Base material pretreatment method for improving performance of pure nickel coating and preparation method of pure nickel coating

Abstract

The invention provides a base material pretreatment method for improving the performance of a pure nickel coating and a preparation method of the pure nickel coating, and belongs to the field of green energy. The base material pretreatment method comprises the following steps: S1, preparing a corresponding chemical etching solution according to an iron-based metal material and a nickel-based metal material; and S2, selecting a corresponding chemical etching solution for chemical etching according to the base material. According to the method, the problems of various pretreatment processes, high cost, poor binding force and the like of a traditional electrodeposition method for preparing the pure nickel coating are solved, the pretreatment etching solution is prepared, and then the metal material is put into the pretreatment etching solution to be soaked for a short time, so that uniform fractal morphology appears on the surface of the material; and further, the bonding strength and the molten salt corrosion resistance of the pure nickel coating and the matrix are improved.

Description

Technical Field

[0001] The present invention belongs to the field of green energy, and particularly relates to a substrate material pretreatment method for improving the performance of a pure nickel coating and a preparation method of a pure nickel coating. Background Art

[0002] In the fields of green energy generation such as solar thermal power generation, molten salt energy storage, and new generation nuclear power, molten salt is widely used as a heat transfer / storage medium. It has the advantages of high boiling point, low melting point, and low viscosity. However, molten salt is highly corrosive at high temperatures, and the compatibility of molten salt with structural materials is the key to restricting the high reliability and long life operation of the above green energy power generation. The use of structural materials with high corrosion resistance can certainly improve the safety of the power generation system, but its construction cost is significantly increased. Therefore, it is particularly important to develop molten salt corrosion-resistant coatings to improve the molten salt corrosion resistance of low-cost materials. Studies have shown that pure nickel coatings can significantly improve the molten salt corrosion resistance of materials.

[0003] However, the traditional electrodeposition method for preparing pure nickel coatings requires pretreatment of the original material such as surface stress relief, organic solvent degreasing, anode degreasing, and pre-plating, which has many process steps and high costs. Despite this, the pure nickel coatings prepared after these pretreatment steps often fail due to incomplete surface cleaning, inappropriate surface roughness, etc., resulting in poor bonding strength or even peeling.

[0004] Therefore, developing an appropriate pretreatment method for electroplating nickel to reduce process steps, reduce costs, and improve the bonding between the pure nickel coating and the substrate is of extremely important practical significance for the safe and reliable development of the new energy power generation field. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a substrate material pretreatment method for improving the performance of pure nickel coating. The present invention solves the problems of numerous pretreatment processes, high cost, and poor bonding strength in preparing pure nickel coating by traditional electrodeposition method. By preparing a pretreatment etching solution, and then placing the metal material into the pretreatment etching solution for a short time, a uniform fractal morphology appears on the surface of the material, thereby improving the bonding strength between the pure nickel coating and the substrate. At the same time, the surface of the pure nickel coating prepared by the pretreatment method also has a fractal morphology, which will form a dense spinel protective layer in the molten salt, further improving the material's resistance to molten salt corrosion.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a substrate material pretreatment method for improving the performance of pure nickel coating, comprising the following steps:

[0008] S1. Prepare the corresponding chemical etching solution according to the substrate material:

[0009] When the base material is an iron-based metal material, the chemical etching solution is prepared by mixing hydrogen peroxide and concentrated hydrochloric acid in a volume ratio of (1-3):1 to obtain an etching solution A;

[0010] When the base material is a nickel-based metal material, the chemical etching solution is prepared by mixing hydrogen peroxide, concentrated hydrochloric acid, and concentrated nitric acid in a volume ratio of (3-8):(2-6):1 to obtain an etching solution B;

[0011] S2. Chemical etching according to the substrate material:

[0012] When the base material is an iron-based metal material, the iron-based metal material is completely immersed in the etching solution A until the fractal dimension of the surface of the iron-based metal material reaches 1.9 or more;

[0013] When the base material is a nickel-based metal material, the nickel-based metal material is completely immersed in the etching solution B until the fractal dimension of the surface of the nickel-based metal material reaches 1.9 or more.

[0014] Preferably, the concentration of hydrogen peroxide in S1 is 25±5% by mass; the concentration of concentrated hydrochloric acid is 36±1% by mass; and the concentration of concentrated nitric acid is 69±1% by mass.

