulfate, and the other to a solution of chromium sulfate. Mixtures of the solutions are left for 10-15 minutes for complete complexation, and then a chromium complexonate solution is added slowly to the iron complexonate solution with continuous stirring. Ammonium acetate, aluminum sulfate, aqueous solutions of ascorbic acid and sorbitol are successively added to the resulting mixture, and the volume of the electrolyte is adjusted to the working water.

The electrodeposition of the coatings is carried out at a cathodic current density of 10-50 A / dm ² , at a temperature of 20-25 ° C, pH 1.5-3, with continuous stirring using soluble anodes.

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

The current yield of the alloy from the proposed electrolyte is increased by 20-25% compared with the known electrolyte.

The corrosion rate of coatings obtained from the inventive electrolyte is 1.5-2.0 times less than that of the known electrolyte.

Using the proposed electrolyte allows you to precipitate bright shiny coatings with a low level of internal stresses (0.08-0.12 hPa). Precipitation has good adhesion to the base and does not exfoliate from the base after heating at 250 ° C for an hour and subsequent sudden cooling.

Table Electrolyte components, g / l and research results The composition of the examples 1 2 3 Iron sulfate thirty 40 fifty Chromium sulfate 60 70 80 Ammonium Acetate fifty 55 60 Trilon B 40 45 fifty Aluminum sulfate 40 45 fifty Vitamin C twenty 25 thirty Sorbitol 3 4 5 The current density, A / DM ² 10 thirty fifty Temperature ° C twenty 35 fifty pH 1,5 2,5 3,5 Stirring rpm 60 60 60 Current output,% fifteen 32 39 The content of chromium,% 14 23 26 The corrosion rate, g / m ² · h 0.11 0.09 0.04 Appearance of coatings Light gray shiny Bright shiny Light semi-shiny

Claims (1)

An electrolyte for the deposition of an iron-chromium alloy containing sulfuric acid iron, sulfuric acid chromium, an ammonium salt, complexing agent Trilon B and distilled water, characterized in that it additionally contains aluminum sulfate, ascorbic acid and sorbitol, and as a salt ammonium, it contains acetic acid ammonium in the following ratio of components, g / l: sulfuric acid iron 30-50 sulfuric acid chromium 60-80 acetic acid ammonium 50-60 Trilon B 40-50 aluminum sulfate 40-50 ascorbic acid 20-30 sorbitol 3-5 distilled water to the working volume.