阅读说明：本技术 一种高耐蚀性复合镀层及其制备方法和应用 (High-corrosion-resistance composite plating layer and preparation method and application thereof ) 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：本发明涉及一种高耐蚀性复合镀层及其制备方法和应用,所述复合镀层包括依次电镀于待镀件表面的镍层、钯镍合金层、铂金层和硬金层,所述复合镀层还设置有防护层,所述防护层涂覆于硬金层的上表面。本发明所述组合镀层的电镀工艺简单,工业化应用性强,且电镀成本较低；所述复合镀层的耐盐水阳极电解腐蚀性能优异,并通过防护层的设置显著提高了所述复合镀层的耐磨性能。本发明将所述复合镀层应用于Type C充电连接器阳极端子的表面加工展现出良好的耐盐水阳极电解腐蚀性能和耐磨性。(The invention relates to a high-corrosion-resistance composite plating layer and a preparation method and application thereof. The electroplating process of the combined coating is simple, the industrial applicability is strong, and the electroplating cost is low; the saline water anodic electrolytic corrosion resistance of the composite coating is excellent, and the wear resistance of the composite coating is remarkably improved through the arrangement of the protective layer. The surface processing of applying the composite coating to the anode terminal of the Type C charging connector shows good brine anodic electrolytic corrosion resistance and wear resistance.)

1. A high corrosion resistance composite plating layer is characterized in that: the composite coating comprises a nickel layer, a palladium-nickel alloy layer, a platinum layer and a hard gold layer which are sequentially electroplated on the surface of the piece to be plated.

2. The composite plating layer with high corrosion resistance according to claim 1, wherein: the composite coating is also provided with a protective layer, and the protective layer is coated on the upper surface of the hard gold layer.

3. The composite plating layer with high corrosion resistance according to claim 1, wherein: the thickness of the nickel layer is 2-5 μm, the thickness of the palladium-nickel alloy layer is 0.8-3 μm, the thickness of the platinum layer is 0.25-0.5 μm, and the thickness of the hard gold layer is 0.025-0.25 μm.

4. A method for preparing a composite coating with high corrosion resistance according to claims 1 to 3, characterized in that: the method comprises the following steps:

(1) carrying out electroplating pretreatment on a piece to be plated;

(2) placing the part to be plated treated in the step (1) in a sulfur-free and pore-free nickel ion plating solution, taking the part to be plated as a cathode, depositing the part to be plated on the surface of the part to be plated through electrodeposition to obtain a sulfur-free and pore-free nickel layer, and washing the part with water for multiple times;

(3) placing the part to be plated treated in the step (2) in a palladium ion-nickel ion plating solution, performing electrodeposition to obtain a high-corrosion-resistance palladium-nickel alloy layer, and washing the high-corrosion-resistance palladium-nickel alloy layer for multiple times by using deionized water;

(4) placing the part to be plated treated in the step (3) in a platinum plating solution, performing electrodeposition to obtain a platinum layer, and washing the platinum layer for multiple times by using deionized water;

(5) and (4) placing the part to be plated treated in the step (4) in a hard gold plating solution, depositing the part to be plated on the surface of the part to be plated through electrodeposition to obtain a hard gold layer, washing the part to be plated with deionized water for multiple times, and drying the part to be plated to obtain the high-corrosion-resistance composite plating layer.

5. The method for preparing the composite coating with high corrosion resistance according to claim 4, wherein the method comprises the following steps: the cathodic current density of the electrodeposition in the step (2) is 0.5-15 ASD.

6. The method for preparing the composite coating with high corrosion resistance according to claim 4, wherein the method comprises the following steps: the sulfur-free pore-free nickel ion plating solution comprises the following raw materials: 40-130g/L of nickel ions, 5-45g/L of nickel chloride, 30-50g/L of boric acid, 0.05-0.2g/L of additive and the balance of water.

7. The method for preparing the composite coating with high corrosion resistance according to claim 6, wherein the method comprises the following steps: the additive is alkyl sulfate or alkyl sulfonate.

8. The method for preparing the composite coating with high corrosion resistance according to claim 4, wherein the method comprises the following steps: the palladium ion-nickel ion plating solution comprises the following raw materials: 15-25g/L of palladium ions, 1.6-2.5g/L of nickel ions, 55-70g/L of ammonium sulfate, 2.5-3.5g/L of alpha-olefin sodium sulfonate and the balance of water.

