A method for preparing a micro-arc oxidation film layer of a large-surface-area rare earth magnesium alloy part

Abstract

This invention discloses a method for preparing a micro-arc oxidation film on large surface area rare earth magnesium alloy parts, belonging to the field of surface treatment technology for metallic materials. The invention first forms a thin and dense film on the surface of the magnesium alloy part through a pretreatment process, and then performs micro-arc oxidation in an electrolyte using a low current density loading mode. The pretreatment solution composition for preparing the large surface area micro-arc oxidation film is: sodium dihydrogen phosphate 10-80 g / L, trisodium phosphate 10-80 g / L, and inorganic acid 1-15 g / L. The electrolyte composition is: sodium silicate 3-15 g / L, potassium hydroxide 2-25 g / L, and potassium dihydrogen phosphate 2-30 g / L. The process parameters are: current density: 0.2-1.5 A / dm², frequency 100-1200 Hz, duty cycle 20-60%, processing time 30-120 min, and temperature 10-30 °C. This invention can solve the problems of localized porosity and ablation in the current micro-arc oxidation film of large surface area rare earth magnesium alloy parts.

Description

Technical Field

[0001] This application relates to the field of surface treatment technology for metallic materials, and in particular to a method for preparing a micro-arc oxidation film layer for large surface area rare earth magnesium alloy parts. Background Technology

[0002] The weaponry field faces the mission requirement of lightweighting. With the constraints of structural optimization and weight reduction, high-strength and heat-resistant rare earth magnesium alloys from aerospace materials are gradually being used in strategic / tactical weapons. However, the poor corrosion resistance of magnesium alloys limits their reliability and long-term service stability in weaponry. Furthermore, the high humidity and high salt spray environment poses challenges to magnesium alloy surface protection technology. Micro-arc oxidation, as an environmentally friendly emerging surface treatment technology, has been initially applied to magnesium alloy products.

[0003] The micro-arc oxidation film preparation technology enables the rapid acquisition of a protective film with high-performance protective effects at room temperature. Currently, this technology is being used to process 5m... 2 The above-mentioned rare earth magnesium alloy parts have difficulties, which are reflected in the poor reliability of the preparation of micro-arc oxidation film layers for large surface area rare earth magnesium alloy parts. That is, problems such as local porosity and ablation are prone to occur during the preparation of micro-arc oxidation film layers for large surface area parts, which makes the long-term service reliability of aerospace equipment a bottleneck problem.

[0004] To address the aforementioned issues, this invention provides a method for preparing a micro-arc oxidation film layer on large surface area rare earth magnesium alloy parts. In engineering applications, this technology can prepare rare earth magnesium alloy parts with a surface area of ​​over 5 m², avoiding problems such as local porosity and ablation during the micro-arc oxidation process of rare earth magnesium alloys, and ensuring the stability and reliability of national weaponry in long-term service. Summary of the Invention

[0005] The purpose of this application is to solve the problems of local porosity and ablation in the preparation of micro-arc oxidation films for large surface area rare earth magnesium alloy parts in the aerospace field, thereby ensuring the reliability and stability of aircraft, satellites, and weapon systems in service. Compared with existing technologies, this application provides a method for preparing micro-arc oxidation films for large surface area rare earth magnesium alloy parts, which is carried out according to the following steps:

[0006] Step 1, prepare the pretreatment solution: Dissolve 10-80 g / L sodium dihydrogen phosphate, 10-80 g / L trisodium phosphate, and 1-15 g / L inorganic acid in deionized water, then mix them together and stir thoroughly.

[0007] Step 2, prepare micro-arc oxidation electrolyte: dissolve 3-15 g / L sodium silicate, 2-25 g / L potassium hydroxide, and 2-30 g / L potassium dihydrogen phosphate in deionized water, mix them thoroughly together, and stir well.

[0008] Step 3, Pre-treatment of rare earth magnesium alloy parts: Place the rare earth magnesium alloy parts into the cleaning tank, turn on the two negative pressure pumps, and start the intermittent working mode at the same time, so that the filter screen moves left and right, the oil suction roller is responsible for sucking up the oil, and then clean it with pure water.

