A method and device for repairing local micro-arc oxidation film of light alloy workpiece

Abstract

The invention relates to a method for repairing a local micro-arc oxidation film layer of a light alloy, which comprises the following steps in sequence: determining a region to be repaired on a workpiece; measuring an average film thickness m of the workpiece; pre-treating the region to be repaired on the workpiece; configuring a local micro-arc oxidation electrolyte according to the alloy type of the workpiece; processing a local micro-arc oxidation film layer repairing device adapted to the region to be repaired on site; installing the local micro-arc oxidation film layer repairing device on the workpiece, setting micro-arc oxidation parameters according to the alloy type of the workpiece to perform a micro-arc oxidation reaction, and stopping the micro-arc oxidation reaction process when the film layer thickness h of the region to be repaired after repair and the average film layer thickness m of the workpiece satisfy |h‑m|≤5μm, and the local micro-arc oxidation film layer of the light alloy workpiece is repaired, thereby reducing the difference between the film thickness of the region to be repaired after repair and the film thickness of the surrounding region on the workpiece, making the surface uniformity of the workpiece better to avoid unevenness of the workpiece surface, and improving the repair effect of the local micro-arc oxidation film layer.

Description

Technical Field

[0001] The present invention relates to the technical field of metal surface treatment, in particular to a method for repairing a local micro-arc oxidation film layer of a light alloy workpiece, and also to a device for repairing a local micro-arc oxidation film layer of a light alloy workpiece. Background Art

[0002] Microarc oxidation (MAO), also known as microplasma oxidation (MPO) or anodic spark deposition, is a process that uses a combination of electrolyte and corresponding electrical parameters to grow a ceramic film mainly composed of matrix metal oxide on the surface of aluminum, magnesium, titanium and their alloys by relying on the instantaneous high temperature and high pressure generated by arc discharge. The microarc oxidation film is firmly bonded to the substrate, has a dense structure, high toughness, and good wear resistance, corrosion resistance, high temperature impact resistance, and electrical insulation. This technology is simple to operate and easy to adjust the film function. It also has a simple process and does not cause environmental pollution. It is a new green and environmentally friendly material surface treatment technology with broad application prospects in the fields of aerospace, ships, machinery, electronics, and decoration.

[0003] Although micro-arc oxidation technology has been initially applied in aerospace, ships, machinery, electronics, decoration and other fields, it has not been widely used due to its high power requirements and too many uncertain factors in film growth under high voltage. In addition, light alloy parts subjected to micro-arc oxidation have the following problems:

[0004] 1) During the production process of light alloy products, it cannot be guaranteed that the composition and structure of the entire product are the same at every location, and the current distribution during micro-arc oxidation is uneven, which will lead to a large difference in the thickness of the micro-arc oxidation layer in the product and poor uniformity; the thinner film layer will be corroded first, resulting in product damage;

[0005] 2) Light alloy products will produce component segregation or defects during forging, casting and other processes, which will cause problems such as film layer failure to oxidize and defects in the oxide film layer;

[0006] 3) Light alloy products are easily scratched during assembly and transportation, causing local film breakage and cracking.

[0007] The above-mentioned local film weakness, defects and damage will directly affect the overall corrosion resistance of the light alloy product, thereby shortening the service life of the light alloy product.

[0008] At present, there are two methods for repairing micro-arc oxidation films. One is the overall oxidation method, which is to transport light alloy products or disassembled film-defective parts to a special oxidation workshop for film stripping and overall oxidation treatment. This method is not only time-consuming, labor-intensive and costly, but also only applicable to smaller light alloy products or film-defective parts, and has a smaller scope of application. The other is the local oxidation method. Compared with the former, the local oxidation method does not require the transportation of light alloy products or disassembled film-defective parts, but only needs to repair the defective parts of the film. It takes less time, has a smaller repair workload, and has a lower repair cost, and has a wider scope of application.

