CN116676647A - A kind of preparation method of strengthened nickel coating - Google Patents

Abstract

The invention discloses a preparation method of a reinforced nickel coating, which comprises the following steps: (1) pretreating a sample; (2) Dropwise adding carbon sol into the electroplating solution under the conditions of heating and stirring the electroplating solution to obtain nickel-carbon composite electrodeposition plating solution; (3) Immersing the pretreated sample serving as a cathode and a nickel plate serving as an anode into a nickel-carbon composite electrodeposition plating solution, wherein the positive electrode of a pulse power supply is connected with the anode, the negative electrode is connected with the cathode, and the two electrodes are parallel and opposite to each other for pulse electrodeposition; according to the method, the strength, the wear resistance and the corrosion resistance of the nickel coating are improved by introducing carbon sol into the electrolyte and adopting a pulse electrodeposition method.

Description

A kind of preparation method of strengthened nickel coating

technical field

The invention relates to a preparation method of a nickel coating, in particular to a preparation method of a strengthened nickel coating.

Background technique

Nickel coating is often used in industrial production due to its good corrosion resistance and wear resistance. However, in order to reduce costs, simplify the process, and enhance the overall performance of the coating, the nickel coating is often co-deposited with hard particles to form a high-performance composite coating.

Nickel composite coatings use micron-sized hard particles as coating reinforcements. With the advancement of industry, this composite coating preparation process has been unable to meet the contemporary pursuit of higher performance coatings. Comparing with micron-particle reinforced composite coatings, nanoparticle-reinforced composite coatings have higher hardness, strength and friction and wear resistance, so nano-composite coatings have become a research hotspot in recent years. In the existing process, particles such as SiC and graphite powder are directly added into the electroplating solution to achieve the purpose of composite electrodeposition. This kind of process has the phenomenon that graphite particles are easy to agglomerate, it is difficult to achieve the effect of dispersion strengthening, and the obtained composite coating has poor strength and wear resistance.

Contents of the invention

Purpose of the invention: the purpose of this invention is to provide a method for preparing a reinforced nickel coating that improves the strength, wear resistance and corrosion resistance of the nickel coating.

Technical solution: The preparation method of the reinforced nickel coating of the present invention comprises the following steps:

(1) Pretreat the sample;

(2) under the conditions of heating and stirring the electroplating solution, dropwise adding carbon sol to the electroplating solution to obtain a nickel-carbon composite electrodeposition plating solution;

(3) The pretreated sample is used as the cathode, and the nickel plate is used as the anode, immersed in the nickel-carbon composite electrodeposition plating solution, the positive electrode of the pulse power supply is connected to the anode, the negative electrode is connected to the cathode, and the two electrodes are parallel to each other for pulse electrodeposition.

Preferably, in step (2), the carbon sol content in the composite electrodeposition plating solution is 10-40 mL/L, wherein the carbon sol concentration is 0.01-0.03 g/L.

Carbon sol has good dispersion properties, good electrical conductivity and self-lubricating properties. The composite coating formed by carbon nanoparticles and other metals can improve the related mechanical properties of the coating. The addition of carbon particles can refine the grain size and hardness. And strength can also be improved; in addition, nano-carbon particles with high-efficiency self-lubricating effect can greatly improve the friction and wear resistance of the coating.

The carbon sol is obtained by electrolysis in 0.1-0.2M HNO ₃ , 0.1-0.2M (CH ₂ OH) ₂ and 0.1-2g/L C ₁₂ H ₂₅ SO ₄ Na.

Preferably, the pulse electrodeposition parameters are: current density 30-50 mA/cm ² , duty ratio 60-80%, frequency 500-1500 Hz, deposition time 20-40 minutes. Pulse electrodeposition, compared with the ordinary DC electrodeposition process, the pulse electrodeposition process has better surface brightness, friction and wear resistance, corrosion resistance, high conductivity and other properties, and can obtain high quality, thin and uniform precious metals Coating can greatly save production costs.

Preferably, in step (2), the electroplating solution includes: 140-160g/L NiSO ₄ particles, 12-18g/L NH ₄ Cl, 15-20g/L H ₃ BO ₃ and 0.2-1g/LC ₁₂ H ₂₅ SO ₄ Na, water as solvent.

Preferably, in step (1), the sample is brass, pure copper, carbon steel, aluminum alloy and the like. Use a cutting machine or scissors to make the sample into a sample with a size of 15mm×20mm, so as to be suitable for the electroplating tank device.