9. The method for preparing the composite coating with high corrosion resistance according to claim 4, wherein the method comprises the following steps: and (6) coating lubricating oil on the surface of the to-be-plated part obtained in the step (5), drying and curing to form a protective layer, and thus obtaining the high-corrosion-resistance composite plating layer.

10. Use of the high corrosion resistance composite plating layer according to any one of claims 1 to 9 in an electronic device.

Technical Field

The invention relates to the technical field of electroplating, in particular to a high-corrosion-resistance composite plating layer and a preparation method and application thereof.

Background

In the electronic industry, when electronic devices mainly comprising Type C and Micro-USB charging connectors and the like are used, the anode signal pin terminal of the electronic devices is often subjected to serious anodic electrolytic corrosion due to the entering of liquid corrosive media such as moisture, sweat or saline water, and further the charging function is disabled. In order to solve the problem of anodic electrolytic corrosion of the electronic devices, the introduction of the rhodium ruthenium plating is found in the industry to effectively improve the anodic electrolytic corrosion resistance of the electronic devices, but in recent years, the price of rhodium continuously rises, and the average price of rhodium rises from 663 USD/exterior in 2016 to 20662 USD/exterior in 2021 statistically, and the rise exceeds 300%, so that the application of the rhodium ruthenium plating greatly improves the electroplating cost of the electronic devices and is not beneficial to industrial production. Then, plating layers of various metals and combinations thereof, such as platinum, gold, silver, palladium, copper, nickel tungsten, and the like, are continuously developed for improving the anodic electrolytic corrosion resistance in electronic devices while achieving a reduction in the plating cost. However, the anodic electrolytic corrosion resistance exhibited by the plating layer having a low noble metal content is not ideal, and the structure of the combined plating layer is complicated, wherein the noble metal plating layer has a high thickness, and the plating cost cannot be reduced. Furthermore, the most commonly used electroplating bottom layer in electronic devices is a nickel layer, but the porosity of semi-bright nickel generally used in the industry at present is high, and the semi-bright nickel cannot meet the pore-free requirement of other plating layers electroplated on the nickel layer, so that the anodic electrolytic corrosion resistance of the semi-bright nickel is influenced. Based on the consideration of cost control and process simplification of industrial application, the electroplating coating applied to electronic devices needs to be further improved to improve the resistance to anodic electrolytic corrosion, and realize the reduction of electroplating cost and the simplification of electroplating process.

Disclosure of Invention

In order to solve the above-mentioned deficiencies of the prior art, it is an object of the present invention to provide a high corrosion resistance composite plating layer having a simple structure and good resistance to anodic electrolytic corrosion by brine and wear.

The second purpose of the invention is to provide a preparation method of the high-corrosion-resistance composite plating layer, and the high-corrosion-resistance composite plating layer is applied to surface processing of electronic devices. The preparation method of the high-corrosion-resistance composite plating layer is simple, short in flow, easy to implement industrially, energy-saving and consumption-reducing.

The purpose of the invention is realized by the following technical scheme: the composite plating layer comprises a nickel layer, a palladium-nickel alloy layer, a platinum layer and a hard gold layer which are sequentially electroplated on the surface of a piece to be plated.

Preferably, the composite plating layer is further provided with a protective layer, and the protective layer is coated on the upper surface of the hard gold layer.

Preferably, the nickel layer has a thickness of 2 to 5 μm, the palladium-nickel alloy layer has a thickness of 0.8 to 3 μm, the platinum layer has a thickness of 0.25 to 0.5 μm, and the hard gold layer has a thickness of 0.025 to 0.25 μm.

In the invention, a nickel layer is used as a bottom plating layer to be combined with a base material, a palladium-nickel alloy layer is used as an intermediate plating layer, a platinum layer and a hard gold layer are used as surface layers to form the composite plating layer, and meanwhile, in order to further improve the wear resistance and fretting corrosion resistance of the composite plating layer, a protective layer is arranged on the surface of the hard gold layer. The nickel layer is compact and flat, the pores are few, the crystal grains are fine, the bonding capacity with a to-be-plated piece base material is strong, the palladium content in the palladium-nickel alloy layer electroplated on the surface of the nickel layer is high, and the conductivity and the corrosion resistance of the plating layer are greatly improved. According to the invention, the thickness of the platinum layer can be greatly reduced through the combination of the nickel layer and the palladium-nickel alloy layer, and the platinum layer is high in catalytic activity, so that the hard gold layer is arranged on the surface of the platinum layer and can be used as a solid lubricant to reduce the friction coefficient of a coating, prevent the platinum from being directly exposed to a friction section, reduce the generation of organic polymers in the application process of sliding friction and fretting friction, and maintain good electrical property. The arrangement of the protective layer is beneficial to further improving the wear resistance of the composite coating. The coatings with different grain sizes in the multilayer composite coatings are mutually stacked, so that the transmission of corrosive media can be effectively hindered, and the saline water anodic electrolytic corrosion resistance of the composite coatings can be remarkably improved by the coatings without pores or with low porosity.

