Preparation method of stainless steel nickel-plated strip with high-temperature discoloration resistance

Abstract

The embodiment of the invention provides a preparation method of a stainless steel nickel-plated strip with high-temperature discoloration resistance, which comprises the following steps: firstly, pretreating a stainless steel strip, then electroplating nickel on the surface of the stainless steel strip for multiple times, and finally, dewatering the surface and drying in vacuum to obtain the stainless steel nickel-plated strip, wherein the pretreatment comprises chemical oil removal, electrolytic oil removal and activation; the multiple times of nickel electroplating sequentially comprise nickel pre-plating, dark nickel plating, semi-bright nickel plating and all-bright nickel plating, the thicknesses of the nickel pre-plating, the dark nickel plating, the semi-bright nickel plating and the all-bright nickel plating are 0.1-0.5, 0.2-0.8, 0.5-2 and 0.5-2 microns respectively, and the total thickness is 1-4 microns; the prepared stainless steel nickel-plated strip not only has good appearance, but also has good high-temperature discoloration resistance, the surface of the stainless steel nickel-plated strip can keep good metallic luster after the stainless steel nickel-plated strip is baked at 800 DEG C for 20 minutes, stable roughness and conductivity are maintained, and the stainless steel nickel-plated strip has excellent surface stability.

Description

Technical Field

[0001] The invention relates to the technical field of metal surface treatment, and in particular to a method for preparing a stainless steel nickel-plated strip with high-temperature discoloration resistance. Background Art

[0002] Nickel-plated stainless steel strips have been widely used in electronics, automobiles, construction, home appliances and other industries due to their good corrosion resistance, wear resistance, electrical conductivity, weldability and other advantages. With the further expansion of its application areas, the market has put forward higher requirements for nickel-plated stainless steel strips. Among them, when nickel-plated stainless steel strips are used in high-temperature environments, the properties of the nickel layer on their surface will directly affect the application performance of nickel-plated stainless steel strips. For example, when baked at 800°C, the surface of conventional nickel-plated stainless steel strips is prone to lose its metallic luster and turn white due to complex reasons such as impurities and oxidation. This not only affects the aesthetics of nickel-plated stainless steel strips, but also has a potential impact on the corrosion resistance, electrical conductivity and other properties of its surface. Summary of the invention

[0003] In view of this, the present invention provides a method for preparing a stainless steel nickel-plated strip with resistance to high-temperature discoloration, which significantly optimizes the anti-discoloration ability of the stainless steel nickel-plated strip, so that the metallic luster of the surface can be maintained when baked at 800°C, which not only improves the surface aesthetics of the stainless steel nickel-plated strip, but also ensures the stability of its surface corrosion resistance, conductivity and other properties.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] In a first aspect, an embodiment of the present invention provides a method for preparing a stainless steel nickel-plated strip with high temperature discoloration resistance, the method comprising: first pre-treating the stainless steel strip, then electroplating nickel on its surface multiple times, and finally removing water from the surface and vacuum drying to obtain the stainless steel nickel-plated strip; wherein the pre-treatment comprises chemical degreasing, electrolytic degreasing and activation; the multiple electroplating nickels are pre-nickel plating, dark nickel plating, semi-bright nickel plating and full-bright nickel plating in sequence, with thicknesses of 0.1-0.5, 0.2-0.8, 0.5-2 and 0.5-2 μm, respectively, and a total thickness of 1-4 μm;

[0006] In a second aspect, an embodiment of the present invention provides a method for preparing a stainless steel nickel-plated strip having high temperature discoloration resistance, the preparation method further comprising:

[0007] (1) The stainless steel strip is placed in a degreasing solution for degreasing. First, soak it for 1 minute as a solution to chemically degrease the surface of the stainless steel strip, and then use 2-7A / dm 2The current density is used for electrolytic degreasing, and then hot water washing is performed to obtain a degreased stainless steel strip; the formula of the degreasing solution is 30-60g / L sodium hydroxide, 30-60g / L sodium carbonate, 30-60g / L trisodium phosphate, 1-3ml / L detergent, the treatment temperature is 30-70℃, and the time is 5-10min;

[0008] (2) placing the degreased stainless steel strip in an aqueous solution containing an anode activator for activation treatment, and then washing with water to obtain an activated stainless steel strip; the concentration of the anode activator is 35-135 g / L, the activation time is 1-5 min, and the current density is 1-3 A / dm 2 , control the Baume degree of the solution to be 8-12;

