Preparation method of high-corrosion-resistance nickel-plated aluminum flat wire

Abstract

The embodiment of the invention provides a preparation method of a high-corrosion-resistance nickel-plated aluminum flat wire, and the method comprises the steps: taking an aluminum flat wire as a base material, and obtaining the high-corrosion-resistance nickel-plated aluminum flat wire through surface oil removal, acid pickling, gradient zinc immersion treatment, continuous nickel electroplating, surface protection and drying, wherein the aluminum flat wire is a series 1 aluminum flat wire, and the mark of the aluminum flat wire is one of 1060, 1070, 1085, 1090, 1100, 1050, 1145 and 1235; wherein the gradient zinc immersion treatment comprises a primary zinc immersion process, a zinc removal process and a secondary zinc immersion process; the continuous electroplating nickel is dark nickel and comprises three layers of nickel, the thicknesses of the three layers of nickel are 1-3 microns, 1-4 microns and 1-4 microns respectively, and the total thickness of the three layers of nickel is 3-10 microns; the nickel-plated aluminum flat wire prepared by the method has good bending resistance and excellent corrosion resistance, and can realize better machinability and structural stability when being actually applied as a battery connecting piece material, so that the safety of a battery pack and a device is improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal surface treatment, and in particular to a method for preparing a highly corrosion-resistant nickel-plated aluminum flat wire. Background Art

[0002] Aluminum metal has been widely used in electronic circuits due to its good conductivity, good ductility, low density and low cost. In the field of lithium-ion batteries, aluminum and copper are usually used as connecting materials for battery packs. As a connecting material, the electrical conductivity of aluminum is very important for electron transmission in the circuit. However, aluminum also faces the problem of surface corrosion during use. Taking the application of aluminum bar as an example, even after the surface is treated with glue, the surface salt spray resistance is still poor. Therefore, electroplating nickel on the surface of aluminum flat wire is an effective method to achieve both high electrical conductivity and good corrosion resistance. However, conventional processes for electroplating nickel on the surface of aluminum flat wire have problems such as poor bonding strength and many pores in the plating layer, which affect the bending and corrosion resistance of the nickel-plated aluminum flat wire as a connector, especially after the surface is treated with glue, its corrosion resistance will be very poor. Summary of the invention

[0003] In view of this, the present invention provides a method for preparing a highly corrosion-resistant nickel-plated aluminum flat wire, which significantly optimizes the bonding strength and corrosion resistance problems of the nickel-plated aluminum flat wire. The nickel-plated aluminum flat wire prepared in this way has good bending resistance and good salt spray resistance after lamination, and has good application potential.

[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 highly corrosion-resistant nickel-plated aluminum flat wire, the method comprising: using an aluminum flat wire as a substrate, performing surface degreasing, pickling, gradient zinc dipping treatment, continuous nickel electroplating, surface protection, and drying to obtain a highly corrosion-resistant nickel-plated aluminum flat wire;

[0006] Wherein, the aluminum flat wire is a series 1 aluminum flat wire, and the grade is one of 1060, 1070, 1085, 1090, 1100, 1050, 1145, 1235;

[0007] Wherein, the gradient zinc immersion treatment includes a primary zinc immersion, zinc stripping and a secondary zinc immersion process;

[0008] Wherein, the continuous electroplated nickel is dark nickel, comprising three layers of nickel, with thicknesses of 1-3, 1-4, and 1-4 μm, respectively, for a total of 3-10 μm;

[0009] In a second aspect, an embodiment of the present invention provides a method for preparing a highly corrosion-resistant nickel-plated aluminum flat wire, the preparation method further comprising:

[0010] (1) The aluminum flat wire is immersed in an alkaline degreasing solution, and then the entire strip surface is rinsed / washed with pure water to obtain the degreasing aluminum flat wire; the degreasing solution comprises 2-20 g / L sodium hydroxide, 20-50 g / L sodium carbonate, and 20-50 g / L trisodium phosphate, and the treatment temperature is 45-75° C. for 3-5 min;

[0011] (2) placing the degreased aluminum flat wire in a pickling solution for treatment, and then immersing / cleaning the entire strip surface with pure water to obtain the pickled aluminum flat wire; the formula of the pickling solution is 100-150 mL / L of descaling agent and 300-500 mL / L of nitric acid, and the pickling time is 1-3 min;

