Gradient micro-arc oxidation preparation system and method

Abstract

The invention belongs to the technical field of metal material surface oxidation, and particularly relates to a gradient micro-arc oxidation preparation system and method. The system comprises a pretreatment device, an electrolyte batching device and a micro-arc oxidation device, and the pretreatment device is used for removing oil stains and oxide layers on the surfaces of workpieces and mechanically polishing the surfaces of the workpieces; the electrolyte batching device is used for mixing and preparing electrolyte used for workpiece micro-arc oxidation; the micro-arc oxidation device comprises a reactor containing electrolyte, and a workpiece is subjected to micro-arc oxidation in the reactor; the pretreatment device, the electrolyte batching device and the micro-arc oxidation device are sequentially connected according to an industrial production sequence. In addition, the invention further discloses a gradient micro-arc oxidation preparation method. The uniform and smooth color gradient effect on the surface of the metal material is achieved by accurately regulating and controlling key parameters such as electrolyte components, voltage, current density, oxidation time and temperature in the oxidation process.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material surface oxidation, and in particular relates to a gradual micro-arc oxidation preparation system and method. Background Art

[0002] Micro-arc oxidation (MAO) is a technology that uses a high voltage electric field to induce micro-arc discharge in an electrolyte to form a hard and corrosion-resistant oxide film on the metal surface. With the increase in industrial demand, the traditional micro-arc oxidation process often faces problems such as single film color and uneven surface properties. In order to meet the aesthetic and functional requirements of different application fields, micro-arc oxidation technology came into being. By controlling the formation process of the oxide film, different color changes of the metal surface film can be achieved, such as white, black, etc.

[0003] At present, micro-arc oxidation technology has been widely used in the treatment of metal surfaces such as aluminum alloys, magnesium alloys, and titanium alloys, especially in the aviation, automobile, and construction industries, because of its decorative and protective properties. However, the existing micro-arc oxidation technology focuses on generating a single color or local color changes, and it is difficult to achieve a gradual change effect from light to dark or multiple colors on the metal surface. In order to solve this problem, it is particularly important to develop a gradual oxidation technology that can accurately control the color change during the oxidation process.

[0004] Therefore, the present invention proposes a micro-arc oxidation preparation method and a system thereof that can achieve a color gradient effect, thereby improving the effect of the prior art in color gradient control. Summary of the invention

[0005] The purpose of the present invention is to provide a gradual micro-arc oxidation preparation method, which aims to achieve a uniform and smooth color gradient effect on the surface of metal materials (such as aluminum alloys, titanium alloys, magnesium alloys, etc.) by accurately controlling key parameters such as electrolyte composition, voltage, current density, oxidation time and temperature during the oxidation process. In addition, the present invention also provides a gradual micro-arc oxidation preparation system, which can efficiently and accurately implement the above method, thereby meeting the multiple requirements of decorativeness and functionality in different application scenarios.

[0006] To achieve the above purpose, the technical solution adopted is: A gradual micro-arc oxidation preparation system, comprising: A pretreatment device, which is used to remove oil and oxide layers on the surface of the workpiece, and to mechanically polish the surface of the workpiece; An electrolyte batching device, which is used to mix and prepare the electrolyte used for micro-arc oxidation of workpieces; and a micro-arc oxidation device, the micro-arc oxidation device comprising a reactor containing an electrolyte, wherein the workpiece is micro-arc oxidized in the reactor; The pretreatment device, the electrolyte batching device and the micro-arc oxidation device are connected in sequence according to the industrial production sequence.

[0007] According to the gradual micro-arc oxidation preparation system of the present invention, further, the reactor includes a reaction box, a column and a hanger; the column is arranged on the side of the reaction box, and the column can move left and right in the horizontal direction; the hanger is slidably arranged on the upper part of the column in the vertical direction through the mounting beam, and the hanger is located above the reaction box, and the material used for the hanger is stainless steel or titanium alloy material.

[0008] According to the gradual micro-arc oxidation preparation system of the present invention, further, the micro-arc oxidation device also includes a power box and a refrigeration system.

