Preparation method of micro-arc oxidation ceramic membrane for adjusting pore structure and micro-arc oxidation solution

Abstract

The invention belongs to the technical field of micro-arc oxidation surface treatment, and particularly relates to a preparation method of a micro-arc oxidation ceramic membrane for adjusting a pore structure and a micro-arc oxidation solution, the preparation method of the micro-arc oxidation ceramic membrane comprises the following steps: preparing the micro-arc oxidation solution which comprises 10-30 g / L of a membrane growth promoting agent, 8-18 g / L of a complexing agent, 0-35 g / L of a pore adjusting agent and 0.05-0.2 ml / L of a catalyst; 0-2 g / L of a pH control agent; a direct-current pulse power supply is adopted for carrying out micro-arc oxidation treatment, the current frequency of pulse current is 50-500 Hz, the duty ratio is 1.5%-12%, the termination voltage is 500-600 V, the termination current is 3-8 A / dm <-2 >, the current density is given in four stages in a constant current mode, and the growth speed of the ceramic membrane in different voltage intervals is controlled; under the combined action of the electrolytic solution and a current given strategy, the pore characteristics of the micro-arc oxidation ceramic membrane are flexibly adjusted, the hardness, the corrosion resistance, the wear resistance, the surface roughness, the light absorption / emissivity, the biological activity and other properties of the ceramic membrane are balanced, and the optimal configuration of the properties of a light alloy material is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-arc oxidation surface treatment, and particularly relates to a method for preparing a micro-arc oxidation ceramic film with adjusted pore structure and a micro-arc oxidation solution. Background Art

[0002] Micro-arc oxidation (MAO) is a technology that uses electrochemical conversion principles to grow porous ceramic films on the surfaces of light alloy metals such as aluminum, magnesium, and titanium. This technology provides surface strengthening, corrosion protection, and surface modification. For example, aluminum oxide films form on aluminum alloy surfaces to improve surface hardness and wear resistance, magnesium oxide films form on magnesium alloy surfaces to improve corrosion resistance, and porous TiO2 films form on titanium alloy surfaces during bio-implantation to enhance bioactivity. In addition to oxide ceramic films that are converted in situ on metal surfaces, color-enhancing oxides can also be incorporated to impart different colors and enhance optical properties. These include black coatings with light absorption and high emissivity, and decorative red, yellow, and green colored films. The structural and functional properties of MAO porous ceramic films are closely related to their pore characteristics. Modulating the pore characteristics of light alloy MAO ceramic films is crucial to their performance and applications.

[0003] However, the current common pore characteristic adjustment methods mostly focus on reducing porosity and pore size, and porosity and pore size are positively correlated. There is a lack of more flexible adjustment means, and there is a problem that it is very difficult to obtain pore characteristics of low porosity / high pore size or high porosity / low pore size. Summary of the Invention

[0004] In response to the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure and a micro-arc oxidation solution, which can perform diversified adjustments to the structural characteristics of the ceramic membrane, such as the porosity and average pore size, to achieve optimized matching of the mechanical properties, surface quality, and optical properties of the ceramic membrane.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a method for preparing a micro-arc oxidation ceramic film with adjusted pore structure, the preparation method comprising the following steps: Step 1: Prepare a micro-arc oxidation solution; the solution includes 10-30 g / L of a film growth promoter, 8-18 g / L of a complexing agent, 0-35 g / L of a pore regulator, 0.05-0.2 ml / L of a catalyst, and 0-2 g / L of a pH control agent; Step 2: Pretreatment of light metal materials; Step 3: placing the pretreated light metal material into the micro-arc oxidation solution of step 1, and performing micro-arc oxidation treatment using a DC pulse power supply and a segmented given current strategy; Step 4: Wash and dry the light metal material after micro-arc oxidation treatment.

[0006] Furthermore, the DC pulse power supply in step 3 is in constant current mode, and the parameters of the pulse current are: current frequency of 50-500Hz, duty cycle of 1.5%-12%, termination voltage of 500-600V, and termination current of 3-8A / dm -2 .

[0007] Furthermore, the micro-arc oxidation treatment time in step 3 is 20-60 minutes, and the temperature of the micro-arc oxidation solution is 20-40°C.

[0008] Furthermore, the segmented current setting strategy in step 3 is: the current density in the first stage is 1-2.5A / dm -2 , maintain for 4-10min; in the second stage, the current density is set at 2-4.5A / dm -2 , maintain for 5-15min; in the third stage, the current density is set at 2.5-6.5A / dm -2 , maintain for 5-20min; in the fourth stage, the current density is set to 3-8A / dm -2 , maintain for 6-15 minutes.