The other purpose of the invention is realized by the following technical scheme: a preparation method of the high-corrosion-resistance composite plating layer comprises the following steps:

(1) carrying out electroplating pretreatment on a piece to be plated;

(2) placing the part to be plated treated in the step (1) in sulfur-free and pore-free nickel ion plating solution at 50-65 ℃, taking the part to be plated as a cathode, depositing the part to be plated on the surface of the part to be plated through electrodeposition to obtain a sulfur-free and pore-free nickel layer, and washing the part with water for multiple times;

(3) placing the part to be plated treated in the step (2) in a palladium ion-nickel ion plating solution at 45-55 ℃, performing electrodeposition to obtain a high-corrosion-resistance palladium-nickel alloy layer, and washing the high-corrosion-resistance palladium-nickel alloy layer for multiple times by using deionized water;

(4) placing the part to be plated treated in the step (3) in a platinum plating solution at 45-55 ℃, obtaining a platinum layer through electrodeposition, and washing the platinum layer for multiple times by using deionized water;

(5) and (3) placing the part to be plated treated in the step (4) in a hard gold plating solution at 55-65 ℃, depositing on the surface of the part to be plated through electrodeposition to obtain a hard gold layer, washing the hard gold layer for multiple times by using deionized water, and drying to obtain the high-corrosion-resistance composite plating layer.

Preferably, the cathodic current density in step (2) is from 0.5 to 15 ASD; the cathode current density in the step (3) is 3-12 ASD; the cathode current density in the step (4) is 1-3 ASD; the cathode current density in the step (5) is 3-5 ASD.

In the invention, the increase of the cathode current density can improve the cathode polarization degree and can also accelerate the deposition rate of metal ions, but when the cathode current density is too high, the cathode polarization action is strong, so that the coating is burnt; when the current density is too low, the metal deposition rate is too low, and the inorganic heavy metal impurities are co-deposited to the plating layer too much, resulting in an increase in porosity. Therefore, in the steps (2) to (5), the cathode current density is strictly limited to obtain a coating with fine and uniform crystal grains and densely arranged, and the pores between the coating and the coating are reduced to improve the brine anodic corrosion resistance of the composite coating. In addition, in the electrodeposition process, metal ions can move faster along with the increase of the temperature, so that the activity of the metal ions and the conductivity of the plating solution are increased, the deposition speed is increased, when the temperature is too high, the deposition rate is too high, the plating layer cannot be uniformly deposited, and when the temperature is too low, the activity of the metal ions is reduced, and the deposition speed is reduced. Therefore, the temperature of the plating solution is strictly controlled in the steps (2) to (5) of the application, so that the composite plating layer is moderate in deposition speed and uniform in deposition.

Preferably, the sulfur-free and pore-free nickel ion plating solution comprises the following raw materials: 40-130g/L of nickel ions (added by nickel sulfamate or nickel sulfate), 5-45g/L of nickel chloride, 30-50g/L of boric acid, 0.05-0.2g/L of additive and the balance of water; the PH value of the sulfur-free pore-free nickel ion plating solution is 2.5-4.5.

Preferably, the additive is an alkyl sulfate or alkyl sulfonate. More preferably, the additive is specifically sodium dodecyl sulfate, sodium hexadecyl sulfate, sodium dodecyl sulfate or sodium hexadecyl sulfonate.

In the sulfur-free pore-free nickel ion plating solution, nickel sulfamate or nickel sulfate is used as main salt to provide nickel ions required in the electrodeposition process; the nickel chloride is used as auxiliary salt, so that the conductivity of the plating solution can be improved, and the cathode polarization effect can be improved; boric acid is used as a pH buffering agent for adjusting and stabilizing the pH value of the plating solution; the addition of the additive is beneficial to the uniform coverage of the whole coating on the surface of the substrate and the elimination of pores. The nickel layer obtained by the electro-deposition of the sulfur-free pore-free nickel ion plating solution is compact and flat, has no pores or few pores, has fine grains, has good bonding force with a to-be-plated piece base material, has the sulfur content of less than 0.002 wt%, belongs to a sulfur-free nickel layer, has no pollution and harm to the environment, and is clean and environment-friendly.

