Chemical nickel plating solution and preparation method thereof

Abstract

The invention belongs to the technical field of chemical nickel plating, and particularly relates to a chemical nickel plating solution and a preparation method thereof. The chemical nickel plating solution comprises the following raw materials: 30-50 parts of a nickel source, 20-40 parts of a reducing agent, 10-20 parts of a complexing agent, 3-10 parts of a pH buffer agent, 5-10 parts of a thiourea stabilizer, 0.5-2 parts of a bipyridine ionic liquid surfactant and 1000 parts of deionized water. The chemical nickel plating solution has the advantages of being high in nickel plating speed, compact and uniform in nickel plating layer, good in abrasion resistance and salt resistance and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical nickel plating, and in particular relates to a chemical nickel plating solution and a preparation method thereof. Background Art

[0002] Electroless plating, also known as autocatalytic plating, is a process in which metal ions in the plating solution are reduced and deposited onto the substrate in the absence of an applied current using a reducing agent. The resulting metal coating is continuous, and the metal itself possesses catalytic activity. Electroless plating utilizes the metal already reduced and deposited onto the substrate surface as new catalytic sites, and the reaction continues on the deposited metal surface, resulting in a continuous metal coating. Electroless nickel plating technology has developed rapidly. Initially, research aimed to address certain challenges that electroplating could not address, using electroless nickel as an alternative to electroplating. With increasing research and demand, functional coatings have been developed for many other applications, such as corrosion resistance, wear resistance, coating uniformity, and electromagnetic shielding. Electroless nickel plating also offers pollution-free emissions, making it suitable for plating complex parts made of various materials (including non-metallic materials). It has found widespread application in aerospace, petrochemicals, electronics, transportation, and IT industries.

[0003] Additives (including buffers, surfactants, brighteners, and complexing agents) are essential for achieving high-performance electroless nickel coatings. Surfactants play a crucial role in the electroless plating process. Electroless plating surface treatment techniques typically utilize appropriate surfactants to increase the reaction rate, improve coating unevenness, and maintain bath stability. Commonly used surfactants include dodecyl sulfate, dodecyl sulfonate, polyethylene glycol, and OP-10. Furthermore, electroless nickel plating solutions are thermodynamically unstable systems, often containing particles such as colloids and solid impurities. Without stabilizers, nickel ions interact with these particles, leading to significant nickel ion consumption. Excessive amounts of particles can even cause spontaneous decomposition of the bath.

[0004] Compared to electroplating, chemical nickel plating processes are slower. Furthermore, the chemical nickel plating solution used in chemical nickel plating is less stable, leading to uneven coating quality and even defects during the plating process. This limits its application in large-scale production. In recent years, with advances in materials science and chemical engineering, researchers have been committed to developing novel chemical nickel plating solution formulas to enhance the overall performance of the plating solution. These methods primarily include optimizing the type and concentration of nickel salts, introducing highly effective corrosion inhibitors and chelating agents, selecting novel environmentally friendly stabilizers, and adding surfactants with specific functionalities. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide an electroless nickel plating solution and a preparation method thereof to solve the problems of slow nickel plating rate and poor coating quality of the electroless nickel plating solution. In order to achieve the above object, the present invention adopts the following technical solutions: A chemical nickel plating solution, the raw materials of which, calculated by weight, include: 30-50 parts of a nickel source, 20-40 parts of a reducing agent, 10-20 parts of a complexing agent, 3-10 parts of a pH buffer, 5-10 parts of a thiourea stabilizer, 0.5-2 parts of a bipyridinium ionic liquid surfactant, and 1000 parts of deionized water; The structural formula of the bipyridinium ionic liquid surfactant is: or ; The structural formula of the thiourea stabilizer is: .

[0006] In some embodiments, the nickel source is selected from one or more of nickel sulfate, nickel chloride, nickel carbonate, nickel hypophosphite, nickel methanesulfonate, nickel acetate, nickel nitrate, and nickel sulfamate.

[0007] In some embodiments, the reducing agent is selected from one or more of sodium hypophosphite, sodium hypophosphite, potassium hypophosphite, sodium formaldehyde bisulfite, sodium borohydride, ascorbic acid, dimethylamine borane, and formaldehyde.

