RU2489528C1 - Galvanic composite material based on stannum-zinc alloy - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: composite material obtained by means of a galvanic method contains stannum, zinc, plastic fluor at the following component ratio, wt %: plastic fluor 0.09-0.13; stannum 70-83; zinc is the rest.

EFFECT: increasing corrosion resistance of coatings based on stannum-zinc alloy.

2 tbl, 1 dwg, 5 ex

Description

The invention relates to the field of electrochemistry, in particular, electroplating, electrochemical deposition of a composite material based on a tin-zinc alloy, and can be used in mechanical engineering, automotive, marine transport and other industries in order to increase the corrosion resistance of various materials based on tin alloy zinc.

An increase in the corrosion resistance of tin-zinc alloy materials can be achieved by the introduction of non-metal additives.

Known tin-zinc alloys obtained from citrate electrolytes and having:

1. High stability of the chemical composition. (Patent 5118394 (USA), MKI ⁵ C25D 3/32. Electroplating bath ⁺ contaning citric acid or citrate for fin or tin alloy plating / T. Makino, A. Maeda. (USA) - Application 05.12.90; Publ. 06/12/92. Bull. No. 31);

2. The uniform surface structure. (Patent 4168223 (USA), С25D 3/32, С25D 3/60. Electroplating bate for depositing tin or tin alloy with brightness / S.Jgarashi, F. Goshikaru, T.Jgarashi. (USA). - Application. 15.11.78 ; Published on February 18, 79. Bull. No. 15).

A significant disadvantage of these alloys is that the corrosion resistance is insufficient.

Closest to the alleged invention in technical essence is a tin-zinc alloy of the following composition, wt.%:

tin 70-83; Zinc rest.

(Denisenko E.A., Selivanov V.P., Tokareva A.V., Kutyrev I.M., Balakay V.I., Levitskaya S.V. Low-concentrated electrolyte for applying a semi-shiny coating with tin-zinc alloy. Patent 2313621, RU, IPC C25D / 60, Bull .. No. 36, publ. 12/27/91).

However, this alloy has insufficient corrosion resistance.

The task of the invention is to increase the corrosion resistance of a material based on a tin-zinc alloy doped with fluoroplastic.

The task is achieved by obtaining a composite material of the tin-zinc-fluoroplastic alloy (fluoroplastic is introduced into the electrolyte in the form of a fluoroplastic emulsion (FE) F-4D-E (TU 6-05-041-508-79)) with the following ratio of components, wt.% :

ftoroplast 0.09-0.13; tin 70-83; zinc rest.

The presence of fluoroplastic in the tin-zinc-fluoroplastic composite material leads to an increase in its corrosion resistance due to the introduction of fluoroplastic into the coating and changes in its structure, which is confirmed by studies using structural electron microscopy (CEM) (Fig. 1) and X-ray electron microscopy ( SEM).

It was found that the inclusion of dispersed particles of 0.2-0.3 μm fluoroplastic in the coating leads to structural changes in the metal matrix of the tin-zinc alloy (Fig. 1b). The mass fraction of fluorine according to SEM in the inventive composite material based on a tin-zinc alloy is 0.11 wt.%.

The increase in the content of fluoroplastic above the upper claimed limit leads to an increase in internal stresses, deterioration in quality and lower corrosion resistance of the composite material.

A decrease in the fluoroplastic content in the alloy below the lower claimed limit leads to a decrease in the corrosion resistance of the composite material.

To test the proposed composition of the tin-zinc-fluoroplastic alloy composite material, compositions were obtained whose chemical composition is given in Table 1, where 2, 3, 4, the fluoroplastic content at the lower, middle, and upper levels, respectively, and 1 and 5 the fluoroplastic content in the composition beyond the boundary values.

The composite material of the tin-zinc-fluoroplastic alloy was obtained by the electrochemical method from an electrolyte of the following composition, mol / l:

tin sulfate 0.08-0.09; zinc sulfate 0,065-0,085 lemon acid 0.31-0.33; sodium citrate 0.65-0.68, OS-20 g / l 0.70-0.80; diphenylamine g / l 0.20-0.32; F-4D-E (TU 6-05-041-508-79) g / l 0.25-0.30.

Electrolysis modes: pH 6.0-6.5, temperature 18-20 ° C, cathodic current density 1.0-4.5 A / dm ² , without stirring.