[0012] (3) The surface of the aluminum flat wire after pickling is subjected to zinc immersion treatment. First, a zinc immersion is performed. The solution used is 250-350 mL / L of a quaternary zinc precipitation solution, wherein the zinc ion concentration is 12-19 g / L, the solution temperature is 20-35° C., and the Baume degree of the solution is controlled to be ≥17; then, 250-550 mL / L of nitric acid is used for zinc stripping, and the treatment temperature is 20-50° C.; finally, a secondary zinc immersion is performed. The solution used is 280-480 mL / L of a quaternary zinc precipitation solution, wherein the zinc ion concentration is 16-21 g / L, the solution temperature is 15-35° C., and the Baume degree of the solution is controlled to be ≥17, and then the entire strip surface is rinsed / washed with pure water to obtain a zinc-impregnated aluminum flat wire;

[0013] (4) Electroplating dark nickel on the surface of the zinc-impregnated aluminum flat wire in (3), the formula of the nickel electroplating solution is 270-520mL / L of nickel sulfamate, 5-20g / L of nickel chloride, 30-60g / L of boric acid, the electroplating temperature is 35-65°C, and the solution Baume degree is 22-28; the nickel electroplating is carried out in three steps, first using 4-8A / dm 2 The first layer of nickel is electroplated at a current density of 5-20A / dm with a thickness of 1-3μm and a solution pH of 2.5-3.5; the pH of the electroplating solution is adjusted to 4.0-4.5 and allowed to stand for 1 minute. 2 The second layer of nickel is electroplated at a current density of 5-20A / dm 2 The third layer of nickel is electroplated at a current density of 1-4 μm thick, and the total thickness of the nickel layer is 3-10 μm; finally, the nickel-plated aluminum flat wire is obtained by four-stage water washing;

[0014] (5) Surface protection of the nickel-plated aluminum flat wire includes two passivation processes. First, the nickel-plated track is passivated and nickel-plated using a plating solution containing 120-280 mL / L of additives at a temperature of 40-70 ° C and a current density of 0-2.5 A / dm 2After being sprayed with pure water, the surface of the nickel-plated track is passivated for the second time (nickel protection) at a temperature of 40-70°C and a current density of 0-2.5A / dm 2 ; Nickel-plated aluminum flat wire after surface protection treatment.

[0015] (6) The surface moisture of the nickel-plated aluminum flat wire after the surface protection treatment in (5) is completely dried by air blowing, and the wire is placed in an oven for drying at a temperature of 100-150°C.

[0016] The high corrosion resistance nickel-plated aluminum flat wire can still achieve salt spray performance of level 9 for 24 hours after being baked at a high temperature of 250-300°C for 20-60s.

[0017] The embodiment of the present invention provides a method for preparing a highly corrosion-resistant nickel-plated aluminum flat wire, the method comprising: using an aluminum flat wire as a substrate, and obtaining a highly corrosion-resistant nickel-plated aluminum flat wire by surface degreasing, pickling, gradient zinc dipping treatment, continuous nickel electroplating, surface protection, and drying. The gradient zinc dipping treatment includes a single zinc dipping, zinc stripping, and a secondary zinc dipping process; the continuous nickel electroplating is dark nickel, including three layers of nickel, with thicknesses of 1-3, 1-4, and 1-4 μm, respectively, for a total of 3-10 μm; the nickel-plated aluminum flat wire thus prepared has both good bending resistance and excellent corrosion resistance, and can achieve better processability and structural stability when actually used as a battery connector material, thereby improving the safety of battery packs and devices.

[0018] Compared with the prior art, the method for preparing a highly corrosion-resistant nickel-plated aluminum flat wire provided by the present invention has the following beneficial effects:

[0019] Even after the conventional aluminum strip is coated with glue, the neutral salt spray resistance of the coating is still poor. The present invention performs structural design and process optimization in the process of continuous nickel electroplating. Through the three-layer nickel structure and timely ion concentration balance treatment, the internal stress accumulation of the nickel layer during the growth process on the surface of the aluminum strip is effectively reduced, and the bonding strength and toughness of the nickel layer and the aluminum strip are improved. Therefore, the prepared nickel-plated aluminum strip exhibits better bending resistance. After bending at 90°, 180° and 10 times, no metal burrs are generated at the bending parts; at the same time, due to the low stress characteristics of the electroplated nickel layer, the nickel layer in its surface protection is smoother and denser, the surface porosity is smaller, and the composite structure is more stable. After high-temperature baking at 250-300°C for 20-60s, the surface nickel layer still maintains good protection performance, and the neutral salt spray performance can still reach 96h 9 level. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of the preparation of a highly corrosion-resistant nickel-plated aluminum flat wire in an embodiment of the present invention;

[0021] Figure 2This is a schematic structural diagram of a highly corrosion-resistant nickel-plated aluminum flat wire according to an embodiment of the present invention;

[0022] Figure 3 This is a corrosion resistance test diagram of the high corrosion resistance nickel-plated aluminum flat wire in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] 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.