[0008] In some embodiments, the complexing agent is selected from one or more of succinic acid, citric acid, sodium citrate, lactic acid, malic acid, glycine, tetrasodium ethylenediaminetetraacetic acid, and ethylenediaminetetraacetic acid.

[0009] In some embodiments, the pH buffer is selected from one or more of glacial acetic acid, sodium acetate, sodium succinate, and sodium bicitrate.

[0010] In some embodiments, the raw materials include, by weight: 40 parts of nickel source nickel sulfate, 25 parts of reducing agent sodium hypophosphite, 15 parts of complexing agent citric acid, 5 parts of pH buffer sodium acetate, 10 parts of thiourea stabilizer, 2 parts of bipyridinium ionic liquid surfactant, and 1000 parts of deionized water.

[0011] In some embodiments, the raw materials include, by weight: 50 parts of nickel source nickel chloride, 20 parts of reducing agent sodium hypophosphite, 10 parts of chelating agent lactic acid, 7 parts of pH buffer sodium acetate, 8 parts of thiourea stabilizer, 1.5 parts of bipyridinium ionic liquid surfactant, and 1000 parts of deionized water.

[0012] In some embodiments, the raw materials include, by weight: 35 parts of nickel source nickel sulfamate, 20 parts of reducing agent sodium hypophosphite, 20 parts of chelating agent malic acid, 8 parts of pH buffer sodium succinate, 6 parts of thiourea stabilizer, 2 parts of bipyridinium ionic liquid surfactant, and 1000 parts of deionized water.

[0013] The present invention also provides a method for preparing the chemical nickel plating solution, comprising the following steps: Add nickel source, reducing agent, complexing agent, pH buffer, thiourea stabilizer, bipyridinium ionic liquid surfactant and deionized water to the reactor by weight, stir evenly, and then adjust the pH value to 5.0 with sulfuric acid to obtain chemical nickel plating solution. Compared with the prior art, the present invention has the following beneficial effects: 1) The chemical nickel plating solution of the present invention has the properties of fast nickel plating speed, dense and uniform nickel plating layer, good wear resistance and salt resistance, etc.

[0014] 2) Thiourea stabilizer used in the present invention It can efficiently adsorb particles, inhibit the interaction between particles and nickel ions, avoid spontaneous decomposition of chemical nickel plating solution, improve the stability of the plating solution, accelerate the nickel plating rate, and obtain a bright, uniform and consistent coating.

[0015] 3) The bispyridinium ionic liquid surfactant used in the present invention has a stronger wetting effect than the sodium dodecyl sulfate commonly used in the art, which can ensure that the nickel plating solution is in full contact with the metal to be plated, allowing the generated bubbles to escape quickly, thereby reducing the plating defects caused by bubbles, and improving the nickel plating rate and the uniformity and wear resistance of the nickel plating layer. DETAILED DESCRIPTION

[0016] The following non-limiting examples are provided to enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way. The following are merely illustrative of the scope of the present invention, and those skilled in the art may make various changes and modifications to the present invention based on the disclosed content, which should also fall within the scope of the present invention.

[0017] When numerical ranges are given in the examples, it should be understood that, unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs.

[0018] The present invention is further described below by way of specific examples. Unless otherwise specified, the various chemical reagents used in the examples of the present invention were obtained through conventional commercial channels.

[0019] Example 1 A chemical nickel plating solution, calculated by weight, comprises the following raw materials: nickel sulfate (nickel source), sodium hypophosphite (reducing agent), citric acid (complexing agent), sodium acetate (pH buffer), thiourea (stabilizer), 40 parts nickel source, 25 parts sodium hypophosphite (reducing agent), 15 parts citric acid (complexing agent), 5 parts sodium acetate (pH buffer), and thiourea (complexing agent). 10 parts, bipyridinium ionic liquid surfactant 2 parts, 1000 parts of deionized water.

