High-corrosion-resistance nickel coating, preparation method thereof and electroplating solution
阅读说明：本技术 一种高耐蚀性镍镀层及其制备方法和电镀液 (High-corrosion-resistance nickel coating, preparation method thereof and electroplating solution ) 是由 祁富安 全成军 肖家庆 于 2021-09-28 设计创作，主要内容包括：本发明涉及电镀技术领域,尤其涉及一种高耐蚀性镍镀层及其制备方法和电镀液。所述镍镀层为无孔隙镍镀层,所述镍镀层中硫含量<＝0.002wt％。电镀液包括如下重量份的原料：镍离子40～130g/L、氯化镍0～45g/L、硼酸30～50g/L、添加剂0.05～0.2g/L。制备方法包括如下步骤：(1)对金属基材进行前处理；(2)将金属基材置于电镀液中进行镍镀。采用该电镀液有助于形成耐腐蚀性能优异的无硫无孔隙镍层；采用该电镀液的制备方法操作简单,生产成本低,生产效率高,有利于工业化大生产,得到的高耐蚀镍镀层稳定性高,具有优异的耐蚀性能。(The invention relates to the technical field of electroplating, in particular to a high-corrosion-resistance nickel coating, a preparation method thereof and electroplating solution. The nickel plating layer is a non-porous nickel plating layer, and the sulfur content in the nickel plating layer is less than 0.002 wt%. The electroplating solution comprises the following raw materials in parts by weight: 40-130 g/L of nickel ions, 0-45 g/L of nickel chloride, 30-50 g/L of boric acid and 0.05-0.2 g/L of additive. The preparation method comprises the following steps: (1) pretreating a metal base material; (2) and putting the metal substrate in an electroplating solution for nickel plating. The adoption of the electroplating solution is beneficial to forming a sulfur-free and pore-free nickel layer with excellent corrosion resistance; the preparation method of the electroplating solution is simple to operate, low in production cost, high in production efficiency and beneficial to industrial mass production, and the obtained high-corrosion-resistance nickel plating layer is high in stability and excellent in corrosion resistance.)
1. A high corrosion resistance nickel plating layer is characterized in that: the nickel coating is a non-porous nickel coating, and the high-corrosion-resistance nickel coating is used for electroplating on a metal substrate.
2. The high corrosion resistance nickel plating layer of claim 1, wherein: the sulfur content in the nickel plating layer is less than 0.002 wt%.
3. The high corrosion resistance nickel plating layer of claim 1, wherein: the high-corrosion-resistance nickel coating further comprises a connecting layer, the lower surface of the connecting layer is attached to a metal base material, the upper surface of the connecting layer is attached to the nickel coating, and the connecting layer is at least one of a nickel preplating connecting layer, a zinc connecting layer or an alkali cyanide copper layer.
4. The high corrosion resistance nickel plating layer of claim 1, wherein: the thickness of the nickel coating is 1.0-10.0 μm.
5. An electroplating solution for electroplating a high corrosion resistant nickel coating, comprising: the feed comprises the following raw materials in parts by weight: 40-130 g/L of nickel ions, 0-45 g/L of nickel chloride, 30-50 g/L of boric acid and 0.05-0.2 g/L of additive.
6. The electroplating bath for electroplating a nickel coating with high corrosion resistance as claimed in claim 5, wherein: the nickel ions adopt at least one of nickel sulfamate and nickel sulfate.
7. The electroplating bath for electroplating a nickel coating with high corrosion resistance as claimed in claim 5, wherein: the additive is at least one of alkyl sulfate, alkyl sulfonate and derivatives thereof.
8. A method for preparing a nickel plating layer with high corrosion resistance according to any one of claims 1 to 4, wherein: the method comprises the following steps:
(1) pretreating a metal base material;
(2) and putting the metal base material into an electroplating solution for electroplating the high-corrosion-resistance nickel coating to carry out nickel plating, thereby obtaining the metal base material electroplated with the high-corrosion-resistance nickel coating.
