Preparation method of micro-arc oxidation layer for improving heat-conducting property of B30 copper-nickel alloy

Abstract

The invention discloses a preparation method of a micro-arc oxidation layer for improving the heat-conducting property of B30 copper-nickel alloy, and relates to the technical field of metal surface modification.The preparation method comprises the steps that B30 copper-nickel alloy is cut, polished, washed and dried, and then a copper-nickel alloy sample is obtained; sodium silicate, sodium hydroxide and boron nitride are added into deionized water and stirred to be fully dissolved, and an electrolyte is obtained; and the copper-nickel alloy sample serves as an anode, a stainless steel plate serves as a cathode, micro-arc oxidation treatment is conducted in electrolyte, and the copper-nickel alloy sample with the micro-arc oxidation film is obtained. The improved micro-arc oxidation electrolyte is simple in preparation process, a formed micro-arc oxidation film can effectively block external corrosive media, relieve corrosion and prolong the service life of equipment, the heat conduction performance needed by practical application can be improved, and the application scene of B30 copper-nickel alloy in maritime work equipment is widened.

Description

Technical Field

[0001] This invention relates to the field of metal surface modification technology, and in particular to a method for preparing a micro-arc oxidation layer to improve the thermal conductivity of B30 copper-nickel alloy. Background Technology

[0002] B30 copper-nickel alloy is widely used in marine heat exchangers due to its excellent anti-fouling and thermal conductivity properties. However, in actual marine applications, it often suffers from perforation corrosion due to the complex marine environment and harsh internal working conditions, and existing protective measures are insufficient to effectively protect it.

[0003] Micro-arc oxidation (MAO) is a surface treatment technology that uses a high voltage applied to the surface of metals and their alloys to generate arc discharge and grow porous oxide-based ceramic films in situ through plasma chemistry, thermochemistry, and electrochemistry. MAO technology is widely used in material surface treatment, and the prepared films have high hardness, wear resistance, good insulation properties, and excellent corrosion resistance.

[0004] Boron nitride (BN) possesses excellent thermal conductivity, primarily due to its unique hexagonal layered crystal structure. Within the layers, B and N atoms form a regular hexagonal grid through strong covalent bonds, resulting in high structural symmetry and minimal phonon scattering during transport. Furthermore, the similar mass of B and N atoms further reduces scattering, leading to a long mean free path and high phonon transport speed. Simultaneously, high-purity materials reduce phonon scattering caused by impurities and defects. With its high insulation, chemical stability, and high-temperature adaptability, it is widely used in fields such as electronic heat dissipation and composite materials. Summary of the Invention

[0005] In order to overcome the above-mentioned problems in the prior art, the present invention proposes a method for preparing a micro-arc oxide layer to improve the thermal conductivity of B30 copper-nickel alloy.

[0006] The technical solution adopted by this invention to solve its technical problem is: a method for preparing a micro-arc oxidation layer to improve the thermal conductivity of B30 copper-nickel alloy, comprising the following steps: Step 1: Cut, grind, rinse, and dry the B30 copper-nickel alloy to obtain a copper-nickel alloy sample; Step 2: Add sodium silicate, sodium hydroxide, and boron nitride to deionized water and stir until fully dissolved to obtain the electrolyte; Step 3: Using the copper-nickel alloy sample obtained in Step 1 as the anode and the stainless steel plate as the cathode, perform micro-arc oxidation treatment in the electrolyte obtained in Step 2 to obtain a copper-nickel alloy sample with a micro-arc oxidation film.

[0007] In the above-mentioned method for preparing a micro-arc oxidation layer to improve the thermal conductivity of B30 copper-nickel alloy, the content of sodium silicate in the electrolyte in step 2 is 5~15g / L, the content of sodium hydroxide is 1~3g / L, and the content of boron nitride is 0.01~0.05g / L.

[0008] In the above-mentioned method for preparing a micro-arc oxidation layer to improve the thermal conductivity of B30 copper-nickel alloy, the electrolyte in step 2 contains 10 g / L sodium silicate, 1 g / L sodium hydroxide, and 0.01~0.05 g / L boron nitride.

