Copper-tin electroplating solution as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of composite coatings, and particularly relates to a copper-tin electroplating solution and a preparation method and application thereof.The preparation method of the electroplating solution comprises the steps that citric acid is dispersed in water, potassium hydroxide is added, and a reaction solution 1 is obtained; basic cupric carbonate is added into the reaction solution until the solution becomes clear and does not generate bubbles, the solution is cooled, monopotassium phosphate is added, and a reaction solution 2 is obtained; dissolving potassium stannate in a dilute alkali hot solution, and after the potassium stannate is completely dissolved, adding hydrogen peroxide to obtain a reaction solution 3; and adding the cooled reaction liquid 3 into the reaction liquid 2 to obtain the electroplating liquid. The preparation method of the electroplating solution is simple and almost free of pollution, the electroplating solution is used for electroplating a metal test piece, and an obtained plating layer has high corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of composite coating technology, specifically relating to a copper-tin electroplating solution, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Electroplating is a widely used method for metal surface treatment. It involves forming one or more layers of metal or alloy coating on the metal surface through electrolysis to improve the material properties.

[0004] As a crucial component for connecting pipes, couplings play a vital role in industries such as petroleum, chemical, and shipbuilding. Because the working environments in these industries are typically highly corrosive, the corrosion resistance of the couplings directly affects the safe and stable operation of the entire system.

[0005] With the development of industrial technology, higher requirements have been placed on the corrosion resistance of couplings. Traditional anti-corrosion methods such as coatings and heat treatment can no longer fully meet the stringent requirements of modern industry. Electroplating technology, due to its ability to provide a uniform, dense coating with good adhesion to the substrate, has become an effective means to improve the corrosion resistance of couplings. However, existing electroplating technologies often suffer from complex electroplating solution preparation and operation, high pollution levels, and coating adhesion and corrosion resistance that fail to meet current needs, thus reducing the service life of couplings and increasing maintenance costs.

[0006] For example, CN104060308A discloses a pure tin electroplating solution and its application. The acidic plating solution uses a mixed solution of methanesulfonic acid and sulfuric acid, the tin salt uses a mixed solution of soluble divalent tin salt and hydrogen peroxide, and antioxidants, auxiliary agents, brighteners, wetting agents, surfactants and other components are added. In the electroplating process of this solution, it takes a long time to achieve the same coating thickness, the additive content is high, the crystals are not fine enough, and the density of the coating is poor.

[0007] CN 104928735 A discloses a cyanide-free tin bronze electroplating solution for steel parts. It uses an electrolyte to electrolyze a copper plate and adds stannous pyrophosphate to obtain the electroplating solution. However, the ratio of copper to tin in this electroplating solution is not easy to control, and the formula uses divalent tin for electroplating. Divalent tin in the electrolyte is unstable and easily generates tetravalent tin, which reduces the electroplating effect. Summary of the Invention

[0008] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a copper-tin electroplating solution, its preparation method and application, and this invention solves at least one of the above problems.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] In a first aspect, the present invention provides a method for preparing a copper-tin electroplating solution, comprising:

[0011] Dissolve citric acid in water, add potassium hydroxide, and obtain reaction solution 1;

[0012] Add basic copper carbonate to reaction solution 1, cool, and then add potassium dihydrogen phosphate to obtain reaction solution 2.

[0013] Dissolve potassium stannate in an alkaline solution, add hydrogen peroxide, and obtain reaction solution 3;

[0014] The cooled reaction solution 3 is added to the reaction solution 2 to obtain a copper-tin electroplating solution.

[0015] In some embodiments, when preparing reaction solution 1, the mass ratio of citric acid to potassium hydroxide is (5-10):(2-5).

[0016] In some embodiments, the mass ratio of citric acid to basic copper carbonate is (5-10):

[0017] (1-3).

[0018] In some embodiments, the amount of potassium dihydrogen phosphate added after cooling is 10-50 g / L; preferably 15-18 g / L.