9. The method of claim 8, wherein the nickel plating layer with high corrosion resistance is prepared by: in the step (2), the cathode current density of electroplating is 0.5-15 ASD.
10. The method of claim 8, wherein the nickel plating layer with high corrosion resistance is prepared by: in the step (2), the temperature of the electroplating solution is 50-65 ℃, and the pH value of the electroplating solution is 2.5-4.5.
Technical Field
The invention relates to the technical field of electroplating, in particular to a high-corrosion-resistance nickel coating, a preparation method thereof and electroplating solution.
Background
The engineering nickel plating layer is widely used in the industry, and can be used as a surface plating layer of a device and also can be used as a bottom layer of the device. At present, the standard of American society for testing and materials-ASTM-B689-97, namely the standard of nickel plating for electroplating engineering, is mostly adopted for electroplating nickel in the industry, wherein a Type 2 sulfur-containing semi-bright plating layer becomes a standard bottom layer or a surface layer in the electronic industry. However, the sulfur-containing semi-bright nickel plating layer has high porosity due to high sulfur codeposition and codeposition of other organic additives, so that the nickel plating layer has poor corrosion resistance, and the porosity of noble metal plating layers on the surface of the nickel bottom layer, such as gold, palladium, nickel and the like, is increased, thereby reducing the corrosion resistance. Therefore, for electronic products such as high-speed connectors, backplane connectors, Data, servers, connectors for military industry and other important applications of high-end gold-plated and palladium-nickel-plated electronic products, such as connectors in the communication industry, the conventional sulfur-containing semi-bright nickel is used as a bottom layer, but the thickness of the surface noble metal layer must be increased to ensure the lowest porosity or no porosity so as to meet the requirement of high corrosion resistance, but the electroplating cost is obviously increased. If the requirements of the corrosion resistance of the product are met and the thickness and the cost of the noble metal are kept unchanged or lower, the bottom nickel electroplating process is required to be improved to reduce or even completely eliminate the porosity of the bottom nickel plating layer, so that when the noble metal layer on the surface layer is electroplated, the pores of the noble metal layer can be obviously reduced under the same thickness, or the thinner noble metal surface layer is electroplated to reduce the cost and obtain the same corrosion resistance as the traditional semi-bright nickel bottom layer.
Disclosure of Invention
In order to overcome the defects and shortcomings in the prior art, the invention aims to provide a high-corrosion-resistance nickel coating which has excellent corrosion resistance, can be well combined with a base material, has low production cost and long service life, and can well protect electronic products such as connectors and the like.
The invention also aims to provide the electroplating solution for the high-corrosion-resistance nickel plating layer and the preparation method of the electroplating solution.
The purpose of the invention is realized by the following technical scheme: the high-corrosion-resistance nickel plating layer is a non-porous nickel plating layer, the sulfur content in the nickel plating layer is less than 0.002 wt%, and the high-corrosion-resistance nickel plating layer is used for electroplating on a metal base material.
Furthermore, the high-corrosion-resistance nickel plating layer further comprises a connecting layer, the lower surface of the connecting layer is attached to a metal substrate, and the upper surface of the connecting layer is attached to the nickel plating layer.
Further, the connecting layer is at least one of a nickel preplating connecting layer, a zinc connecting layer or an alkali cyanide copper layer.
Further, the base material is a stainless steel base material or a tungsten alloy base material, and the connecting layer is a nickel preplating connecting layer. When the substrate layer adopted in the invention is the stainless steel substrate layer or the tungsten alloy substrate layer, the surface of the stainless steel substrate layer or the tungsten alloy substrate layer is electroplated with the nickel pre-plating connecting layer in advance, and the nickel pre-plating connecting layer enables the nickel plating bottom layer and the substrate layer to have good binding force and not to fall off easily.