Preferably, in step (1), the pretreatment of the sample includes surface smoothing treatment, alkali cleaning and activation treatment

Preferably, the smoothing treatment is as follows: paste insulating glue on the surface of the sample, and expose an exposed surface with a certain area, use sandpaper of different meshes to polish the exposed surface from coarse to fine, and finally use deionized water The samples were cleaned and dried before use.

Preferably, the composition of the alkali washing liquid in the alkali washing step 2 is: 35-60g/L NaOH and 8-13g/L NaH ₂ PO ₄ ·H ₂ O, and water is used as a solvent. The alkali washing lasts 10 minutes, and after the alkali washing is completed, the sample is washed with deionized water.

Preferably, the activation treatment is as follows: the cathode of the sample, the stainless steel plate is used as the anode, the cathode and anode electrodes are immersed in the activation solution, the positive pole of the DC power supply is connected to the anode, the negative pole is connected to the cathode, the two electrodes are parallel to each other, and the activation treatment is carried out in a constant current mode. .

Preferably, the activation solution includes 15-25g/LC ₆ H ₈ O ₇ and 60-70g/LC ₆ H ₅ O ₇ (NH ₄ ) ₃ , and water is used as a solvent.

Preferably, in the activation treatment, the current density is 30-40 mA/cm ² , and the activation time is 90 seconds.

Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) This method improves the strength and wear resistance of the nickel coating by introducing carbon sol into the electrolyte and adopting the method of pulse electrodeposition. and corrosion resistance; (2) Adding 15ML/L of carbon sol with a concentration of 0.025g/L, the hardness reaches a maximum of 420HV, and the corrosion rate is 7.11×10 ^-3 mm/year, compared to the amount of carbon sol without adding carbon sol Reduced by 44.9%; (3) the device required for preparing the nickel phosphorus-carbon nanocomposite coating is simple, and the manufacturing process is simple: the equipment only needs an electroplating pool, a DC power supply, and wires, fixtures, etc., and the cost is low; Reagent market sales source is extensive, therefore is suitable for large-scale industrial production; (4) the electroplating solution nickel-phosphorus plating solution used in this method can be stored for a long time, and the chemical reagent used in electroplating is little for environmental pollution; (5) activation all The stainless steel plate used as the anode is very inert, and no new substances will be produced in the reaction to pollute the activation solution, so it can be reused many times.

Description of drawings

Fig. 1 is the surface topography scanning figure prepared in implementation example 1, comparative example 1, comparative example 2; Wherein, figure (a) is the pure nickel coating of comparative example 1; Figure (b) is that embodiment 1 adds 15mL/L The nickel-carbon composite coating of carbon sol; Figure (c) is the nickel-carbon composite coating of comparative example 2 adding 50mL/L carbon sol;

Fig. 2 is the cross-sectional topography scanning figure of the pure nickel and nickel-carbon composite coating prepared in embodiment 1, comparative example 1, comparative example 2; Wherein, figure (a) is comparative example 1 pure nickel coating; Figure (b) ) is the nickel-carbon composite coating that adds 15mL/L carbon sol for embodiment 1; Figure (c) is the nickel-carbon composite coating that adds 50mL/L carbon sol for comparative example 2;

Fig. 3 is the XRD figure and the grain size contrast figure of the pure nickel and nickel-carbon composite coating prepared in embodiment example 1, comparative example 1, comparative example 2; Wherein, figure (a) is pure nickel and nickel-carbon composite coating XRD figure; Figure (b) is the average grain size comparison chart of pure nickel and nickel-carbon composite coating;

Fig. 4 is a surface topography diagram of friction and wear scars and a cross-sectional scanning diagram of the wear scars of pure nickel and nickel-carbon composite coatings prepared in Example 1, Comparative Example 1, and Comparative Example 2. Wherein, figure (a) is the pure nickel coating of comparative example; Figure (b) is the nickel-carbon composite coating of embodiment 1 adding 15mL/L carbon sol; Figure (c) is the nickel-carbon composite coating of comparative example 2 adding 50mL/L carbon sol Nickel carbon composite coating;

Fig. 5 is the comparison diagram of the hardness of pure nickel and nickel-carbon composite coatings prepared in Examples 1 to 5, Comparative Example 1 and Comparative Example 2;

Fig. 6 is a graph comparing polarization curves of pure nickel and nickel-carbon composite coatings prepared in Example 1, Comparative Example 1, and Comparative Example 2.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the embodiments.