[0020] The preparation method of the above-mentioned chemical nickel plating solution comprises the following steps: A nickel source, a reducing agent, a complexing agent, a pH buffer, a thiourea stabilizer, a bipyridinium ionic liquid surfactant and deionized water were added to a reactor in parts by weight, stirred evenly, and then the pH value was adjusted to 5.0 with sulfuric acid to obtain a chemical nickel plating solution.

[0021] Example 2 A chemical nickel plating solution, calculated by weight, comprises the following raw materials: nickel source nickel chloride 50 parts, reducing agent sodium hypophosphite 20 parts, complexing agent lactic acid 10 parts, pH buffer sodium acetate 7 parts, thiourea stabilizer 8 parts, bipyridinium ionic liquid surfactant 1.5 parts, 1000 parts of deionized water.

[0022] The preparation method of the above-mentioned chemical nickel plating solution comprises the following steps: A nickel source, a reducing agent, a complexing agent, a pH buffer, a thiourea stabilizer, a bipyridinium ionic liquid surfactant and deionized water were added to a reactor in parts by weight, stirred evenly, and then the pH value was adjusted to 4.5 with sulfuric acid to obtain a chemical nickel plating solution.

[0023] Example 3 A chemical nickel plating solution, calculated by weight, comprises the following raw materials: nickel source nickel sulfamate 35 parts, reducing agent sodium hypophosphite 20 parts, complexing agent malic acid 20 parts, pH buffer sodium succinate 8 parts, thiourea stabilizer 6 parts, bipyridinium ionic liquid surfactant 2 parts, 1000 parts of deionized water.

[0024] The preparation method of the above-mentioned chemical nickel plating solution comprises the following steps: A nickel source, a reducing agent, a complexing agent, a pH buffer, a thiourea stabilizer, a bipyridinium ionic liquid surfactant and deionized water were added to a reactor in parts by weight, stirred evenly, and then the pH value was adjusted to 4.0 with sulfuric acid to obtain a chemical nickel plating solution.

[0025] Comparative Example 1 On the basis of Example 1, thiourea stabilizer The common stabilizer 2,4-dithiobiuret was used instead, and other operations and conditions were the same as those in Example 1.

[0026] Comparative Example 2 Based on Example 1, the bipyridinium ionic liquid surfactant The reaction mixture was replaced with sodium lauryl sulfate, and other operations and conditions were the same as those in Example 1.

[0027] Comparative Example 3 Based on Example 1, the bipyridinium ionic liquid surfactant Replace with , other operations and conditions are the same as in Example 1.

[0028] Performance Testing The nickel plating process steps adopted in the present invention are: polishing of the magnesium alloy sample---deionized water cleaning---ultrasonic cleaning---alkaline cleaning (ammonia water)---deionized water cleaning---one-step acid pickling activation (10% H2SO4 solution)---deionized water rinsing---nickel plating in a chemical nickel plating solution to form a Ni-P coating (temperature is 80°C).

[0029] Nickel plating rate: Nickel plating is continued in the chemical nickel plating solution for 1 hour, and then the coating thickness is measured at 5-8 points using an X-ray fluorescence spectrometer (XRF), and the average value is taken in μm / h.

[0030] Appearance inspection: Observe whether the nickel plating layer is bright and whether the brightness is uniform.

[0031] Salt spray test: refer to GB / T2423.17-93 medium salt spray test standard (NSS), the conditions are: the salt solution uses 5% sodium chloride, the pH is between 6.5-7.2, continuous atomization is used, the temperature is maintained at 35℃, and the salt spray deposition rate is maintained at 1.5mL / (h.80cm 2 ) and observe whether there is peeling, cracking, wrinkling, and bubbles.

[0032] Hardness test: The hardness of the Ni-P coating was measured using an HVS-1000A microhardness tester with a load of 100 g and a loading time of 20 s. Five tests were performed on each sample and the average value was taken. The microhardness value was calculated using the following formula: HV = 1854.4P / d 2 ; d = NV; where HV is the microhardness value of the Ni-P coating; P is the load; d is the diagonal length of the indentation; N is the diagonal length in the eyepiece; and V is the objective lens magnification. The results are shown in Table 1.