Further, the base material is a magnesium alloy base material or an aluminum alloy base material, and the connecting layer is a zinc connecting layer. When the base material layer adopted in the invention is the magnesium alloy base material layer or the aluminum alloy base material layer, the magnesium alloy base material layer or the aluminum alloy base material layer is subjected to zinc dipping treatment in advance, and the surface of the base material layer is formed with the zinc connecting layer in advance, so that the binding force between the nickel plating bottom layer and the base material layer is favorably improved, and the nickel plating bottom layer is not easy to fall off.
Furthermore, the base material is a zinc base material or a zinc alloy base material, and the connecting layer is an alkali copper cyanide connecting layer. When the base material adopted in the invention is a zinc base material or a zinc alloy base material, the surface of the zinc base material or the zinc alloy base material is pre-plated with the alkali cyanide copper-nickel connection layer in advance, and the use of the alkali cyanide copper connection layer enables the nickel plating layer and the base material to have good binding force and not to fall off easily.
Furthermore, the thickness of the nickel coating is 1.0-10.0 μm. By adopting the thickness, the invention can obtain the pore-free bottom nickel plating layer with high corrosion resistance, the thickness of the nickel plating layer is not thick, and the production cost is low. Furthermore, the thickness of the nickel coating is 2.0-5.0 μm, and the nickel coating can be used as a bottom layer of a noble metal layer of an electronic product, so that the corrosion resistance of the electronic product layer is improved.
The other purpose of the invention is realized by the following technical scheme: an electroplating solution for electroplating a high-corrosion-resistance nickel coating comprises the following raw materials in parts by weight: 40-130 g/L of nickel ions, 0-45 g/L of nickel chloride, 30-50 g/L of boric acid and 0.05-0.2 g/L of additive.
According to the invention, the raw materials are compounded to prepare the electroplating solution for electroplating the high-corrosion-resistance nickel coating, the raw materials are well matched, and the electroplating solution is adopted for electroplating, so that a sulfur-free pore-free nickel coating with excellent corrosion resistance or a pore-free nickel coating with extremely low sulfur content is formed on the surface of the base material by electroplating, the production cost is low, and the industrial mass production is facilitated.
Further, the nickel ions adopt at least one of nickel sulfamate and nickel sulfate.
Further, the additive is at least one of alkyl sulfate, alkyl sulfonate and derivatives thereof. Further, the additive is at least one of sodium dodecyl sulfate, sodium hexadecyl sulfate, sodium dodecyl sulfate and sodium hexadecyl sulfonate. The additive is beneficial to obtaining the sulfur-free pore-free nickel plating layer or the pore-free nickel plating layer with extremely low sulfur content. By using the above additives, a sulfur-free, void-free nickel coating can be obtained even in low speed stirring applications such as rack plating.
The invention also provides a preparation method of the high-corrosion-resistance nickel plating layer, which comprises the following steps:
(1) pretreating a metal base material;
(2) and putting the metal base material into an electroplating solution for electroplating the high-corrosion-resistance nickel coating to carry out nickel plating, thereby obtaining the metal base material electroplated with the high-corrosion-resistance nickel coating.
Further, in the step (2), the cathode current density of electroplating is 0.5-15 ASD. The electroplating cathode current density mainly depends on the electroplating mode and the stirring intensity. For example, in the low-speed rolling rack plating application, the current density range which can be used is 0.5-3 ASD because the plating solution is stirred weakly; in the high-speed continuous plating application, the plated product travels at a high speed in the plating solution, and the pumped high-flow high-speed stirring plating solution is adopted to impact the plated product, so that the usable current density range can be as high as 5-15 ASD, and the required plating thickness can be obtained in a short time. The high-speed stirring is also beneficial to the hydrogen separated from the surface of the plated part to quickly separate from the surface of the plated part and the nickel coating, thereby obviously reducing the porosity of the nickel coating and improving the corrosion resistance.
Further, in the step (2), the temperature of the electroplating solution is 50-65 ℃, and the pH value of the electroplating solution is 2.5-4.5.