Table 1 The composition of the tin-zinc-fluoroplastic alloy composite material and the tin-zinc alloy prototype, wt.% Composite material and prototype Ftoroplast Zinc Tin one 0,07 31.93 68 2 0.09 29.91 70 Suggested 3 0.11 22.89 77 four 0.13 16.87 83 5 0.15 14.85 85 Prototype - 23 77

Example 1. Composite material of chemical composition, wt.%: Fluoroplastic 0.07, tin 68, the rest zinc, precipitated from the electrolyte composition, mol / l: tin sulfate 0.07, zinc sulfate 0.055, citric acid 0.30, sodium citrate 0.60, OS-20 preparation 0.65 g / l, diphenylamine 0.15 g / l, PE 0.2 g / l at pH 5.0, temperature 15 ° C and cathodic current density 0.5 A / dm ² . The electrolyte was prepared as follows: zinc sulfate was dissolved in a small amount of water, and then introduced into sodium citrate solution. Tin sulfate was dissolved directly in a solution of citric acid. Then, the resulting solutions were poured with thorough stirring, and diphenylamine, an OS-20 preparation, dissolved previously in water and PE, were added. After that, the volume of electrolyte was adjusted to a predetermined value and its pH was adjusted.

Example 2. Composite material of chemical composition, wt.%: Fluoroplastic 0.09, tin 70, the rest zinc, precipitated from the electrolyte composition, mol / l: tin sulfate 0.08, zinc sulfate 0.065, citric acid 0.31, sodium citrate 0.65, preparation OS-20 0.70 g / l, diphenylamine 0.20 g / l, PE 0.25 g / l at pH 6.0, temperature 18 ° C and cathodic current density 1.0 A / dm ² . The electrolyte was prepared according to the method described above.

Example 3. Composite material of chemical composition, wt.%: Fluoroplastic 0.11, tin 77, the rest of the zinc, precipitated from the electrolyte composition, mol / l: tin sulfate 0.085, zinc sulfate 0.075, citric acid 0.32, sodium citrate 0, 67, the preparation OS-20 0.75 g / l, diphenylamine 0.26 g / l, PE 0.26 g / l at a pH of 6.2, a temperature of 19 ° C and a cathodic current density of 2.8 A / dm ² . The electrolyte was prepared according to the method described above.

Example 4. Composite material of chemical composition, wt.%: Fluoroplastic 0.13, tin 83, zinc the rest, precipitated from the electrolyte of the composition, mol / l: tin sulfate 0.09, zinc sulfate 0.085, citric acid 0.33, sodium citrate 0.68, OS-20 preparation 0.80 g / l, diphenylamine 0.32 g / l, PE 0.3 g / l at pH 6.5, temperature 20 ° C and cathodic current density 4.5 A / dm ² . The electrolyte was prepared according to the method described above.

Example 5. Composite material of chemical composition, wt.%: Fluoroplastic 0.15, tin 85, zinc, the rest, precipitated from the electrolyte composition, mol / l: tin sulfate 0.1, zinc sulfate 0.95, citric acid 0.4, sodium citrate 0.75, preparation OS-20 0.9 g / l, diphenylamine 0.37 g / l, PE 0.4 g / l at pH 7.0, temperature 25 ° C and cathodic current density 5.0 A / dm ² . The electrolyte was prepared according to the method described above.

The prototype is a tin-zinc alloy of chemical composition, wt.%: Tin 77, zinc the rest was precipitated from the electrolyte composition, mol / l: tin sulfate 0.09, zinc sulfate 0.08, citric acid 0.33, sodium citrate 0.67 , the drug OS-20 0.84 g / l, diphenylamine 0.3 g / l, at a pH of 6.2, a temperature of 19 ° C and a cathodic current density of 2.7 A / DM ² . (Denisenko E.A., Selivanov V.N., Tokareva A.V., Kutyrev I.M., Balakai V.I., Levitskaya S.V. Low-concentration electrolyte for applying a semi-brilliant coating with tin-zinc alloy. Patent 2313621, RU, IPC C25D / 60, Bull. No. 36, publ. 27.12.91).

Physico-mechanical properties of the proposed composite material of the tin-zinc-fluoroplastic alloy and the prototype tin-zinc alloy are shown in table 2.

As can be seen from table 2, the corrosion resistance of the composite material of the tin-zinc-fluoroplastic alloy deposited from the inventive electrolyte No. 3 exceeds the corrosion resistance of the tin-zinc alloy (prototype) by 1, 2 times.

table 2 Corrosion resistance of the proposed tin-zinc-fluoroplastic alloy composite material and tin-zinc alloy prototype Physico-mechanical properties of the tin-zinc-fluoroplastic composite material and the tin-zinc alloy prototype The proposed composition one 2 3 four 5 prototype Corrosion resistance (corrosion rate), m ² / h 4.45 4.30 4.20 4.23 4.41 4.95 Microhardness, MPa 150 145 110 106 105 117 Adhesion to the base of steel, copper and its alloys Meets GOST 8.302-88 The content of fluoroplastic in the coating, wt.% 0,07 0.09 0.11 0.13 0.15 - The tin content in the alloy, wt.% 68 70 77 83 85 77

Claims (1)

A galvanic composite material based on a tin-zinc alloy, characterized in that it additionally contains fluoroplastic, in the following ratio of components, wt.%:
ftoroplast 0.09-0.13 tin 70-83 zinc rest

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