Preparation method of silver-plated graphite composite coating for electric brush

Abstract

The invention discloses a preparation method of an electric brush silver plating-graphite composite coating, which comprises the following steps: 1) sequentially carrying out activation and electric purification pretreatment on a substrate, and then carrying out surface modification on the pretreated substrate by using a dispersing agent to obtain a surface-modified substrate; 2) setting a closed area for the surface-modified substrate; and (3) the closed area is subjected to silver pre-plating treatment, and a silver pre-plating base body is obtained. According to the invention, the problem that the graphite content in the plating layer is low when the voltage is high when the silver-graphite composite plating layer is plated by an electric brush is solved, so that the production efficiency is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of brush-plated silver-graphite composite coatings, in particular to a preparation method of brush-plated silver-graphite composite coatings. Background Art

[0002] Brush plating is a traditional metal protection process. Compared with other processes such as electroplating, brush plating can be performed simply and safely without disassembling parts of complex equipment. It is applicable to a wide range of materials, and the thickness of the coating can be precisely controlled. It can effectively repair corrosion, scratches, pits and other damage on the surface of complex structure equipment. However, the brush plating of a single metal has poor wear resistance and corrosion resistance. For example, the hardness of a single silver plating layer is low, it is not easy to resist discoloration, and it is easy to fall off due to wear, causing the copper substrate serving as the anode to be corroded rapidly, thereby accelerating the shedding of the silver layer. In contrast, composite brush plating improves the bonding strength between the coating and the substrate by adding graphene to the silver plating solution, thereby improving the wear resistance and corrosion resistance of the coating. Therefore, composite brush plating is an ideal protection process.

[0003] In the composite brush plating process, a plating pen filled with plating solution is used as the anode, and the plating pen is moved back and forth on the substrate for brush plating. However, the voltage applied during the electroplating process and the speed of brush plating have an impact on the graphite content in the composite coating. In production practice, it is found that excessively high voltage in the silver graphene electroplating process causes the OH- on the surface of the cathode copper substrate to be reduced to H 2 , bubbles are generated, and the graphite content in the coating is reduced. Therefore, a small voltage of 0.8-1V is usually used for brush plating. However, the use of a small voltage makes the current density relatively small, the coating deposition rate is slow, and the efficiency of the process production is reduced. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings of the prior art that the use of small voltage leads to relatively small current density, slow coating deposition rate and reduced process production efficiency, the present invention provides a method for preparing a brush-plated silver-graphite composite coating, which has the advantages of increasing the content of graphite in the composite coating by brush plating under high voltage.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a brush-plated silver-graphite composite coating comprises the following steps: 1) firstly perform activation and electro-cleaning pretreatment on the substrate in sequence, and then use a dispersant to perform surface modification on the pretreated substrate to obtain a surface-modified substrate; 2) providing a closed area on the surface-modified substrate; 3) Pre-silvering the enclosed area to obtain a pre-silvering substrate.

[0006] Preferably, the method for preparing a brush-plated silver-graphite composite coating of the present invention further comprises step 4), wherein step 4) specifically comprises brush-plating the pre-silver-plated substrate to obtain a brush-plated substrate.

[0007] Preferably, the method for preparing a brush-plated silver-graphite composite coating of the present invention further comprises step 5), wherein step 5) specifically comprises cleaning and drying the brush-plated substrate.

[0008] Preferably, in step 1), the activation and electro-cleaning pretreatment times are both 10-30 seconds.

[0009] Preferably, in step 1), the concentration of the dispersant is 1-2 g / L; and / or, the surface modification time is 10-15 min.

[0010] Preferably, in step 1), the substrate is polished with 200-1000 mesh sandpaper before activation and electro-cleaning pretreatment.

[0011] Preferably, the dispersant includes one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and didodecyldimethylammonium bromide.

[0012] Preferably, in step 3), the pre-silver plating voltage is 2-3V and the time is 1-3min.

[0013] Preferably, in step 4), the brush plating voltage is 2-3V, and the brush plating method is periodic brush plating.

[0014] Preferably, the periodic brush plating operation is as follows: the back and forth brush plating speed is controlled at 3-10 cm / s, every 3-5 back and forth is a cycle, the cycle interval is 5-15 seconds, the plating solution stays in the closed area during brush plating, and the plating solution gradually flows out during the cycle interval.