[0026] Example

[0027] This embodiment uses an aluminum flat wire as an electroplating substrate, and takes the preparation of a nickel-plated aluminum flat wire with a total thickness of a nickel-plated layer of 3-10 μm as an example. The specific preparation steps are as follows:

[0028] (1) The aluminum flat wire is immersed in an alkaline degreasing solution, and then the entire strip surface is rinsed / washed with pure water to obtain the degreasing aluminum flat wire; the degreasing solution comprises 2-20 g / L sodium hydroxide, 20-50 g / L sodium carbonate, and 20-50 g / L trisodium phosphate, and the treatment temperature is 45-75° C. for 3-5 min;

[0029] (2) placing the degreased aluminum flat wire in a pickling solution for treatment, and then immersing / cleaning the entire strip surface with pure water to obtain the pickled aluminum flat wire; the formula of the pickling solution is 100-150 mL / L of descaling agent and 300-500 mL / L of nitric acid, and the pickling time is 1-3 min;

[0030] (3) The surface of the aluminum flat wire after pickling is subjected to zinc immersion treatment. First, a zinc immersion is performed. The solution used is 250-350 mL / L of a quaternary zinc precipitation solution, wherein the zinc ion concentration is 12-19 g / L, the solution temperature is 20-35° C., and the Baume degree of the solution is controlled to be ≥17; then, 250-550 mL / L of nitric acid is used for zinc stripping, and the treatment temperature is 20-50° C.; finally, a secondary zinc immersion is performed. The solution used is 280-480 mL / L of a quaternary zinc precipitation solution, wherein the zinc ion concentration is 16-21 g / L, the solution temperature is 15-35° C., and the Baume degree of the solution is controlled to be ≥17, and then the entire strip surface is rinsed / washed with pure water to obtain a zinc-impregnated aluminum flat wire;

[0031] (4) Electroplating dark nickel on the surface of the zinc-impregnated aluminum flat wire in (3), the formula of the nickel electroplating solution is 270-520mL / L of nickel sulfamate, 5-20g / L of nickel chloride, 30-60g / L of boric acid, the electroplating temperature is 35-65°C, and the solution Baume degree is 22-28; the nickel electroplating is carried out in three steps, first using 4-8A / dm 2 The first layer of nickel is electroplated at a current density of 5-20A / dm with a thickness of 1-3μm and a solution pH of 2.5-3.5; the pH of the electroplating solution is adjusted to 4.0-4.5 and allowed to stand for 1 minute. 2 The second layer of nickel is electroplated at a current density of 5-20A / dm 2 The third layer of nickel is electroplated at a current density of 1-4 μm thick, and the total thickness of the nickel layer is 3-10 μm; finally, the nickel-plated aluminum flat wire is obtained by four-stage water washing;

[0032] (5) Surface protection of the nickel-plated aluminum flat wire includes two passivation processes. First, the nickel-plated track is passivated and nickel-plated using a plating solution containing 120-280 mL / L of additives at a temperature of 40-70 ° C and a current density of 0-2.5 A / dm 2 After being sprayed with pure water, the surface of the nickel-plated track is passivated for the second time (nickel protection) at a temperature of 40-70°C and a current density of 0-2.5A / dm 2 ; Nickel-plated aluminum flat wire after surface protection treatment.

[0033] (6) The surface moisture of the nickel-plated aluminum flat wire after the surface protection treatment in (5) is completely dried by air blowing, and the wire is placed in an oven for drying at a temperature of 100-150°C.

[0034] Comparative Example 1

[0035] Compared with the embodiment, in the nickel plating process in step (4), the comparative example is 5-12A / dm 2A layer of dark nickel is directly electroplated on the surface of the zinc-impregnated aluminum flat wire in (3) at a current density of , the thickness of which is consistent with the total thickness of the three layers of nickel in Example 1, which is 3-10 μm, and the pH value of the solution is 4.5. The other steps and solutions are consistent with the example.

[0036] Comparative Example 2

[0037] Compared with the embodiment, after completing the nickel electroplating in step (4), the surface protection in step (5) is not performed, and the surface blowing and baking in step (6) are directly used. The other steps and solutions are consistent with the embodiment.

