Preparation method for regulating and controlling pore size of micro-arc oxidation film layer of metal material

Abstract

The invention provides a preparation method for regulating and controlling the pore size of a micro-arc oxidation film layer of a metal material, which belongs to the technical field of surface treatment of metal materials and comprises the following steps: 1) polishing an anode metal material; and 2) carrying out micro-arc oxidation on the pretreated metal material by adopting a micro-arc oxidation synchronous auxiliary device under the action of a magnetic field to obtain a micro-arc oxidation film layer, thereby realizing regulation and control on the pore size of the micro-arc oxidation film layer of the metal material. The micro-arc oxidation coating is prepared by externally applying the magnetic field intensity and changing the size and direction of the magnetic field intensity, the pore size of the coating is changed, the growth rate of a film layer is increased by introducing an electromagnetic field, the performance of the film layer is improved, and the larger the magnetic field intensity is, the smaller the pores are, the denser the micro-arc oxidation coating is, and the better the corrosion resistance is; and the control of the pore size is beneficial to the loading and release of the medicine. In addition, when the surface of the metal material is parallel to a magnetic line of force, pores are small, the micro-arc oxidation coating is compact, and when the metal material is perpendicular to the magnetic line of force, the pores are large.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material surface treatment, and in particular relates to a preparation method for regulating the pore size of a metal material micro-arc oxidation film layer. Background Art

[0002] Micro-arc oxidation is called plasma electrolytic oxidation, which is developed on the basis of anodizing technology, and the coating formed is better than anodizing. The micro-arc oxidation process mainly relies on the matching and adjustment of electrolyte and electrical parameters. Under the instantaneous high temperature and high pressure generated by arc discharge, a modified ceramic coating mainly composed of matrix metal oxide and supplemented by electrolyte components grows on the surface of valve metals such as aluminum, magnesium, titanium and their alloys. It has high strength and adhesion to the substrate, and its anti-corrosion and wear resistance are significantly better than traditional anodized coatings. Therefore, its application in marine ships and aviation components has attracted widespread attention.

[0003] In the prior art, the application number is 201010146480.4, and the patent name is an invention patent for a method for preparing a micro-arc oxidation film under the action of a magnetic field. The principle is to prepare a micro-arc oxidation film under the action of a magnetic field. The addition of a magnetic field reduces the polarization tendency of the electrolyte concentration difference, accelerates the solute transfer process, promotes the micro-arc oxidation reaction, increases the film growth rate, and thereby improves the film performance.

[0004] The spark discharge phenomenon in the micro-arc oxidation process causes a large number of irregular holes in the coating. The size and number of surface pores directly affect the corrosion performance of the coating and its ability to serve as a carrier of functional particles. Larger porosity will cause corrosive media to easily penetrate the micro-arc oxidation / substrate interface, accelerating the corrosion rate. Uneven pore sizes will affect the loading efficiency of functional particles. Therefore, in response to the above problems, a method is needed to use magnetic field technology to achieve the regulation of the pore size of the prepared micro-arc oxidation film.

[0005] Changes in magnetic field intensity and direction have different effects on the porosity and pore size of the micro-arc oxidation film. Changes in magnetic field intensity can change arc stability, film formation efficiency, and negative bias voltage, thereby affecting the porosity and thickness of the micro-arc oxidation film; different magnetic field directions affect the motion trajectory of charged particles, the chemical composition of the film, and the growth rate. Therefore, by adjusting the intensity and direction of the applied magnetic field, the purpose of regulating the porosity and pore size of the micro-arc oxidation coating can be achieved. Summary of the invention

[0006] The object of the present invention is to provide a preparation method for regulating the pore size of a metal material micro-arc oxidation film, characterized in that it comprises the following steps:

[0007] Step 1: Polishing the metal material;

[0008] Step 2: Micro-arc oxidation is performed on the pretreated metal material under different magnetic fields to obtain a micro-arc oxidation film layer, thereby achieving regulation of the pore size of the micro-arc oxidation film layer of the metal material.

[0009] Furthermore, step 2 is specifically as follows: by changing the distance and direction between the two magnets, the size and direction of the magnetic field are controlled, and on this basis, a micro-arc oxidation synchronous auxiliary device is used to perform micro-arc oxidation on the pretreated metal material to obtain a micro-arc oxidation film layer, and complete the regulation of the pore size of the micro-arc oxidation film layer of the metal material.