[0009] The present invention also discloses a gradual micro-arc oxidation preparation method, which is implemented according to the gradual micro-arc oxidation preparation system, and comprises: S1. Workpiece pretreatment: soak the workpiece in an organic solvent to remove oil stains on the workpiece surface; then pickle the workpiece to remove the oxide layer on the workpiece surface; mechanically grind the workpiece to remove impurities on the workpiece surface; S2. Prepare an electrolyte by mixing and stirring a metal salt solution, an organic dye, a rare earth element salt, a buffer and a pH adjuster to prepare an electrolyte; S3. Micro-arc oxidation treatment: Place the pre-treated workpiece into the above electrolyte, connect the electrodes and set the micro-arc oxidation parameters, and form a color gradient effect on the workpiece surface through the flow of electrodes and electrolyte.

[0010] According to the gradual micro-arc oxidation preparation method of the present invention, further, in step S1, the organic solvent is acetone or ethanol, and the immersion time is 10 min-30 min.

[0011] According to the gradual micro-arc oxidation preparation method of the present invention, further, in step S1, the pickling solution used for pickling is a mixed solution of nitric acid and hydrofluoric acid, the pickling temperature is 20°C-30°C, and the pickling time is 2min-5min.

[0012] According to the gradual micro-arc oxidation preparation method of the present invention, further, in step S1, the surface roughness Ra of the workpiece is polished to 0.8-3.2 μm by mechanical polishing.

[0013] According to the gradual micro-arc oxidation preparation method of the present invention, further, in step S2, the metal salt solution is a mixture of sodium aluminate, sodium silicate and sodium phosphate; the concentration of sodium aluminate is 150g / L-300g / L, the concentration of sodium silicate is 30g / L-80g / L, and the concentration of sodium phosphate is 20-60g / L.

[0014] According to the gradient micro-arc oxidation preparation method of the present invention, further, in step S2, the concentration of the organic dye is 5g / L-20g / L, and the amount of rare earth element salt added is 3g / L-10g / L.

[0015] According to the gradual micro-arc oxidation preparation method of the present invention, further, in step S3, the micro-arc oxidation parameters include: an initial voltage of 250V-350V, a voltage increase rate of 5V / min-15V / min, a final voltage of 450V-600V, a current density of 3A / dm²-8A / dm², and an oxidation time of 20min-60min.

[0016] The beneficial effects achieved by adopting the above technical solution are: The present invention provides a gradient micro-arc oxidation preparation system and method, which achieves a uniform and smooth color gradient effect on the surface of metal materials (such as aluminum alloys, titanium alloys, magnesium alloys, etc.) by precisely controlling key parameters such as electrolyte composition, voltage, current density, oxidation time and temperature during the oxidation process. Compared with the prior art, the present invention has the following significant advantages: 1. The color gradient effect is precise and controllable: By adjusting multiple parameters in the oxidation process, the present invention can achieve a smooth transition from light color to dark color or multiple colors on the metal surface, meeting diverse aesthetic needs and breaking through the limitation that traditional micro-arc oxidation technology can only achieve single color or partial color change; 2. Improvement of surface properties: Through pretreatment processes, including degreasing with organic solvents, pickling to remove the oxide layer, and mechanical grinding, the roughness and cleanliness of the workpiece surface are effectively controlled, thereby improving the quality and uniformity of the oxide film. The oxide film has good corrosion resistance, wear resistance and hardness, which can greatly extend the service life of metal materials; 3. Simple and efficient process: The gradient micro-arc oxidation method proposed in the present invention can not only accurately control the color change, but also adopts an efficient process flow. Through the coordinated work of the electrolyte batching device and the micro-arc oxidation device, it can realize automated and continuous processing in industrial production, significantly improving production efficiency; 4. Wide applicability: This method can be widely used in the surface treatment of metal materials such as aluminum alloy, titanium alloy, magnesium alloy, etc. It is particularly suitable for aviation, automobile, construction, decoration and other fields. It can meet different functional and decorative requirements and provide more design possibilities for metal surface treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention, wherein the drawings are only used to illustrate some embodiments of the present invention, but not to limit all embodiments of the present invention thereto.

[0018] Figure 1 It is a schematic structural diagram of the pretreatment device of the present invention.

[0019] Figure 2 It is a structural schematic diagram of the electrolyte batching device of the present invention.

[0020] Figure 3 It is a schematic structural diagram of the micro-arc oxidation treatment device of the present invention.