[0009] (3) Pre-nickel plating is performed on the surface of the activated stainless steel strip, and the current density during electroplating is 1.5-3A / dm 2 The thickness of the pre-nickel plating layer is 0.1-0.5 μm, and then the stainless steel pre-nickel plating strip is obtained by washing with water; the formula of the pre-nickel plating solution is 160-280 g / L nickel chloride, 100-180 ml / L hydrochloric acid, 3-30 ml / L additives, the Baume degree of the solution is controlled to be 14-18, the pH is 0.1-0.5, and the temperature of the solution during electroplating is 20-50°C;

[0010] (4) Dark nickel is electroplated on the surface of the stainless steel pre-nickel-plated strip in (3), and the current density during electroplating is 1.5-3A / dm 2 , the thickness of the dark nickel layer is 0.2-0.8 μm, and a stainless steel dark nickel plated strip is obtained; the formula of the dark nickel plating solution is nickel sulfate 220-380 g / L, nickel chloride 20-60 g / L, boric acid 30-60 g / L, the Baume degree of the solution is controlled to be 18-24, the pH is 3.2-3.8, and the temperature of the solution during electroplating is 40-55°C;

[0011] (5) Electroplating semi-bright nickel on the surface of the dark nickel-plated stainless steel strip in (4) at a current density of 3-10A / dm 2 , the thickness of the semi-bright nickel layer is 0.5-2μm, and a stainless steel semi-bright nickel-plated strip is obtained; the formula of the semi-bright nickel plating solution is nickel sulfate 220-400g / L, nickel chloride 20-60g / L, boric acid 30-60g / L, and a semi-bright agent, the Baume degree of the solution is controlled to be 20-25, the pH is 4.0-4.5, and the temperature of the solution during electroplating is 40-70°C;

[0012] (6) Electroplating the surface of the semi-bright nickel-plated stainless steel strip in (5) with full-bright nickel, with a current density of 3-10A / dm 2The thickness of the all-bright nickel layer is 0.5-2μm, and then the stainless steel nickel-plated strip is obtained by washing with hot water; the formula of the all-bright nickel plating solution is nickel sulfate 220-400g / L, nickel chloride 20-60g / L, boric acid 30-60g / L, and a brightening agent, and the Baume degree of the solution is controlled to be 20-25, the pH is 4.0-4.5, and the temperature of the solution during electroplating is 40-70℃;

[0013] (7) The surface of the nickel-plated stainless steel strip in (6) is dried by blowing, and the strip is placed in a vacuum drying oven for drying at a temperature of 130° C. for 30 h.

[0014] The high temperature discoloration of the stainless steel nickel-plated strip is that after being baked at 800° C. for 20 minutes, the surface metal nickel layer does not lose its metallic luster and turns white.

[0015] The embodiment of the present invention provides a method for preparing a stainless steel nickel-plated strip with high-temperature discoloration resistance, the method comprising: first pre-treating the stainless steel strip, then electroplating nickel on its surface multiple times, and finally removing water from the surface and vacuum drying to obtain the stainless steel nickel-plated strip; wherein the pre-treatment comprises chemical degreasing, electrolytic degreasing and activation; the multiple nickel electroplatings are pre-nickel plating, dark nickel plating, semi-bright nickel plating and full-bright nickel plating in sequence, with thicknesses of 0.1-0.5, 0.2-0.8, 0.5-2 and 0.5-2 μm, respectively, and a total thickness of 1-4 μm; the stainless steel nickel-plated strip prepared in this way not only has a good appearance, but also has good high-temperature discoloration resistance, and after baking at 800°C for 20 minutes, the surface can maintain a good metallic luster, and maintains stable roughness and conductivity, and has excellent surface stability.

[0016] Compared with the prior art, the method for preparing a stainless steel nickel-plated strip with high temperature discoloration resistance provided by the present invention has the following beneficial effects:

[0017] Compared with the stainless steel nickel-plated strip prepared by the conventional process, the present invention innovatively applies pre-nickel plating and modified nickel in the process of nickel electroplating, thereby improving the overall compactness of the nickel layer, thereby obtaining a stainless steel nickel-plated strip with a good appearance; therefore, after the stainless steel nickel-plated strip prepared by the present invention is baked at 800° C. for 20 minutes, its surface still maintains a metallic luster and does not turn white, and its surface properties remain stable, and the conductivity is almost unchanged compared with before the high-temperature treatment; BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a flow chart of the preparation of a stainless steel nickel-plated strip according to an embodiment of the present invention;

[0019] Figure 2 This is a real-life image of an embodiment of the present invention after baking at 800°C for 20 minutes;

[0020] Figure 3 This is a real image of the comparative example of the present invention after baking at 800°C for 20 minutes. DETAILED DESCRIPTION

[0021] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0023] Before further describing the present invention in detail, the nouns and terms involved in the embodiments of the present invention are explained. The nouns and terms involved in the embodiments of the present invention are subject to the following explanations.