[0009] A Chinese invention patent application with patent application number CN201910926320.2 (publication number CN110565147A) discloses a device and method for local micro-arc oxidation of titanium alloy workpieces, the device comprising a mobile micro-arc oxidation power supply, a workpiece to be processed, a movable stainless steel cathode tube, an oxidation tank, a solution circulation recovery device, and a solution cooling system; when in use, the area that does not require micro-arc oxidation is first masked with ink, and then the local micro-arc oxidation process is used for repair treatment, and the local micro-arc oxidation control of the titanium alloy surface is achieved by constraining the workpiece surface electric field through a tubular stainless steel cathode tube, and the solution flows through the surface of the workpiece to be processed through the tubular stainless steel cathode port, and then flows back to the oxidation tank for recovery.

[0010] The above-mentioned local micro-arc oxidation device and method for titanium alloy workpieces have the following shortcomings: ① Since the thickness of the micro-arc oxidation film layer on different workpieces to be repaired or different areas on the same workpiece is different, and the degree of defect of the micro-arc oxidation film layer in each area to be repaired is different, the conditions of each area to be repaired are quite different. Micro-arc oxidation is performed on the area to be repaired on the surface of the workpiece based only on intuitive observation, which can easily cause a large difference in film thickness between the repaired area and the surrounding area on the repaired workpiece, resulting in an uneven surface of the workpiece, resulting in poor repair effect of the micro-arc oxidation film layer on the workpiece surface or even failure of the repair; ② Since the device needs to apply ink before local micro-arc oxidation repair and the ink needs to be removed after repair, the local micro-arc oxidation repair method has many steps and a complicated process. Moreover, the ink curing takes more than 4 hours, which makes the local micro-arc oxidation repair method time-consuming. Summary of the invention

[0011] The first technical problem to be solved by the present invention is to provide a method for repairing the local micro-arc oxidation film layer of a light alloy workpiece in response to the above-mentioned technical status, which can reduce the difference between the film thickness of the repaired area to be repaired and the film thickness of the surrounding area on the workpiece, make the surface uniformity of the workpiece better and avoid the uneven phenomenon, thereby improving the repair effect of the local micro-arc oxidation film layer of the light alloy workpiece.

[0012] The second technical problem to be solved by the present invention is to provide a light alloy workpiece local micro-arc oxidation film repair device that realizes the above-mentioned light alloy workpiece local micro-arc oxidation film repair method in response to the above-mentioned technical status quo, which can simplify the light alloy workpiece local micro-arc oxidation film repair process and shorten the time for light alloy workpiece local micro-arc oxidation film repair.

[0013] The third technical problem to be solved by the present invention is to provide a device for repairing local micro-arc oxidation film layers of light alloy workpieces, which realizes the above-mentioned method for repairing local micro-arc oxidation film layers of light alloy workpieces in response to the above-mentioned technical status quo, and can make the volume of the micro-arc oxidation reaction tank smaller, thereby reducing the waste of electrolyte.

[0014] The technical solution adopted by the present invention to solve the first technical problem mentioned above is: a method for repairing a local micro-arc oxidation film layer of a light alloy workpiece, characterized in that it includes the following steps in sequence:

[0015] Step 1: Determine the area to be repaired on the workpiece: mark the weak part of the film layer on the workpiece, and measure the diameter of the smallest circle that can cover the weak part, and make the area inside the smallest circle the area to be repaired;

[0016] Step 2, measuring the average film thickness m of the workpiece: the average film thickness m of the workpiece is obtained from the film thickness of the area to be repaired on the workpiece and the film thickness outside the area to be repaired;

[0017] Step 3: pre-treat the area to be repaired on the workpiece: including grinding, polishing, cleaning, and two cold spraying treatments in sequence, wherein the spraying component of the first cold spraying treatment is stainless steel powder, and the spraying component of the second cold spraying treatment is the basic element powder or main element powder of the light alloy workpiece;

[0018] Step 4: Prepare the micro-arc oxidation electrolyte according to the alloy type of the workpiece;

[0019] Step 5: On-site processing of a local micro-arc oxidation film repair device adapted to the area to be repaired;

[0020] Step six, install a local micro-arc oxidation film repair device on the workpiece, and set the micro-arc oxidation parameters according to the type of workpiece alloy to perform micro-arc oxidation reaction on the area to be repaired. When the film thickness h of the repaired area and the average film thickness m of the workpiece satisfy |hm|≤5μm, the micro-arc oxidation reaction process can be stopped, and the local micro-arc oxidation film repair of the light alloy workpiece is completed.