[0021] The meanings of the numbers in the figure are: 1. electrolyte dosing device, 101. barrel body, 102. barrel cover, 103. stirring pump, 104. feed port, 105. rotating shaft, 106. blade, 107. sensor; 2. Pretreatment device, 201. Cleaning barrel, 202. Pickling barrel, 203. Polishing box, 204. Slave console; 3. Micro-arc oxidation device, 301. power supply box, 3011. electrode, 302. liquid storage tank, 3021. flow control valve, 303. reaction box, 3031. support, 3032. hanger, 3033. installation beam; 4. Refrigerator, 401. Refrigeration pump. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings of specific embodiments of the present invention to clearly and completely describe the exemplary scheme of the embodiment of the present invention. Unless otherwise defined, the technical terms or scientific terms used in the present invention should be the common meanings understood by people with ordinary skills in the field.

[0023] On the one hand, if Figure 1-Figure 3 As shown, the present invention provides a gradual micro-arc oxidation preparation system, including a pretreatment device 2, an electrolyte dosing device 1 and a micro-arc oxidation device 3. Among them, the pretreatment device 2 is used to remove oil stains and oxide layers on the surface of the workpiece, and to mechanically polish the surface of the workpiece; the electrolyte dosing device 1 is used to mix and prepare the electrolyte used for micro-arc oxidation of the workpiece; the micro-arc oxidation device 3 includes a reactor containing electrolyte, and the workpiece is micro-arc oxidized in the reactor; the pretreatment device 2, the electrolyte dosing device 1 and the micro-arc oxidation device 3 are connected in sequence according to the industrial production order (not shown in the figure).

[0024] like Figure 3 As shown, the reactor of the micro-arc oxidation device 3 includes a reaction box 303, a column 3031 and a hanger 3032; wherein the column 3031 is arranged on the side of the reaction box 303, and the column 3031 can move left and right in the horizontal direction; further, the reaction box 303 is used to contain an electrolyte.

[0025] The hanger 3032 is disposed on the upper part of the column 3031 through the mounting beam 3033 . The hanger 3032 can slide in the vertical direction, and the hanger 3032 is located above the reaction box 303 .

[0026] Furthermore, the material used for the hanger 3032 is stainless steel or titanium alloy material to avoid corrosion of the electrolyte in the hanger 3032. The hanger 3032 is used to firmly fix the workpiece and is connected to the electrode 3011 to ensure that the position of the workpiece in the electrolyte is stable so that the current can pass evenly through the surface of the workpiece.

[0027] like Figure 3 As shown, the micro-arc oxidation device 3 also includes a power box 301 and a refrigeration system.

[0028] Furthermore, the power box 301 is equipped with a feedback control system, which can adjust the voltage and current in real time according to the set parameters to ensure that the oxidation process is carried out within the set range.

[0029] Furthermore, the power box 301 is externally connected to at least two electrodes 3011 , and the electrodes 3011 are immersed in the electrolyte in the reaction box 303 .

[0030] Furthermore, the refrigeration system includes a refrigerator 4 and a refrigeration pump 401 which are connected to the reaction box 303 through a pipeline. The refrigerator 4 and the refrigeration pump 401 are used together to maintain the low temperature state of the electrolyte in the reaction box 303.

[0031] Furthermore, if Figure 3 As shown, the micro-arc oxidation device 3 also includes a liquid storage tank 302 connected to the reaction box 303 through a connecting pipe, and the reaction box 303 and the liquid storage tank 302 form a circulation system. Further, a flow regulating valve 3021 is installed on the connecting pipe, and the flow regulating valve 3021 can adjust the flow of the electrolyte, so that the electrolyte in the reaction box 303 forms a specific flow pattern around the workpiece, achieving a color gradient effect, and taking away the heat generated by the micro-arc discharge.

[0032] like Figure 1 As shown, the pretreatment device 2 includes a cleaning barrel 201, a pickling barrel 202, a polishing box 203 and a main control console 204. The cleaning barrel 201 contains an organic solvent, the pickling barrel 202 contains a pickling liquid, and the polishing box 203 contains grinding balls. The movements of the cleaning barrel 201, the pickling barrel 202 and the polishing box 203 are all controlled by the main control console 204.

[0033] Furthermore, a temperature control device and a time control device are installed in the cleaning barrel 201 to control the soaking temperature and time.

[0034] Furthermore, the pickling barrel 202 is provided with a liquid inlet and a liquid outlet to facilitate the replacement and discharge of the pickling liquid.