[0015] The beneficial effects of the present invention are as follows: (1) The present invention modifies the surface of the substrate so that the graphite nanoparticles in the coating are more evenly dispersed, and then the plastic substrate is pasted along the edge of the area to be brush-plated to form a closed area, and brush-plating is performed in this area, so that the composite plating solution can periodically stay on the surface of the cathode substrate, and when a large voltage is applied, graphite can enter the coating, thereby increasing the graphite content in the coating. In this way, the graphite content in the composite coating can be increased by brush plating at a high voltage. (2) The present invention overcomes the problem of low graphite content in the coating when the voltage is high during brush plating of silver-graphite composite coating, thereby greatly improving production efficiency. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with specific embodiments.

[0017] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0018] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0019] The electro-cleaning solution used in the following examples is: NaOH 20g / L, Na 2 CO 3 20g / L, Na 3 PO 4 70g / L, NaCl2g / L, working voltage 10-12V. Activation liquid for activation: H 2 SO 4 80g / L, (NH 4 ) 2 SO 4 100g / L, working voltage 10-12V.

[0020] Composite plating solution: AgI 40g / L, C 4 H 5 NO 2 80g / L, K 4 P 2 O 7 120g / L, KOH 40g / L, pH 8.0-9.0, graphite powder 2.5g / L. Pre-silvering solution: AgI 40g / L, C 4 H 5 NO 2 80g / L, K 4 P 2 O 7 120g / L, KOH 40g / L, pH 8.0-9.0.

[0021] The present invention uses a micro Vickers hardness tester HVD-10AP to test the hardness of the substrate surface, sets the test force to 100 gf, the force holding time to 10 seconds, tests 6 data points on each sample surface, and calculates the average value and the fluctuation range of the value. A scanning electron microscope is used to take a surface backscattered electron microscopic image with a magnification of 20,000 times, and the image analysis software Image-Pro is used to calculate the area percentage of black graphite in the image, which is calculated as the volume fraction of graphite in the coating, and then the mass percentage of graphite in the coating is calculated according to the density of silver in the graphite.

[0022] Embodiment 1: A method for preparing a brush-plated silver-graphite composite coating, comprising the following steps: 1) firstly subjecting a substrate to activation and electro-cleaning pretreatment in sequence, and then using a dispersant to surface-modify the pretreated substrate to obtain a surface-modified substrate; wherein the activation and electro-cleaning pretreatment times are both 10 seconds. The concentration of the dispersant is 1g / L; and the surface modification time is 10 minutes. Before the activation and electro-cleaning pretreatment, the copper substrate is polished with 200-mesh and 1000-mesh sandpapers, respectively, the electro-cleaning and activation times are 30 seconds, the voltage is 8V, and the surface is rinsed with deionized water. The dispersant includes sodium dodecyl sulfate.

[0023] 2) Set up a closed area for the surface-modified substrate. The specific operation is: soak the two treated copper substrates in the dispersant solution for 15 minutes respectively; use protective glue to cover the area that does not need brush plating, and then use an insulating plastic substrate with a height of 1 cm to stick along the edge of the brush plating area, and leave an opening of about 1 cm in width so that the plating solution can flow out slowly. The area of ​​the brush plating area is about 40cm 2 .

[0024] 3) Pre-silvering the enclosed area to obtain a pre-silvered substrate, wherein the pre-silvering voltage is 2V and the time is 1 minute.

[0025] 4) Brush plating the pre-silver-plated substrate to obtain a brush-plated substrate. The brush plating voltage is 2V, and the brush plating method is periodic brush plating. The periodic brush plating operation is: the back-and-forth brush plating speed is controlled at 3 cm / s, every 3 back-and-forths is a cycle, the cycle interval is 5 seconds, the plating solution stays in the closed area during brush plating, and the plating solution gradually flows out during the cycle interval. 5) Clean and dry the brush plated substrate, specifically by using ultrasonic cleaning for 10 minutes and then blowing it dry.

[0026] Comparative Example 1: A method for preparing a brush-plated silver-graphite composite coating, comprising the following steps: 1) firstly subjecting a substrate to activation and electro-cleaning pretreatment in sequence; wherein the activation and electro-cleaning pretreatment times are both 10 seconds. Before the activation and electro-cleaning pretreatments, the copper substrate is polished with 200-mesh and 1000-mesh sandpapers respectively, the electro-cleaning and activation times are 30 seconds respectively, the voltage is 8V, and the surface is rinsed with deionized water.