[0024] Example

[0025] This embodiment uses a 430 stainless steel strip with a thickness of 0.3 mm as the electroplating substrate, and takes the preparation of a nickel-plated stainless steel strip with a total nickel plating thickness greater than 2 μm as an example. The specific preparation steps are as follows:

[0026] (1) The stainless steel strip is placed in a degreasing solution for degreasing. First, it is immersed in the solution for 1 minute to chemically degrease the surface of the stainless steel strip, and then 5A / dm 2 The current density is used for electrolytic degreasing, and then hot water washing is performed to obtain a degreased stainless steel strip; the formula of the degreasing solution is 30-60g / L sodium hydroxide, 30-60g / L sodium carbonate, 30-60g / L trisodium phosphate, 1-3ml / L detergent, the treatment temperature is 30-70℃, and the time is 5-10min;

[0027] (2) placing the degreased stainless steel strip in an aqueous solution containing an anode activator for activation treatment, and then washing with water to obtain an activated stainless steel strip; the concentration of the anode activator is 35-135 g / L, the activation time is 1-5 min, and the current density is 1-3 A / dm 2 , control the Baume degree of the solution to be 8-12;

[0028] (3) Pre-nickel plating is performed on the surface of the activated stainless steel strip, and the current density during electroplating is 1.5-3A / dm 2The thickness of the pre-nickel plating layer is 0.1-0.5 μm, and then the stainless steel pre-nickel plating strip is obtained by washing with water; the formula of the pre-nickel plating solution is 160-280 g / L nickel chloride, 100-180 ml / L hydrochloric acid, 3-30 ml / L additives, the Baume degree of the solution is controlled to be 14-18, the pH is 0.1-0.5, and the temperature of the solution during electroplating is 20-50°C;

[0029] (4) Dark nickel is electroplated on the surface of the stainless steel pre-nickel-plated strip in (3), and the current density during electroplating is 1.5-3A / dm 2 , the thickness of the dark nickel layer is 0.2-0.8 μm, and a stainless steel dark nickel plated strip is obtained; the formula of the dark nickel plating solution is nickel sulfate 220-380 g / L, nickel chloride 20-60 g / L, boric acid 30-60 g / L, the Baume degree of the solution is controlled to be 18-24, the pH is 3.2-3.8, and the temperature of the solution during electroplating is 40-55°C;

[0030] (5) Electroplating semi-bright nickel on the surface of the dark nickel-plated stainless steel strip in (4) at a current density of 3-10A / dm 2 , the thickness of the semi-bright nickel layer is 0.5-2μm, and a stainless steel semi-bright nickel-plated strip is obtained; the formula of the semi-bright nickel plating solution is nickel sulfate 220-400g / L, nickel chloride 20-60g / L, boric acid 30-60g / L, and a semi-bright agent, the Baume degree of the solution is controlled to be 20-25, the pH is 4.0-4.5, and the temperature of the solution during electroplating is 40-70°C;

[0031] (6) Electroplating the surface of the semi-bright nickel-plated stainless steel strip in (5) with full-bright nickel, with a current density of 3-10A / dm 2 The thickness of the all-bright nickel layer is 0.5-2μm, and then the stainless steel nickel-plated strip is obtained by washing with hot water; the formula of the all-bright nickel plating solution is nickel sulfate 220-400g / L, nickel chloride 20-60g / L, boric acid 30-60g / L, and a brightening agent, and the Baume degree of the solution is controlled to be 20-25, the pH is 4.0-4.5, and the temperature of the solution during electroplating is 40-70℃;

[0032] (7) The surface of the nickel-plated stainless steel strip in (6) is dried by blowing, and the strip is placed in a vacuum drying oven for drying at a temperature of 130° C. for 30 h.