[0009] In the above-mentioned method for preparing a micro-arc oxidation layer to improve the thermal conductivity of B30 copper-nickel alloy, in step 1, the substrate surface is polished sequentially with SiC sandpaper of 200#, 400#, 1200#, and 2000#, and then ultrasonically cleaned and dried with anhydrous ethanol.

[0010] The above-mentioned method for preparing a micro-arc oxidation layer to improve the thermal conductivity of B30 copper-nickel alloy, wherein the specific conditions for micro-arc oxidation in step 3 are as follows: the micro-arc oxidation power supply adopts constant current control, and the current density is 3~5A / cm. 2 The frequency is 1000~2000Hz, the duty cycle is 20~25%, the electrolyte temperature is 20~30℃, the processing time is 5-10 minutes, and the stirring speed is 400-600rpm.

[0011] The beneficial effects of this invention are that the improved micro-arc oxidation electrolyte preparation process is simple, and the micro-arc oxidation film formed can not only effectively block external corrosive media, alleviate corrosion, and extend the service life of equipment, but also improve the thermal conductivity required for practical applications, thus broadening the application scenarios of B30 copper-nickel alloy in marine engineering equipment. Attached Figure Description

[0012] Figure 1 This is a microscopic morphology diagram of the micro-arc oxidation film in Example 1 of the present invention; Figure 2 The Nyquist plots of the electrochemical impedance spectra of Examples 1 to 5 and Comparative Example 1 of this invention were tested in 3.5 wt% NaCl solution. Figure 3 Bode plots of electrochemical impedance spectroscopy measured in 3.5 wt% NaCl solution in Examples 1 to 5 and Comparative Example 1 of the present invention; Figure 4 The cyclic polarization curves of Examples 1 to 5 and Comparative Example 1 of this invention were tested in a 3.5 wt% NaCl solution. Figure 5 This is a comparison chart of the thermal diffusivity measured in Examples 1 to 5 and Comparative Example 1 of the present invention. Detailed Implementation

[0013] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0014] Example 1 Step 1: Cut the B30 copper-nickel alloy into 10×10×3mm pieces, and successively polish the surface of the substrate with SiC sandpaper of 200#, 400#, 1200# and 2000#. Then, use anhydrous ethanol to ultrasonically clean for 10 minutes and dry to obtain the B30 copper-nickel alloy sample. Step 2: Add 5 g / L sodium silicate, 1 g / L sodium hydroxide, and 0.01 g / L boron nitride to deionized water and stir until fully dissolved to obtain the electrolyte; Step 3: Using the copper-nickel alloy sample from Step 1 as the anode and the stainless steel plate as the cathode, perform micro-arc oxidation treatment in the electrolyte obtained in Step 2 to obtain a copper-nickel alloy sample with a micro-arc oxide film; the micro-arc oxidation power supply adopts constant current control, and the current density is 5A / cm². 2 The frequency was 2000Hz, the duty cycle was 25%, the electrolyte temperature was 30℃, the processing time was 5 minutes, and the stirring speed was 500rpm.

[0015] The microstructure of the micro-arc oxidation film obtained in Example 1 is shown in the figure below. Figure 1 As shown.

[0016] Example 2 Step 1: Cut the B30 copper-nickel alloy into 10×10×3mm pieces, and successively polish the surface of the substrate with SiC sandpaper of 200#, 400#, 1200# and 2000#. Then, use anhydrous ethanol to ultrasonically clean for 10 minutes and dry to obtain the B30 copper-nickel alloy sample. Step 2: Add 10 g / L sodium silicate, 1 g / L sodium hydroxide, and 0.02 g / L boron nitride to deionized water and stir until fully dissolved to obtain the electrolyte; Step 3: Using the copper-nickel alloy sample from Step 1 as the anode and the stainless steel plate as the cathode, perform micro-arc oxidation treatment in the electrolyte obtained in Step 2 to obtain a copper-nickel alloy sample with a micro-arc oxide film; the micro-arc oxidation power supply adopts constant current control, and the current density is 5A / cm². 2 The frequency was 2000Hz, the duty cycle was 25%, the electrolyte temperature was 30℃, the processing time was 5 minutes, and the stirring speed was 500rpm.