[0027] 2) Set up a closed area for the surface-modified substrate. The specific operation is: soak the two treated copper substrates in the dispersant solution for 15 minutes respectively; use protective glue to cover the area that does not need brush plating, and then use an insulating plastic substrate with a height of 1 cm to stick along the edge of the brush plating area, and leave an opening of about 1 cm in width so that the plating solution can flow out slowly. The area of ​​the brush plating area is about 40cm 2 .

[0028] 3) Pre-silvering the enclosed area to obtain a pre-silvered substrate, wherein the pre-silvering voltage is 2V and the time is 1 minute.

[0029] 4) Brush plating the pre-silver-plated substrate to obtain a brush-plated substrate. The brush plating voltage is 2V, and the brush plating method is periodic brush plating. The periodic brush plating operation is: the back-and-forth brush plating speed is controlled at 3 cm / s, every 3 back-and-forths is a cycle, the cycle interval is 5 seconds, the plating solution stays in the closed area during brush plating, and the plating solution gradually flows out during the cycle interval. 5) Clean and dry the brush plated substrate, specifically by using ultrasonic cleaning for 10 minutes and then blowing it dry.

[0030] Example 1 and Comparative Example 1 were used to test the carbon content and hardness of the substrate surface. The test results showed that the graphite content in the unmodified sodium dodecyl sulfate coating on the substrate surface (comparison sample) was about 5.9wt.%, and the hardness was 112.3±9HV. The carbon content in the modified coating (experimental sample) was 9.3wt.%, and the hardness was 120.5±4HV. It can be seen that the graphite content in the coating was significantly increased after modification with the surfactant, and the numerical fluctuation during the coating hardness test was greatly reduced, indicating that the organizational structure of the coating was more uniform.

[0031] Embodiment 2: A method for preparing a brush-plated silver-graphite composite coating, comprising the following steps: 1) firstly subjecting a substrate to activation and electro-cleaning pretreatment in sequence, and then using a dispersant to surface-modify the pretreated substrate to obtain a surface-modified substrate; wherein the activation and electro-cleaning pretreatment times are both 30 seconds. The concentration of the dispersant is 2 g / L; and the surface modification time is 15 minutes. Before the activation and electro-cleaning pretreatment, the copper substrate is polished with 200-mesh and 1000-mesh sandpapers, respectively, the electro-cleaning and activation times are 30 seconds, the voltage is 8V, and the surface is rinsed with deionized water. The dispersant includes sodium dodecyl sulfate.

[0032] 2) Set up a closed area for the surface-modified substrate. The specific operation is: soak the two treated copper substrates in the dispersant solution for 15 minutes respectively; use protective glue to cover the area that does not need brush plating, and then use an insulating plastic substrate with a height of 1 cm to stick along the edge of the brush plating area, and leave an opening of about 1 cm in width so that the plating solution can flow out slowly. The area of ​​the brush plating area is about 40cm 2 .

[0033] 3) Pre-silvering the enclosed area to obtain a pre-silvered substrate, wherein the pre-silvering voltage is 3V and the time is 3 minutes.

[0034] 4) Brush plating the pre-silver-plated substrate to obtain a brush-plated substrate. The brush plating voltage is 3V, and the brush plating method is periodic brush plating. The periodic brush plating operation is: the back-and-forth brush plating speed is controlled at 10 cm / s, every 5 back-and-forths is a cycle, and the cycle interval is 15 seconds. During the brush plating, the plating solution stays in the closed area, and the plating solution gradually flows out during the cycle interval.

[0035] 5) Clean and dry the brush plated substrate, specifically by using ultrasonic cleaning for 10 minutes and then blowing it dry.

[0036] Comparative Example 2: A method for preparing a brush-plated silver-graphite composite coating, comprising the following steps: 1) firstly performing activation and electro-cleaning pretreatment on a substrate in sequence, and then using a dispersant to perform surface modification on the pre-treated substrate to obtain a surface-modified substrate; wherein the activation and electro-cleaning pretreatment times are both 30 seconds. The concentration of the dispersant is 2g / L; and the surface modification time is 15min. Before the activation and electro-cleaning pretreatment, the copper substrate is polished with 200-mesh and 1000-mesh sandpapers respectively, the electro-cleaning and activation times are 30 seconds respectively, the voltage is 8V, and the surface is rinsed with deionized water. The dispersant includes sodium dodecyl sulfate.