Preferably, the palladium ion-nickel ion plating solution comprises the following raw materials of 15-25g/L of palladium ions (added by tetraammine palladium chloride), 1.6-2.5g/L of nickel ions (added by nickel sulfate), 55-70g/L of ammonium sulfate, 2.5-3.5g/L of alpha-olefin sodium sulfonate and the balance of water; the PH value of the palladium ion-nickel ion plating solution is 7-9.

In the palladium ion-nickel ion plating solution, tetraamminepalladium chloride is adopted to provide palladium ions for the plating solution, nickel sulfate is adopted to provide nickel ions for nickel salt, the mass concentration of the palladium ions is controlled to be 15-25g/L, a palladium-nickel alloy plating layer with the palladium content of 90-98% can be obtained, the plating layer obtained by electrodeposition of the palladium ion-nickel ion plating solution is a non-porous palladium-nickel alloy plating layer, and the plating layer can obtain good conductivity and corrosion resistance by improving the palladium content.

Preferably, the preparation method of the high corrosion resistance composite plating layer further comprises the step (6), wherein the surface of the to-be-plated piece obtained in the step (5) is coated with lubricating oil, and a protective layer is formed after drying and curing, so that the high corrosion resistance composite plating layer is obtained. Wherein the lubricating oil is any one of perfluoropolyethers, polyphenylene ethers, long-chain hydrocarbon oil and fluorocarbon ethers. The lubricating oil is coated on the surface of the hard gold layer and forms a protective layer after drying and curing, so that the wear resistance and fretting corrosion resistance of the composite coating can be obviously improved.

The invention has the beneficial effects that: the invention forms a nickel layer, a palladium-nickel alloy layer, a platinum layer, a hard gold layer and a protective layer on the surface of the piece to be plated in sequence by controlling the electroplating pretreatment of the substrate, the plating solution and the electrodeposition conditions, the structure of the composite plating layer is reasonably arranged, and the electrolytic corrosion resistance and the wear resistance of the brine anode are obviously improved. And the combination of the nickel layer and the palladium-nickel alloy layer can reduce the thickness of the noble metal plating layer under the condition of keeping better corrosion resistance, thereby obviously reducing the electroplating cost. The preparation process has the advantages of simple flow, short time, mild and controllable conditions, and suitability for industrial implementation and application.

Detailed Description

The present invention will be further described with reference to the following examples for facilitating understanding of those skilled in the art, and the description of the embodiments is not intended to limit the present invention.

In a typical embodiment of the invention, the high-corrosion-resistance composite plating layer comprises a nickel layer, a palladium-nickel alloy layer, a platinum layer and a hard gold layer which are sequentially electroplated on the surface of an element to be plated.

Preferably, the composite plating layer is further provided with a protective layer, and the protective layer is coated on the upper surface of the hard gold layer.

Preferably, the nickel layer has a thickness of 2 to 5 μm, the palladium-nickel alloy layer has a thickness of 0.8 to 3 μm, the platinum layer has a thickness of 0.25 to 0.5 μm, and the hard gold layer has a thickness of 0.025 to 0.25 μm. In an embodiment of the present invention, the nickel layer may have a thickness of 2.0 μm, 3.0 μm, 3.8 μm, 4 μm, and 5 μm, the palladium-nickel alloy layer may have a thickness of 0.8 μm, 1.3 μm, and 3 μm, the platinum layer may have a thickness of 0.25 μm, 0.4 μm, and 0.5 μm, and the hard gold layer may have a thickness of 0.025 μm, 0.08 μm, 0.1 μm, 0.2 μm, and 0.25 μm.