Example 1

The preparation method of reinforced nickel coating of the present invention, comprises the steps:

(1) Sample pretreatment

Grinding: Use a cutting machine or scissors to make a H62 brass sheet with a thickness of 1mm into a sample with a size of 15mm×20mm, which is suitable for the electroplating tank device, and paste insulating glue on one surface of the brass sheet sample. Use 800# sandpaper, 1000# sandpaper, 1500# sandpaper, and 2000# sandpaper to polish the other exposed surface in order from coarse to fine, and then clean it with deionized water;

Alkali cleaning: Put the polished brass sample into an alkaline washing solution at 75°C for alkaline washing. The alkaline washing time is 10 minutes. After the alkaline washing is completed, the sample is cleaned with deionized water; specifically, the composition of the alkaline washing solution For: 10g NaOH powder and 2g NaH ₂ PO ₄ ·H ₂ O powder as solute, 188mL deionized water as solvent;

Activation: The brass sample after alkali cleaning is clamped on the fixed fixture as the cathode, the stainless steel plate with a specification of 40mm×40mm×3mm is used as the anode, the cathode and anode electrodes are immersed in the activation solution, the positive pole of the DC power supply is connected to the anode, and the negative pole is connected to the cathode , the two electrodes are parallel to each other, the current density is set to 30mA/cm ² , the brass sample is activated in a constant current mode, the activation time is 90s, and the entire activation process is carried out at room temperature. After the activation, the brass sample was taken out, washed with deionized water and dried; specifically, the composition of the activation solution was: 5g of C ₆ H ₈ O ₇ powder and 13g of C ₆ H ₅ O ₇ (NH ₄ ) ₃ powder as the solute, and 182 mL of deionized water as the solvent.

(2) Preparation of nickel-carbon composite electrodeposition plating solution

The preparation of carbon sol comprises the following steps:

Step 1, preparing an electrolyte solution, the concentration of the electrolyte solution is 0.1M HNO ₃ , 0.1M (CH ₂ OH) ₂ and 0.5g/L C ₁₂ H ₂₅ SO ₄ Na as the solute, and the solvent is water;

Step 2. Use two high-purity graphite plates with a specification of 100mm×50mm×3mm as electrodes, fix the two graphite plates with crocodile clips with pure copper rods, immerse them in the electrolyte, and make the two graphite plates parallel to each other relatively fixed. Put the entire electrolytic cell device in an ultrasonic instrument with a vibration frequency of 40KHz, turn on the ultrasonic instrument, connect the positive and negative poles of the DC power supply to the copper rods, set the DC power supply constant current mode, the current density is 5mA/cm ² , and the electrolysis reaction lasts for 22 hours Finally, carbon sol was obtained with a concentration of 0.025g/L.

Use a magnetic stirrer to heat and stir the plating solution under the reaction conditions of 300r/min and 60°C, slowly add carbon sol dropwise to the plating solution to obtain a nickel-carbon composite electrodeposition plating solution; the composition of the plating solution is: 30g NiSO ₄ particles, 3g NH ₄ Cl powder, 3g H ₃ BO ₃ powder and 0.1g C ₁₂ H ₂₅ SO ₄ Na powder were used as solute, and 164mL of deionized water was used as solvent. After the plating solution was fully dissolved, 15mL of carbon sol was added.

(3) Clamp the processed brass sample on the fixed fixture as the cathode, use a high-purity nickel plate with a specification of 40mm×40mm×3mm and a purity of ≥99.9% as the anode, and immerse the cathode and anode electrodes in the electroplating solution, pulse power supply The positive electrode is connected to the anode nickel plate, and the negative electrode is connected to the cathode brass sample. The two electrodes are parallel to each other, and the pulse electrodeposition parameters are set: current density 40mA/cm ² , duty cycle 75%, frequency 1000Hz. Start the pulse power switch for electrodeposition, and the electrodeposition time is 30 minutes; take out the brass sample in step 4, rinse it with deionized water, and dry it to obtain a nickel-carbon composite coating with 15mL/L carbon sol added.

Example 2

On the basis of Example 1, the addition amount of carbon sol was changed to 10mL/L, and other conditions were unchanged.

Example 3

On the basis of Example 1, the addition amount of carbon sol was changed to 20mL/L, and other conditions were unchanged.

Example 4

On the basis of Example 1, the addition amount of carbon sol was changed to 30mL/L, and the rest of the conditions were unchanged.