[0035] In the actual process, the workpiece is first placed in the cleaning barrel 201 for cleaning for 10 minutes to 30 minutes to remove the oil on the surface of the workpiece. For workpieces with heavy oil stains, the immersion time can be appropriately extended or multiple immersions can be used to ensure that the oil on the surface of the workpiece is completely removed. Then, the workpiece is placed in the pickling barrel 202 and pickled for 2 minutes to 5 minutes at a temperature range of 20°C to 30°C to remove the oxide layer on the surface of the workpiece. After the pickling is completed, rinse the workpiece thoroughly with a large amount of clean water to prevent acid residue. Finally, the workpiece is placed in the polishing box until the surface roughness Ra of the workpiece reaches 0.8μm-3.2μm.

[0036] like Figure 2 As shown, the electrolyte dosing device 1 includes a barrel body 101, a barrel cover 102, a stirring pump 103 and blades 106, wherein the stirring pump 103 is fixed on the barrel cover 102 by bolts, the rotating shaft 105 of the stirring pump 103 passes through the barrel cover 102 and enters the barrel body 101, and a plurality of blades 106 are fixed on the lower middle part of the rotating shaft 105.

[0037] Furthermore, the blades 106 are at least a two-layer structure, and each layer has at least four blades 106 .

[0038] Furthermore, the barrel cover 102 is provided with a plurality of feed ports 104, which are used to add different raw materials such as metal salts, organic dyes, rare earth element salts, pH adjusters and buffers into the barrel body 101, so as to ensure that the adding process is accurate and convenient.

[0039] Furthermore, a sensor 107 is connected to the lower side of the barrel cover 102 , and the sensor 107 includes a temperature sensor and a pH sensor for monitoring the temperature and pH of the electrolyte in the barrel body 101 in real time.

[0040] It should be understood that, in the actual process, the electrolyte prepared in the electrolyte dosing device 1 is introduced into the storage box 302 of the micro-arc oxidation device 3 through a pipeline, and then introduced into the reaction box 303.

[0041] On the other hand, the present invention also provides a gradual micro-arc oxidation preparation method, which is as follows: 1. Workpiece pretreatment: S11. Removal of oil stains: Place the (metal) workpiece to be treated in an organic solvent cleaning tank. The organic solvent can be an acetone (C3H6O) solution or a C2H5OH (ethanol) solution, or a mixed solution of the two. The immersion time is set between 10min and 30min according to the degree of oil pollution on the workpiece. For workpieces with heavy oil pollution, the immersion time can be appropriately extended or multiple immersions can be used to ensure that the oil pollution on the workpiece surface is completely removed.

[0042] S12. Pickling: Choose the appropriate pickling solution for pickling according to the metal material of the workpiece. Take aluminum alloy workpiece as an example, put it into a mixed pickling solution containing nitric acid (HNO3) and hydrofluoric acid (HF), the pickling temperature is controlled at 20℃-30℃, and the pickling time is 2min-5min. During the pickling process, stir the pickling solution so that the pickling solution is fully in contact with the surface of the workpiece to effectively remove the oxide scale and impurities. After the pickling is completed, use a large amount of clean water to thoroughly rinse the workpiece to prevent acid residue.

[0043] S13. Mechanical grinding: The workpiece surface is processed by mechanical grinding methods such as a grinder (grinding box 203) to make the workpiece surface roughness Ra reach 0.8μm-3.2μm, ensuring that the surface cleanliness meets the requirements of the subsequent oxidation process. Furthermore, the workpiece surface can also be manually polished using sandpaper with a mesh size of 200-800 mesh.

[0044] 2. Prepare electrolyte: S21. Basic electrolyte composition: The basic composition of the electrolyte is determined according to the metal material of the workpiece. For example, for aluminum alloy workpieces, the electrolyte is mainly a mixture of sodium aluminate (Na[Al(OH)4]), sodium silicate (Na2SiO3) and sodium phosphate (Na3PO4). Among them, the concentration range of sodium aluminate (Na[Al(OH)4]) is 150g / L-300g / L, the concentration range of sodium silicate (Na2SiO3) is 30g / L-80g / L, and the concentration range of sodium phosphate (Na3PO4) is 20g / L-60g / L. The solvent used is deionized water (H2O).

[0045] It should be understood that workpieces made of different metal materials should use corresponding metal salt systems to ensure the normal growth of the oxide film on the surface of the workpiece.

[0046] S22. Add additives: Additives are added to the electrolyte in S21, including organic dyes and rare earth element salts, wherein the type and concentration of the organic dyes are selected according to the desired color gradient effect.