[0019] In some embodiments, the alkaline solution is a KOH solution; preferably, the concentration of the KOH solution is 5-10 g / L; and the temperature of the KOH solution is 58-62°C.

[0020] In some embodiments, when preparing reaction solution 3, the mass ratio of potassium stannate to KOH is 25:(3-5).

[0021] In some embodiments, the concentration of hydrogen peroxide in reaction solution 3 is 1-8 mL / L.

[0022] In some embodiments, the mixing ratio of reaction solution 2 to reaction solution 3 is 1:(0.8-1.2), preferably 1:1.

[0023] In some embodiments, the pH of the copper-tin plating solution is 8-11; preferably, citric acid or potassium hydroxide is used to adjust the pH of the plating solution to 8.5-9.5.

[0024] In some embodiments, the water is deionized water.

[0025] A second aspect of the present invention provides a copper-tin electroplating solution, which is prepared by the above method.

[0026] A third aspect of the present invention provides a composite coating obtained by electroplating the aforementioned copper-tin plating solution onto a substrate surface.

[0027] The fourth aspect of the present invention provides the application of the above-mentioned copper-tin electroplating solution in the preparation of composite coatings, wherein the composite coating is preferably a composite coating for petroleum equipment.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. This invention prepares a citric acid-based electroplating solution. The preparation method of this electroplating solution is simple, and the obtained copper-tin alloy coating exhibits excellent corrosion resistance, wear resistance, and mechanical properties. The coating is uniform, dense, non-porous, and has a smooth surface, further improving its corrosion resistance and giving it a bright color. Compared with other electroplating systems, this process is not only simpler to operate, but also uses a citric acid system instead of a strong acid, preventing contamination from strong acids.

[0030] 2. The electroplating solution of this invention uses tetravalent tin, which enhances the stability of the solution and prevents the performance of the copper-tin plating layer from deteriorating due to changes in the composition of the solution. This process is not only simpler to operate, but also relatively low in cost and virtually pollution-free. Therefore, the citric acid-based copper-tin alloy electroplating process has broad application potential and practical value in the industrial field. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0032] Figure 1 These are macroscopic morphology and cross-sectional views of the copper-tin plating layer of the plated part in Embodiment 4 of the present invention, where a is the macroscopic morphology of the copper-tin plating layer and b is the cross-sectional view of the plated part.

[0033] Figure 2 The XRD pattern of the copper-tin plating layer on the part in Embodiment 4 of the present invention;

[0034] Figure 3 This is a microscopic morphology diagram of the copper-tin plating layer on the part in Embodiment 4 of the present invention;

[0035] Figure 4 This is a schematic diagram of the EDS surface composition of the copper-tin plating layer of the plated part in Embodiment 4 of the present invention, wherein a is a comprehensive surface scan diagram of various elements, b is a surface scan diagram of Cu, c is a surface scan diagram of Sn, d is a surface scan diagram of Fe, and e is a surface scan diagram of C.

[0036] Figure 5 This is a polarization curve diagram of the copper-tin plating layer on the plated part in Embodiment 4 of the present invention;

[0037] Figure 6 This is an impedance curve of the copper-tin plating layer on the part in Embodiment 4 of the present invention;

[0038] Figure 7 This is an impedance curve of the copper-tin plating layer on the plated part in Embodiment 5 of the present invention. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0040] Example 1

[0041] This embodiment provides a method for preparing a copper-tin electroplating solution, the specific steps of which are as follows:

[0042] (1) Weigh 160g of citric acid and dissolve it in 1L of deionized water, then add 60g of potassium hydroxide to obtain potassium citrate solution;

[0043] (2) Add 28g of basic copper carbonate to the above potassium citrate solution until the solution becomes clear and no bubbles are produced. The reaction is complete. After cooling the solution, add 18g of potassium dihydrogen phosphate to obtain copper citrate.