[0021] In order to facilitate the grinding of the area to be repaired of the workpiece, in step three, ① if the average film thickness of the workpiece m ≥ 100mm, use an angle grinder grinding wheel to grind the area to be repaired to reveal the metallic luster; ② if 100mm>the average film thickness of the workpiece m>30mm, use an angle grinder polishing sheet to grind to reveal the metallic luster; ③ if the average film thickness of the workpiece m ≤ 30mm, use 80-grit sandpaper to manually grind out the metallic luster, and then polish.

[0022] In order to facilitate cold spraying of various light alloys to obtain a uniform micro-arc oxidation reaction matrix, in step three, ① if the workpiece is a magnesium alloy workpiece, the first cold spraying process is: using stainless steel powder with a particle size of 50-150 μm as a powder spraying component, controlling the spraying distance to be 20-50 mm, the sandblasting rate to be 15-35 mm / s, and the particle incident angle to be 50°-90°, and the second cold spraying process is: using compressed nitrogen as gas, the gas flow rate to be 275-320 L / min, the spraying pressure to be 2.8-3.2 MPa, the temperature of the cold spraying working gas to be 200-300°C, the spraying distance to be 40-70 mm, the sandblasting rate to be 30-60 mm / s, the powder spraying component to be Mg 10-25%, Zn 0.3-0.5%, Mn 0.3-0.5%, the balance to be Al, and the powder feeding rate to be 3-10 g / min;

[0023] ② If the workpiece is an aluminum alloy workpiece, the first cold spraying process is: using stainless steel powder with a particle size of 50-150μm as the powder spraying component, controlling the spraying distance to be 15-40mm, the sandblasting rate to be 15-35mm / s, and the particle incident angle to be 50-90°. The second cold spraying process is: using compressed nitrogen as the gas, the main gas flow rate to be 275-320L / min, the spraying pressure to be 4-7MPa, the temperature of the cold spraying working gas to be 400-600℃, the spraying distance to be 20-40mm, the sandblasting rate to be 15-45mm / s, the powder spraying component to be Al, and the powder feeding rate to be 3-10g / min;

[0024] ③ If the workpiece is a titanium alloy workpiece, the first cold spraying process is: using stainless steel powder with a particle size of 50-150μm as the powder spraying component, controlling the spraying distance to 10-40mm, the sandblasting rate to 15-35mm / s, and the particle incident angle to 50-90°. The second cold spraying process is: using compressed nitrogen as the gas, the gas flow rate to 275-320L / min, the spraying pressure to 2.8-3.2MPa, the temperature of the cold spraying working gas to 500-600℃, the spraying distance to 15-40mm, the sandblasting rate to 10-30mm / s, the powder spraying component to Ti, and the powder feeding rate to 3-10g / min.

[0025] In order to facilitate the growth of a denser and tougher micro-arc oxidation film on the surface of various light alloy workpieces, in step 4, ① if the workpiece is a magnesium alloy workpiece, the electrolyte formula is:

[0026] Film-forming agent: at least one of silicate 10-30 g / L, aluminate 8-30 g / L, phosphate 8-10 g / L, acid zirconate 5-20 g / L,

[0027] At least one of the pH adjusting reagents KOH 1-5 g / L and NaOH 1-5 g / L,

[0028] At least one of the first additives NaF 0.5-3 g / L and KF 0.5-3 g / L,

[0029] The second additive is at least one of 5-15 ml / L glycerol, 5-15 ml / L triethanolamine, and 5-15 g / L sodium citrate.