[0015] Preferably, when the base material in S2 is an iron-based metal material, the ratio of the volume of etching solution A to the surface area of ​​the iron-based metal material is > 10 mL / cm 2 .

[0016] Preferably, when the base material in S2 is an iron-based metal material, the ratio of the volume of etching solution B to the surface area of ​​the nickel-based metal material is > 10 mL / cm 2 .

[0017] Preferably, the soaking time in S2 is 20 to 40 minutes.

[0018] The present invention also provides a method for preparing a pure nickel coating, comprising the following steps:

[0019] The base material is pretreated according to the above base material pretreatment method, and then nickel is plated on the surface of the base material by an electrodeposition method to obtain a pure nickel coating.

[0020] Beneficial technical effects:

[0021] (1) The present invention has no requirements on the surface state and cleanliness of the metal base material. The pretreatment of the coating preparation can be completed by simply placing the original metal material into the prepared pretreatment etching solution for a short time, and the surface state of the material after treatment is uniform, which greatly simplifies the numerous steps of the traditional pretreatment process and significantly reduces the cost.

[0022] (2) Through the pretreatment step of the metal substrate material of the present invention, a uniform fractal morphology is formed on the surface of the metal material, and the fractal dimension reaches above 1.9, which significantly improves the bonding force between the pure nickel coating and the substrate. After the pretreatment step proposed by the present invention, the surface of the pure nickel coating prepared by the electrodeposition method also has a fractal morphology, which will generate a dense spinel protective layer during the molten salt corrosion process, further improving the molten salt corrosion resistance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the surface morphology of the substrate material after pretreatment in Example 1.

[0024] Figure 2 This is the surface morphology of the pure nickel coating obtained in Example 1.

[0025] Figure 3 This is the cross-sectional morphology of the pure nickel coating obtained in Example 1.

[0026] Figure 4 This is the test result of the pure nickel coating obtained in Example 1.

[0027] Figure 5 This is a comparison chart of the bonding conditions of the pure nickel coatings obtained in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0028] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0029] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0030] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0031] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0033] The raw materials in the present invention without special explanation are all commercially available conventional raw materials.

[0034] In the following examples, the concentration of hydrogen peroxide is 25±5% by mass; the concentration of concentrated hydrochloric acid is 36±1% by mass; and the concentration of concentrated nitric acid is 69±1% by mass.

[0035] Example 1

[0036] 1) The base material is 316L austenitic stainless steel (iron-based metal material). The base sample is cut from the plate by wire cutting. The sample size is 20×5×3mm, and the surface is rough and has obvious oil stains.

[0037] 2) Prepare chemical etching solution corresponding to iron-based metal materials:

[0038] Take 25 mL of hydrogen peroxide (25%) and 25 mL of concentrated hydrochloric acid, mix the two, and obtain 50 mL of chemical etching solution for iron-based metal materials;

[0039] 3) Soak the material for chemical etching:

[0040] Completely immerse the iron-based metal material in the prepared chemical etching solution for the iron-based metal material, and the ratio of the solution volume to the sample surface area is >10mL / cm 2 , the immersion time was 30 min, and then the pure nickel coating was prepared on the sample treated by electrodeposition.

[0041] Example 2

[0042] 1) The matrix material is nickel-based metal material. The matrix sample is cut from the plate by wire cutting. The sample size is 20×5×3mm, and the surface is rough and has obvious oil stains.

[0043] 2) Prepare chemical etching solution corresponding to iron-based metal materials:

[0044] Take 30 mL of hydrogen peroxide (30%), 20 mL of concentrated hydrochloric acid, and 10 mL of concentrated nitric acid and mix them to obtain a total of 60 mL of chemical etching solution for iron-based metal materials;

[0045] 3) Soak the material for chemical etching:

[0046] Completely immerse the iron-based metal material in the prepared chemical etching solution for the iron-based metal material, and the ratio of the solution volume to the sample surface area is >10mL / cm 2 , the immersion time was 40 min, and then the pure nickel coating was prepared on the sample treated by electrodeposition.

[0047] Example 3

[0048] The method of this embodiment is the same as that of embodiment 1, except that 25 mL of hydrogen peroxide and 75 mL of concentrated hydrochloric acid are used.