[0044] (3) Add 6g KOH to 1L of deionized water, stir well, and heat to 60℃ to prepare a dilute alkaline hot solution; dissolve 50g potassium stannate in the dilute alkaline hot solution. After the potassium stannate is completely dissolved in the dilute alkaline hot solution, add 2ml hydrogen peroxide to obtain a potassium stannate solution, and let it stand to cool.

[0045] (4) The cooled potassium stannate solution is slowly added to copper citrate under stirring to mix the two metal salt solutions. Then, the pH of the solution is adjusted to 10 using citric acid or potassium hydroxide to obtain copper-tin electroplating solution.

[0046] Example 2

[0047] This embodiment provides a method for preparing a copper-tin electroplating solution, the specific steps of which are as follows:

[0048] (1) Weigh 100g of citric acid and dissolve it in 1L of deionized water, then add 40g of potassium hydroxide to obtain potassium citrate solution;

[0049] (2) Add 20g of basic copper carbonate to the above potassium citrate solution until the solution becomes clear and no bubbles are produced. The reaction is complete. After cooling the solution, add 16g of potassium dihydrogen phosphate to obtain copper citrate.

[0050] (3) Add 3g KOH to 1L of deionized water, stir well, and heat to 58℃ to prepare a dilute alkaline hot solution; dissolve 25g potassium stannate in the dilute alkaline hot solution. After the potassium stannate is completely dissolved in the dilute alkaline hot solution, add 2ml hydrogen peroxide to obtain a potassium stannate solution, and let it stand and cool.

[0051] (4) The cooled potassium stannate solution is slowly added to copper citrate under stirring to mix the two metal salt solutions. Then, the pH of the solution is adjusted to 8 using citric acid or potassium hydroxide to obtain copper-tin electroplating solution.

[0052] Example 3

[0053] This embodiment provides a method for preparing a copper-tin electroplating solution, the specific steps of which are as follows:

[0054] (1) Weigh 120g of citric acid and dissolve it in 1L of deionized water, then add 50g of potassium hydroxide to obtain potassium citrate solution;

[0055] (2) Add 30g of basic copper carbonate to the above potassium citrate solution until the solution becomes clear and no bubbles are produced. The reaction is complete. After cooling the solution, add 15g of potassium dihydrogen phosphate to obtain copper citrate.

[0056] (3) Add 5g KOH to 1L of deionized water, stir well, and heat to 62℃ to prepare a dilute alkaline hot solution; dissolve 50g of potassium stannate in the dilute alkaline hot solution. After the potassium stannate is completely dissolved in the dilute alkaline hot solution, add 4ml of hydrogen peroxide to obtain a potassium stannate solution, and let it stand and cool.

[0057] (4) The cooled potassium stannate solution is slowly added to copper citrate under stirring to mix the two metal salt solutions. Then, the pH of the solution is adjusted to 11 using citric acid or potassium hydroxide to obtain copper-tin electroplating solution.

[0058] Example 4

[0059] This embodiment provides a composite electroplating layer, and the specific preparation steps are as follows:

[0060] (1) Select Q235 steel sheet as electroplating part. First, use sandpaper to polish the plated part to remove the surface rust and make the plated part surface flat and smooth. Then, rinse the plated part surface with a lot of distilled water to remove the impurities on the plated part surface. Finally, rinse with alcohol and blow dry for later use.

[0061] (2) The electroplating solution of Example 1 was added to the electroplating tank and heated in a water bath to keep the electroplating solution at 50°C. The three-electrode electroplating technology was adopted, with the anodes connected in parallel as tin and copper sheets, and the cathode as the Q235 steel sheet of the plated part. The electroplating time was 35 min and the voltage was 5V. The plated part was electroplated to obtain an electroplated sample.

[0062] Example 5

[0063] This embodiment provides a composite electroplating layer. The difference between the preparation steps and those in Embodiment 4 is that the electroplating solution of Embodiment 2 is selected for electroplating.