[0038] Comparative Example 3

[0039] Compared with the embodiment, in the nickel plating process in step (4), the comparative example is 5-12A / dm 2 A layer of dark nickel is directly electroplated on the surface of the zinc-impregnated aluminum flat wire in (3) at a current density of , and the thickness is consistent with the total thickness of the three layers of nickel in Example 1, which is 3-10 μm. Then, the surface protection of step (5) is not performed, and the surface is directly blown and dried in step (6). The other steps and solutions are consistent with the example.

[0040] Comparative Example 4

[0041] Compared with the embodiment, in the nickel plating process in step (4), only the pH of the solution for plating the first layer of nickel is adjusted from 3 to 4.5, and the other steps and solutions are consistent with the embodiment.

[0042] Comparative Example 5

[0043] Compared with the embodiment, in the nickel plating process in step (4), only the pH of the solution for plating the first layer of nickel is adjusted from 3 to 1.5, and the other steps and solutions are consistent with the embodiment.

[0044] Please refer to Table 1 and Table 2, which are the comparison summaries of all embodiments and comparative examples in the present invention, from which it can be seen that:

[0045] 1) By comparing Example 1 with Comparative Example 1, Comparative Example 2 and Comparative Example 3, it can be seen that the nickel-plated aluminum flat wire obtained by surface degreasing, pickling, gradient zinc treatment, continuous nickel electroplating, surface protection and drying in Example 1 has the best bending resistance and corrosion resistance. After bending at 90°, 180° and 10 times, no metal burrs are generated at the bending part. At the same time, after being baked at 250-300°C for 20-60s, the salt spray performance can still reach 24h 9, which is closely related to the continuous nickel electroplating and surface protection steps; compared with the one layer of nickel in comparative example 1, the electroplated nickel layer in embodiment 1 is composed of three layers of nickel, and there is a 1 minute standing time between the preparation process of each layer of nickel, which effectively balances the ion concentration in the nickel plating process, reduces the internal stress accumulation of the nickel layer during the growth process, and improves the bonding force and toughness of the nickel layer, thereby showing better bending resistance; compared with comparative example 2 and comparative example 3, embodiment 1 and comparative example 1 show better corrosion resistance, among which embodiment 1 has the best corrosion resistance, because the low stress characteristics of the electroplated nickel layer make the nickel layer in the surface protection smoother and denser, and the surface porosity is smaller, so the salt spray resistance is better, while the surfaces of comparative examples 2 and 3 are not treated with surface protection, and the electroplated nickel layer cannot be effectively protected;

[0046] 2) By comparing Example 1 with Comparative Example 4 and Comparative Example 5, it can be seen that when the first layer of nickel is plated in the continuous nickel electroplating process, the pH of the solution affects the bending resistance and corrosion resistance of the final electroplated nickel layer. When the pH of the solution is 2.5-3.5 when the first layer of nickel is plated, the growth rate of nickel is appropriate, which not only achieves high preparation efficiency but also avoids high stress and high porosity caused by excessive rate; when the pH of the solution is 1 when the first layer of nickel is plated and is not allowed to stand, the too fast reaction rate will cause a large amount of internal stress to accumulate in the nickel layer, resulting in a decrease in the bending resistance of the final electroplated nickel layer, and affecting the effect of subsequent surface protection, and the corrosion resistance is also reduced accordingly; when the pH of the solution is 4.0-4.5 when the first layer of nickel is plated, although the bending resistance and corrosion resistance of the electroplated nickel layer are not much different, the preparation efficiency is too low and the time cost is increased.

[0047] Table 1

[0048]

[0049] Table 2

[0050]

[0051]

[0052] To sum up, compared with the nickel-plated aluminum flat wire prepared by the existing preparation process, the example of the present invention provides a method for preparing a highly corrosion-resistant nickel-plated aluminum flat wire. Compared with the nickel-plated aluminum flat wire prepared by the conventional process, the nickel-plated aluminum flat wire prepared in the present invention not only has good bending resistance, but also has no metal burrs at the bending points at 90°, 180° and after being bent 10 times. It also has excellent corrosion resistance. After being baked at a high temperature of 250-300°C for 20-60s, the salt spray performance can still reach level 9 for 24h. When it is actually used as a battery connector material, it can achieve better processability and structural stability, thereby improving the safety of battery packs and devices.

[0053] 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.

[0054] 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.