In an exemplary embodiment of the present invention, the method for preparing the high corrosion resistance composite plating layer comprises the following steps:

(6) carrying out electroplating pretreatment on a piece to be plated;

(7) placing the part to be plated treated in the step (1) in sulfur-free and pore-free nickel ion plating solution at 50-65 ℃, taking the part to be plated as a cathode, depositing the part to be plated on the surface of the part to be plated through electrodeposition to obtain a sulfur-free and pore-free nickel layer, and washing the part with water for multiple times;

(8) placing the part to be plated treated in the step (2) in a palladium ion-nickel ion plating solution at 45-55 ℃, performing electrodeposition to obtain a high-corrosion-resistance palladium-nickel alloy layer, and washing the high-corrosion-resistance palladium-nickel alloy layer for multiple times by using deionized water;

(9) placing the part to be plated treated in the step (3) in a platinum plating solution at 45-55 ℃, obtaining a platinum layer through electrodeposition, and washing the platinum layer for multiple times by using deionized water;

(10) and (3) placing the part to be plated treated in the step (4) in a hard gold plating solution at 55-65 ℃, depositing on the surface of the part to be plated through electrodeposition to obtain a hard gold layer, washing the hard gold layer for multiple times by using deionized water, and drying to obtain the high-corrosion-resistance composite plating layer.

Preferably, the cathodic current density in step (2) is from 0.5 to 15 ASD; the cathode current density in the step (3) is 3-12 ASD; the cathode current density in the step (4) is 1-3 ASD; the cathode current density in the step (5) is 3-5 ASD.

Preferably, the sulfur-free and pore-free nickel ion plating solution comprises the following raw materials: 40-130g/L of nickel ions (added by nickel sulfamate or nickel sulfate), 5-45g/L of nickel chloride, 30-50g/L of boric acid, 0.05-0.2g/L of additive and the balance of water; the PH value of the sulfur-free pore-free nickel ion plating solution is 2.5-4.5.

Preferably, the additive is an alkyl sulfate or alkyl sulfonate. More preferably, the additive is specifically sodium dodecyl sulfate, sodium hexadecyl sulfate, sodium dodecyl sulfate or sodium hexadecyl sulfonate.

Preferably, the palladium ion-nickel ion plating solution comprises the following raw materials of 15-25g/L of palladium ions (added by tetraammine palladium chloride), 1.6-2.5g/L of nickel ions (added by nickel sulfate), 55-70g/L of ammonium sulfate, 2.5-3.5g/L of alpha-olefin sodium sulfonate and the balance of water; the PH value of the palladium ion-nickel ion plating solution is 7-9.

Preferably, the preparation method of the high corrosion resistance composite plating layer further comprises the step (6), wherein the surface of the to-be-plated piece obtained in the step (5) is coated with lubricating oil, and a protective layer is formed after drying and curing, so that the high corrosion resistance composite plating layer is obtained. Wherein the lubricating oil is any one of perfluoropolyethers, polyphenylene ethers, long-chain hydrocarbon oil and fluorocarbon ethers.

Example 1

The composite plating layer with high corrosion resistance comprises a nickel layer, a palladium-nickel alloy layer, a platinum layer and a hard gold layer which are sequentially electroplated on the surface of a piece to be plated. The thickness of the nickel layer is 3.8 mu m, the thickness of the palladium-nickel alloy layer is 0.8 mu m, the thickness of the platinum layer is 0.4 mu m, and the thickness of the hard gold layer is 0.08 mu m.

The preparation method of the high-corrosion-resistance composite plating layer comprises the following steps:

(1) carrying out electroplating pretreatment on a piece to be plated;

(2) placing the part to be plated treated in the step (1) in a sulfur-free and pore-free nickel ion plating solution at 50 ℃, wherein the part to be plated is a cathode, depositing the part to be plated on the surface of the part to be plated through electrodeposition to obtain a sulfur-free and pore-free nickel layer, and washing the part to be plated with deionized water for multiple times;

(3) placing the part to be plated treated in the step (2) in a palladium ion-nickel ion plating solution at 45 ℃, performing electrodeposition to obtain a high-corrosion-resistance palladium-nickel alloy layer, and washing the high-corrosion-resistance palladium-nickel alloy layer for multiple times by using deionized water;

(4) placing the part to be plated treated in the step (3) in a platinum plating solution at 45 ℃, obtaining a platinum layer through electrodeposition, and washing the platinum layer for multiple times by using deionized water;

(5) and (4) placing the part to be plated treated in the step (4) in a hard gold plating solution at 55 ℃, depositing on the surface of the part to be plated through electrodeposition to obtain a hard gold layer, washing the part with deionized water for multiple times, and finally drying the part by blowing air.

The cathode current density in the step (2) is 5 ASD; the cathode current density in the step (3) is 5 ASD; the cathode current density in the step (4) is 2 ASD; the cathode current density in the step (5) is 5 ASD.