[0030] The third additive is at least one of nano-aluminum oxide 0.5-3g / L and nickel acetate 0.3-0.8g / L.

[0031] Solvent: deionized water;

[0032] ② If the workpiece is an aluminum alloy workpiece, the electrolyte formula is:

[0033] Film-forming agents: at least two of silicate 3-20 g / L, tungstate 1-5 g / L, aluminate 1-5 g / L,

[0034] At least one of the pH adjusting reagents KOH 1-5 g / L and NaOH 1-5 g / L,

[0035] The first additive is borax 3-10g / L,

[0036] The second additive is at least one of nano titanium dioxide 0.3-0.8 g / L, nano silicon dioxide 0.5-1.5 g / L, and nano aluminum oxide 0.5-1.5 g / L.

[0037] Solvent: deionized water;

[0038] ③If the workpiece is a titanium alloy workpiece, the electrolyte formula is:

[0039] Film-forming agent: one of silicate 10-30 g / L, aluminate 8-30 g / L, phosphate 8-10 g / L,

[0040] pH adjustment reagent: one of KOH 1-5g / L and NaOH 1-5g / L,

[0041] The first additive is at least one of NaF 0.5 to 3 g / L and KF 0.5 to 3 g / L,

[0042] The second additive is at least one of 5 to 15 g / L sodium citrate and 5 to 15 g / L disodium ethylenediaminetetraacetate,

[0043] Solvent: deionized water.

[0044] In order to facilitate the growth of a denser and tougher micro-arc oxidation film on the surface of various light alloy workpieces, in step five, ① if the workpiece is a magnesium alloy workpiece, the micro-arc oxidation process parameters are: frequency of 800-1200Hz, duty cycle of 10-20%, number of positive pulses of 3, number of negative pulses of 1, negative voltage of 50-150V, and the positive voltage follows the following rules: when the film thickness h≥100mm, the micro-arc oxidation positive voltage is 450-500V, when 100mm>h>30mm, the micro-arc oxidation positive voltage is 350-400V, when the film thickness h≤30mm, the micro-arc oxidation positive voltage is 250-300V;

[0045] ② If the workpiece is an aluminum alloy workpiece, the micro-arc oxidation process parameters are: frequency of 500-1200Hz, duty cycle of 10-30%, number of positive pulses of 3, number of negative pulses of 1, negative voltage of 50-150V, and the positive voltage follows the following rules: when the film thickness h≥100mm, the micro-arc oxidation positive voltage is 500-550V, when 100mm>h>30mm, the micro-arc oxidation positive voltage is 400-480V, when the film thickness h≤30mm, the micro-arc oxidation positive voltage is 300-350V;

[0046] ③ If the workpiece is a titanium alloy workpiece, the micro-arc oxidation process parameters are: frequency of 300-800Hz, duty cycle of 20-40%, number of positive pulses of 3, number of negative pulses of 1, negative voltage of 50-150V, and the positive voltage follows the following rules: when the film thickness h≥100mm, the micro-arc oxidation positive voltage is 450-500V, when 100mm>h>30mm, the micro-arc oxidation positive voltage is 400-420V, when the film thickness h≤30mm, the micro-arc oxidation positive voltage is 300-350V.

[0047] The technical solution adopted by the present invention to solve the second and third technical problems is: a device for repairing a local micro-arc oxidation film layer of a light alloy workpiece, comprising:

[0048] A micro-arc oxidation reaction tank is provided with an interface, and is also connected with a liquid inlet pipe and a liquid outlet pipe;

[0049] A mobile power source is arranged outside the micro-arc oxidation reaction tank and has a positive electrode and a negative electrode, wherein the positive electrode of the mobile power source is used to be electrically connected to the workpiece to be repaired;

[0050] It is characterized by: it also includes

[0051] A stainless steel electrode, contained in the micro-arc oxidation reaction tank and electrically connected to the negative electrode of the mobile power supply;

[0052] A conical insulating tube, the interior of which is communicated with the interior of the micro-arc oxidation reaction tank, and the small-diameter end of the conical insulating tube is sealed with the interface, and the large-diameter end of the conical insulating tube is used to seal with the surface of the workpiece to be repaired.