[0037] 2) The copper substrate is not treated in any way, and the brush plating area is about 40cm 2 .

[0038] 3) Pre-silvering the enclosed area to obtain a pre-silvered substrate, wherein the pre-silvering voltage is 3V and the time is 3 minutes.

[0039] 4) Brush plating the pre-silver-plated substrate to obtain a brush-plated substrate. The brush plating voltage is 3V, and the brush plating method is periodic brush plating. The periodic brush plating operation is: the back-and-forth brush plating speed is controlled at 10 cm / s, every 5 back-and-forths is a cycle, and the cycle interval is 15 seconds. During the brush plating, the plating solution stays in the closed area, and the plating solution gradually flows out during the cycle interval.

[0040] 5) Clean and dry the brush plated substrate, specifically by using ultrasonic cleaning for 10 minutes and then blowing it dry.

[0041] Example 2 and Comparative Example 2 were tested on the carbon content and hardness of the substrate surface. The test results showed that the carbon content and hardness of the sample coating (experimental sample) brush-plated in the closed area formed by the insulating plastic substrate were 9.3wt.%, and the hardness was 120.5±4HV. The carbon content and hardness of the sample coating (comparative sample) normally brush-plated were 6.8wt.%, and 106.86±4HV, indicating that the composite plating solution brush-plated in the closed area can stay on the surface of the cathode substrate, increase the graphite content in the coating, and thus improve its hardness.

[0042] Embodiment 3: A method for preparing a brush-plated silver-graphite composite coating, comprising the following steps: 1) firstly subjecting a substrate to activation and electro-cleaning pretreatment in sequence, and then using a dispersant to perform surface modification on the pre-treated substrate to obtain a surface-modified substrate; wherein the activation and electro-cleaning pretreatment times are both 10 seconds. The concentration of the dispersant is 1 g / L; and the surface modification time is 10 minutes. Before the activation and electro-cleaning pretreatments, the copper substrate is polished with 200-mesh and 1000-mesh sandpapers, respectively, the electro-cleaning and activation times are 30 seconds, the voltage is 8V, and the surface is rinsed with deionized water. The dispersant includes sodium dodecyl sulfate.

[0043] 2) Set up a closed area for the surface-modified substrate. The specific operation is: soak the two treated copper substrates in the dispersant solution for 15 minutes respectively; use protective glue to cover the area that does not need brush plating, and then use an insulating plastic substrate with a height of 1 cm to stick along the edge of the brush plating area, and leave an opening of about 1 cm in width so that the plating solution can flow out slowly. The area of ​​the brush plating area is about 40cm 2 .

[0044] 3) Pre-silvering the enclosed area to obtain a pre-silvered substrate, wherein the pre-silvering voltage is 2V and the time is 1 minute.

[0045] 4) Brush plating the pre-silver-plated substrate to obtain a brush-plated substrate. The brush plating voltage is 2V, and the brush plating method is periodic brush plating. The periodic brush plating operation is: the back-and-forth brush plating speed is controlled at 4 cm / s, every 4 back-and-forths is a cycle, the cycle interval is 8 seconds, the plating solution stays in the closed area during brush plating, and the plating solution gradually flows out during the cycle interval.

[0046] 5) Clean and dry the brush plated substrate, specifically by using ultrasonic cleaning for 10 minutes and then blowing it dry.

[0047] Comparative Example 3: A method for preparing a brush-plated silver-graphite composite coating, comprising the following steps: 1) firstly performing activation and electro-cleaning pretreatment on a substrate in sequence, and then performing surface modification on the pre-treated substrate using a dispersant to obtain a surface-modified substrate; wherein the activation and electro-cleaning pretreatment times are both 10 seconds. The concentration of the dispersant is 1g / L; and the surface modification time is 10min. Before the activation and electro-cleaning pretreatment, the copper substrate is polished with 200-mesh and 1000-mesh sandpapers respectively, the electro-cleaning and activation times are 30 seconds respectively, the voltage is 8V, and the surface is rinsed with deionized water. The dispersant includes sodium dodecyl sulfate.