[0009] Step 4: Mount the part onto the electrode and turn on the micro-arc oxidation power supply;

[0010] Step 5: Prepare the micro-arc oxidation film using the following electrical parameters: current density: 0.2-1.5 A / dm2, frequency: 100-1200 Hz, duty cycle: 20-60%, processing time: 30-120 min, temperature: 10-30 ℃.

[0011] Step 6: Dry the rare earth magnesium alloy micro-arc oxidation film layer using an electric heating oven. A dense conductive film layer is formed on the rare earth magnesium alloy substrate through a pretreatment process, so that the current is evenly distributed in the early stage of rare earth magnesium alloy micro-arc oxidation, avoiding local film layer looseness caused by excessive local current, thereby obtaining a high-quality micro-arc oxidation film layer.

[0012] Furthermore, in step 1, the preferred mass ratio of sodium dihydrogen phosphate, trisodium phosphate, phosphoric acid, and deionized water is 40–50:15–20:1–5:1000.

[0013] Furthermore, in step 2, the preferred mass ratio of sodium silicate, potassium hydroxide, potassium dihydrogen phosphate, and deionized water is 30–50:5–20:5–15:1000.

[0014] Furthermore, in step 3, a phosphate solution is used for pretreatment at a temperature of 15–50°C for a time of 5–20 min.

[0015] Furthermore, in step 4, a threaded connection is used for electrode mounting.

[0016] Furthermore, in step 5, the current density is 0.2–1.5 A / dm², the frequency is 100–1200 Hz, the duty cycle is 20–60%, the processing time is 30–120 min, and the electrolyte temperature is 10–30 °C.

[0017] Furthermore, in step 6, the drying temperature is 40–60°C, and the drying time is 2–6 hours.

[0018] Furthermore, the cleaning mechanism includes a cleaning tank, with water nozzles fixedly installed on the inner wall of the cleaning tank. Negative pressure pumps are fixedly connected to both ends of the cleaning tank. An air inlet pipe is fixedly connected to the bottom end of the negative pressure pump, and an air outlet pipe is fixedly connected to the other end of the negative pressure pump. A filter screen is slidably connected to the inner wall of the cleaning tank. Multiple air-blowing boxes located on the filter screen are fixedly connected to the inner walls of both sides of the cleaning tank. Each air-blowing box includes a box body. A T-shaped pipe is fixedly connected to the inner wall of the box body. One end of the T-shaped pipe is connected to and communicates with the outer side of the air outlet pipe. An elastic bladder is fixedly connected to the bottom end of the T-shaped pipe. A branch pipe is fixedly connected to the other end of the T-shaped pipe. A pressure limiting valve is fixedly connected inside the branch pipe. A vent is opened at the outer end of the box body away from the air outlet pipe. An aeration plate with multiple small holes is fixedly connected to the outer end of the box body. A waterproof and breathable membrane is fixedly connected to the inner wall of the small holes.

[0019] Furthermore, the filter plate includes multiple floats, with a filter screen fixedly connected between two floats. The filter screen is made of a lightweight and flexible material.

[0020] Furthermore, both ends of the float are equipped with sliders, and the inner wall of the cleaning tank has multiple grooves corresponding to the sliders. The sliders slide inside the grooves. The float is made of lightweight plastic material and has a hollow interior design.

[0021] Compared to existing technologies, the advantages of this application are:

[0022] (1) The present invention uses a pretreatment process to form a dense conductive film on a rare earth magnesium alloy substrate, so that the current is evenly distributed in the early stage of micro-arc oxidation of rare earth magnesium alloy, avoiding local film looseness caused by excessive local current, thereby obtaining a high-quality micro-arc oxidation film.

[0023] (2) A micro-arc oxidation film layer is prepared by using a small current density to avoid ablation of large surface area parts.

[0024] (3) The pretreatment solution is simple to prepare, easy to operate, and low in cost.