[0053] In order to make the conical insulating tube and the surface of the workpiece to be repaired seal better, the large-diameter end of the conical insulating tube is provided with a flexible skirt, and the flexible skirt is used to fit the surface of the workpiece to be repaired. The design of the flexible skirt can not only make the large-diameter end of the conical insulating tube fit better with the surface of the workpiece to be repaired, but also increase the contact area between the large-diameter end of the conical insulating tube and the surface of the workpiece to be repaired. Both aspects can make the conical insulating tube and the surface of the workpiece to be repaired seal better.

[0054] In order to facilitate the connection between the conical insulating cylinder and the micro-arc oxidation reaction tank, and at the same time, in order to make the interface between the conical insulating cylinder and the micro-arc oxidation reaction tank more sealed, the small-diameter end of the conical insulating cylinder is provided with a slot toward the interface, and the interface is sealed and plugged into the slot. The cooperation of the slot and the interface makes it more convenient to connect the micro-arc oxidation reaction tank with the conical insulating cylinder, and because the outer wall of the slot is coated on the outer wall of the interface, the electrolyte in the micro-arc oxidation reaction tank is less likely to leak from the interface, so that the interface between the conical insulating cylinder and the micro-arc oxidation reaction tank is more sealed.

[0055] In order to facilitate the liquid inlet into the micro-arc oxidation reaction tank, it also includes an electrolytic cell for containing electrolyte, the inlet of the liquid inlet pipe is inserted in the electrolytic cell, and the liquid inlet pipe is provided with a motor; the outlet of the liquid outlet pipe is inserted in the electrolytic cell, and the liquid outlet pipe is provided with a cooling device for cooling the electrolyte.

[0056] Compared with the prior art, the advantages of the present invention are as follows: the method for repairing a local micro-arc oxidation film layer on a light alloy workpiece measures the average film thickness m of the workpiece, and before repairing the local micro-arc oxidation film layer on the light alloy workpiece, the area to be repaired on the workpiece is first ground, polished, cleaned, and cold sprayed twice to make the area to be repaired on the workpiece flat, thereby providing a uniform surface substrate for the growth of the micro-arc oxidation film layer; finally, by quantitatively comparing the film layer grown by micro-arc oxidation in the area to be repaired on the workpiece with the average film thickness m, the difference in film thickness between the repaired area to be repaired and the surrounding area on the workpiece can be reduced, so that the surface uniformity of the workpiece is better, thereby avoiding the phenomenon of unevenness, and improving the repair effect of the micro-arc oxidation film layer on the light alloy workpiece; The local micro-arc oxidation film repair device for alloy workpieces isolates the inside of a micro-arc oxidation reaction tank from the outside through a conical insulating cylinder to prevent the electrolyte from leaking from the edge of the large-diameter end of the conical insulating cylinder to the surface of the area on the workpiece to be repaired that does not need to be repaired and destroying the normal film on the workpiece to be repaired. There is no need to coat the surface of the area on the workpiece to be repaired that does not need to be repaired with ink and then remove it. This can not only simplify the repair process of the local micro-arc oxidation film on light alloy workpieces, shorten the time for repairing the local micro-arc oxidation film on light alloy workpieces, thereby improving the film repair efficiency, but also the shape design of the insulating cylinder can allow the volume of the micro-arc oxidation reaction tank to be designed to be smaller, thereby avoiding the waste of electrolyte, effectively saving raw materials, and reducing the cost of film repair.

[0057] Instruction Manual

[0058] Figure 1 This is a schematic diagram of the structure of a device for repairing a local micro-arc oxidation film layer on a light alloy workpiece in this embodiment;

[0059] Figure 2 for Figure 1 The enlarged view of point A in the middle;

[0060] Figure 3 This is a flow chart of the repair of a local micro-arc oxidation film layer on a light alloy workpiece in this embodiment. DETAILED DESCRIPTION

[0061] The embodiments of the present invention are described in further detail below.