[0009] Furthermore, the light metal material pretreatment process in step 2 is to sequentially perform alkaline washing to remove oil, pickling to remove surface oxides, water washing, and drying on the light metal material.

[0010] Furthermore, the light metal material is magnesium, aluminum, titanium and alloys thereof.

[0011] Furthermore, in the process of configuring the micro-arc oxidation solution of the present invention, the film growth promoter is one or more of silicate, phosphate, and polyphosphate, the complexing agent is EDTA salt and / or citrate, the pore regulator is borate and / or molybdate, the catalyst is hydrochloric acid; and the pH control agent is potassium hydroxide or sodium hydroxide.

[0012] Furthermore, the film growth promoting agent includes sodium silicate, potassium silicate, sodium phosphate, potassium phosphate, sodium hexametaphosphate, and sodium pyrophosphate; the pore regulating agent includes sodium tetraborate, sodium metaborate, sodium molybdate, potassium molybdate, and ammonium molybdate; and the complexing agent includes disodium EDTA, dipotassium EDTA, sodium citrate, and potassium citrate.

[0013] Furthermore, in the process of preparing the micro-arc oxidation solution, the order of adding the reagents is: complexing agent - film growth promoter - pore regulator - pH control agent - catalyst.

[0014] Furthermore, the pH value of the micro-arc oxidation solution prepared in step 1 is 11-13.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: First, the micro-arc oxidation solution provided by the present invention introduces the pore-forming effect of the pore regulator, enriching the means of regulating the pore structure of the micro-arc oxidation ceramic membrane. Combined with current and voltage regulation, it can achieve ceramic membrane pore characteristics such as low porosity / high pore size or high porosity / low pore size that are difficult to achieve by conventional means; secondly, the basic parameters of the pulse current and the current setting strategy provided by the present invention match the micro-arc oxidation solution, and the voltage is quickly increased to above 400V in the low-voltage stage, which is beneficial to promote the formation of low-melting point / low-evaporation point oxides and enhance the pore-forming effect of the pore regulator. At the same time, by adjusting the current, voltage, and processing time through the current setting strategy, the pore-forming effect can be optimized, thereby regulating the pore characteristics; in addition, by changing the current density in the high-voltage stage, it also has a significant regulatory effect on the pore structure, significantly broadening the application of micro-arc oxidation ceramic membranes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments will be briefly described below. It should be noted that the drawings described below only relate to some embodiments of the present disclosure and are not intended to limit the present disclosure. Figure 1 These are the statistical results of the porosity and average pore diameter of the micro-arc oxidation ceramic films of the light alloy samples processed in Examples 1 to 4 of the present invention.

[0017] Figure 2 This is the microstructure of the micro-arc oxidation ceramic film of the 7075 aluminum alloy sample treated in Example 1 of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0019] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal manner unless otherwise explicitly defined herein.

[0020] References to "embodiments" herein mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it necessarily refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0021] On the one hand, the present invention provides a micro-arc oxidation solution, which specifically includes 10-30g / L of a film growth promoter, for example, 10g / L, 14g / L, 17g / L, 20g / L, 25g / L, 28g / L, 30g / L, etc.; 8-18g / L of a complexing agent, for example, 8g / L, 10g / L, 11g / L, 14g / L, 15g / L, 17g / L, 18g / L, etc.; 0-35g / L of pore regulator, for example, can be 0g / L, 5g / L, 16g / L, 20g / L, 22g / L, 35g / L, etc.; 0.05-0.2ml / L of catalyst, for example, can be 0.05g / L, 0.1g / L, 0.15g / L, 0.2g / L, etc.; 0-2g / L of pH control agent, for example, can be 0g / L, 0.5g / L, 1g / L, 1.5g / L, 2g / L, etc.

[0022] The film growth promoting agent is one or more of silicates, phosphates, and polyphosphates, including sodium silicate, potassium silicate, sodium phosphate, potassium phosphate, sodium hexametaphosphate, and sodium pyrophosphate; the pore regulating agent is borate and molybdate, including sodium tetraborate, sodium metaborate, sodium molybdate, potassium molybdate, and ammonium molybdate; the complexing agent is EDTA salt and citrate, including disodium EDTA, dipotassium EDTA, sodium citrate, and potassium citrate; the catalyst is hydrochloric acid; and the pH control agent is potassium hydroxide or sodium hydroxide.