[0017] Example 3 Step 1: Cut the B30 copper-nickel alloy into 10×10×3mm pieces, and successively polish the surface of the substrate with SiC sandpaper of 200#, 400#, 1200# and 2000#. Then, use anhydrous ethanol to ultrasonically clean for 10 minutes and dry to obtain the B30 copper-nickel alloy sample. Step 2: Add 10 g / L sodium silicate, 2 g / L sodium hydroxide, and 0.03 g / L boron nitride to deionized water and stir until fully dissolved to obtain the electrolyte; Step 3: Using the copper-nickel alloy sample from Step 1 as the anode and the stainless steel plate as the cathode, perform micro-arc oxidation treatment in the electrolyte obtained in Step 2 to obtain a copper-nickel alloy sample with a micro-arc oxide film; the micro-arc oxidation power supply adopts constant current control, and the current density is 5A / cm². 2 The frequency was 2000Hz, the duty cycle was 25%, the electrolyte temperature was 30℃, the processing time was 5 minutes, and the stirring speed was 500rpm.

[0018] Example 4 Step 1: Cut the B30 copper-nickel alloy into 10×10×3mm pieces, and successively polish the surface of the substrate with SiC sandpaper of 200#, 400#, 1200# and 2000#. Then, use anhydrous ethanol to ultrasonically clean for 10 minutes and dry to obtain the B30 copper-nickel alloy sample. Step 2: Add 15 g / L sodium silicate, 2 g / L sodium hydroxide, and 0.04 g / L boron nitride to deionized water and stir until fully dissolved to obtain the electrolyte; Step 3: Using the copper-nickel alloy sample from Step 1 as the anode and the stainless steel plate as the cathode, perform micro-arc oxidation treatment in the electrolyte obtained in Step 2 to obtain a copper-nickel alloy sample with a micro-arc oxide film; the micro-arc oxidation power supply adopts constant current control, and the current density is 5A / cm². 2 The frequency was 2000Hz, the duty cycle was 25%, the electrolyte temperature was 30℃, the processing time was 5 minutes, and the stirring speed was 500rpm.

[0019] Example 5 Step 1: Cut the B30 copper-nickel alloy into 10×10×3mm pieces, and successively polish the surface of the substrate with SiC sandpaper of 200#, 400#, 1200# and 2000#. Then, use anhydrous ethanol to ultrasonically clean for 10 minutes and dry to obtain the B30 copper-nickel alloy sample. Step 2: Add 15 g / L sodium silicate, 3 g / L sodium hydroxide, and 0.05 g / L boron nitride to deionized water and stir until fully dissolved to obtain the electrolyte; Step 3: Using the copper-nickel alloy sample from Step 1 as the anode and the stainless steel plate as the cathode, perform micro-arc oxidation treatment in the electrolyte obtained in Step 2 to obtain a copper-nickel alloy sample with a micro-arc oxide film; the micro-arc oxidation power supply adopts constant current control, and the current density is 5A / cm². 2 The frequency was 2000Hz, the duty cycle was 25%, the electrolyte temperature was 30℃, the processing time was 5 minutes, and the stirring speed was 500rpm.

[0020] Comparative Example 1 Step 1: Cut the B30 copper-nickel alloy into 10×10×3mm pieces, and successively polish the surface of the substrate with SiC sandpaper of 200#, 400#, 1200# and 2000#. Then, use anhydrous ethanol to ultrasonically clean for 10 minutes and dry to obtain the B30 copper-nickel alloy sample. Step 2: Add 10 g / L sodium silicate and 1 g / L sodium hydroxide to deionized water and stir until fully dissolved to obtain the electrolyte; Step 3: Using the copper-nickel alloy sample from Step 1 as the anode and the stainless steel plate as the cathode, perform micro-arc oxidation treatment in the electrolyte obtained in Step 2 to obtain a copper-nickel alloy sample with a micro-arc oxide film; the micro-arc oxidation power supply adopts constant current control, and the current density is 5A / cm². 2 The frequency was 2000Hz, the duty cycle was 25%, the electrolyte temperature was 30℃, the processing time was 5 minutes, and the stirring speed was 500rpm.