[0047] For example, to achieve a gradient from green to blue, an organic dye containing a copper phthalocyanine structure is selected, and its concentration range is 5g / L-20g / L.

[0048] The rare earth element salt is selected from rare earth lanthanum salt (LaCl3) or rare earth cerium salt (Ce(NO3)3) and the like, and the added amount of the rare earth element salt is 3g / L-10g / L.

[0049] These additives play an important role in the growth process of the oxide film. Organic dyes can give the oxide film color, and rare earth element salts can adjust the growth rate and microstructure of the oxide film, helping to achieve a gradient color effect.

[0050] At the same time, in order to maintain the pH value of the electrolyte stable, add an appropriate amount of sodium hydroxide (NaOH) or hydrochloric acid (HCl), and match with a buffer such as boric acid (H3BO3) or citric acid (C6H8O7). Control the pH value of the electrolyte within the range of 8-12. Control the temperature of the electrolyte within the range of 25℃-35℃ and stir thoroughly for at least 30 minutes.

[0051] Furthermore, the electrolyte is stirred in the mixing barrel 1, wherein the stirring speed of the blade 106 is 200r / min-500r / min.

[0052] 3. Micro-arc oxidation treatment: S31. Equipment connection and parameter setting: The pre-treated workpiece is hung on the hanger 3032 and placed in the electrolyte in the reaction box 303. The workpiece is brought into contact with the electrode 3011 by controlling the movement of the hanger 3032. The oxidation parameters are set according to the material of the workpiece. For example, for an aluminum alloy workpiece, the initial voltage of the power box 301 is set between 250V and 350V, and then the voltage is increased at a rate of 5V / min-15V / min, and the final voltage reaches 450V-800V. The current density is controlled at 3A / dm²-8A / dm², and the oxidation time is determined according to the size of the workpiece, the required oxide film thickness and the color effect, and is generally in the range of 20-80 minutes.

[0053] S32. Color gradient control: The color gradient effect is achieved through the unique distribution of electrodes 3011 and the flow system of the electrolyte. Figure 3 As shown, in terms of the distribution of the electrodes 3011, the electrodes 3011 are unevenly distributed, so that the electric field strength at different parts of the workpiece is different. In addition, by adjusting the shape, spacing and arrangement of the electrodes 3011, in the area with strong electric field strength, the micro-arc discharge is more intense, the oxide film grows faster, and the color changes significantly; while in the area with weak electric field strength, the oxide film grows relatively slowly and the color changes more gently.

[0054] In terms of electrolyte flow control, the electrolyte is continuously circulated in the reaction box 303 and the storage box 302 to form a specific flow pattern on the surface of the workpiece. The electrolyte flows around the workpiece at a certain flow rate, causing the electrolyte composition and concentration in different areas of the workpiece to change dynamically. For example, near the electrolyte inlet of the reaction box 303, the supply of fresh electrolyte makes the oxidation reaction conditions in this area different from those near the outlet of the reaction box 303, resulting in different oxidation degrees and achieving a color gradient effect. At the same time, the flow of the electrolyte can also take away the heat generated by the micro-arc discharge to ensure the stability of the oxidation process.

[0055] Example 1: Micro-arc oxidation treatment of an aluminum alloy workpiece (electronic product housing).

[0056] a. Workpiece pretreatment: like Figure 1 As shown, the aluminum alloy workpiece is placed in an acetone (C3H6O) solution in a cleaning barrel 201 and soaked for 20 minutes to remove surface oil stains. Then the aluminum alloy workpiece is placed in a mixed pickling solution of nitric acid (HNO3, volume fraction of 10%) and hydrofluoric acid (HF, volume fraction of 3%) in a pickling barrel 202, and pickled at 25°C for 3 minutes. The pickling solution is continuously stirred during the pickling process. After pickling, the aluminum alloy workpiece is rinsed with a large amount of clean water to ensure that there is no acid residue. Finally, the aluminum alloy workpiece is placed in a polishing box 203 for polishing until the surface roughness Ra of the aluminum alloy workpiece reaches 1.6μm.