[0055] 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 highly corrosion-resistant nickel-plated aluminum flat wire, characterized in that: The method comprises: Aluminum flat wire is used as a substrate, and a zinc-coated aluminum flat wire is obtained by surface degreasing, pickling, and gradient zinc dipping, wherein the aluminum flat wire is a 1 series aluminum flat wire, and the grade is one of 1060, 1070, 1085, 1090, 1100, 1050, 1145, and 1235; wherein the gradient zinc dipping treatment includes a primary zinc dipping, a zinc stripping, and a secondary zinc dipping process; The zinc-coated aluminum flat wire is subjected to continuous nickel electroplating, surface protection, and drying to obtain a nickel-plated aluminum flat wire, wherein the continuous electroplated nickel is dark nickel, comprising three layers of nickel with thicknesses of 1-3 μm, 1-4 μm, and 1-4 μm, respectively, for a total of 3-11 μm.

2. The method for preparing a highly corrosion-resistant nickel-plated aluminum flat wire according to claim 1, characterized in that: The preparation method further comprises: (1) The aluminum flat wire is immersed in an alkaline degreasing solution, and then the entire strip surface is rinsed / washed with pure water to obtain the degreasing aluminum flat wire; the degreasing solution comprises 2-20 g / L sodium hydroxide, 20-50 g / L sodium carbonate, and 20-50 g / L trisodium phosphate, and the treatment temperature is 45-75° C. for 3-5 min; (2) placing the degreased aluminum flat wire in a pickling solution for treatment, and then immersing / cleaning the entire strip surface with pure water to obtain the pickled aluminum flat wire; the formula of the pickling solution is 100-150 mL / L of descaling agent and 300-500 mL / L of nitric acid, and the pickling time is 1-3 min; (3) The surface of the aluminum flat wire after pickling is subjected to zinc immersion treatment. First, a zinc immersion is performed. The solution used is 250-350 mL / L of a quaternary zinc precipitation solution, wherein the zinc ion concentration is 12-19 g / L, the solution temperature is 20-35° C., and the Baume degree of the solution is controlled to be ≥17; then, 250-550 mL / L of nitric acid is used for zinc stripping, and the treatment temperature is 20-50° C.; finally, a secondary zinc immersion is performed. The solution used is 280-480 mL / L of a quaternary zinc precipitation solution, wherein the zinc ion concentration is 16-21 g / L, the solution temperature is 15-35° C., and the Baume degree of the solution is controlled to be ≥17, and then the entire strip surface is rinsed / washed with pure water to obtain a zinc-impregnated aluminum flat wire; (4) Electroplating dark nickel on the surface of the zinc-impregnated aluminum flat wire in (3), the formula of the nickel electroplating solution is 270-520mL / L of nickel sulfamate, 5-20g / L of nickel chloride, 30-60g / L of boric acid, the electroplating temperature is 35-65°C, and the solution Baume degree is 22-28; the nickel electroplating is carried out in three steps, first using 4-8A / dm 2 The first layer of nickel is electroplated at a current density of 5-20A / dm with a thickness of 1-3μm and a solution pH of 2.5-3.5; the pH of the electroplating solution is adjusted to 4.0-4.5 and allowed to stand for 1 minute. 2 The second layer of nickel is electroplated at a current density of 5-20A / dm 2 The third layer of nickel is electroplated at a current density of 1-4 μm thick, and the total thickness of the nickel layer is 3-10 μm; finally, the nickel-plated aluminum flat wire is obtained by four-stage water washing; (5) Surface protection of the nickel-plated aluminum flat wire includes two passivation processes. First, the nickel-plated track is passivated and nickel-plated using a plating solution containing 120-280 mL / L of additives at a temperature of 40-70 ° C and a current density of 0-2.5 A / dm 2 After being sprayed with pure water, the surface of the nickel-plated track is passivated for the second time (nickel protection) at a temperature of 40-70°C and a current density of 0-2.5A / dm 2 ; Nickel-plated aluminum flat wire after surface protection treatment; (6) The surface moisture of the nickel-plated aluminum flat wire after the surface protection treatment in (5) is completely dried by air blowing, and the wire is placed in an oven for drying at a temperature of 100-150°C.

3. The method for preparing a highly corrosion-resistant nickel-plated aluminum flat wire according to claim 2, characterized in that: After the highly corrosion-resistant nickel-plated aluminum flat wire is baked at a high temperature of 250-300° C. for 20-60 seconds, the salt spray performance can still reach level 9 for 24 hours.

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