[0023] In the present invention, the pore modifier used generates corresponding low-melting / low-volatility oxides (such as B2O3 and MoO3) during the micro-arc oxidation process. The transient ultra-high temperature generated by the micro-arc causes these oxides to evaporate into gases, thereby creating micropores and micro-arc discharge channels within the molten oxide film, thereby regulating the pore structure. The complexing agent used in the present invention stabilizes the acid ions generated by the hydrolysis of the volatile oxides, improving the pore-forming effect of the pore modifier and increasing the service life of the micro-arc oxidation solution. The catalyst used in the present invention generates a strong oxidizing substance during the electrochemical reaction, thereby increasing the reaction rate of the pore modifier.

[0024] The order of adding reagents in the preparation process of micro-arc oxidation solution is: complexing agent-film growth promoter-pore regulator-PH control agent-catalyst.

[0025] In some embodiments of the present invention, each time a chemical reagent is added, the solution needs to be stirred to completely dissolve it before adding the next reagent.

[0026] The pH value of the micro-arc oxidation solution is preferably 11-13, for example, it can be 11, 12, or 13.

[0027] The present invention also provides a method for preparing a micro-arc oxidation ceramic film with adjusted pore structure, comprising the following steps: Step 1: Prepare micro-arc oxidation solution; Step 2: Pretreatment of light metal materials; Step 3: placing the pretreated light metal material into the micro-arc oxidation solution of step 1, and performing micro-arc oxidation treatment using a DC pulse power supply and a segmented given current strategy; Step 4: Wash and dry the light metal material after micro-arc oxidation treatment.

[0028] In the process of micro-arc oxidation treatment using a DC pulse power supply, the current frequency of the pulse current is preferably 50-500 Hz, for example, 50 Hz, 100 Hz, 200 Hz, 300 Hz, 400 Hz, 500 Hz, the duty cycle is preferably 1.5%-12%, for example, 1.5%, 2.5%, 5%, 8%, 10%, 11%, 12%, the termination voltage is preferably 500-600 V, and the termination current is preferably 3-8 A / dm -2 .

[0029] In step 3, the micro-arc oxidation treatment time is preferably 20-60 min, for example, 20 min, 30 min, 40 min, 50 min, 60 min, and the electrolyte temperature is preferably 20-40°C, for example, 20°C, 30°C, 40°C.

[0030] In some embodiments of the present invention, the process of micro-arc oxidation treatment is as follows: first, a light metal material and a stainless steel plate are used as an anode and a cathode, respectively, connected to a DC pulse power supply, and placed in a configured micro-arc oxidation solution; then the power is turned on, and the micro-arc oxidation treatment is carried out for 20-60 minutes; finally, the power is turned off and the light metal material is removed. During the process, the electrolyte temperature is controlled at 20-40°C using a circulating water cooling pipe, and air is introduced from the bottom of the micro-arc oxidation solution using an air pump for continuous stirring. The temperature control of the micro-arc oxidation solution stipulated in the present invention has important benefits for pore structure regulation. If the temperature is too high, the oxidation reaction rate will be high, and the low melting point / low evaporation point oxide will have a strong pore-forming effect, resulting in a high porosity and a large average pore size of the ceramic membrane; if the temperature is too low, the oxidation reaction rate will be slow, and the effect of the pore regulator will be insufficient.

[0031] The given current density strategy in step 3 is: the given current density in the first stage is preferably 1-2.5A / dm -2 , for example, it can be 1A / dm -2 , 1.2A / dm -2 , 1.5A / dm -2 , 2A / dm -2 , 2.5A / dm -2 , maintain for 4-10 minutes, for example, 4 minutes, 5 minutes, 8 minutes, 10 minutes, etc.; the second stage is given a current density of 2-4.5A / dm -2 , for example, it can be 2A / dm -2 , 2.1A / dm -2 、3A / dm -2 , 4A / dm -2 , 4.5A / dm -2 etc., and maintain for 5-15 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 10 minutes, 15 minutes; in the third stage, the current density is given as 2.5-6.5A / dm -2 , for example, it can be 2.5A / dm -2 , 2.8A / dm -2 、3A / dm -2 , 3.5A / dm -2 , 6A / dm -2 , 6.5A / dm -2 etc., and maintain for 5-20 minutes, for example, 5 minutes, 10 minutes, 12 minutes, 15 minutes, 20 minutes, etc.; in the fourth stage, the current density is set to 3-8A / dm -2 , for example, it can be 3A / dm -2 , 3.5A / dm -2 , 4.5A / dm -2 , 8A / dm -2 etc., and maintained for 6-15 min, for example, 6 min, 8 min, 10 min, 15 min, etc.