[0057] b. Prepare 10L electrolyte: like Figure 2 As shown, deionized water, sodium aluminate, sodium silicate, sodium phosphate, organic dyes with copper phthalocyanine structure and rare earth lanthanum salt are added into the barrel 101 through the feed port 104. Subsequently, sodium hydroxide (NaOH) is added into the barrel 101 to adjust the pH value of the electrolyte to 10, and an appropriate amount of boric acid (H3BO3) is added as a buffer. Finally, the electrolyte is stirred at a temperature of 30°C for 40 minutes, and the stirring speed of the blade 106 is 300r / min.

[0058] The final electrolyte contained 250 g / L sodium aluminate (Na[Al(OH)4]), 60 g / L sodium silicate (Na2SiO3), 40 g / L sodium phosphate (Na3PO4), 12 g / L copper phthalocyanine, and 6 g / L rare earth lanthanum salt (LaCl3).

[0059] After the electrolyte in the barrel 101 is prepared, it is introduced into the storage box 302 in the micro-arc oxidation device 3 through a pipeline, and then introduced into the reaction box 303.

[0060] c. Micro-arc oxidation treatment: like Figure 2 and Figure 3 As shown, the pretreated aluminum alloy workpiece is placed in the electrolyte in the reaction box 303 through the hanger 3032 and connected to the electrode 3011. The initial voltage of the power box 301 starts from 300V and increases to 500V at a rate of 10V / min. The current density is controlled at 5A / dm² and the oxidation time is 30min.

[0061] During the micro-arc oxidation process of the aluminum alloy workpiece, the multiple electrodes 3011 in the reaction box 303 are asymmetrically distributed, and the spacing between the electrodes 3011 gradually decreases at one end close to the aluminum alloy workpiece, so that the surface of the aluminum alloy workpiece forms a gradient effect from white to dark blue.

[0062] During the oxidation process, the electrolyte flows around the aluminum alloy workpiece at a flow rate of 0.5 L / min in the circulation structure formed by the reaction box 303 and the storage box 302, ensuring the stability of the oxidation process and the uniformity of the color gradient.

[0063] Example 2: Micro-arc oxidation treatment of a magnesium alloy workpiece (automobile decorative part).

[0064] a. Workpiece pretreatment: like Figure 1 As shown, the magnesium alloy workpiece is placed in the ethanol (C2H5OH) solution in the cleaning barrel 201 and soaked for 15 minutes to remove surface oil stains. Then the magnesium alloy workpiece is placed in a mixed pickling solution of chromic acid (H2CrO4, volume fraction of 5%) and phosphoric acid (H3PO4, volume fraction of 10%) in the pickling barrel 202, pickled at 30°C for 4 minutes, and the pickling solution is continuously stirred during the pickling process. After pickling, the magnesium alloy workpiece is rinsed with a large amount of clean water to ensure that there is no acid residue. Finally, the magnesium alloy workpiece is placed in the grinding box 203 for grinding until the surface roughness Ra of the magnesium alloy workpiece reaches 2.0μm.

[0065] b. Prepare electrolyte: like Figure 2 As shown, deionized water, magnesium sulfate, potassium silicate, special organic dye (a specific type that can achieve a gradual change from blue to red and yellow for magnesium alloy) and rare earth cerium salt are added into the barrel body 101 through the feed port 104 .

[0066] Then, sodium hydroxide (NaOH) and hydrochloric acid (HCl) are added into the barrel 101 to adjust the pH value of the electrolyte to 9, and an appropriate amount of citric acid (C6H8O7) is added as a buffer. Finally, the electrolyte is stirred at a temperature of 32° C. for 35 minutes, and the stirring speed of the blade 106 is 400 r / min.

[0067] The concentration of magnesium sulfate (MgSO4) in the final electrolyte is 200 g / L, the concentration of potassium silicate (K2SiO3) is 70 g / L solution, the concentration of special organic dye is 15 g / L, and the concentration of rare earth cerium salt (Ce(NO3)3) is 8 g / L.

[0068] After the electrolyte in the barrel 101 is prepared, it is introduced into the storage box 302 in the micro-arc oxidation device 3 through a pipeline, and then introduced into the reaction box 303.

[0069] c. Micro-arc oxidation treatment: like Figure 2 and Figure 3 As shown, the pretreated magnesium alloy workpiece is placed in the electrolyte in the reaction box 303 through the hanger 3032 and connected to the electrode 3011. The initial voltage of the power box 301 starts from 320V and increases to 500V at a rate of 8V / min. The current density is controlled at 6A / dm² and the oxidation time is 40min.