[0025] (4) The magnesium alloy parts are placed on the filter plate inside the cleaning tank. Then, the negative pressure pumps on the left and right sides of the cleaning tank are turned on at the same time. The negative pressure pumps start to work intermittently, and the two negative pressure pumps work in a staggered manner. When the negative pressure pump on the left side works, it sends the outside gas to multiple air vents through the air outlet pipe. Then, the elastic bladder is extended by the three-way pipe, which causes the filter plate to start to tilt. The float on the far left descends, which stretches multiple flexible filters, causing the parts on the filter plate to start to tilt and roll to the left, making full contact and friction with the water, thus improving the efficiency of oil droplet separation from the parts.

[0026] (5) The negative pressure pump on the left side stops working. The elastic bladder tends to contract under the elastic action. At the same time, the float is also squeezing the elastic bladder. Finally, it reaches the threshold value of the pressure relief valve. The branch pipe starts to ventilate, so that the aeration plate continuously blows out multiple bubbles. The bubbles can make the nearby oil droplets attach to them, thereby carrying the oil droplets to float up and accelerating the rate of oil-water separation.

[0027] (6) The negative pressure pump on the right side also starts to work, and in the same way, the filter screen plate tilts to the right. This cycle repeats, and the filter screen plate is constantly shaking left and right. During this time, multiple filter screens switch between bending and straightening, so that the parts are constantly changing positions and each part is in full contact with water. Attached Figure Description

[0028] Figure 1 This is an overall sectional view of the present application;

[0029] Figure 2 This is a diagram illustrating the overall structure of this application;

[0030] Figure 3 This is a diagram of the overall internal structure of this application;

[0031] Figure 4 This is a structural diagram of the internal structure of the air blast box in this application;

[0032] Figure 5 This is a top view of the filter plate structure of this application;

[0033] Figure 6 This is a structural diagram of the elastic capsule variation in this application;

[0034] Figure 7 This is a structural diagram showing the variation of the filter plate in this application;

[0035] Figure 8 This is an overall structural diagram of Embodiment 5 of this application;

[0036] Figure 9 This is a diagram showing the internal changes of the float in this application;

[0037] Figure 10 This is a half-sectional view of the oil suction roller in this application;

[0038] Figure 11 Microscopic morphology of the micro-arc oxide film after pretreatment.

[0039] Explanation of the labels in the diagram:

[0040] 1. Cleaning tank; 2. Water nozzle; 3. Negative pressure pump; 4. Air inlet pipe; 5. Air outlet pipe; 6. Air blower box; 61. Box body; 62. T-joint pipe; 63. Branch pipe; 64. Vent hole; 65. Pressure relief valve; 7. Elastic bladder; 8. Aeration plate; 9. Filter plate; 91. Float rod; 92. Filter screen; 93. Sliding block; 931. Movable block; 932. Magnetic sheet; 933. Elastic rope; 10. Oil suction roller; 11. Sliding shaft; 12. Moving valve; 13. Magnetic plate; 14. Oil suction hole; 15. Oil-absorbing resin. Detailed Implementation

[0041] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0042] This application discloses a method for preparing a micro-arc oxidation film on large surface area rare earth magnesium alloy parts, including a cleaning mechanism, which can be achieved through the following key steps:

[0043] During the preparation of the pretreatment solution, the solutions should be dissolved separately, and sodium dihydrogen phosphate, trisodium phosphate, and inorganic substances should be added in sequence and mixed thoroughly.

[0044] Micro-arc oxidation is performed using a low current density loading method;

[0045] After micro-arc oxidation, the product is quickly rinsed and then promptly placed in an oven for drying.

[0046] To make the operation method, applicability, and film performance of the present invention clearer and more explicit, the following embodiments are used to further illustrate the present invention. The accompanying drawings are part of the present invention and, together with the embodiments, are used to illustrate the features of the present invention.