[0032] In some embodiments of the present invention, based on the pulse current parameters provided by the present invention, the current setting strategy is adopted to match the provided solution formula, and the voltage is quickly increased to above 400V in the low-voltage stage, which is beneficial to promote the formation of low-melting-point / low-evaporation-point oxides and enhance the pore-forming effect of the pore regulator. At the same time, by adjusting the current, voltage, and processing time through the current setting strategy, the pore-forming effect can be optimized, thereby regulating the pore characteristics; in addition, by changing the current density in the high-voltage stage, there is also a significant regulatory effect on the pore structure.

[0033] In some embodiments of the present invention, the light metal material is magnesium, aluminum, titanium and alloys thereof.

[0034] The technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention: Example 1

[0035] A method for preparing a 7075 aluminum alloy micro-arc oxidation ceramic film with high porosity and low pore size is provided, comprising the following steps: 1) Prepare 100L of micro-arc oxidation solution with the following chemical reagent concentrations: 5g / L sodium silicate, 15g / L sodium phosphate, 6g / L disodium EDTA, 5g / L sodium citrate, 5g / L sodium tetraborate, 15g / L sodium molybdate, 0.5g / L sodium hydroxide, and 0.15ml / L hydrochloric acid. The preparation process follows the following sequence: disodium EDTA - sodium citrate - sodium silicate - sodium phosphate - sodium tetraborate - sodium molybdate - sodium hydroxide - hydrochloric acid. After adding each chemical reagent, use gas agitation to thoroughly mix the solution before adding the next reagent.

[0036] 2) Place the aluminum alloy sheet sample in a 40°C sodium hydroxide + sodium carbonate solution for degreasing for 10 minutes, then rinse with deionized water, and then place it in a room temperature dilute hydrochloric acid solution for pickling for 5 minutes to remove the oxide on the sample surface, and finally rinse it with water again.

[0037] 3) Connect the sample to the anode copper busbar with an aluminum wire and immerse the sample in the micro-arc oxidation solution. Turn on the air pump to allow air to continuously flow into the solution and stir it continuously. Turn on the water cooling device to allow the water cooling pipe to continuously cool the solution.

[0038] 4) Turn on the micro-arc oxidation power supply equipment, adjust the current frequency to 500 Hz, the duty cycle to 8%, and the operating mode to constant current mode.

[0039] 5) Set the automatic given current program: the first stage, current density 1.5A / dm -2 , maintain for 5min; the second stage, current density 2A / dm -2 , maintain for 7min; the third stage, current density 2.8A / dm -2 , maintain for 12 minutes; the fourth stage, current density 3.5A / dm -2 , and maintain for 10 minutes. Start the power supply and carry out micro-arc oxidation treatment.

[0040] The power supply was cut off, the sample was taken out and cleaned, and a 7075 aluminum alloy sample with a micro-arc oxidation ceramic film with high porosity and low pore size was obtained.

[0041] Example 2 A method for preparing a 6061 aluminum alloy micro-arc oxidation ceramic film with high porosity and high pore size is provided, comprising the following steps: 1) Prepare 100L of micro-arc oxidation solution with the following chemical reagent concentrations: 8g / L sodium silicate, 24g / L sodium hexametaphosphate, 5g / L disodium EDTA, 5g / L sodium citrate, 3g / L sodium tetraborate, 2g / L sodium molybdate, 0.5g / L sodium hydroxide, and 0.05ml / L hydrochloric acid. The preparation process follows the following sequence: disodium EDTA - sodium citrate - sodium silicate - sodium hexametaphosphate - sodium tetraborate - sodium molybdate - sodium hydroxide - hydrochloric acid. After adding each chemical reagent, use gas agitation to thoroughly mix the solution before adding the next reagent.

[0042] 2) Place the aluminum alloy sheet sample in a 40°C sodium hydroxide + sodium carbonate solution for degreasing for 10 minutes, then rinse with deionized water, and then place it in a room temperature dilute hydrochloric acid solution for pickling for 5 minutes to remove the oxide on the sample surface, and finally rinse it with water again.

[0043] 3) Connect the sample to the anode copper busbar with an aluminum wire and immerse the sample in the micro-arc oxidation solution. Turn on the air pump to allow air to continuously flow into the solution and stir it continuously. Turn on the water cooling device to allow the water cooling pipe to continuously cool the solution.