The sulfur-free pore-free nickel ion plating solution comprises the following raw materials: 110g/L of nickel ions (added by nickel sulfamate), 5g/L of nickel chloride, 30g/L of boric acid, 0.05g/L of sodium hexadecylsulfonate and the balance of water; the pH of the sulfur-free and pore-free nickel ion plating solution is 4.5.

The palladium ion-nickel ion plating solution comprises the following raw materials: 15g/L of palladium ions (added by tetraammine palladium chloride), 1.6g/L of nickel ions (added by nickel sulfate), 55g/L of ammonium sulfate, 2.5g/L of alpha-olefin sodium sulfonate and the balance of water; the pH of the palladium ion-nickel ion plating solution is 7.5.

The platinum plating solution is prepared from Preciousfab Pt2000 of the Japan EEJA company; the hard Gold plating solution is prepared from commercial hard Gold liquid medicine-technical Gold 1020C EG.

Example 2

The composite plating layer with high corrosion resistance comprises a nickel layer, a palladium-nickel alloy layer, a platinum layer and a hard gold layer which are electroplated on the surface of a piece to be plated. The thickness of the nickel layer is 3.8 mu m, the thickness of the palladium-nickel alloy layer is 1.3 mu m, the thickness of the platinum layer is 0.4 mu m, and the thickness of the hard gold layer is 0.08 mu m.

The preparation method of the high-corrosion-resistance composite plating layer comprises the following steps:

(1) carrying out electroplating pretreatment on a piece to be plated;

(2) placing the part to be plated treated in the step (1) in a sulfur-free and pore-free nickel ion plating solution at 55 ℃, taking the part to be plated as a cathode, depositing the part to be plated on the surface of the part to be plated through electrodeposition to obtain a sulfur-free and pore-free nickel layer, and washing the part to be plated with water for multiple times;

(3) placing the part to be plated treated in the step (2) in a palladium ion-nickel ion plating solution at 50 ℃, performing electrodeposition to obtain a high-corrosion-resistance palladium-nickel alloy layer, and washing the high-corrosion-resistance palladium-nickel alloy layer for multiple times by using deionized water;

(4) placing the part to be plated treated in the step (3) in platinum plating solution at 50 ℃, obtaining a platinum layer through electrodeposition, and washing the platinum layer for multiple times by using deionized water;

placing the part to be plated treated in the step (4) in a hard gold plating solution at 60 ℃, and depositing the cathode current density in the step (2) on the surface of the part to be plated through electrodeposition to be 5 ASD; the cathode current density in the step (3) is 5 ASD; the cathode current density in the step (4) is 2 ASD; the cathode current density in the step (5) is 5 ASD.

The sulfur-free pore-free nickel ion plating solution comprises the following raw materials: 80g/L of nickel ions (added by nickel sulfamate), 15g/L of nickel chloride, 40g/L of boric acid, 0.1g/L of sodium dodecyl sulfate and the balance of water; the pH value of the sulfur-free pore-free nickel ion plating solution is 4.

The palladium ion-nickel ion plating solution comprises the following raw materials: 20g/L of palladium ions (added by tetraammine palladium chloride), 2g/L of nickel ions (added by nickel sulfate), 60g/L of ammonium sulfate, 3.0g/L of alpha-olefin sodium sulfonate and the balance of water; the pH of the palladium ion-nickel ion plating solution is 8.

The platinum plating solution is prepared from Preciousfab Pt2000 of the Japan EEJA company; the hard Gold plating solution is prepared from commercial hard Gold liquid medicine-technical Gold 1020C EG.

Example 3

The composite plating layer with high corrosion resistance comprises a nickel layer, a palladium-nickel alloy layer, a platinum layer and a hard gold layer which are electroplated on the surface of a piece to be plated. The thickness of the nickel layer is 5 mu m, the thickness of the palladium-nickel alloy layer is 1.3 mu m, the thickness of the platinum layer is 0.5 mu m, and the thickness of the hard gold layer is 0.08 mu m.

The preparation method of the high-corrosion-resistance composite plating layer comprises the following steps:

(1) carrying out electroplating pretreatment on a piece to be plated;

(2) placing the part to be plated treated in the step (1) in a sulfur-free and pore-free nickel ion plating solution at 65 ℃, taking the part to be plated as a cathode, depositing the part to be plated on the surface of the part to be plated through electrodeposition to obtain a sulfur-free and pore-free nickel layer, and washing the part with water for multiple times;

(3) placing the part to be plated treated in the step (2) in a palladium ion-nickel ion plating solution at 55 ℃, performing electrodeposition to obtain a high-corrosion-resistance palladium-nickel alloy layer, and performing multi-cleaning with deionized water;

(4) placing the part to be plated treated in the step (3) in a platinum plating solution at 55 ℃, obtaining a platinum layer through electrodeposition, and washing the platinum layer for multiple times by using deionized water;

(5) and (4) placing the part to be plated treated in the step (4) in a hard gold plating solution at 65 ℃, depositing on the surface of the part to be plated through electrodeposition to obtain a hard gold layer, washing with deionized water for multiple times, and drying.