[0062] The device for repairing a local micro-arc oxidation film layer of a light alloy workpiece in this embodiment comprises a micro-arc oxidation reaction tank 7, a mobile power source (not shown in the figure), a stainless steel electrode 6 and a conical insulating cylinder 3. The micro-arc oxidation reaction tank 7 is provided with an interface 71, and the micro-arc oxidation reaction tank 7 is also connected with a liquid inlet pipe 4 and a liquid outlet pipe 5 (see FIG. Figure 2 The mobile power source is arranged outside the micro-arc oxidation reaction tank 7 and has a positive electrode and a negative electrode, and the positive electrode of the mobile power source is used to be electrically connected to the workpiece 2 to be repaired (see Figure 1The stainless steel electrode 6 is placed inside the micro-arc oxidation reaction tank 7 and is electrically connected to the negative electrode of the mobile power source (see Figure 2 The interior of the conical insulating tube 3 is connected to the interior of the micro-arc oxidation reaction tank 7, and the small-diameter end of the conical insulating tube 3 is sealed with the interface 71, and the large-diameter end of the conical insulating tube 3 is used to seal with the surface of the workpiece 2 to be repaired.

[0063] The local micro-arc oxidation film repair device for light alloy workpieces in this embodiment isolates the inside of the micro-arc oxidation reaction tank 7 from the outside through the conical insulating cylinder 3 to prevent the electrolyte from leaking from the large-diameter end edge of the conical insulating cylinder 3 to the surface of the area to be repaired that does not need to be repaired on the workpiece 2 to damage the normal film layer on the workpiece 2 to be repaired. There is no need to coat the surface of the area to be repaired that does not need to be repaired on the workpiece 2 to be repaired with ink and then remove it. This can not only simplify the local micro-arc oxidation film repair process of light alloy workpieces and shorten the working hours, thereby improving the film repair efficiency, but also the shape design of the insulating cylinder can allow the volume of the micro-arc oxidation reaction tank 7 to be designed to be smaller, thereby avoiding the waste of electrolyte, effectively saving raw materials, and reducing the cost of film repair.

[0064] like Figure 2 As shown, the large-diameter end of the conical insulating cylinder 3 is provided with a flexible skirt 31, which is used to fit with the surface of the workpiece 2 to be repaired, so that not only the large-diameter end of the conical insulating cylinder 3 can better fit with the surface of the workpiece 2 to be repaired, but also the contact area between the large-diameter end of the conical insulating cylinder 3 and the surface of the workpiece 2 to be repaired can be increased. Both aspects can make the conical insulating cylinder 3 and the surface of the workpiece 2 to be repaired better sealed. The small-diameter end of the conical insulating cylinder 3 is provided with a slot 32 toward the interface 71, and the interface 71 is sealed and plugged into the slot 32. The cooperation of the slot 32 and the interface 71 makes it more convenient to connect the micro-arc oxidation reaction tank 7 with the conical insulating cylinder 3, and the slot 32, because the outer wall of the slot 32 is covered on the outer wall of the interface 71, can make the electrolyte in the micro-arc oxidation reaction tank 7 less likely to leak from the interface 71, so that the interface 71 between the conical insulating cylinder 3 and the micro-arc oxidation reaction tank 7 has better sealing.

[0065] like Figure 1As shown, the local micro-arc oxidation film repair device for a light alloy workpiece in this embodiment also includes an electrolytic cell 1 for containing an electrolyte, the inlet of a liquid inlet pipe 4 is inserted into the electrolytic cell 1, and a motor 41 is provided on the liquid inlet pipe 4. The outlet of the liquid outlet pipe 5 is inserted into the electrolytic cell 1, which can facilitate the recycling of the electrolyte, and the electrolytic cell 1 can be placed at any position, and the electrolyte can be recycled without being placed directly below the area to be repaired on the workpiece, so that the use of the local micro-arc oxidation film repair device for a light alloy workpiece can reduce the requirements for the space around the area to be repaired on the workpiece, thereby having a wider range of applications; a cooling device 51 for cooling the electrolyte is provided on the liquid outlet pipe 5, so that the local micro-arc oxidation film repair device for a light alloy workpiece can conveniently control the temperature of the electrolyte.