[0010] Furthermore, the micro-arc oxidation synchronous auxiliary device includes a cooling tank, an electrolytic cell and a voltage regulation control system, a cooling liquid is provided in the cooling tank, the electrolytic cell is arranged in the cooling tank and is separated from the cooling tank by the cooling liquid, an electrolyte is provided in the electrolytic cell, a stainless steel sheet, a magnetic field component and a metal material are arranged inside the electrolyte, the stainless steel sheet is connected to the output negative pole of the power box as a cathode, the metal material is arranged inside the magnetic field component and connected to the output positive pole of the power box as an anode.

[0011] Furthermore, the magnetic field assembly includes two magnets, and the metal material is arranged between the two magnets.

[0012] Further, micro-arc oxidation treatment is performed, the frequency of micro-arc oxidation is 50-1000 Hz, the voltage is 200-500 V, the duty cycle is 10-90%, the oxidation time is 3-60 min, the electrolyte temperature is -10-35° C., and the surface magnetic induction intensity of the magnetic field component is 100-5000 Gs.

[0013] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0014] 1. The present invention adds a magnetic field device during the micro-arc oxidation process. The magnetic field can change the motion trajectory of charged particles in the electrolyte, thereby affecting the distribution and migration of ions in the electrolyte. This influence will change the current distribution and film formation during the micro-arc oxidation process, thereby affecting the size of the film pores and improving the corrosion resistance of the magnesium alloy.

[0015] 2. The present invention has proved that the strength and direction of the magnetic field have a significant effect on the pore size of the micro-arc oxidation film by regulating the magnetic field device. The greater the magnetic field strength, the smaller the pore size of the micro-arc oxidation film and the stronger its corrosion resistance. The pore size of the micro-arc oxidation film is different when the magnetic field direction is different. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a schematic structural diagram of a magnetic field generating device used in a preparation method for regulating the pore size of a micro-arc oxidation film of a metal material.

[0017] Figure 2Surface morphologies of different magnesium alloy micro-arc oxidation films prepared by the method of the present invention using different magnetic field intensities and a magnesium alloy micro-arc oxidation film prepared without a magnetic field.

[0018] Figure 3 This is a surface morphology diagram of a metal material micro-arc oxidation film layer prepared by the method of the present invention with the magnetic field lines perpendicular to the surface of the magnesium alloy material and the magnetic field lines parallel to the surface of the magnesium alloy.

[0019] Figure 4 The polarization curve diagram of the magnesium alloy micro-arc oxidation film layer prepared by the method of the present invention and the magnesium alloy micro-arc oxidation film layer obtained without the action of a magnetic field.

[0020] Figure 5 The surface morphology of the titanium alloy micro-arc oxidation film layer prepared by the method of the present invention with a magnetic field and the titanium alloy micro-arc oxidation film layer prepared without a magnetic field is shown.

[0021] Figure 6 Surface morphology of an aluminum alloy micro-arc oxidation film layer prepared by the method of the present invention with a magnetic field and an aluminum alloy micro-arc oxidation film layer prepared without a magnetic field.

[0022] Among them, 1. power box; 2. stainless steel sheet; 3. metal material; 4. magnetic field component; 5. electrolytic cell; 6. cooling tank. DETAILED DESCRIPTION

[0023] A method for preparing a micro-arc oxidation film for regulating the pore size of a metal material according to the present invention will be described in more detail below in conjunction with a schematic diagram, wherein a preferred embodiment of the present invention is shown. It should be understood that those skilled in the art can modify the present invention described herein while still achieving the beneficial effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art and not as a limitation to the present invention.

[0024] A preparation method for regulating the pore size of a metal material micro-arc oxidation film layer comprises the following steps:

[0025] Step 1: Grind and polish the surface of the metal material 3.

[0026] Step 2: Use the micro-arc oxidation synchronous auxiliary device to cooperate with the magnetic field component 4 to adjust the size and direction of the magnetic field strength to achieve the regulation of the pore size of the micro-arc oxidation film layer of the metal material and complete the preparation of the micro-arc oxidation film layer of the metal material.

[0027] The structure of the micro-arc oxidation synchronous auxiliary device is as follows Figure 1As shown, it includes an electrolytic cell 5, in which an electrolyte is placed, a cooling tank 6 is arranged outside the electrolytic cell 5, and a cooling tank 6 is arranged inside the cooling tank, and the electrolytic cell 5 and the cooling tank 6 are separated by cooling water. The magnetic field component 4 is composed of two magnets of 45mm×45mm×9mm, which are arranged in the electrolytic cell 5, and the metal material 3 obtained after polishing in step 1 is installed between the two magnets, and the metal material 3 is connected to the output positive pole of the power box 1 as an anode, and the stainless steel sheet 2 is connected to the output negative pole of the power box 1 as a cathode. The frequency of micro-arc oxidation is 50-1000Hz, the voltage is 200-500V, the duty cycle is 10-90%, the oxidation time is 3-60min, the electrolyte temperature is -10-35℃, and the surface magnetic induction intensity of the magnetic field component is 100-5000Gs. By adjusting the distance and direction between the two magnets, the magnetic field strength and direction are adjusted, and the micro-arc oxidation film coating is obtained, and the influence of the magnitude and direction of the magnetic field strength on the performance of the micro-arc oxidation film layer is explored.