[0033] It can be seen that the chemical nickel plating solution prepared by the present invention has the properties of fast nickel plating speed, dense and uniform nickel plating layer, good wear resistance and salt resistance. On the one hand, due to the presence of particles such as colloid particles and solid impurities in the chemical nickel plating solution, the above particles have high surface activity, and the thiourea stabilizer used in the present invention The invention can efficiently adsorb particles, inhibit the interaction between particles and nickel ions, prevent spontaneous decomposition of the chemical nickel plating solution, improve the stability of the plating solution, accelerate the nickel plating rate, and obtain a bright, uniform coating. Furthermore, the bipyridinium ionic liquid surfactant used in the present invention has a stronger wetting effect than the sodium dodecyl sulfate commonly used in the art, enabling the nickel plating solution to fully contact the metal to be plated, allowing generated bubbles to quickly escape, thereby reducing coating defects caused by bubbles and improving the nickel plating rate and the uniformity and wear resistance of the nickel plating layer.

[0034] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A chemical nickel plating solution, calculated by weight, comprising: 30-50 parts of nickel source, 20-40 parts of reducing agent, 10-20 parts of complexing agent, 3-10 parts of pH buffer, 5-10 parts of thiourea stabilizer, 0.5-2 parts of bipyridinium ionic liquid surfactant, and 1000 parts of deionized water; The structural formula of the bipyridinium ionic liquid surfactant is: or ; The structural formula of the thiourea stabilizer is: .

2. The chemical nickel plating solution according to claim 1, wherein The nickel source is selected from one or more of nickel sulfate, nickel chloride, nickel carbonate, nickel hypophosphite, nickel methanesulfonate, nickel acetate, nickel nitrate and nickel sulfamate.

3. The chemical nickel plating solution according to claim 1, wherein The reducing agent is selected from one or more of sodium hypophosphite, sodium hypophosphite, potassium hypophosphite, sodium formaldehyde bisulfite, sodium borohydride, ascorbic acid, dimethylamine borane and formaldehyde.

4. The chemical nickel plating solution according to claim 1, wherein The complexing agent is selected from one or more of succinic acid, citric acid, sodium citrate, lactic acid, malic acid, glycine, tetrasodium ethylenediaminetetraacetic acid and ethylenediaminetetraacetic acid.

5. The chemical nickel plating solution according to claim 1, wherein The pH buffer is selected from one or more of glacial acetic acid, sodium acetate, sodium succinate, and sodium hydrogen citrate.

6. The chemical nickel plating solution according to claim 1, wherein Calculated by weight, the raw materials include: 40 parts of nickel source nickel sulfate, 25 parts of reducing agent sodium hypophosphite, 15 parts of complexing agent citric acid, 5 parts of pH buffer sodium acetate, 10 parts of thiourea stabilizer, 2 parts of bipyridinium ionic liquid surfactant, and 1000 parts of deionized water.

7. The chemical nickel plating solution according to claim 1, wherein Calculated by weight, the raw materials include: 50 parts of nickel source nickel chloride, 20 parts of reducing agent sodium hypophosphite, 10 parts of complexing agent lactic acid, 7 parts of pH buffer sodium acetate, 8 parts of thiourea stabilizer, 1.5 parts of bipyridinium ionic liquid surfactant, and 1000 parts of deionized water.

8. The chemical nickel plating solution according to claim 1, wherein Calculated by weight, the raw materials include: 35 parts of nickel source nickel sulfamate, 20 parts of reducing agent sodium hypophosphite, 20 parts of complexing agent malic acid, 8 parts of pH buffer sodium succinate, 6 parts of thiourea stabilizer, 2 parts of bipyridinium ionic liquid surfactant, and 1000 parts of deionized water.

9. A method for preparing the chemical nickel plating solution according to any one of claims 1 to 8, comprising the following steps: A nickel source, a reducing agent, a complexing agent, a pH buffer, a thiourea stabilizer, a bipyridinium ionic liquid surfactant and deionized water were added to a reactor in parts by weight, stirred evenly, and then the pH value was adjusted to 5.0 with sulfuric acid to obtain a chemical nickel plating solution.

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