[0064] Example 6

[0065] This embodiment provides a composite electroplating layer. The difference between the preparation steps and those in Embodiment 4 is that the electroplating solution used in Embodiment 3 is selected for electroplating.

[0066] Performance testing

[0067] Experimental Example 1

[0068] Taking the sample of Example 4 as an example, the coating of the sample was observed and its performance was tested.

[0069] 1. The electroplated sample of Example 4 was analyzed using a SU8600N electron microscope, and the microstructure was further analyzed using an EMAX-act electrocooled X-ray energy dispersive spectroscopy (EDS) instrument attached to the scanning electron microscope. The copper-tin plating was analyzed using a DX-2700BH multi-functional X-ray diffractometer (XRD) with a Cu target, a scanning voltage of 40 kV, a current of 40 mA, a scanning speed of 4° / min, a step size of 0.02°, and a scanning range of 5–85°.

[0070] The macroscopic morphology of the copper-tin plating layer in Example 4 is as follows: Figure 1 As shown in (a), the coating exhibits a bright color, is uniform and dense, and is free of pores; the sample was observed using an electron microscope, as shown... Figure 1 As shown in (b), the thickness of the copper-tin plating is approximately 10.01 μm.

[0071] Phase analysis of copper-tin plating was performed using X-ray diffraction, and the results are as follows: Figure 2 As shown, the main phase of the coating is Cu. 13.7 Sn and Fe, Cu 13.7 Sn plating makes the surface of the composite coating on the workpiece dense and smooth, and also provides good corrosion resistance.

[0072] The copper-tin plating was characterized using SEM, such as... Figure 3 The image shows the microstructure of the copper-tin plating layer, which has relatively uniform crystal size and a dense surface.

[0073] like Figure 4 The diagram shows the EDS composition of the copper-tin plating layer, which contains 84.71 wt.% Cu, 10.63 wt.% Sn, and small amounts of Fe and C. The composite plating layer has a dense and smooth surface with good corrosion resistance.

[0074] 2. The electroplated sample of Example 4 was tested using a JC2000D3M contact angle measuring instrument. The test results showed that the contact angle of the copper-tin plating layer was 114.72°, indicating that it is hydrophobic.

[0075] 3. Tafel curves and electrochemical impedance spectroscopy (EIS) of copper-tin plating in 3.5% NaCl solution were measured using a GAMRY Reference 3000 electrochemical workstation. A saturated calomel electrode was used as the reference electrode, and the copper-tin plating sample was used as the working electrode.

[0076] Taking the electroplated sample of Example 4 as an example, such as Figure 5 The figure shows the polarization curves of the copper-tin alloy plating and the substrate in Example 4. The self-corrosion potential of the substrate (-0.5840 mV) is much smaller than that of the copper-tin plating (-0.1970 mV), proving that the substrate has a higher corrosion tendency than the copper-tin plating. The self-corrosion current density of the substrate (18.9 μA / cm²) is also shown. 2 (3.39 μA / cm) is greater than that of copper-tin plating. 2 This demonstrates that the corrosion rate of the substrate is higher than that of the copper-tin plating. For example... Figure 6 The impedance curves of the copper-tin plating layer and the substrate of the electroplated sample in Example 4 are shown. The impedance radius of the copper-tin plating layer is much larger than that of the substrate, indicating that the copper-tin plating layer has a better impedance radius and thus better corrosion resistance.

[0077] Experimental Example 2

[0078] The electroplated sample of Example 5 was subjected to performance testing using the same method as in the experimental example (same or similar test results will not be repeated). The thickness of the copper-tin plating layer on the sample of Example 5 was found to be 8.67 μm, and the main phase of the copper-tin plating layer was Cu. 13.7 Sn and Fe have a contact angle of 114.72° and are hydrophobic.