Further, the preparation method of the high-corrosion-resistance nickel plating layer comprises the following steps:
(1) pretreating a metal base material;
(2) and putting the metal base material subjected to nickel pre-plating into an electroplating solution for electroplating the high-corrosion-resistance nickel plating layer to carry out nickel plating, thereby obtaining the metal base material electroplated with the high-corrosion-resistance nickel plating layer.
Further, in the step (1), the pretreatment step is: pre-plating nickel on the surface of the metal base material to form a pre-plated nickel connecting layer. Furthermore, the surface of the metal substrate is cleaned and activated before nickel pre-plating.
Further, in the step (1), the nickel pre-plating step comprises: and placing the metal substrate in a nickel preplating solution for nickel preplating to form a nickel preplating connecting layer.
Further, in the step (1), the nickel pre-plating solution comprises the following raw materials: nickel chloride of 220-260g/L and hydrochloric acid solution of 80-120mL/L, wherein the concentration of the adopted hydrochloric acid is 28-38 wt%.
Further, in the step (1), the cathode current density of the nickel preplating is 5ASD (A/dm)2) The temperature of the plating solution is room temperature.
The invention has the beneficial effects that: the high-corrosion-resistance nickel plating layer is electroplated on the base material by adopting the non-porous nickel plating layer, and can be well combined with the base material, so that the high-corrosion-resistance nickel plating layer has good corrosion resistance, the production cost is low, the service life is long, and electronic products such as connectors and the like are well protected; the raw materials of the electroplating solution of the high-corrosion-resistance nickel plating layer can be well matched, and the electroplating solution is favorable for forming a sulfur-free and pore-free nickel layer with excellent corrosion resistance; the preparation method of the electroplating solution is simple to operate, low in production cost, high in production efficiency and beneficial to industrial mass production, and the obtained high-corrosion-resistance nickel plating layer is high in stability and excellent in corrosion resistance.
Drawings
FIG. 1 is a schematic diagram of a 3-electrode system for measuring corrosion current (Tafel) according to the present invention.
FIG. 2 is a Tafel plot of the conventional semi-bright nickel plating of comparative example 1 versus the highly corrosion resistant nickel plating of example 1.
Detailed Description
For the understanding of those skilled in the art, the present invention will be further described with reference to the following examples and accompanying drawings 1-2, and the content of the embodiments is not intended to limit the present invention.
In one exemplary embodiment of the invention, the high-corrosion-resistance nickel coating is a non-porous nickel coating, the sulfur content of the nickel coating is less than 0.002 wt%, and the high-corrosion-resistance nickel coating is used for electroplating on a substrate.
Furthermore, the high-corrosion-resistance nickel coating also comprises a connecting layer, the lower surface of the connecting layer is attached to a metal substrate, the upper surface of the connecting layer is attached to the nickel coating, and the connecting layer is at least one of a nickel preplating connecting layer, a zinc connecting layer or an alkali cyanide copper layer.
Furthermore, the thickness of the nickel coating is 1.0-10.0 μm. Furthermore, the thickness of the nickel coating is 2.0-5.0 μm.
The other purpose of the invention is realized by the following technical scheme: an electroplating solution for electroplating a high-corrosion-resistance nickel coating comprises the following raw materials in parts by weight: 40-130 g/L of nickel ions, 0-45 g/L of nickel chloride, 30-50 g/L of boric acid and 0.05-0.2 g/L of additive.
Further, the nickel ions adopt at least one of nickel sulfamate and nickel sulfate.
Further, the additive is at least one of alkyl sulfate, alkyl sulfonate and derivatives thereof.
The invention also provides a preparation method of the high-corrosion-resistance nickel plating layer, which comprises the following steps:
(1) pretreating a metal base material;
(2) and putting the metal base material into an electroplating solution for electroplating the high-corrosion-resistance nickel coating to carry out nickel plating, thereby obtaining the metal base material electroplated with the high-corrosion-resistance nickel coating.