[0047] Example 1

[0048] In this embodiment, a micro-arc oxide film is prepared on the surface of a VK80Z magnesium alloy part, and the following steps are performed:

[0049] (1) Preparation of pretreatment solution: Dissolve 40 g / L sodium dihydrogen phosphate, 20 g / L trisodium phosphate and 2 g / L phosphoric acid in deionized water, mix them together and stir thoroughly.

[0050] (2) Preparation of micro-arc oxidation electrolyte: Dissolve 12 g / L sodium silicate, 8 g / L potassium hydroxide and 15 g / L potassium dihydrogen phosphate in deionized water, mix them thoroughly and stir well.

[0051] (3) Please refer to 1-2, pretreatment of rare earth magnesium alloy parts: Place the rare earth magnesium alloy parts into the cleaning box 1, turn on the two negative pressure pumps 3, and simultaneously start the intermittent working mode, so that the filter plate 9 shakes left and right, the oil suction roller is responsible for sucking oil, and then clean it with pure water.

[0052] (4) Mount the parts on the electrodes and turn on the micro-arc oxidation power supply;

[0053] (5) The micro-arc oxidation film was prepared using the following electrical parameters: current density: 0.6A / dm2, frequency: 500Hz, duty cycle: 40%, processing time: 60min, electrolyte temperature: 20℃.

[0054] (6) The rare earth magnesium alloy micro-arc oxide film layer was dried in an electric heating oven at a temperature of 45°C for 3 hours.

[0055] Example 2

[0056] In this embodiment, a micro-arc oxide film is prepared on the surface of a VK90Z magnesium alloy part, and the following steps are performed:

[0057] (1) Preparation of pretreatment solution: Dissolve 50 g / L sodium dihydrogen phosphate, 15 g / L trisodium phosphate and 2 g / L sulfuric acid in deionized water, mix them together and stir thoroughly.

[0058] (2) Preparation of micro-arc oxidation electrolyte: Dissolve 10 g / L sodium silicate, 15 g / L potassium hydroxide and 20 g / L potassium dihydrogen phosphate in deionized water, mix them thoroughly and stir well.

[0059] (3) Pretreatment of rare earth magnesium alloy parts: Place the rare earth magnesium alloy parts into the cleaning box 1, turn on the two negative pressure pumps 3, and simultaneously start the intermittent working mode to make the filter plate 9 swing left and right, and the oil suction roller is responsible for sucking oil, and then clean it with pure water.

[0060] (4) Mount the parts on the electrodes and turn on the micro-arc oxidation power supply;

[0061] (5) The micro-arc oxidation film was prepared using the following electrical parameters: current density: 0.5A / dm2, frequency: 600Hz, duty cycle: 45%, processing time: 60min, electrolyte temperature: 20℃.

[0062] (6) The rare earth magnesium alloy micro-arc oxide film layer was dried in an electric heating oven at a temperature of 45°C for 3 hours.

[0063] Example 3

[0064] In this embodiment, a micro-arc oxide film is prepared on the surface of a VK100Z magnesium alloy part, and the following steps are performed:

[0065] (1) Preparation of pretreatment solution: Dissolve 50 g / L sodium dihydrogen phosphate, 20 g / L trisodium phosphate and 1 g / L oxalic acid in deionized water, mix them together and stir thoroughly.

[0066] (2) Preparation of micro-arc oxidation electrolyte: Dissolve 15g / L sodium silicate, 20g / L potassium hydroxide and 25g / L potassium dihydrogen phosphate in deionized water, mix them thoroughly and stir well.

[0067] (3) Pretreatment of rare earth magnesium alloy parts: Place the rare earth magnesium alloy parts into the cleaning box 1, turn on the two negative pressure pumps 3, and simultaneously start the intermittent working mode to make the filter plate 9 swing left and right, and the oil suction roller is responsible for sucking oil, and then clean it with pure water.

[0068] (4) Mount the parts on the electrodes and turn on the micro-arc oxidation power supply;

[0069] (5) The micro-arc oxidation film was prepared using the following electrical parameters: current density: 0.4A / dm2, frequency: 500Hz, duty cycle: 50%, processing time: 60min, electrolyte temperature: 20℃.

