SU863723A1 - Electrolyte for precipitating lead-tin alloy coatings - Google Patents

Description

(54) ELECTROLYTE FOR DEPOSITING COATINGS FROM LEAD-TIN ALLOYS

The invention relates to electroplating, in particular to electrolytic deposition of coatings of lead-tin alloy containing 10 + 5% tin (PIC-UC on products made of steel, aluminum and its alloys, copper or nickel for corrosion protection and anti-friction coating.

A known electrolyte for the deposition of tin-lead alloy coatings containing tin and lead salts, potassium pyrophosphate, hydrolyzed glue and surfactants, for example, 4,4-diamino-3,3 dimethoxy diphenylmethane. High-quality coatings are obtained from this electrolyte. who have qualities with good soldering ability ij.

However, this electrolyte is intended for the deposition of an alloy with a high content of tin (POS-60), which does not correspond to the alloy of POS-10.

Closest to the invention is an electrolyte for precipitating

lead-tin alloy containing coatings, lead and tin salts, resorcinol or hydrochloric acid hydrazine, and hydrolyzed glue. The electrolyte also contains boric and hydrofluoric acid. Good quality coatings are obtained from this electrolyte 2.

However, the hydrofluoric electrolyte is susceptible to the hydrolysis of salts,

10, which is the reason for the change in the composition of the electrolyte and, therefore, the percentage composition of the deposited alloy and the incompatibility with the POS-10 alloy. In addition, the composition of the alloy varies

IS depending on the applied density of the toga: so, when it changes from 1.3 to 5.4 A / dm2, the content of oloz in the alloy ranges from 17.6 to 12.4Z (with the same quantitative

20 electrolyte ratio). The use of boron fluoride electrolyte requires special surface preparation before coating (sandblasting, degreasing, etching in hydrofluoric or hydrofluoric acid for steel products, zincate and nickel sublayer for aluminum products), and also requires special ventilation devices and expensive acid-resistant filters. The aim of the invention is to increase the stability of the composition of the alloy. This goal is achieved by the fact that the electrolyte additionally contains potassium pyrophosphate and a surfactant in the following ratio of components, g / l: Lead salt {in terms of metal) 27-33 Salt tin (in terms of metal) 6-10 Potassium pyrophosphate 600-650 Resorcinol or hydrazine hydrochloride 4-10 Hydrolyzed glue 0.8-1.5 surfactant 0.35-10 At the same time, as the surfactant, the electrolyte contains iso-octylphenol polyethylene glycol in the amount of 0.35-0.7 g / l), sodium salt dibutyl naph. clay-1-sulfonic acid in the amount of 0.5-1.0 g / l (surfactant-2), three sodium salt of M - (- 2-ethylhexoxy propyl) -N-ethylhexanyl-carboxypropionyl aspartic acid (40% - nt aqueous solution in the amount of 1-2 g / l (surfactant-3), sodium salt of di-2-ethylhexyl sulfonate ester (60% aqueous solution) in the amount of 5-10 g / l (surfactant 4) disodium salt of diethyl ether N -dicyloxypropyl-N - (p-sulfo-propionyl) aspartic acid (35% aqueous solution in an amount of 0.45-0.9 g / l (surfactant-5) and sodium salt di- 2-ethylhexoxytetraethyl glycol ether of sul pho succinic acid {40% aqueous solution) in lichestve 0,55-0,7 g / l (SAW b). As a surfactant, the electrolyte may also contain alkylenediamine adylated polyglyceride derivatives in the amount of 0.3-0.8 g / l (surfactant-7). The presence of reducing substances, hydrazine hydrochloride or resorcinol, in the electrolyte eliminates the oxidation of divalent tin (Sn and sludge formation in the electrolyte and in combination with surfactants ensures the stability of the electrolyte itself and the stability of the alloy during long-term operation from 1 up to 5 A / dm and a temperature of 18–50 s. The electrolyte is prepared as follows: A solution of the lead pyrophosphate complex and a solution of the tin pyrophosphate complex are prepared separately. It is prepared by dissolving lead nitric acid in distilled water or condensate at a temperature of 60-70 ° C, then the pyrophosphate of calcum, previously dissolved in hot distilled aluminum (6070c), is added to the aqueous solution of lead salt with stirring. removing nitrate ions, after which the precipitate of lead pyrophosphate is dissolved in an aqueous solution of potassium pyrophosphate. A complex tin salt is also prepared, starting from tin dichloride. Then, hydrazine hydrochloride (or resorcinol) and pre-hydrolyzed glue are sequentially added to the solution of the pyrophosphate complex of tin, the mixture is added to the solution of the pyrophosphate sushd, after which the surfactant is introduced and the solution is adjusted to, 2, the electrolyte dissipation measured by the three cathodes, is 42.9-30, -29.1% (in electrolyte with surfactant-1), 47.9-29.522, 5% (with surfactant-2), 48.8-28.2.2-23 (with a surfactant-3 and a surfactant-6), electrolyte stability is estimated by the accumulation,% of tetravalent tin (ciSrrVB, depending on the amount omitted Thus, by passing 40-60 A h / l, the content of uS increases from 2.7 to 5.7% (in electrolyte with surfactant-1), in electrolyte with surfactant-2, when passing A h / l LSn increases with 5.7 to 14%, and in an electrolyte with a surfactant-3 and a surfactant-6, by passing 20-50 AH / L L, the Sgg rises from 3 to 8%. From the electrolyte according to the invention, the precipitate is almost porous (0.170, 39 pores / cm ) coatings up to 50 microns thick at a speed of 0.2-1 microns / min and a current output of 70-83%, hardness