[0028] Example 1

[0029] Step 1: Grind and polish the surface of AZ31 magnesium alloy 10mm×10mm×5mm material;

[0030] Step 2: Use the above device, such as Figure 1 As shown, the composition of the electrolyte in the electrolytic cell 5 is 5g / L Na3PO4+1g / LKOH, the AZ31 magnesium alloy obtained after polishing in step 1 is installed between two magnets 4, so that the AZ31 magnesium alloy is parallel to the magnetic field line, and the magnetic induction intensity is 2800Gs, the AZ31 magnesium alloy is connected to the output positive pole of the power box 1 as an anode, and the stainless steel sheet 2 is connected to the output negative pole of the power box 1 as a cathode. The applied voltage is set to 300V, the frequency of micro-arc oxidation is 1000Hz, the duty cycle is 10%, the micro-arc oxidation time is 10min, the oxidation temperature is maintained at 10-15°C, the distance between the two magnets is 3cm, and the micro-arc oxidation film layer is prepared by the method of the present invention.

[0031] By testing and comparing the micro-arc oxidation film of metal materials under different magnetic fields and the micro-arc oxidation film of metal materials without magnetic fields, the results show that:

[0032] (1) The surface of the metal coating was observed using a scanning electron microscope. Figure 2 As shown, compared with the coating surface without magnetic field, the pores on the surface of the metal material without magnetic field are larger, and the pores on the surface with magnetic field are smaller, and the pores gradually decrease with the increase of magnetic field intensity.

[0033] (2) The surface of the metal coating was observed using a scanning electron microscope. Figure 3As shown in the figure, when the material surface is parallel to the magnetic lines of force, the pores of the film layer are significantly reduced; when the material surface is perpendicular to the magnetic lines of force, the pores of the film layer are larger. The reason is that when the material surface is perpendicular to the magnetic lines of force, the Lorentz force on the charged particles is larger, causing the particles to be more dispersed when moving on the surface, thereby forming larger pores on the surface. At the same time, when the microconductor cuts the magnetic lines of force during movement, it will generate additional electromotive force, and the magnitude of the electromotive force is related to the direction of cutting the magnetic lines of force. When the material surface is parallel to the magnetic lines of force, the additional electromotive force generated is smaller, resulting in a lower growth rate of the film layer, thereby forming a denser film layer.

[0034] (3) Test the corrosion resistance of metal coatings. The results are as follows: Figure 4 As shown in Table 1, the corrosion resistance of the micro-arc oxidation coating of the metal material without the magnetic field is poor. For the micro-arc oxidation film layer with the magnetic field, as the magnetic field intensity increases, the corrosion current gradually decreases, the corrosion potential gradually increases, and the corrosion resistance is enhanced.

[0035] Table 1 shows the corrosion current and corrosion potential of the metal material micro-arc oxidation film layer prepared by the method of the present invention and the metal material micro-arc oxidation film layer obtained without the action of a magnetic field.

[0036]

[0037] Example 2

[0038] Step 1: Grind and polish the surface of Ti2AlNb20mm×10mm×2mm material;

[0039] Using the above device, such as Figure 1 As shown, the composition of the electrolyte in the electrolytic cell 5 is 8g / L (NaPO3)6 + 20g / L NaAlO2, the Ti2AlNb obtained after polishing in step 1 is installed between two magnets 4, so that the Ti2AlNb is parallel to the magnetic field line, the magnetic induction intensity is 3000Gs, the Ti2AlNb is connected to the output positive pole of the power box 1 as an anode, and the stainless steel sheet 2 is connected to the output negative pole of the power box 1 as a cathode. The applied voltage is set to 350V, the duty cycle is 10%, the frequency of micro-arc oxidation is 250Hz, the micro-arc oxidation time is 10min, the oxidation temperature is maintained at 5-15°C, the distance between the two magnets is 3cm, and the micro-arc oxidation film layer is prepared by the method of the present invention.