[0070] (6) The rare earth magnesium alloy micro-arc oxide film layer was dried in an electric heating oven at a temperature of 55°C for 2.5 hours.

[0071] Please see Figure 11 The figure shows the microstructure of the micro-arc oxide film after pretreatment.

[0072] Example 4

[0073] Please see Figure 1-3 Based on the above, a cleaning mechanism is added, including a cleaning tank 1, a water nozzle 2 fixedly installed on the inner wall of the cleaning tank 1, a negative pressure pump 3 fixedly connected to both ends of the cleaning tank 1, an air inlet pipe 4 fixedly connected to the bottom end of the negative pressure pump 3, an air outlet pipe 5 fixedly connected to the other end of the negative pressure pump 3, a filter plate 9 slidably connected to the inner wall of the cleaning tank 1, and multiple air blowers 6 located on the filter plate 9 fixedly connected to the inner walls on both sides of the cleaning tank 1.

[0074] Please see Figure 4The air-blowing box 6 includes a box body 61. A three-way pipe 62 is fixedly connected to the inner wall of the box body 61. One end of the three-way pipe 62 is connected to and communicates with the outer side of the air outlet pipe 5. An elastic bladder 7 is fixedly connected to the bottom end of the three-way pipe 62. A branch pipe 63 is fixedly connected to the other end of the three-way pipe 62. A pressure limiting valve 65 is fixedly connected inside the branch pipe 63. A vent hole 64 is opened at the outer end of the box body 61 away from the air outlet pipe 5. An aeration plate 8 with multiple small holes is fixedly connected to the outer end of the box body 61. A waterproof and breathable membrane is fixedly connected to the inner wall of the small holes.

[0075] Please see Figure 5 The filter plate 9 includes multiple floats 91, and a filter 92 is fixedly connected between two floats 91. The filter 92 is made of a lightweight and flexible material.

[0076] In actual operation, select the negative pressure pump 3 with intermittent working mode or connect the negative pressure pump 3 electrically to a control panel. Use the control panel to control the intermittent operation of the negative pressure pump 3. The duration of each operation depends on the gas capacity of the elastic bladder 7.

[0077] Please see Figure 5 Both ends of the float 91 are equipped with sliders 93. The inner wall of the cleaning tank 1 is provided with multiple grooves corresponding to the sliders 93, and the sliders 93 slide inside the grooves.

[0078] The float 91 is made of lightweight plastic material and has a hollow interior design.

[0079] The density of the float 91 is much less than that of water, and it is hollow inside. The buoyancy of multiple floats 91 is enough to "lift" the entire filter plate 9 upward.

[0080] Please see Figure 6-7 During operation: Magnesium alloy parts are placed on the filter plate 9 inside the cleaning tank 1. Then, the negative pressure pumps 3 on the left and right sides of the cleaning tank 1 are turned on simultaneously. The negative pressure pumps 3 start to work intermittently, and the two negative pressure pumps 3 work in a staggered manner. When the negative pressure pump 3 on the left side works, the outside gas is sent to multiple air vents 6 through the air outlet pipe 5. Then, the elastic bladder 7 is extended by means of the three-way pipe 62 (in the initial state, under the action of the float 91, the filter plate 9 is in a horizontal state and has an upward tendency), so that the filter plate 9 begins to tilt. The leftmost float 91 descends, thereby stretching multiple flexible filters 92, so that the parts on the filter plate 9 begin to tilt and roll to the left, fully contacting and rubbing with water, improving the efficiency of oil droplet separation from the parts.

[0081] Next, the negative pressure pump 3 on the left side stops working, and the elastic bladder 7 tends to contract under the elastic action. At the same time, the float 91 also squeezes the elastic bladder 7, eventually reaching the threshold value of the pressure relief valve 65. The branch pipe 63 starts to ventilate, causing the aeration plate 8 to continuously blow out multiple bubbles. The bubbles can cause nearby oil droplets to attach to them, thereby carrying the oil droplets to float up and accelerating the rate of oil-water separation.