Example 5

On the basis of Example 1, the addition amount of carbon sol was changed to 40mL/L, and other conditions were unchanged.

Comparative example 1

On the basis of Example 1, no carbon sol was added, and other conditions remained unchanged.

Comparative example 2

On the basis of Example 1, the addition amount of carbon sol was changed to 50mL/L, and other conditions were unchanged.

Microstructure characterization and phase testing:

As shown in Figure 1, it is the surface morphology of implementation example 1 (Fig. 1b), comparative example 1 (Fig. 1a) and comparative example 2 (Fig. 1c), as can be seen from the figure Comparative example 1 pure nickel coating and embodiment 1 The surface morphology of nickel-carbon composite coating is small protrusion structure. Example 1 The surface of the pure nickel coating added with 15mL/L carbon sol is finer and smoother than that of the pure nickel coating, which is mainly due to the addition of carbon particles to refine the grains. However, as the amount of carbon sol added increased, the surface of the coating in Comparative Example 2 became rougher, because too much carbon sol would intensify the hydrogen evolution reaction during the electrodeposition process, resulting in changes in surface morphology.

Figure 2 is the cross-sectional morphology of Example 1 (Fig. 2b), Comparative Example 1 (Fig. 2a) and Comparative Example 2 (Fig. 2c). From (2a) and (2b) in the figure, it can be seen that the nickel with carbon sol The carbon composite coating will become thicker with the addition of carbon sol, which is because the addition of carbon particles is beneficial to improve its electrodeposition efficiency. It can be seen from Figure (2c) that the thickness of the nickel-carbon composite coating decreases, because excessive carbon particles will lead to the possibility of agglomeration, which will reduce the efficiency of electrodeposition.

As shown in Figure 3, the XRD comparison chart and the average grain size comparison chart of Example 1 and Comparative Example 1 and Comparative Example 2, it can be seen from the figure that the addition of carbon particles will not change the phase of the coating. According to the XRD patterns of Example 1 and Comparative Example 1 and Comparative Example 2, the average grain size of the coating was calculated using the Scherrer equation. The comparison results show that the average grain size of Example 1 is the smallest. This shows that the addition of carbon particles can refine the grain size of the pulse electrodeposited nickel coating, which also explains the strengthening mechanism of the coating.

Performance Testing:

1. Abrasion resistance test

A HSR-2M high-speed reciprocating friction and wear testing machine was used to test the wear resistance of the nickel-carbon composite coating in Example 1 and the coatings in Comparative Example 1 and Comparative Example 2. In the test, a hard zirconia ball with a diameter of 4mm is applied, and a 500g load is applied, and the surface of the coating is rubbed back and forth for 10 minutes, and finally wear marks are obtained. A 3D video microscope was used to take pictures and measure the wear scars to obtain the wear cross-sectional morphology of the pure nickel coating and the nickel-carbon composite coating. The test results are shown in Figure 4.

Figure (4a) is the pure nickel coating of comparative example 1; Figure (b) is the nickel-carbon composite coating of embodiment 1 adding 15mL/L carbon sol; Figure (c) is the nickel of comparative example 2 adding 50mL/L carbon sol As for the carbon composite coating, it can be seen from the figure that the wear amounts of Comparative Example 1, Example 1, and Comparative Example 2 are 7.52×10 ^-4 mm ³ , 4.14×10 ^-4 mm ³ , and 6.17×10 ^-4 mm ³ . The wear amount of the nickel-carbon composite coating added with 15mL/L concentration of carbon sol in Example 1 is the smallest, which is 44.9% less than that of the pure nickel coating in Comparative Example 1. It can be seen that adding an appropriate amount of carbon particles can effectively improve the wear resistance of nickel-phosphorus coatings, but the thickness of nickel-phosphorus-carbon nanocomposite coatings with excessive carbon sol addition becomes thinner and the wear resistance decreases.

2. Hardness test

HXS-1000TAC semi-automatic hardness tester was used to test the hardness of the coatings of Examples 1-5, Comparative Example 1 and Comparative Example 2. The test uses a load of 300g to test the coating, including the process of loading for 10s, holding for 15s, and unloading for 15s. A diamond-shaped imprint is obtained. The Vickers hardness value of the coating is obtained through measurement and calculation. The test results are shown in Figure 5.