[0033] Comparative Example 1

[0034] Compared with the embodiment, the dark nickel plating process in step (4) is not performed in this comparative example. The nickel layer on the surface of the stainless steel comprises three layers, namely, pre-plated nickel, semi-bright nickel and full-bright nickel. The other steps and solutions are consistent with the embodiment.

[0035] Comparative Example 2

[0036] Compared with the embodiment, this comparative example only increases the current density of the all-bright nickel plating in step (6) to 6A / dm 2 , other steps and solutions are consistent with those in the embodiment.

[0037] Comparative Example 3

[0038] Compared with the embodiment, step (6) of this comparative example is modified as "use dust-free paper to absorb the moisture on the surface of the stainless steel nickel-plated strip, and put it into an oven for drying at a temperature of 130°C for 30 hours." The other steps and solutions are consistent with the embodiment.

[0039] Comparative Example 4

[0040] Compared with the embodiment, the vacuum drying time in step (7) is reduced from 30 h to 12 h, and the other steps and solutions are consistent with the embodiment.

[0041] Please refer to Table 1 and Table 2 for a comparison summary of all embodiments and comparative examples in the present invention, from which it can be seen that:

[0042] 1) By comparing Example 1 with Comparative Example 1 and Comparative Example 2, it can be seen that in Example 1, 1.5-3A / dm 2 The dark nickel layer prepared by the current density effectively improves the overall stability of the nickel layer on the surface of the stainless steel strip, solves the problem of surface discoloration of the stainless steel nickel-plated strip at high temperature, and after the high-temperature test of baking at 800°C for 20min, the surface nickel layer is dense and complete and maintains the metallic luster, without whitening or fogging, and the roughness and conductivity of its surface are almost unchanged before and after the high-temperature test, indicating that the nickel layer has good stability. The reason is that the dark nickel layer prepared by the appropriate current density effectively improves the overall density of the nickel layer, reduces the surface pores of the subsequent semi-bright nickel and full-bright nickel, and improves the overall stability of the nickel layer at high temperature. In Comparative Example 1, no dark nickel plating and in Comparative Example 2, dark nickel plating with excessive current will affect the overall density of the nickel layer on the surface of the stainless steel nickel-plated strip, and the pores, impurities and other factors present therein will affect the stability of the nickel layer at high temperature, and the corresponding Comparative Example 1 and Comparative Example 2 both have surface whitening.

[0043] 2) By comparing Example 1 with Comparative Example 3 and Comparative Example 4, it can be seen that the surface dehydration and drying conditions of the stainless steel nickel-plated strip will also affect its stability at high temperatures. After dehydration by airflow, Example 1 is combined with long-term vacuum drying to completely remove the moisture on the surface of the material and in the microscopic pores, avoiding the oxidation phenomenon of the stainless steel nickel-plated strip due to the participation of moisture on the surface at high temperatures, and further reducing the whitening and fogging of the nickel layer due to oxidation. The treatment methods in Comparative Examples 3 and 4 cannot guarantee the complete removal of moisture on the surface of the stainless steel nickel-plated strip, so in the high-temperature discoloration test, the surface condition of the stainless steel nickel-plated strip is not as good as the stainless steel nickel-plated strip in Example 1.

[0044] Table 1

[0045]

[0046] Table 2

[0047]

[0048] In summary, compared with the nickel-plated stainless steel strip prepared by the existing preparation process, the embodiment of the present invention provides a method for preparing a stainless steel nickel-plated strip with resistance to high-temperature discoloration, the method comprising: first pre-treating the stainless steel strip, then electroplating nickel on its surface multiple times, and finally removing water from the surface and vacuum drying to obtain the stainless steel nickel-plated strip; wherein the pre-treatment comprises chemical degreasing, electrolytic degreasing and activation; the multiple nickel electroplatings are pre-nickel plating, dark nickel plating, semi-bright nickel plating and full-bright nickel plating, respectively, with thicknesses of 0.1-0.5, 0.2-0.8, 0.5-2 and 0.5-2 μm, respectively, and a total thickness of 1-4 μm; the stainless steel nickel-plated strip prepared in this way not only has a good appearance, but also has good resistance to high-temperature discoloration. After baking at 800°C for 20 minutes, the surface can maintain a good metallic luster, and maintain stable roughness and conductivity, and has excellent surface stability.

[0049] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] In this document, the terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion of elements other than those listed and may also include additional elements not expressly listed.