[0082] At the same time, the negative pressure pump 3 on the right side also starts to work, and on the same principle, it causes the filter plate 9 to tilt to the right. This cycle repeats, and the filter plate 9 is constantly shaking left and right. During this time, multiple filters 92 are also switching between bending and straightening, so that the parts are constantly changing positions and each part is in full contact with water.

[0083] When the oil and water begin to separate, the oil can be skimmed off using an oil strainer. Once no more oil droplets float to the surface, the separation is complete.

[0084] Example 5

[0085] Please see Figure 8 Based on Example 4, the following addition is made: a magnetic plate 13 is slidably connected to the outer end of the cleaning tank 1, and the slider 93 slides inside the float 91.

[0086] Please see Figure 9 The slider 93 includes a movable block 931, a magnetic sheet 932 is fixedly connected to the top of the movable block 931, and a plurality of elastic ropes 933 are fixedly connected between the bottom end of the movable block 931 and the inner wall of the float 91.

[0087] To facilitate the disassembly and cleaning of the filter screen plate 9, the magnetic force of the magnetic plate 13 can be used to make the magnetic sheet 932 repel the magnetic plate 932, stretch the elastic rope 933, and retract the slider 93 into the interior of the float rod 91, so that the filter screen plate 9 can finally be disengaged from the slide groove and begin to rise.

[0088] Specifically, filter 92 can be an oil separator filter, which filters oil droplets through tiny pores.

[0089] In actual use, the filter screen 9 can be rolled up to wrap the last batch of parts and then taken out from the cleaning box 1. At this time, there is no need to use tools to remove the oil layer on it.

[0090] Please see Figure 3 The top of the cleaning tank 1 is provided with a pair of movable grooves with friction texture. The inner wall of the movable groove is movably connected to a sliding shaft 11. One end of the sliding shaft 11 extends to the outside of the cleaning tank 1. One end of the sliding shaft 11 is rotatably connected to a movable valve 12. An oil suction roller 10 is fixedly connected between the two sliding shafts 11.

[0091] Please see Figure 10The oil suction roller 10 has an oil suction hole 14 at its outer end, and an oil suction resin 15 is detachably connected inside the oil suction roller 10.

[0092] During operation: Because the surface of the movable groove has friction texture, the sliding shaft 11 will start to roll when it slides on it. When the oil and water start to separate into obvious layers, the movable valve 12 can be pushed slowly by hand to make the sliding shaft 11 rotate with the oil suction roller 10 on the surface of the oil layer. The oil-absorbing resin 15 inside will absorb the dirty oil. After cleaning, the parts can be taken out.

[0093] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and its improved concept, should be covered within the scope of protection of this application.

Claims

1. A method for preparing a micro-arc oxidation film layer on large surface area rare earth magnesium alloy parts, comprising a cleaning mechanism, characterized in that, The following steps are used to prepare rare earth magnesium alloy parts with a surface area of ​​more than 5 m²: Step 1, prepare the pretreatment solution: Dissolve 10~80g / L sodium dihydrogen phosphate, 10~80g / L trisodium phosphate, and 1~15g / L inorganic acid in deionized water, then mix them together and stir thoroughly. Step 2, prepare micro-arc oxidation electrolyte: dissolve 3~15g / L sodium silicate, 2~25g / L potassium hydroxide, and 2~30g / L potassium dihydrogen phosphate in deionized water, mix them thoroughly together, and stir well. Step 3, pretreatment of rare earth magnesium alloy parts: Place the rare earth magnesium alloy parts into the cleaning tank (1), turn on the two negative pressure pumps (3), and start the intermittent working mode at the same time, so that the filter screen plate (9) shakes left and right, the oil suction roller is responsible for sucking oil, and then clean it with pure water. Step 4: Mount the part onto the electrode and turn on the micro-arc oxidation power supply; Step 5: Prepare the micro-arc oxidation film layer using the following electrical parameters: current density: 0.2-1.5A / dm2, frequency: 100-1200Hz, duty cycle: 20-60%, processing time: 30-120min, temperature: 10-30℃. Step 6: Dry the rare earth magnesium alloy micro-arc oxide film layer using an electric heating oven.