In the step (2), the cathode current density of electroplating is 0.5-15 ASD.
Furthermore, the high-corrosion-resistance nickel plating layer further comprises a connecting layer, the lower surface of the connecting layer is attached to the base material, and the upper surface of the connecting layer is attached to the nickel plating layer.
Further, the connecting layer is at least one of a nickel preplating connecting layer, a zinc connecting layer or an alkali cyanide copper layer.
In a typical embodiment of the present invention, the substrate is a stainless steel substrate or a tungsten alloy substrate, and the connection layer is a nickel pre-plating connection layer.
Furthermore, the thickness of the nickel preplating connecting layer is 0.05-0.15 mu m.
In a typical embodiment of the present invention, the substrate is a magnesium alloy substrate or an aluminum alloy substrate, and the connection layer is a zinc connection layer.
In a typical embodiment of the present invention, the substrate is a zinc substrate or a zinc alloy substrate and the tie layer is an alkali copper cyanide tie layer.
In an exemplary embodiment of the present invention, a method for preparing a nickel plating layer with high corrosion resistance comprises the steps of:
(1) pre-treating the metal base material, namely pre-plating nickel on the surface of the metal base material in advance to form a pre-plated nickel connecting layer;
(2) and putting the metal base material subjected to nickel pre-plating into an electroplating solution for electroplating the high-corrosion-resistance nickel plating layer to carry out nickel plating, thereby obtaining the metal base material electroplated with the high-corrosion-resistance nickel plating layer.
Further, in the step (1), the nickel pre-plating step comprises: and placing the metal substrate in a nickel preplating solution for nickel preplating to form a nickel preplating connecting layer.
Further, in the step (1), the nickel pre-plating solution comprises the following raw materials: nickel chloride of 220-260g/L and hydrochloric acid solution of 80-120mL/L, wherein the concentration of the adopted hydrochloric acid is 28-38 wt%.
Further, in the step (1), the cathode current density of the nickel preplating is 5ASD (A/dm)2) The temperature of the plating solution is room temperature. The thickness of the nickel preplating connecting layer is 0.05-0.15 mu m.
Example 1
In the embodiment, the nickel coating with high corrosion resistance is a non-porous nickel coating, and the sulfur content in the nickel coating is less than 0.002 wt%. The high corrosion resistant nickel plating layer is used for electroplating on a metal substrate.
In this embodiment, the electroplating solution for electroplating the high-corrosion-resistant nickel plating layer includes the following raw materials in parts by weight: 110g/L of nickel ions, 5g/L of nickel chloride, 45g/L of boric acid and 0.05g/L of sodium dodecyl sulfate. The nickel ions adopt nickel sulfamate.
This example electroplated a nickel coating on phosphor bronze, said nickel coating having a thickness of 2 μm.
The preparation method of the high corrosion resistant nickel plating layer of the embodiment comprises the following steps:
(1) pretreating a metal base material, wherein the metal base material is phosphor bronze;
(2) and putting the metal base material into an electroplating solution for electroplating the high-corrosion-resistance nickel coating to carry out nickel plating, thereby obtaining the metal base material electroplated with the high-corrosion-resistance nickel coating.
Further, in the step (2), the cathode current density of the electroplating is 5ASD (A/dm)2). The temperature of the plating solution was 60 ℃ and the pH of the plating solution was 4.0. Magnetic stirring is adopted, and the stirring conditions are as follows: 4cm rotor, 1300 RPM.
In this example, the above-mentioned plating solution and preparation method were used to plate a highly corrosion-resistant, non-porous nickel layer with a thickness of 2 μm on phosphor bronze, and a neutral salt spray test was carried out according to ASTM B117-03, and the nickel layer was not corroded in 120 hours, and the test results are shown in Table 1.