[0021] To better illustrate the advantages of this invention, the following verification scheme provided by this invention is given: To verify the corrosion resistance and thermal conductivity of the membranes prepared by this invention, electrochemical and laser thermal conductivity tests were conducted on B30 copper-nickel alloy and the membranes prepared in Examples 1 to 5 and Comparative Example 1.

[0022] Electrochemical testing was performed on B30 copper-nickel alloy, as well as Examples 1-5 and Comparative Example 1, in 3.5 wt% NaCl solution using electrochemical impedance spectroscopy (EIS). The frequency range was 10⁻² to 10⁵ Hz, the AC amplitude was 10 mV, and cyclic polarization testing was conducted within the range of -0.5 to 1 V vs. OCP at a scan rate of 1 mV / s. The experimental data are shown in the appendix. Figure 2-4 .

[0023] The thermal conductivity test involved placing B30 copper-nickel alloy, as well as Examples 1-5 and Comparative Example 1, into a furnace. At a controlled temperature within the furnace, a laser source emitted light pulses that uniformly irradiated the lower surface of the sample, heating it. An infrared detector was used to measure the corresponding temperature rise on the upper surface of the sample, obtaining a curve showing the relationship between temperature (detector signal) increase and time. A suitable model was used for fitting to obtain the thermal diffusivity. The experimental data results are shown in the appendix. Figure 5 .

[0024] The above tests show that the present invention embeds boron nitride in the micro-arc oxidation film layer. By utilizing the layered structure of boron nitride, which is similar to graphite, the heat transfer inside the material is accelerated, forming a more effective heat conduction network. This results in a film with excellent pitting corrosion resistance and good thermal conductivity, thus broadening the application scenarios of copper-nickel alloys in marine engineering equipment.

[0025] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its scope and spirit, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. A method for preparing a micro-arc oxidation layer for improving the thermal conductivity of a B30 copper-nickel alloy, characterized in that, The method comprises the following steps: Step 1: cutting, polishing, washing and drying the B30 copper-nickel alloy to obtain a copper-nickel alloy sample; Step 2: adding sodium silicate, sodium hydroxide and boron nitride into deionized water, and stirring until completely dissolved to obtain an electrolyte; Step 3: taking the copper-nickel alloy sample obtained in step 1 as an anode, taking a stainless steel plate as a cathode, and performing micro-arc oxidation treatment in the electrolyte obtained in step 2 to obtain a copper-nickel alloy sample with a micro-arc oxidation film.

2. The method for preparing a micro-arc oxidation layer to improve the thermal conductivity of B30 copper-nickel alloy according to claim 1, characterized in that, In the electrolyte in step 2, the content of sodium silicate is 5-15 g / L, the content of sodium hydroxide is 1-3 g / L, and the content of boron nitride is 0.01-0.05 g / L.

3. The method according to claim 1, wherein the B30 copper-nickel alloy micro-arc oxidation layer is prepared by the method, characterized in that, In the electrolyte in step 2, the content of sodium silicate is 10 g / L, the content of sodium hydroxide is 1 g / L, and the content of boron nitride is 0.01-0.05 g / L.

4. The method for preparing a micro-arc oxidation layer to improve the thermal conductivity of B30 copper-nickel alloy according to claim 1, characterized in that, In step 1, the surface of the substrate is polished with SiC sandpaper of 200#, 400#, 1200# and 2000# in sequence, ultrasonic cleaned with anhydrous ethanol and dried.

5. The method for preparing a micro-arc oxidation layer to improve the thermal conductivity of B30 copper-nickel alloy according to claim 1, characterized in that, The conditions of micro-arc oxidation in step 3 are as follows: the micro-arc oxidation power source is controlled by constant current, the current density is 3-5 A / cm 2 , the frequency is 1000-2000 Hz, the duty cycle is 20-25%, the electrolyte temperature is 20-30 DEG C, the processing time is 5-10 minutes, and the stirring speed is 400-600 rpm.

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