The cathode current density in the step (2) is 15 ASD; the cathode current density in the step (3) is 5 ASD; the cathode current density in the step (4) is 3 ASD; the cathode current density in the step (5) is 5 ASD.

The sulfur-free pore-free nickel ion plating solution comprises the following raw materials: 130g/L of nickel ions (added by nickel sulfamate), 10g/L of nickel chloride, 50g/L of boric acid, 0.2g/L of additive and the balance of water; the pH of the sulfur-free and pore-free nickel ion plating solution is 3.5.

The palladium ion-nickel ion plating solution comprises the following raw materials: 20g/L of palladium ions (added by tetraammine palladium chloride), 2g/L of nickel ions (added by nickel sulfate), 60g/L of ammonium sulfate, 3.5g/L of alpha-olefin sodium sulfonate and the balance of water; the pH of the palladium ion-nickel ion plating solution is 8.

The platinum plating solution is prepared from Preciousfab Pt2000 of the Japan EEJA company; the hard Gold plating solution is prepared from commercial hard Gold liquid medicine-technical Gold 1020C EG.

Example 4

The composite plating layer with high corrosion resistance comprises a nickel layer, a palladium-nickel alloy layer, a platinum layer and a hard gold layer which are electroplated on the surface of a piece to be plated. The thickness of the nickel layer is 5 mu m, the thickness of the palladium-nickel alloy layer is 1.3 mu m, the thickness of the platinum layer is 0.5 mu m, and the thickness of the hard gold layer is 0.08 mu m.

The preparation method of the high-corrosion-resistance composite plating layer comprises the following steps:

(1) carrying out electroplating pretreatment on a piece to be plated;

(2) placing the part to be plated treated in the step (1) in a sulfur-free and pore-free nickel ion plating solution at 60 ℃, taking the part to be plated as a cathode, depositing the part to be plated on the surface of the part to be plated through electrodeposition to obtain a sulfur-free and pore-free nickel layer, and washing the part to be plated with water for multiple times;

(3) placing the part to be plated treated in the step (2) in a palladium ion-nickel ion plating solution at 50 ℃, performing electrodeposition to obtain a high-corrosion-resistance palladium-nickel alloy layer, and washing the high-corrosion-resistance palladium-nickel alloy layer for multiple times by using deionized water;

(4) placing the part to be plated treated in the step (3) in platinum plating solution at 50 ℃, obtaining a platinum layer through electrodeposition, and washing the platinum layer for multiple times by using deionized water;

(5) placing the part to be plated treated in the step (4) in a hard gold plating solution at 60 ℃, depositing the part to be plated on the surface of the part to be plated through electrodeposition to obtain a hard gold layer, washing the part to be plated with deionized water for multiple times, and drying the part to be plated;

(6) and (5) coating lubricating oil on the surface of the to-be-plated part obtained in the step (5), and drying and curing to form a protective layer, so as to obtain the high-corrosion-resistance composite plating layer.

The cathode current density in the step (2) is 5 ASD; the cathode current density in the step (3) is 5 ASD; the cathode current density in the step (4) is 2 ASD; the cathode current density in the step (5) is 5 ASD.

The sulfur-free pore-free nickel ion plating solution comprises the following raw materials: 110g/L of nickel ions (added by nickel sulfamate), 5g/L of nickel chloride, 45g/L of boric acid, 0.1g/L of sodium hexadecylsulfate and the balance of water; the pH of the sulfur-free and pore-free nickel ion plating solution is 4.0.

The palladium ion-nickel ion plating solution comprises the following raw materials: 20g/L of palladium ions (added by tetraammine palladium chloride), 2g/L of nickel ions (added by nickel sulfate), 60g/L of ammonium sulfate, 3g/L of alpha-olefin sodium sulfonate and the balance of water; the pH of the palladium ion-nickel ion plating solution is 8.