[0070] During the micro-arc oxidation treatment of the magnesium alloy workpiece, the multiple electrodes 3011 in the reaction box 303 are distributed in a zoned manner. The areas and spacings of the electrodes 3011 in different regions are different, which makes the electric field strength different, so that the surface of the decorative part presents a gradient effect from blue to red and yellow, meeting the aesthetic requirements of the workpiece while improving the corrosion resistance of the workpiece.

[0071] During the oxidation process, the electrolyte flows around the magnesium alloy workpiece at a flow rate of 0.8 L / min in the circulation structure formed by the reaction box 303 and the storage box 302, ensuring the stability of the oxidation process and the uniformity of the color gradient.

[0072] Example 3: Micro-arc oxidation treatment of titanium alloy workpieces (aerospace interior parts).

[0073] a. Workpiece pretreatment: like Figure 1 As shown, the titanium alloy workpiece is placed in a mixed solution of ethanol (C2H5OH) and acetone (C3H6O) in a cleaning barrel 201 and immersed for 30 minutes to remove surface oil stains; wherein the volume ratio of ethanol (C2H5OH) to acetone (C3H6O) is 1:1. Then, the titanium alloy workpiece is placed in a polishing box 203 for polishing until the surface roughness Ra of the titanium alloy workpiece reaches 0.8 μm.

[0074] b. Prepare electrolyte: like Figure 2 As shown, deionized water, sodium titanate, potassium dihydrogen phosphate, potassium aluminate, special organic dyes (which can achieve a gradual change effect of titanium alloy from natural color to blue-gray) and rare earth lanthanum salts are added into the barrel body 101 through the feed port 104.

[0075] Subsequently, potassium hydroxide (KOH) and phosphoric acid (H3PO4) are added into the barrel 101 to adjust the pH value of the electrolyte to 11, and an appropriate amount of borax (Na2B4O7) is added as a buffer. Finally, the electrolyte is stirred at a temperature of 28° C. for 50 minutes, and the stirring speed of the blade 106 is 350 r / min.

[0076] The final electrolyte has a sodium titanate (Na2TiO3) concentration of 180 g / L, a potassium dihydrogen phosphate (KH2PO4) concentration of 50 g / L, a potassium aluminate (K[Al(OH)4]) concentration of 20 g / L, a special organic dye concentration of 10 g / L, and a rare earth lanthanum salt (LaCl3) concentration of 5 g / L.

[0077] After the electrolyte in the barrel 101 is prepared, it is introduced into the storage box 302 in the micro-arc oxidation device 3 through a pipeline, and then introduced into the reaction box 303.

[0078] c. Micro-arc oxidation treatment: like Figure 2 and Figure 3 As shown, the pretreated titanium alloy workpiece is placed in the electrolyte in the reaction box 303 through the hanger 3032 and connected to the electrode 3011. The initial voltage of the power box 301 starts from 280V and increases to 580V at a rate of 12V / min. The current density is controlled at 4A / dm² and the oxidation time is 50min.

[0079] During the micro-arc oxidation treatment of the titanium alloy workpiece, the multiple electrodes 3011 in the reaction box 303 are distributed in a zoned manner. The areas and spacings of the electrodes 3011 in different regions are different, which makes the electric field strength different, so that the surface of the decorative part presents a gradient effect from natural color to gray-blue, which meets the aesthetic requirements of the workpiece and improves the corrosion resistance of the workpiece.

[0080] During the oxidation process, the electrolyte flows around the titanium alloy workpiece at a flow rate of 0.3 L / min in the circulation structure formed by the reaction box 303 and the storage box 302, ensuring the stability of the oxidation process and the uniformity of the color gradient.

[0081] Furthermore, in Examples 1 to 3, the workpiece can be driven to move in the electrolyte in the reaction box 303 by the up and down sliding of the hanger 3032 on the column 3031 and the horizontal left and right movement of the column 3031 (driving the hanger 3032 through the mounting volume 3033), so as to adjust the workpiece to different positions, change the current intensity flowing through the workpiece and the state of the electrolyte, and thus realize the adjustment of the micro-arc oxidation appearance of the workpiece surface.

[0082] It should be noted that when one element is “connected”, “coupled” or “connected” to another element, it may mean that they are directly connected, coupled or connected, but it should be understood that there may be intermediate elements between the two; that is, the positional relationships of direct connection and indirect connection are covered.