[0044] 4) Turn on the micro-arc oxidation power supply equipment, adjust the current frequency to 500 Hz, the duty cycle to 10%, and the operating mode to constant current mode.

[0045] 5) Set the automatic given current program: the first stage, current density 1.2A / dm -2 , maintain for 4 minutes; the second stage, current density 2.1A / dm -2 , maintain for 6 minutes; the third stage, current density 3A / dm -2 , maintain for 10min; the fourth stage, current density 3.8A / dm -2 , and maintain for 10 minutes. Start the power supply and carry out micro-arc oxidation treatment.

[0046] The power supply was cut off, the sample was taken out and cleaned, and a 6061 aluminum alloy sample with a micro-arc oxidation ceramic film with high porosity and low pore size was obtained.

[0047] Example 3 Provided is a method for preparing a TA2 titanium alloy micro-arc oxidation ceramic film with low porosity and low pore size, comprising the following steps: 1) Prepare 100L of micro-arc oxidation solution with the following chemical reagent concentrations: 5g / L sodium silicate, 10g / L sodium hexametaphosphate, 10g / L sodium phosphate, 8g / L disodium EDTA, 8g / L sodium citrate, 8g / L sodium metaborate, 8g / L sodium molybdate, 0.2g / L sodium hydroxide, and 0.1ml / L hydrochloric acid. The preparation process follows the following sequence: disodium EDTA - sodium citrate - sodium silicate - sodium hexametaphosphate - sodium phosphate - sodium metaborate - sodium molybdate - sodium hydroxide - hydrochloric acid. After adding each chemical reagent, use gas agitation to thoroughly mix the solution before adding the next reagent.

[0048] 2) Place the titanium alloy sheet sample in a 40°C sodium hydroxide + sodium carbonate solution for degreasing for 10 minutes, then rinse with deionized water, and then place it in a room temperature dilute hydrochloric acid + hydrofluoric acid solution for pickling for 2 minutes to remove the oxide on the sample surface, and finally rinse it with water again.

[0049] 3) Connect the sample to the anode copper busbar with an aluminum wire and immerse the sample in the micro-arc oxidation solution. Turn on the air pump to allow air to continuously flow into the solution and stir it continuously. Turn on the water cooling device to allow the water cooling pipe to continuously cool the solution.

[0050] 4) Turn on the micro-arc oxidation power supply equipment, adjust the current frequency to 100 Hz, the duty cycle to 5%, and the operating mode to constant current mode.

[0051] 5) Set the automatic given current program: the first stage, current density 1A / dm -2 , maintain for 4min; the second stage, current density 2A / dm -2 , maintain for 5min; the third stage, current density 3.5A / dm -2 , maintain for 10min; the fourth stage, current density 4.5A / dm -2 , and maintain for 8 minutes. Start the power supply and carry out micro-arc oxidation treatment.

[0052] The power supply was cut off, the sample was taken out and cleaned, and a TA2 titanium alloy sample with a micro-arc oxidation ceramic film with high porosity and low pore size was obtained. Example

[0053] A method for preparing a micro-arc oxidation ceramic film of AZ91 magnesium alloy with low porosity and high pore size is provided, comprising the following steps: 1) Prepare 100L of micro-arc oxidation solution with the following chemical reagent concentrations: 15g / L sodium silicate, 5g / L sodium hexametaphosphate, 10g / L sodium phosphate, 12g / L disodium EDTA, 6g / L sodium citrate, 20g / L sodium tetraborate, 2g / L sodium molybdate, 2g / L sodium hydroxide, and 0.2ml / L hydrochloric acid. The preparation process follows the following sequence: disodium EDTA - sodium citrate - sodium silicate - sodium hexametaphosphate - sodium phosphate - sodium tetraborate - sodium molybdate - sodium hydroxide - hydrochloric acid. After adding each chemical reagent, use gas agitation to thoroughly mix the solution before adding the next reagent.

[0054] 2) The magnesium alloy sheet specimens were placed in a 35°C sodium hydroxide + sodium carbonate solution for degreasing for 15 minutes, then rinsed with deionized water, and then pickled in a room temperature dilute hydrochloric acid solution for 2 minutes to remove surface oxides of the specimens, and finally rinsed with water again.

[0055] 3) Connect the sample to the anode copper busbar with an aluminum wire and immerse the sample in the micro-arc oxidation solution. Turn on the air pump to allow air to continuously flow into the solution and stir it continuously. Turn on the water cooling device to allow the water cooling pipe to continuously cool the solution.