It can be seen from Figure 5 that the hardness of the nickel-phosphorus-carbon nanocomposite coating increases as the concentration of the added carbon sol gradually increases, and the corresponding hardnesses of Comparative Example 1, Examples 1-5 and Comparative Example 2 314HV, 420HV, 396HV, 380HV, 368HV, 364HV. When the concentration of added carbon sol reaches 15mL/L, the hardness reaches a maximum value of 420HV. When a higher concentration of carbon sol is added, the hardness of the nickel-phosphorus-carbon nanocomposite coating decreases significantly. This is because when an appropriate amount of carbon sol is added, the addition of carbon particles increases the nucleation points during the electrocrystallization process, making the grains of the coating more refined, thereby enhancing the hardness of the coating. Coarse grains of the layer lead to inconspicuous effect of fine-grain strengthening.

3. Corrosion resistance test

The electrochemical corrosion test of Implementation Example 1, Comparative Example 1 and Comparative Example 2 was carried out by Chenhua Electrochemical Workstation. A saturated calomel electrode and a platinum electrode were used to form a three-electrode system with Embodiment 1, Comparative Example 1 and Comparative Example 2 respectively to test the open circuit potential and polarization curve of the coating in a 3.5 wt% NaCl solution. The test results are shown in Figure 6.

It can be seen from Fig. 6 that the corrosion rates of Comparative Example 1, Example 1 and Comparative Example 2 are 1.11×10 ^-2 mm/year, 7.11×10 ^-3 mm/year, and 1.06×10 ^-2 mm/year, respectively. This result shows that the addition of carbon particles can effectively improve the corrosion resistance of the coating. The self-corrosion potential of Example 1 is the most positive, and the self-corrosion current density is the smallest, which shows that the nickel-carbon composite coating prepared by adding 15mL/L carbon sol has the best corrosion resistance.

Claims (10)

1. The preparation method of the reinforced nickel coating is characterized by comprising the following steps of:

(1) Pretreating a sample;

(2) Dropwise adding carbon sol into the electroplating solution under the conditions of heating and stirring the electroplating solution to obtain nickel-carbon composite electrodeposition plating solution;

(3) And immersing the pretreated sample serving as a cathode and a nickel plate serving as an anode in a nickel-carbon composite electrodeposition plating solution, wherein the positive electrode of a pulse power supply is connected with the anode, the negative electrode is connected with the cathode, and the two electrodes are parallel and opposite to each other for pulse electrodeposition.

2. The method for producing a strengthened nickel coating according to claim 1, wherein in step (2), the carbon sol content in the composite electrodeposition bath is 10 to 40mL/L, and wherein the carbon sol concentration is 0.01 to 0.03g/L.

3. The strengthened nickel coating according to claim 1The preparation method is characterized in that in the step (3), the pulse electrodeposition parameters are as follows: the current density is 30-50 mA/cm ² The duty ratio is 60-80%, the frequency is 500-1500 Hz, and the deposition time is 20-40 minutes.

4. The method of producing a strengthened nickel coating according to claim 1, wherein in step (2), the plating solution comprises: 140-160 g/L NiSO ₄ Particles, 12-18 g/L NH ₄ Cl、15～20g/L H ₃ BO ₃ And 0.2 to 1g/LC ₁₂ H ₂₅ SO ₄ Na, water as solvent.

5. The method of producing a strengthened nickel coating according to claim 1, wherein in step (1), the sample is brass, pure copper, carbon steel or an aluminum alloy.

6. The method for producing a reinforced nickel coating according to claim 1, wherein in the step (1), the pretreatment of the sample comprises a surface smoothing treatment, an alkali washing treatment and an activation treatment.

7. The method for producing a strengthened nickel coating according to claim 6, wherein the alkaline cleaning solution in the alkaline cleaning step two has the composition: 35-60 g/L NaOH and 8-13 g/L NaH ₂ PO ₄ ·H ₂ O, water is the solvent.

8. The method of producing a strengthened nickel coating according to claim 6, wherein the activation treatment is: the sample cathode, stainless steel plate as anode, immerse the cathode and anode in activating solution, the positive pole of DC power source connects with anode, the negative pole connects with cathode, the two electrodes are parallel and opposite to each other, and activating treatment is carried out in constant current mode.

9. The method for producing a reinforced nickel coating according to claim 8, wherein the activating solution contains 15 to 25g/L C ₆ H ₈ O ₇ And 60 to 70g/L C ₆ H ₅ O ₇ (NH ₄ ) ₃ Water is the solvent.

10. The method for producing a reinforced nickel coating according to claim 8, wherein the current density in the activation treatment is 30 to 40mA/cm ² The activation time is 60-120 seconds.