Example 2
In the embodiment, the nickel coating with high corrosion resistance is a non-porous nickel coating, and the sulfur content in the nickel coating is less than 0.002 wt%. The high corrosion resistant nickel plating layer is used for electroplating on a metal substrate.
Furthermore, the high-corrosion-resistance nickel plating layer further comprises a connecting layer, the lower surface of the connecting layer is attached to the base material, and the upper surface of the connecting layer is attached to the nickel plating layer. The connecting layer is a nickel preplating connecting layer. The thickness of the nickel preplating connecting layer is 0.1 mu m.
In this embodiment, the electroplating solution for electroplating the high-corrosion-resistant nickel plating layer includes the following raw materials in parts by weight: 110g/L of nickel ions, 5g/L of nickel chloride, 45g/L of boric acid and 0.05g/L of sodium dodecyl sulfate. The nickel ions adopt nickel sulfamate.
In this embodiment, a nickel connection layer is pre-plated on 304 stainless steel, and then a non-porous nickel plating layer is electroplated, wherein the thickness of the non-porous nickel plating layer is 2 μm.
The preparation method of the high corrosion resistant nickel plating layer of the embodiment comprises the following steps:
(1) pretreating a metal base material, wherein the metal base material is 304 stainless steel; pre-plating nickel on 304 stainless steel to form a pre-plated nickel connecting layer;
(2) and putting the metal base material subjected to nickel pre-plating into an electroplating solution for electroplating the high-corrosion-resistance nickel plating layer to carry out nickel plating, thereby obtaining the metal base material electroplated with the high-corrosion-resistance nickel plating layer.
Further, in the step (1), the nickel pre-plating step comprises: and placing the metal substrate in a nickel preplating solution for nickel preplating to form a nickel preplating connecting layer.
Further, in the step (1), the nickel pre-plating solution comprises the following raw materials: nickel chloride hexahydrate (NiCl)2.6H2O)240g/L and hydrochloric acid (33 wt%) 100 mL/L.
Further, in the step (1), the cathode current density of the nickel preplating is 5ASD (A/dm)2) The temperature of the plating solution is room temperature. The thickness of the nickel preplating connecting layer is 0.1 mu m.
Further, in the step (2), the cathode current density of electroplating is5ASD(A/dm2). The temperature of the plating solution was 60 ℃ and the pH of the plating solution was 4.0. Magnetic stirring is adopted, and the stirring conditions are as follows: 4cm rotor, 1300 RPM. The thickness of the high corrosion resistant nickel plating layer is 2 um.
In this example, a nickel connection layer is pre-plated on 304 stainless steel, and then a 2 μm highly corrosion resistant non-porous nickel plating layer is electroplated by using the above electroplating solution and preparation method, and a neutral salt spray test is performed according to ASTM B117-03, so that the nickel layer is not corroded in 132 hours, and the test results are shown in Table 1.
Example 3
In the embodiment, the nickel coating with high corrosion resistance is a non-porous nickel coating, and the sulfur content in the nickel coating is less than 0.002 wt%. The high corrosion resistant nickel plating layer is used for electroplating on a metal substrate.
In this embodiment, the electroplating solution for electroplating the high-corrosion-resistant nickel plating layer includes the following raw materials in parts by weight: 100g/L of nickel ions, 15g/L of nickel chloride, 50g/L of boric acid and 0.1g/L of sodium dodecyl sulfate. The nickel ions adopt nickel sulfamate.
This example electroplated a nickel coating on phosphor bronze, said nickel coating having a thickness of 2 μm.
The preparation method of the high corrosion resistant nickel plating layer of the embodiment comprises the following steps:
(1) pretreating a metal base material, wherein the metal base material is phosphor bronze;
(2) and putting the metal base material into an electroplating solution for electroplating the high-corrosion-resistance nickel coating to carry out nickel plating, thereby obtaining the metal base material electroplated with the high-corrosion-resistance nickel coating.