[0079] In Example 5, the polarization curves of the copper-tin alloy plating and the substrate of the electroplated sample showed that the self-corrosion potential of the substrate (-0.5840 mV) was much smaller than that of the copper-tin plating (-0.1120 mV), proving that the substrate had a higher corrosion tendency than the copper-tin plating. The self-corrosion current density of the substrate was 18.9 μA / cm². 2 (3.45μA / cm) is greater than that of copper-tin plating. 2 This demonstrates that the corrosion rate of the substrate is higher than that of the copper-tin plating. For example... Figure 7 The impedance curves of the copper-tin plating layer and the substrate of the electroplated sample in Example 5 are shown. The impedance radius of the copper-tin plating layer is much larger than that of the substrate, which proves that the corrosion resistance of the copper-tin plating layer is higher than that of the substrate.

[0080] Experimental Example 3

[0081] The electroplated sample of Example 6 was subjected to performance testing using the same method as in the experimental example (same or similar test results will not be repeated). The thickness of the copper-tin plating layer on the sample of Example 6 was found to be 11.12 μm; the main phase of the coating was Cu. 13.7 Sn and Fe, the contact angle of the copper-tin plating is 112.93°, and it is hydrophobic.

[0082] The polarization curves of the copper-tin plating and the substrate show that the self-corrosion potential of the substrate (-0.5840 mV) is much smaller than that of the copper-tin plating (-0.1820 mV), proving that the substrate has a higher corrosion tendency than the copper-tin plating. The self-corrosion current density of the substrate (18.9 μA / cm²) is also significant. 2 (greater than copper-tin plating (2.65 μA / cm)) 2 This demonstrates that the corrosion rate of the substrate is higher than that of the copper-tin plating, and that the corrosion resistance of the copper-tin plating is higher than that of the substrate.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a copper-tin electroplating solution, characterized in that, include: Dissolve citric acid in water, add potassium hydroxide, and obtain reaction solution 1; Add basic copper carbonate to reaction solution 1, cool, and then add potassium dihydrogen phosphate to obtain reaction solution 2. Dissolve potassium stannate in an alkaline solution, add hydrogen peroxide, and obtain reaction solution 3; The cooled reaction solution 3 is added to the reaction solution 2 to obtain a copper-tin electroplating solution.

2. The method for preparing the copper-tin electroplating solution as described in claim 1, characterized in that, When preparing reaction solution 1, the mass ratio of citric acid to potassium hydroxide is (5-10):(2-5).

3. The method for preparing the copper-tin electroplating solution as described in claim 1, characterized in that, The mass ratio of citric acid to basic copper carbonate is (5-10):(1-3).

4. The method for preparing the copper-tin electroplating solution as described in claim 1, characterized in that, The amount of potassium dihydrogen phosphate added after cooling is 10-50 g / L.

5. The method for preparing the copper-tin electroplating solution as described in claim 1, characterized in that, The alkaline solution is a KOH solution; preferably, the concentration of the KOH solution is 5-10 g / L; more preferably, the temperature of the KOH solution is 58-62℃; even more preferably, when preparing reaction solution 3, the mass ratio of potassium stannate to KOH is 25:(3-5).

6. The method for preparing the copper-tin electroplating solution as described in claim 1, characterized in that, The concentration of hydrogen peroxide in reaction solution 3 is 1-8 mL / L.

7. The method for preparing the copper-tin electroplating solution as described in claim 1, characterized in that, The mixing ratio of reaction solution 2 to reaction solution 3 is 1:(0.8-1.2); preferably 1:

1. Alternatively, the pH of the copper-tin electroplating solution is 8–11.

8. A copper-tin electroplating solution, characterized in that, It is prepared by any one of claims 1-7.

9. A composite coating, characterized in that, It is obtained by electroplating the copper-tin electroplating solution of claim 8 onto the surface of a substrate.

10. The application of the copper-tin electroplating solution as described in claim 8 in the preparation of composite coatings, preferably, the composite coating is a composite coating for petroleum equipment.

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