[0048] 2) Set up a closed area for the surface-modified substrate. The specific operation is: soak the two treated copper substrates in the dispersant solution for 15 minutes respectively; use protective glue to cover the area that does not need brush plating, and then use an insulating plastic substrate with a height of 1 cm to stick along the edge of the brush plating area, and leave an opening of about 1 cm in width so that the plating solution can flow out slowly. The area of ​​the brush plating area is about 40cm 2 .

[0049] 3) Pre-silvering the enclosed area to obtain a pre-silvered substrate, wherein the pre-silvering voltage is 2V and the time is 1 minute.

[0050] 4) brush plating the pre-silver-plated substrate to obtain a brush-plated substrate. The copper substrate is subjected to non-periodic brush plating, the brush plating voltage is 3V, the brush plating speed is controlled at 4 cm / s, and the brush plating lasts for 10 minutes.

[0051] 5) Clean and dry the brush plated substrate, specifically by using ultrasonic cleaning for 10 minutes and then blowing it dry.

[0052] Example 2 and Comparative Example 2 were tested on the carbon content and hardness of the substrate surface. The test results showed that the carbon content and hardness of the sample coating (experimental sample) with periodic controlled speed brush plating were 9.3wt.%, and the hardness was 120.5±4HV, and the carbon content of the sample coating (comparison sample) without periodic controlled speed brush plating was 6.5wt.%, and the hardness was 112.49±3HV, indicating that periodic controlled speed brush plating can increase the graphite content in the coating.

[0053] In summary, the present invention successfully increases the graphite content of the composite coating under high voltage, thereby increasing the hardness.

[0054] The above-mentioned embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, various other corresponding changes and deformations can be made according to the technical solutions and concepts described above, and all these changes and deformations should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a brush-plated silver-graphite composite coating, characterized in that: The following steps are involved: 1) firstly perform activation and electro-cleaning pretreatment on the substrate in sequence, and then use a dispersant to perform surface modification on the pretreated substrate to obtain a surface-modified substrate; 2) providing a closed area on the surface-modified substrate; 3) Pre-silvering the enclosed area to obtain a pre-silvering substrate.

2. The method for preparing a brush-plated silver-graphite composite coating according to claim 1, characterized in that: The method further comprises step 4), wherein step 4) specifically comprises brush plating the pre-silver-plated substrate to obtain a brush-plated substrate.

3. The method for preparing a brush-plated silver-graphite composite coating according to claim 1, characterized in that: The method further comprises step 5), wherein step 5) specifically comprises cleaning and drying the brush-plated substrate.

4. The method for preparing a brush-plated silver-graphite composite coating according to claim 1, characterized in that: In step 1), the activation and electro-cleaning pretreatment times are both 10-30 seconds.

5. The method for preparing a brush-plated silver-graphite composite coating according to claim 1, 2, 3 or 4, characterized in that: In step 1), the concentration of the dispersant is 1-2 g / L; and / or, the surface modification time is 10-15 min.

6. The method for preparing a brush-plated silver-graphite composite coating according to claim 1, 2, 3 or 4, characterized in that: In step 1), the substrate is polished with 200-1000 mesh sandpaper before activation and electro-cleaning pretreatment.

7. The method for preparing a brush-plated silver-graphite composite coating according to claim 1, 2, 3 or 4, characterized in that: The dispersant includes one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and didodecyl dimethyl ammonium bromide.

8. The method for preparing a brush-plated silver-graphite composite coating according to claim 1, 2, 3 or 4, characterized in that: In step 3), the pre-silver plating voltage is 2-3V and the time is 1-3min.

9. The method for preparing a brush-plated silver-graphite composite coating according to claim 2, characterized in that: In step 4), the brush plating voltage is 2-3V, and the brush plating method is periodic brush plating.

10. The method for preparing a brush-plated silver-graphite composite coating according to claim 9, characterized in that: The specific operation of the periodic brush plating is as follows: the back and forth brush plating speed is controlled at 3-10 cm / s, 3-5 back and forth movements constitute a cycle, and the cycle interval is 5-15 seconds. During the brush plating, the plating solution stays in the closed area, and the plating solution gradually flows out during the cycle interval.