[0083] It should be noted that the use of "a" or "an" and similar words does not necessarily indicate a quantitative limitation. "Include" or "comprising" and similar words mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, but do not exclude other elements or objects.

[0084] It should be noted that terms such as "up", "down", "left" and "right" indicating orientation or positional relationship are only used to indicate relative positional relationship. This is for the convenience of describing the present invention and does not mean that the device or element must have a specific orientation, be constructed and operated in a specific orientation. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0085] The preferred embodiments for implementing the present invention have been described in detail above, but it should be understood that the role of these embodiments is only to exemplify, and is not intended to limit the scope, applicability or configuration of the present invention in any way. The protection scope of the present invention is defined by the attached claims and their equivalents. A person of ordinary skill in the art can make many changes to the above embodiments under the guidance of the present invention, and these changes all fall within the protection scope of the present invention.

Claims

1. A gradual micro-arc oxidation preparation system, characterized in that: include: A pretreatment device, which is used to remove oil and oxide layers on the surface of the workpiece, and to mechanically polish the surface of the workpiece; An electrolyte batching device, which is used to mix and prepare the electrolyte used for micro-arc oxidation of workpieces; and a micro-arc oxidation device, the micro-arc oxidation device comprising a reactor containing an electrolyte, wherein the workpiece is micro-arc oxidized in the reactor; The pretreatment device, electrolyte batching device and micro-arc oxidation device are connected in sequence according to industrial production sequence.

2. The gradual micro-arc oxidation preparation system according to claim 1, characterized in that: The reactor comprises a reaction box, a column and a hanger; The column is arranged on the side of the reaction box, and the column can move left and right along the horizontal direction; The hanger is slidably arranged on the upper part of the column along the vertical direction through the mounting beam, and the hanger is located above the reaction box. The material used for the hanger is stainless steel or titanium alloy material.

3. The gradual micro-arc oxidation preparation system according to claim 2, characterized in that: The micro-arc oxidation device also includes a power box and a refrigeration system.

4. A gradual micro-arc oxidation preparation method, implemented according to the gradual micro-arc oxidation preparation system according to any one of claims 1 to 3, characterized in that: include: S1. Workpiece pretreatment: soak the workpiece in an organic solvent to remove oil stains on the workpiece surface; The workpiece is then pickled to remove the oxide layer on the surface of the workpiece; Mechanically grind the workpiece to remove impurities on the workpiece surface; S2. Prepare an electrolyte by mixing and stirring a metal salt solution, an organic dye, a rare earth element salt, a buffer and a pH adjuster to prepare an electrolyte; S3. Micro-arc oxidation treatment: Place the pre-treated workpiece into the above electrolyte, connect the electrodes and set the micro-arc oxidation parameters, and form a color gradient effect on the workpiece surface through the flow of electrodes and electrolyte.

5. The method for preparing the product by gradual micro-arc oxidation according to claim 4, characterized in that: In step S1, the organic solvent is acetone or ethanol, and the soaking time is 10 min-30 min.

6. The method for preparing by gradual micro-arc oxidation according to claim 4, characterized in that: In step S1, the pickling solution used in the pickling is a mixed solution of nitric acid and hydrofluoric acid, the pickling temperature is 20°C-30°C, and the pickling time is 2min-5min.

7. The method for preparing the product by gradual micro-arc oxidation according to claim 4, characterized in that: In step S1, the mechanical grinding grinds the surface roughness Ra of the workpiece to 0.8-3.2 μm.

8. The method for preparing by gradual micro-arc oxidation according to claim 4, characterized in that: In step S2, the metal salt solution is a mixture of sodium aluminate, sodium silicate and sodium phosphate; the concentration of the sodium aluminate is 150g / L-300g / L, the concentration of the sodium silicate is 30g / L-80g / L, and the concentration of the sodium phosphate is 20-60g / L.

9. The method for preparing by gradual micro-arc oxidation according to claim 4, characterized in that: In step S2, the concentration of the organic dye is 5g / L-20g / L, the added amount of the rare earth element salt is 3g / L-10g / L; and the buffer is boric acid or citric acid.

10. The method for preparing by gradual micro-arc oxidation according to claim 4, characterized in that: In step S3, the micro-arc oxidation parameters include: initial voltage of 250V-350V, voltage increase rate of 5V / min-15V / min, final voltage of 450V-600V, current density of 3A / dm²-8A / dm², and oxidation time of 20min-60min.

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