The platinum plating solution is prepared from Preciousfab Pt2000 of the Japan EEJA company; the hard Gold plating solution is prepared from commercial hard Gold liquid medicine-technical Gold 1020C EG.

In the step (6), the lubricating oil is 5% long-chain hydrocarbon oil.

Comparative example 1

This comparative example differs from example 1 in that:

replacing the sulfur-free and pore-free nickel ion plating solution in example 1 with a commercially available semi-bright nickel plating solution, and performing electrodeposition to obtain a semi-bright nickel layer with the thickness of 3.8 μm; the palladium-nickel alloy layer prepared by electrodeposition using a commercially available palladium-nickel plating solution (Pd% @ 77% wt) instead of the palladium ion-nickel ion plating solution of example 1 had a thickness of 0.8 μm, and the platinum plating layer had a thickness of 0.4 μm.

Comparative example 2

This comparative example differs from example 2 in that:

the commercially available semi-bright nickel plating solution is adopted to replace the sulfur-free pore-free nickel ion plating solution in the example 2, and the thickness of the semi-bright nickel layer prepared by electrodeposition is 3.8 mu m; the palladium-nickel alloy layer prepared by electrodeposition with a commercial palladium-nickel plating solution (Pd% @ 77% wt) instead of the palladium ion-nickel ion plating solution of example 2 had a thickness of 1.3 μm; the thickness of the platinum layer is 0.8 μm.

Comparative example 3

This comparative example differs from example 4 in that:

the surface of the composite plating layer of the comparative example is not provided with a protective layer.

In the invention, the part to be plated adopts a Type C male terminal made of phosphor bronze, the part to be plated is respectively provided with the composite plating layers of the embodiments 1-4 and the comparative examples 1-3 to become the part to be plated, a brine anodic electrolytic corrosion test is carried out, and the time of the first corrosion point exceeding 0.05mm appearing on the surface of the Type C male terminal is recorded, namely the endurance time; the Type C male end terminal containing the composite coating prepared in the embodiment 2 and the comparative example 2 is assembled into a Type C male end connector, the Type C male end connector is inserted into a Type C female end connector, 1000 times of plugging tests are carried out, the abrasion marks and the abrasion conditions of the functional area of the Type C male end connector are observed, the Type C male end terminal after the 1000 times of plugging tests is subjected to a saline anodic electrolytic corrosion test, and the tolerance time is recorded.

The test conditions of electrolytic corrosion of the brine anode are as follows: preparing a 5 wt% sodium chloride solution, wherein the temperature is 40 ℃, the magnetic stirring speed is 200RPM, a cathode adopts a platinum titanium sheet, an anode is a plated part to be tested (the plated part to be tested is only exposed out of a testing functional area, and the rest surface area is sealed by nail polish or epoxy resin), the distance between the anode and the cathode is 10-20 mm, and the anode voltage is set to be 5V constant voltage. When the first corrosion point exceeding 0.05mm appears in the test functional area of the plating piece to be tested, the test is considered to be finished, and the endurance time is recorded.

TABLE 1 results of brine anodic electrolytic corrosion performance test of composite coatings obtained in examples 1 to 4

TABLE 2 results of brine anodic electrolytic corrosion test and plug test of example 4 and comparative examples 1-3

It can be seen from the test results in tables 1 and 2 above that, the results of comparative examples 1-2 and examples 1-2 show that the brine anodic electrolytic corrosion resistance of the semi-bright nickel layer formed by electrodeposition using the commonly commercially available semi-bright nickel plating solution and the palladium-nickel alloy layer formed by electrodeposition using the palladium-nickel plating solution (Pd% @ 77% wt) is much lower than that of the composite plating layer containing the sulfur-free non-porous nickel layer and the palladium-nickel alloy (Pd% @ 95.5% wt), and the composite plating layer can reduce the thickness of the platinum layer and significantly reduce the plating cost while ensuring better brine anodic electrolytic corrosion resistance. Compared with the comparative example 3, the composite plating layer Type C male end connector coated with the protective layer has no obvious grinding mark and abrasion in the contact functional area after 1000 times of plugging and unplugging tests, which shows that the arrangement of the protective layer obviously improves the abrasion resistance of the composite plating layer, and further can better maintain the brine anodic electrolytic corrosion resistance after plugging and unplugging tests.

The above specific examples are further illustrative of the technical solutions and advantages of the present invention, and are not intended to limit the embodiments. It will be apparent to those skilled in the art that any obvious alternative is within the scope of the invention without departing from the inventive concept.