[0049] Example 4

[0050] The method of this embodiment is the same as that of embodiment 1, except that 25 mL of hydrogen peroxide and 50 mL of concentrated hydrochloric acid are used.

[0051] Example 4

[0052] The method of this embodiment is the same as that of embodiment 2, except that 80 mL of hydrogen peroxide, 60 mL of concentrated hydrochloric acid, and 10 mL of concentrated nitric acid are used.

[0053] Example 5

[0054] The method of this embodiment is the same as that of embodiment 2, except that 50 mL of hydrogen peroxide, 40 mL of concentrated hydrochloric acid, and 10 mL of concentrated nitric acid are used.

[0055] Comparative Example 1

[0056] The base material is 316L austenitic stainless steel (iron-based metal material). The base sample is cut from the plate by wire cutting. The sample size is 20×5×3mm, and the surface is rough with obvious oil stains.

[0057] The traditional method of grinding-degreasing-activation-preplating was used to treat the surface of iron-based metal materials, and then pure nickel coating was prepared on the treated samples by electrodeposition.

[0058] Experimental Example 1

[0059] The morphology of Example 1 was analyzed.

[0060] like Figure 1 As shown, the chemically etched substrate in Example 1 presents a uniform fractal morphology, and the fractal dimension of the surface calculated by the box counting method is about 1.92.

[0061] like Figure 2 As shown, the chemically etched substrate in Example 1 also has an obvious fractal morphology.

[0062] like Figure 3 As shown, in the chemically etched substrate in Example 1, it can be seen that there is no defect at the junction of the coating and the substrate.

[0063] like Figure 4 As shown, the substrate subjected to chemical etching in Example 1 has no coating peeling phenomenon after cross-cutting, and the coating has excellent bonding strength.

[0064] like Figure 5 As shown, by comparing the coating bonding of Example 1 with that of Comparative Example 1, the present invention prepares a pretreatment etching solution, and then puts the metal material into the pretreatment etching solution for a short time, so that a uniform fractal morphology appears on the surface of the material, thereby improving the bonding strength between the pure nickel coating and the substrate. At the same time, the surface of the pure nickel coating prepared by the pretreatment method also has a fractal morphology, which further improves the material's resistance to molten salt corrosion.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for pretreating a substrate material to improve the performance of a pure nickel coating, characterized in that: The following steps are involved: S1. Prepare the corresponding chemical etching solution according to the substrate material: When the base material is an iron-based metal material, the chemical etching solution is prepared by mixing hydrogen peroxide and concentrated hydrochloric acid in a volume ratio of (1-3):1 to obtain an etching solution A; When the base material is a nickel-based metal material, the chemical etching solution is prepared by mixing hydrogen peroxide, concentrated hydrochloric acid, and concentrated nitric acid in a volume ratio of (3-8):(2-6):1 to obtain an etching solution B; S2. Chemical etching according to the substrate material: When the base material is an iron-based metal material, the iron-based metal material is completely immersed in the etching solution A until the fractal dimension of the surface of the iron-based metal material reaches 1.9 or more; When the base material is a nickel-based metal material, the nickel-based metal material is completely immersed in the etching solution B until the fractal dimension of the surface of the nickel-based metal material reaches 1.9 or more.

2. The matrix material pretreatment method according to claim 1, characterized in that: The concentration of hydrogen peroxide in S1 is 25±5% by mass; the concentration of concentrated hydrochloric acid is 36±1% by mass; and the concentration of concentrated nitric acid is 69±1% by mass.

3. The method for pretreating a substrate material according to claim 1, characterized in that: In S2, when the base material is an iron-based metal material, the ratio of the volume of the etching solution A to the surface area of ​​the iron-based metal material is greater than 10 mL / cm 2 .

4. The method for pretreating a substrate material according to claim 1, characterized in that: In S2, when the base material is an iron-based metal material, the ratio of the volume of etching solution B to the surface area of ​​the nickel-based metal material is greater than 10 mL / cm 2 .

5. The matrix material pretreatment method according to claim 1, characterized in that: The soaking time in S2 is 20 to 40 minutes.

6. A method for preparing a pure nickel coating, characterized in that: The following steps are involved: The base material is pretreated according to the base material pretreatment method according to any one of claims 1 to 5, and then nickel is plated on the surface of the base material by an electrodeposition method to obtain a pure nickel coating.

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