2. The method for preparing a micro-arc oxidation film layer on a large surface area rare earth magnesium alloy part according to claim 1, characterized in that, In step 1, the mass ratio of sodium dihydrogen phosphate, trisodium phosphate, phosphoric acid, and deionized water is 40~50:15~20:1~5:1000.

3. The method for preparing a micro-arc oxidation film layer on a large surface area rare earth magnesium alloy part according to claim 1, characterized in that, In step 2, the mass ratio of sodium silicate, potassium hydroxide, potassium dihydrogen phosphate, and deionized water is 30~50:5~20:5~15:1000.

4. The method for preparing a micro-arc oxidation film layer on a large surface area rare earth magnesium alloy part according to claim 1, characterized in that, In step 3, a phosphate solution is used for pretreatment at a temperature of 15-50°C for 5-20 minutes.

5. The method for preparing a micro-arc oxidation film layer on a large surface area rare earth magnesium alloy part according to claim 1, characterized in that, In step 4, the electrodes are mounted using a threaded connection.

6. The method for preparing a micro-arc oxidation film layer on a large surface area rare earth magnesium alloy part according to claim 1, characterized in that, In step 5, the current density is 0.2~1.5A / dm2, the frequency is 100~1200Hz, the duty cycle is 20~60%, the processing time is 30~120min, and the electrolyte temperature is 10~30℃.

7. The method for preparing a micro-arc oxidation film layer on a large surface area rare earth magnesium alloy part according to claim 1, characterized in that, In step 6, the drying temperature is 40~60℃ and the drying time is 2~6h.

8. The method for preparing a micro-arc oxidation film layer on a large surface area rare earth magnesium alloy part according to claim 1, wherein the cleaning mechanism includes a cleaning tank (1), and a water spray nozzle (2) is fixedly installed on the inner wall of the cleaning tank (1), characterized in that, Negative pressure pumps (3) are fixedly connected to both ends of the cleaning tank (1). An air inlet pipe (4) is fixedly connected to the bottom end of the negative pressure pump (3), and an air outlet pipe (5) is fixedly connected to the other end of the negative pressure pump (3). A filter screen plate (9) is slidably connected to the inner wall of the cleaning tank (1). Multiple air blowers (6) located on the filter screen plate (9) are fixedly connected to the inner walls on both sides of the cleaning tank (1). Each air blower (6) includes a box body (61). A three-way pipe (62) is fixedly connected to the inner wall of the box body (61). One end of (62) is connected to and communicates with the outside of the air outlet pipe (5). An elastic bladder (7) is fixedly connected to the bottom end of the three-way pipe (62). A branch pipe (63) is fixedly connected to the other end of the three-way pipe (62). A pressure limiting valve (65) is fixedly connected inside the branch pipe (63). A vent hole (64) is opened at the outer end of the box body (61) away from the air outlet pipe (5). An aeration plate (8) with multiple small holes is fixedly connected to the outer end of the box body (61). A waterproof and breathable membrane is fixedly connected to the inner wall of the small holes.

9. The method for preparing a micro-arc oxidation film layer for large surface area rare earth magnesium alloy parts according to claim 8, characterized in that, The filter plate (9) includes multiple floats (91), and a filter screen (92) is fixedly connected between two floats (91). The filter screen (92) is made of a lightweight and flexible material.

10. The method for preparing a micro-arc oxidation film layer on a large surface area rare earth magnesium alloy part according to claim 9, characterized in that, Both ends of the float (91) are provided with sliders (93). The inner wall of the cleaning tank (1) is provided with multiple grooves corresponding to the sliders (93). The sliders (93) slide inside the grooves. The float (91) is made of lightweight plastic material and has a hollow interior.

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