Further, in the step (2), the cathode current density of the electroplating is 5ASD (A/dm)2). The temperature of the plating solution was 60 ℃ and the pH of the plating solution was 4.5. Magnetic stirring is adopted, and the stirring conditions are as follows: 4cm rotor, 1300 RPM.
In the embodiment, the electroplating solution and the preparation method are adopted to electroplate the high-corrosion-resistance non-porous nickel plating layer with the thickness of 2 microns on the phosphor bronze, then the hard gold layer with the thickness of 0.076 microns is flash-plated on the surface of the high-corrosion-resistance non-porous nickel plating layer, and then the post-protection water-based hole sealing treatment is carried out. The nickel layer showed corrosion after 96 hours in the neutral salt spray test according to ASTM B117-03, the test results are shown in Table 2.
Example 4
In the embodiment, the nickel coating with high corrosion resistance is a non-porous nickel coating, and the sulfur content in the nickel coating is less than 0.002 wt%. The high corrosion resistant nickel plating layer is used for electroplating on a metal substrate.
In this embodiment, the electroplating solution for electroplating the high-corrosion-resistant nickel plating layer includes the following raw materials in parts by weight: 105g/L of nickel ions, 10g/L of nickel chloride, 40g/L of boric acid and 0.15g/L of sodium dodecyl sulfate. The nickel ions adopt nickel sulfamate.
This example electroplated a nickel coating on phosphor bronze, said nickel coating having a thickness of 2 μm.
The preparation method of the high corrosion resistant nickel plating layer of the embodiment comprises the following steps:
(1) pretreating a metal base material, wherein the metal base material is phosphor bronze;
(2) and putting the metal base material into an electroplating solution for electroplating the high-corrosion-resistance nickel coating to carry out nickel plating, thereby obtaining the metal base material electroplated with the high-corrosion-resistance nickel coating.
Further, in the step (2), the cathode current density of the electroplating is 5ASD (A/dm)2). The temperature of the plating solution was 60 ℃ and the pH of the plating solution was 4.5. Magnetic stirring is adopted, and the stirring conditions are as follows: 4cm rotor, 1300 RPM.
In the embodiment, the electroplating solution and the preparation method are adopted to electroplate the high-corrosion-resistance non-pore space with the thickness of 2 microns on the phosphor bronze, and then the hard gold layer with the thickness of 0.4 micron is flash-plated on the surface of the high-corrosion-resistance non-pore space nickel plating layer without post-protection water-based hole sealing treatment. According to EIA-364-60A nitric acid steam porosity test for 75min, a sulfur-free, pore-free and corrosion-resistant nickel sample can be completely pore-free, and the test results are shown in Table 3.
Comparative example 1
For semi-bright nickel widely used in the electronic industry, such as DOW 'S Nikal MP-200, DOW' S Nikal PC-3 and Enthone-OMI OXR-1300, the bath composition is recommended according to the supplier technology, after 2 mu m of electroplating is carried out on a phosphor bronze substrate under the conditions of 60 ℃, 5ASD,4cm of rotor and 1300RPM magnetic stirring, the neutral salt spray test is carried out according to ASTM B117-03, and the test results show in Table 1, wherein 48-72 Hrs show different degrees of corrosion.
Comparative example 2
A nickel layer of 2 μm was plated on a phosphor bronze substrate with commercial semi-bright nickel-Ehtnone-OMI OXR 1300C, and then a hard gold layer of 0.076 μm in thickness was flash-plated under the same conditions as in example 3, followed by the same post-protective aqueous sealing treatment as in example 3. Neutral salt spray testing was performed according to ASTM B117-03, with corrosion occurring after 48hrs for the sample of OXR 1300C, but not after 96Hrs for the sulfur-free, non-porous, highly corrosion resistant nickel sample of example 3, and the results are shown in Table 2.