[0040] Example 3

[0041] Step 1: Grind and polish the surface of TA2 Ti alloy 20mm×15mm×6mm material;

[0042] Using the above device, such as Figure 1As shown, the composition of the electrolyte in the electrolytic cell 5 is 5g / LNa3PO4+1g / L KOH, the TA2 Ti alloy obtained after polishing in step 1 is installed between two magnets 4, so that the TA2 Ti alloy is parallel to the magnetic field line, the magnetic induction intensity is 3500Gs, the TA2 Ti alloy is connected to the output positive pole of the power box 1 as an anode, and the stainless steel sheet 2 is connected to the output negative pole of the power box 1 as a cathode. The applied voltage is set to 400V, the duty cycle is 10%, the frequency of micro-arc oxidation is 600Hz, the micro-arc oxidation time is 15min, the oxidation temperature is maintained at 5-15°C, the distance between the two magnets is 3cm, and the micro-arc oxidation film layer is prepared by the method of the present invention.

[0043] like Figure 5 As shown, the pores of the titanium alloy micro-arc oxidation film prepared with a magnetic field are smaller than those of the micro-arc oxidation film prepared without a magnetic field, and the micro-arc oxidation film prepared with a magnetic field has better corrosion resistance.

[0044] Example 4

[0045] Step 1: Grind and polish the surface of 2A70 aluminum alloy 15mm×15mm×4mm material;

[0046] Using the above device, such as Figure 1 As shown, the composition of the electrolyte in the electrolytic cell 5 is NaSiO3 (11.3-11.8g / L), KOH (1.3-1.5g / L), and EDTA (1.2-1.3g / L). The aluminum alloy obtained after polishing in step 1 is installed between two magnets 4, so that the aluminum alloy is parallel to the magnetic field line, and the magnetic induction intensity is 4000Gs. The aluminum alloy is connected to the output positive pole of the power box 1 as an anode, and the stainless steel sheet 2 is connected to the output negative pole of the power box 1 as a cathode. The applied voltage is set to 450V, the duty cycle is 10%, the frequency of micro-arc oxidation is 500Hz, the micro-arc oxidation time is 30min, the oxidation temperature is maintained at 10-20°C, the distance between the two magnets is 3cm, and the micro-arc oxidation film layer is prepared by the method of the present invention.

[0047] like Figure 6 As shown, the pores of the aluminum alloy micro-arc oxidation film prepared with a magnetic field are smaller than those of the micro-arc oxidation film prepared without a magnetic field, and the micro-arc oxidation film prepared with a magnetic field has better corrosion resistance.

[0048] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. A method for preparing a metal material micro-arc oxidation film layer to adjust the pore size, characterized in that: The steps include: S1: polishing the metal material (3); S2: By performing micro-arc oxidation on the pretreated metal material under different magnetic fields, a micro-arc oxidation film layer is obtained, thereby realizing the regulation of the pore size of the micro-arc oxidation film layer of the metal material.

2. The method for preparing a metal material micro-arc oxidation film for adjusting the pore size according to claim 1, characterized in that: Specifically, S2 is as follows: by changing the distance and direction between the two magnets, the size and direction of the magnetic field are controlled, and based on this, a micro-arc oxidation synchronous auxiliary device is used to perform micro-arc oxidation on the pretreated metal material to obtain a micro-arc oxidation film layer, and the pore size of the micro-arc oxidation film layer of the metal material is regulated.

3. The method for preparing a metal material micro-arc oxidation film for adjusting the pore size according to claim 2, characterized in that: The micro-arc oxidation synchronous auxiliary device comprises a cooling tank (6), an electrolytic tank (5) and a power supply box (1), wherein a coolant is arranged in the cooling tank, the electrolytic tank is arranged in the cooling tank and is separated from the cooling tank by the coolant, the electrolytic tank is arranged in the electrolytic tank, a stainless steel sheet (2), a magnetic field component (4) and a metal material (3) are arranged in the electrolyte, the stainless steel sheet is connected to the output negative pole of the power supply box as a cathode, the metal material is arranged in the magnetic field component and connected to the output positive pole of the power supply box as an anode.

4. The method for preparing a metal material micro-arc oxidation film for adjusting the pore size according to claim 3, characterized in that: In S2, the micro-arc oxidation frequency of the micro-arc oxidation treatment is 50-1000 Hz, the voltage is 200-500 V, the duty cycle is 10-90%, the oxidation time is 3-60 min, the electrolyte temperature is -10-35° C., and the surface magnetic induction intensity of the magnetic field component is 100-5000 Gs.

5. The method for preparing a metal material micro-arc oxidation film for adjusting the pore size according to claim 3, characterized in that: The magnetic field component comprises two magnets, and the metal material is arranged between the two magnets.

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