The coatings are 9.8-10.6 kg / mm, the friction coefficient is 0.004-0.008 at a specific pressure of 5-15-20 kg / m and a slip speed of 0.12-6 m / s,

The resulting coatings have high adhesion to the substrate. So, when a wasp was applied to nickel and iron, the coating did not peel off until fracture; when deposited onto aluminum, the coating would seal 10–20 thermal shocks (),

The corrosion resistance of the coatings in a solution of sulfuric acid (, 60 hours) is good, in the solution of the foaming agent PO-1 (10% on copper parts is good, and on nickel parts it is satisfactory (darkening is observed). When tested, the coatings in chemzar des OHP-10 after 24 -hour exposure the appearance of the detail does not change.

The table shows the composition. electrolyte, mode and results of electrolysis.

As can be seen from the table, irrespective of the applied current density, coatings with a stable composition precipitate.

alloy corresponding POS-10 (JO-5% olona), at the same time in the electrolyte without a surfactant coating is deposited., containing 17% tin.

Thus, the invention makes it possible to produce coatings of a lead-tin alloy with a stable content of lead and coatings in coatings in a wide range of current densities and electrolyte temperatures of 18-50 C. The economic effect is determined by the simplification of surface preparation (for steel products only degreasing and decatiation in hydrochloric acid, for aluminum - only preliminary nickel plating), lack of ventilation} of first installations and acid-resistant filters, improvement of the quality of coatings, increase of PRODUCTION awn labor and production installations.

Claims (2)

The invention can be applied most effectively in mechanical engineering for applying POS-10 coatings on liners of tractor motors made of aluminum alloys. Claim 1. Electrolyte for deposition of lead-tin alloy sheets containing lead and tin salts of resorcinol or hydrochloric hydrazine and hydrolyzed glue, which, in order to increase the stability of the alloy composition, it also contains potassium pyrophosphate and surfactant (surfactant) in the following ratio of components, g / l: Lead salt (in terms of metal) 27-33 Tin salt (in terms of metal) 6-10 Potassium pyrophosphate 600-650 Resorcinol or hydrazine hydrochloride 4-10 Hydrolyzed glue 0.8-1.5 PAW0.35-10 2, Electrolyte according to claim 1, characterized in that, as a surfactant, it contains polyethylene glycol ether of iso-octylphenol in the amount of. .0.35-0.7 g / l. 3, Electrolyte according to claim 1, characterized in that, as a surfactant, it contains dibtylaphthalene-1-sulfonic acid sodium salt in a quantity of 0.5-1.0 g / l. 4, The electrolyte according to claim 1, which is characterized by the fact that, as a surfactant, it contains 310-U-2-ethylhexoxypropyl) -N ethylhexanyl- / -carboxypropionyl aspartic acid (40% aqueous solution) in the amount of 1-2 g / l. 5. The electrolyte according to claim 1, characterized in that, as a surfactant, it contains sodium sulfate-2-sulphate trisulfate 2-sodium salt (60% aqueous solution) in an amount of 5-10 g / l. 6. The electrolyte according to claim 1, about tl ICH ayuschi and with the fact that as a surfactant it contains the disodium salt of diethyl ether M-decyloxypropyl-M | - sulfopropyl) aspartic acid (35% aqueous solution) in an amount of 0.45-09 g / l. 7. The electrolyte according to claim 1, characterized in that, as a surfactant, it contains sodium sulfate-2-ethylhexoxytetraethylene glycol sulfate (40% aqueous solution) in an amount of 0.55-0.7 g / l. Sources of information taken into account in the examination 1.Vitin I.A. et al. Electrodeposition of tin-lead alloy from potassium pyrophosphate complex electrolytes. - Chemical and electrochemical methods of protection of metals, Saratov, 1977, p.17-18. 2. Fedotyev N.P. et al. Electrolytic alloys. M.-L., Mashgiz, 1962, p.