SU1520150A1 - Method of preparing the surface of steel articles to electrolytic deposition of coatings - Google Patents

Abstract

This invention relates to electroplating, in particular, to methods for pre-conditioning the surface of steel before electroplating. The aim of the invention is to increase the adhesion strength of the coating to the substrate. The method involves treating steel parts for 10-40 minutes at 50-70 ° C and a pH of 1.5-2.5 in an aqueous solution containing 300 g / l of nickel chloride, 0.06-0.6 g / l of sulphate copper, 30 g / l of boric acid and metallic copper in the form of a powder or foil of 0.5-20 dm ² / l in surface area. A copper-nickel coating is deposited on the surface of the steel. An increase in the adherence of the coating to the substrate is achieved by the contact deposition of a copper-nickel alloy under the above conditions. 6 tab.

Description

The invention relates to electroplating, in particular, to methods for pretreating a steel surface by deposition of copper alloys by contact exchange before electroplating, and can be used in. mechanical engineering.

The purpose of the invention is to increase the adhesion strength of the coating to the substrate.

The method consists in processing parts for 10-40 minutes at 50 and a pH of 1.5-2.5 in an aqueous solution containing 300 g / l of nickel chloride, 0.06-0.6 g / l of copper sulphate, 30 g / l of boric acid and metallic copper in the form of powder or foil 0.5 - 20.0 dm / l in surface area. A copper-nickel alloy is deposited on the surface of the steel by contact. The sample of steel processed by this method is not cemented with copper, which makes it possible to deposit copper and other coatings from simple electrolytes on it. The resulting copper and other galvanic coatings are practically non-porous and strongly adhere to the substrate.

Samples of steel St3 are processed, which are cleaned from scale, degreased in hexane, pickled in dilute hydrochloric acid and immersed in a treatment solution for 5-60 minutes. To determine the composition of the contact alloy, the precipitate is etched and carried out

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300 30 0.1 to a pH of 1.5-2

50

0.1

analysis of copper and nickel on the background of ammonium buffer.

The treated parts from parallel series of experiments are covered electrochemically with copper, nickel, cobalt with a thickness of 6 μm, or zinc and cadmium with a thickness of 12 μm. To determine the quality of the coating, the method of applying a grid of scratches and heating the sample is used (GOST 9.302-79, p.29). To quantify the adhesion strength, copper coatings of a thickness of 200 µm are precipitated and the adhesion strength is determined using a PG1M-250 tensile testing machine. The porosity of the coating is determined by the ferrocydide method.

The composition of the solution for contact treatment, g / l:

Nickel chloride

Borna acid

Copper sulphate

Sol Na Acid

Copper is introduced into the solution in the form of foil or powder at the rate of 1 dm / Electrolyte composition for electrochemical deposition of copper, g / l:

Copper sulfate 200

Sulfuric acid

Additive LTI

The composition of the electrolyte for the deposition of nickel, g / l:

Nickel sulfate 200

Nickel chloride 175

Borna acid AO

Electrolyte temperature. The composition of the electrolyte for the deposition of cobalt, g / l:

Cobalt sulfate 300

Sodium chloride 20

Borna acid AO

Te merapypa electrolyte. The composition of electrolytic olite for the deposition of zinc, g / l:

Zinc sulfate 200

Sodium sulfate 70 The composition of the electrolyte for the application of cadmium, g / l:

Cadmium sulfate 50

Sodium sulfate 50

Sulfuric acid 50

The electrolyte temperature is 30 ° C.

The test results are summarized in table 1-6.

The effect of temperature on the sedimentation rate and composition of the alloy, as well as on the strength of adhesion of the copper coating to the surface of the steel treated with the proposed surface is shown

0

five

0

five

0

five

0

five

0

five

Table 1. With increasing temperature, the thickness of the contact coating increases, and the alloy is enriched with nickel. Coating deposition time 15 min. Copper: nickel ratio 1: 600. The concentration of nickel chloride is 300 g / l, pH 1.5.

The effect of the deposition time of the contact coating is shown in Table 2. As the deposition time increases, the coating thickness increases, and the alloy is enriched with copper. Solution temperature 70 С, pH 1.5.

The effect of the concentration of copper ions in the solution on the rate of contact exchange, the composition of the alloy, and the adhesion strength of the nickel coating to the surface treated by the proposed method are given in Table 3. With an increase in the concentration of copper ions in the solution, the copper content in the alloy increases linearly.

Solution temperature, nickel chloride concentration 300 g / l, pH 1.5, precipitation time 25 minutes, coating thickness 6 µm.

The effect of the presence of metallic copper in the solution on the thermal stability of the contact coating is shown in Table 4. The introduction of metallic copper into the solution is a prerequisite for achieving a high heat resistance of the coating. Coatings obtained from a solution that does not contain metallic copper, have a low tericheskoe resistance. In addition, by introducing into the solution metallic copper in the solution, a constant concentration of copper (II) ions, formed during the oxidation of copper with dissolved oxygen and iron (III) ions, is maintained. Temperature, pH 1.5, copper sulfate concentration 0.5 g / l, nickel chloride 300 g / l.

The effect of the pH of the solution on the quality of the contact coating is given in Table 5. Copper sulfate concentration 0.5 g / l, nickel chloride 300 g / l. Temperature, exposure 15 min.

The application of the proposed method, the intermediate contact treatment of steel parts in the preparation of various electroplating coatings, is shown in Table 6.

The processing time is 15 minutes, the electrolyte temperature is 70 s, pH 1.5.

The test results of the method of preparing the surface of steel parts

5 15201

Claims (1)

before the deposition of electroplatings suggests that the method can be used to prepare the surface for electrochemical deposition of copper, nickel, cobalt and zinc, cadmium. Compared with the known method of electrolytic deposition of copper on the surface of steel parts from cyanide electrolyte 0, the proposed method allows to increase the adhesion strength of the coating to the substrate by 1.5-2 times. Claims. The method of preparing the surface of steel parts for the deposition of gal , 0 five 506 Vanical coatings, including contact deposition of copper alloy from salt solutions, characterized in that, in order to achieve adhesion of the coating to the substrate, its alloy with nickel is used as a copper alloy, which is precipitated for 10-40 minutes at an AO temperature -TO C and pH 1.5-2.5 from an aqueous solution containing, g / l: Nickel chloride 300 Copper sulphate 0.06-0.60 Boric acid 30 and metallic copper in the form of powder or foil in the amount of 0.5-20.0 dm / l in surface area. Table 1 Table 2 ) (1: 10,000) (1: 5000) T1: 3000) (U1000) (1: 500) (1: 300) 5.3 5.0 A, 7 4.5 3.5 3.6 A.4 6 ten 18 41 53 85 White || Sv.roz. Rose Red Exfoliate when heated. Satisfactory. Places exfoliate. SUSTAINABLE to heat. Same corny t Table3 Satisfaction- Vesporitovoritelnoe. a little 900 t || 1100 1200 1300 1350 1350 Unsatisfied- Porous major Table4 corny t T a b l and c a 5 6 6 12 12 1520150 10 Table Favorite- Satisfied || | 1 if one full it m t and Satisfactory if ti ii II