[0056] 4) Turn on the micro-arc oxidation power supply equipment, adjust the current frequency to 500 Hz, the duty cycle to 12%, and the operating mode to constant current mode.

[0057] 5) Set the automatic given current program: the first stage, current density 2A / dm -2 , maintain for 4min; the second stage, current density 4A / dm -2 , maintain for 5min; the third stage, current density 6A / dm -2 , maintain for 15min; the fourth stage, current density 8A / dm -2 , and maintain for 10 minutes. Start the power supply and carry out micro-arc oxidation treatment.

[0058] The power supply was cut off, the sample was taken out and cleaned, and an AZ91 magnesium alloy sample with a micro-arc oxidation ceramic film with high porosity and low pore size was obtained.

[0059] The porosity and pore size of the ceramic membranes of the above-mentioned example samples were statistically analyzed using a microscopic morphology analysis method. The results are shown in Table 1: Table 1

[0060] From the above results, it can be seen that the porosity and pore size of the light alloy micro-arc oxidation ceramic membrane can be flexibly adjusted by using the micro-arc oxidation solution and micro-arc oxidation treatment method provided by this patent. In the four embodiments, the porosity adjustment range is 5~18%, and the average pore diameter adjustment range is 2.3~13.4 microns.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure, characterized in that: The preparation method comprises the following steps: Step 1: Prepare a micro-arc oxidation solution; the solution includes 10-30 g / L of a film growth promoter, 8-18 g / L of a complexing agent, 0-35 g / L of a pore regulator, 0.05-0.2 ml / L of a catalyst, and 0-2 g / L of a pH control agent; Step 2: Pretreatment of light metal materials; Step 3: placing the pretreated light metal material into the micro-arc oxidation solution of step 1, and performing micro-arc oxidation treatment using a DC pulse power supply and a segmented given current strategy; Step 4: Wash and dry the light metal material after micro-arc oxidation treatment.

2. The method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure according to claim 1, characterized in that: The DC pulse power supply in step 3 is in constant current mode. The parameters of the pulse current are: current frequency 50-500Hz, duty cycle 1.5%-12%, termination voltage 500-600V, termination current 3-8A / dm -2 .

3. The method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure according to claim 1, characterized in that: The time of the micro-arc oxidation treatment in step 3 is 20-60 minutes, and the temperature of the micro-arc oxidation solution is 20-40°C.

4. The method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure according to claim 1, characterized in that: The segmented current setting strategy in step 3 is: the current density in the first stage is 1-2.5A / dm -2 , maintain for 4-10min; in the second stage, the current density is set at 2-4.5A / dm -2 , maintain for 5-15min; in the third stage, the current density is set at 2.5-6.5A / dm -2 , maintain for 5-20min; in the fourth stage, the current density is set to 3-8A / dm -2 , maintain for 6-15 minutes.

5. The method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure according to claim 1, characterized in that: The light metal material pretreatment process in step 2 is to sequentially perform alkaline washing to remove oil, pickling to remove surface oxides, water washing, and drying on the light metal material.

6. The method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure according to claim 1, characterized in that: The light metal material is magnesium, aluminum, titanium and alloys thereof.

7. The method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure according to claim 1, characterized in that: In the process of preparing the micro-arc oxidation solution in step one, the film growth promoter is one or more of silicate, phosphate, and polyphosphate, the complexing agent is EDTA salt and / or citrate, the pore regulator is borate and / or molybdate, the catalyst is hydrochloric acid; and the pH control agent is potassium hydroxide or sodium hydroxide.

8. The method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure according to claim 7, characterized in that: The film growth promoting agent includes sodium silicate, potassium silicate, sodium phosphate, potassium phosphate, sodium hexametaphosphate, and sodium pyrophosphate; the pore regulating agent includes sodium tetraborate, sodium metaborate, sodium molybdate, potassium molybdate, and ammonium molybdate; and the complexing agent includes disodium EDTA, dipotassium EDTA, sodium citrate, and potassium citrate.

9. The method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure according to claim 1, characterized in that: During the preparation of the micro-arc oxidation solution, the order of adding reagents is: complexing agent - film growth promoter - pore regulator - pH control agent - catalyst.

10. The method for preparing a micro-arc oxidation ceramic membrane with adjusted pore structure according to claim 1, characterized in that: The pH value of the micro-arc oxidation solution prepared in step 1 is 11-13.

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