Comparative example 3
A nickel layer of 2 μm was plated on a phosphor bronze substrate with commercial semi-bright nickel-Ehtnone-OMI OXR 1300C, and then a hard gold layer of 0.4 μm in thickness was plated under the same conditions as in example 4 without post-protective aqueous sealing treatment. According to EIA-364-60A nitric acid steam porosity test for 75min, the sulfur-free, pore-free and corrosion-resistant nickel sample can be completely pore-free, and the OXR 1300C sample finds that the pore number is 3/mm2The test results are shown in Table 3.
In the prior art, the sulfur content of a typical semi-bright nickel plating layer and a typical bright nickel plating layer is usually 0.02 to 0.06 wt%. Comparing the sulfur-free porous nickel plating layers of the examples 1-4 of the present invention with the existing products on the market, the sulfur content of the sulfur-free porous nickel plating layers of the examples 1-4 is less than 0.002 wt%, the sulfur content of a certain semi-bright nickel layer on the market is 0.02 wt%, and the sulfur content of the full-bright nickel layer is 0.05 wt%.
The results of the salt spray tests conducted on the three semi-bright nickel layers of examples 1-2 of the present invention and comparative example 1 are shown in table 1:
TABLE 1 comparison of the results of the neutral salt spray tests on different nickel coatings
Comparing the results of the flash hard gold salt spray test of different nickel base layers of example 3 of the present invention and comparative example 2, the test results are shown in table 2:
TABLE 2 comparison of the results of the flash hard gold neutral salt spray tests on different nickel coatings
The results of the nitric acid porosity tests of 0.4 μm thickness of electroplated hard gold for different nickel underlayers were compared for inventive example 4 and comparative example 3 and are shown in table 3:
TABLE 3 comparison of porosity test results of hard gold layers with different nickel plating layers having a thickness of 0.4 μm
The nickel plating layer obtained by the invention is tested by a Tafel curve test in a 5% sodium chloride neutral brine electrolyte by using a 3-electrode system of an electrochemical workstation, and the corrosion potential of the nickel plating layer is measured, so that the corrosion potential of the sulfur-free pore-free nickel plating layer obtained by the invention is corrected to-0.265V, while the corrosion potential of the traditional semi-bright nickel plating layer is more negative to-0.33V, therefore, the sulfur-free pore-free high-corrosion-resistance nickel plating layer obtained by the invention has stronger inertia and higher stability, and has more excellent corrosion resistance. A schematic of a 3-electrode system for measuring corrosion current and potential (Tafel) is shown in FIG. 1. The auxiliary electrode uses a platinum sheet, the reference electrode uses a mercurous sulfate electrode and a calomel electrode, and the research electrode uses different nickel plating samples. The electrochemical analyzer used in the present invention was electrochemical analyzer CHI 604A. The results of the Tafel curve test for example 1 and comparative example 1 are shown in FIG. 2.
When the thickness of the electroplated sulfur-free pore-free nickel coating is 2 micrometers, a neutral salt spray test is carried out according to the ASTM B117-03 standard, the time can reach 120-132 Hrs, the sulfur-free pore-free nickel coating is 2-3 times of that of a common semi-bright nickel coating with the same thickness, the corrosion resistance is extremely high, and the product performance can be obviously improved. When the sulfur-free and pore-free nickel is used as a bottom layer of a gold-plated electronic product, compared with the traditional semi-bright nickel as the bottom layer, the flash gold (0.05-0.076 mu m) plating layer with the same thickness is subjected to a salt spray test according to the ASTM B117-03 standard, the corrosion resistance can be improved from 48Hrs to 96Hrs, and the corrosion resistance is extremely excellent. The thick gold product with the thickness of 0.4 mu m adopts the sulfur-free pore-free nickel of the invention as a bottom layer, and can achieve no pore completely according to the test of EIA-364-60A nitric acid steam porosity, thereby providing excellent corrosion resistance.
The above-described embodiments are preferred implementations of the present invention, and the present invention may be implemented in other ways without departing from the spirit of the present invention.