[0051] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a stainless steel nickel-plated strip having high temperature discoloration resistance, characterized in that: The method comprises: The stainless steel strip is pre-treated, and then nickel is electroplated on its surface for multiple times, and finally the surface is dehydrated and vacuum dried to obtain a stainless steel nickel-plated strip; wherein the pre-treatment includes chemical degreasing, electrolytic degreasing and activation; the multiple nickel electroplatings are pre-nickel plating, dark nickel plating, semi-bright nickel plating and full-bright nickel plating in sequence, with thicknesses of 0.1-0.5 μm, 0.2-0.8 μm, 0.5-2 μm and 0.5-2 μm respectively, and a total thickness of 1.3-5.3 μm.

2. The method for preparing a stainless steel nickel-plated strip having high temperature discoloration resistance according to claim 1, characterized in that: The preparation method further comprises: (1) The stainless steel strip is placed in a degreasing solution for degreasing. First, soak it for 1 minute as a solution to chemically degrease the surface of the stainless steel strip, and then use 2-7A / dm 2 The current density is used for electrolytic degreasing, and then hot water washing is performed to obtain a degreased stainless steel strip; the formula of the degreasing solution is 30-60g / L sodium hydroxide, 30-60g / L sodium carbonate, 30-60g / L trisodium phosphate, 1-3ml / L detergent, the treatment temperature is 30-70℃, and the time is 5-10min; (2) placing the degreased stainless steel strip in an aqueous solution containing an anode activator for activation treatment, and then washing with water to obtain an activated stainless steel strip; the concentration of the anode activator is 35-135 g / L, the activation time is 1-5 min, and the current density is 1-3 A / dm 2 , control the Baume degree of the solution to be 8-12; (3) Pre-nickel plating is performed on the surface of the activated stainless steel strip, and the current density during electroplating is 1.5-3A / dm 2 The thickness of the pre-nickel plating layer is 0.1-0.5 μm, and then the stainless steel pre-nickel plating strip is obtained by washing with water; the formula of the pre-nickel plating solution is 160-280 g / L nickel chloride, 100-180 ml / L hydrochloric acid, 3-30 ml / L additives, the Baume degree of the solution is controlled to be 14-18, the pH is 0.1-0.5, and the temperature of the solution during electroplating is 20-50°C; (4) Dark nickel is electroplated on the surface of the stainless steel pre-nickel-plated strip in (3), and the current density during electroplating is 1.5-3A / dm 2 , the thickness of the dark nickel layer is 0.2-0.8 μm, and a stainless steel dark nickel plated strip is obtained; the formula of the dark nickel plating solution is nickel sulfate 220-380 g / L, nickel chloride 20-60 g / L, boric acid 30-60 g / L, the Baume degree of the solution is controlled to be 18-24, the pH is 3.2-3.8, and the temperature of the solution during electroplating is 40-55°C; (5) Electroplating semi-bright nickel on the surface of the dark nickel-plated stainless steel strip in (4) at a current density of 3-10A / dm 2 , the thickness of the semi-bright nickel layer is 0.5-2μm, and a stainless steel semi-bright nickel-plated strip is obtained; the formula of the semi-bright nickel plating solution is nickel sulfate 220-400g / L, nickel chloride 20-60g / L, boric acid 30-60g / L, and a semi-bright agent, the Baume degree of the solution is controlled to be 20-25, the pH is 4.0-4.5, and the temperature of the solution during electroplating is 40-70°C; (6) Electroplating the surface of the semi-bright nickel-plated stainless steel strip in (5) with full-bright nickel, with a current density of 3-10A / dm 2 The thickness of the all-bright nickel layer is 0.5-2μm, and then the stainless steel nickel-plated strip is obtained by washing with hot water; the formula of the all-bright nickel plating solution is nickel sulfate 220-400g / L, nickel chloride 20-60g / L, boric acid 30-60g / L, and a brightening agent, and the Baume degree of the solution is controlled to be 20-25, the pH is 4.0-4.5, and the temperature of the solution during electroplating is 40-70℃; (7) The surface of the nickel-plated stainless steel strip in (6) is dried by blowing, and the strip is placed in a vacuum drying oven for drying at a temperature of 130° C. for 30 h.

3. The method for preparing a stainless steel nickel-plated strip having high temperature discoloration resistance according to claim 2, characterized in that: The high temperature discoloration of the stainless steel nickel-plated strip is that after being baked at 800° C. for 20 minutes, the surface metal nickel layer can maintain the metallic luster and does not turn white.

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