[0066] In the following embodiments, the above-mentioned device for repairing a local micro-arc oxidation film layer of a light alloy workpiece is used to repair a local micro-arc oxidation film layer of a light alloy workpiece.

[0067] Example 1

[0068] like Figure 3 As shown, the method for repairing a local micro-arc oxidation film layer of a magnesium alloy workpiece in this embodiment comprises the following steps in sequence:

[0069] 1) Find the weak position of the film layer of the magnesium alloy workpiece, mark it with a red circle, and measure the diameter of the smallest circle that can cover the position, and make the area inside the smallest circle the area to be repaired;

[0070] 2) Measure the film thickness at the marked position and the surrounding film thickness: Use an eddy current thickness gauge to measure the film thickness at the weak position and the film thickness around the weak position to obtain an average film thickness of 25μm, where there are 5-8 measuring points in the marked circle and 5-8 measuring points around the marked circle.

[0071] 3) Use 80-grit sandpaper to manually grind the area to be repaired on the magnesium alloy workpiece to produce a metallic luster, and then polish it.

[0072] 4) Use deionized water to clean the residue from the polished area of ​​the product.

[0073] 5) Cold spraying was performed on the polished area. The first cold spraying process was as follows: stainless steel powder with a particle size of 50 μm was transported to the cold spraying device through a powder feeder, and the surface of the magnesium alloy to be repaired was subjected to cold spraying roughening treatment. The spraying distance was controlled to be 20 mm, the sandblasting rate was 15 mm / s, and the particle incident angle was 50°; the second cold spraying process was as follows: compressed nitrogen was used as the gas, the gas flow rate was 275 L / min, the spraying pressure was 2.8 MPa, the temperature of the cold spraying working gas was 200 °C, the spraying distance was 40 mm, and the sandblasting rate was 30 mm / s; the spraying powder composition was Mg 10%, Zn 0.3%, Mn 0.3%, the balance was Al, and the powder feeding rate was 3 g / min.

[0074] 6) Prepare the electrolyte for local micro-arc oxidation of magnesium alloy workpiece: sodium silicate 10g / L, sodium aluminate 8g / L, NaOH 1g / L; NaF 0.5g / L, glycerol 5ml / L, sodium citrate 5g / L, nickel acetate 0.3g / L, and the solvent is deionized water.

[0075] 7) On-site processing of a local micro-arc oxidation film repair device that matches the area to be repaired: Measure the size of the area to be repaired and process a matching sealing ring according to the size to ensure that the sealing ring can be sealed after installation without leaking electrolyte, such as Figure 2 The matching state of the workpiece 2 and the conical insulating tube 3 is shown in FIG. Figure 1 The assembled device for repairing local micro-arc oxidation film on a light alloy workpiece is shown.

[0076] 8) Install a light alloy workpiece local micro-arc oxidation repair device on the magnesium alloy workpiece to perform local micro-arc oxidation: Figure 2 As shown, the micro-arc oxidation device is installed and micro-arc oxidation is carried out. The process parameters of micro-arc oxidation are: frequency is 800 Hz, duty cycle is 10%, number of positive pulses is 3, number of negative pulses is 1, negative voltage is 50 V, and positive voltage is 250 V. After a large spark is generated at the grinding position, the local micro-arc oxidation of the magnesium alloy workpiece is stopped to measure the film layer. After measurement, the film thickness is 22.5 μm, which satisfies the equation |hm|=2.5 μm<5 μm. There is no color difference between the appearance and the original film layer, and there are no defects.

[0077] Example 2

[0078] like Figure 3 As shown, the method for repairing a local micro-arc oxidation film layer of an aluminum alloy workpiece in this embodiment comprises the following steps in sequence:

[0079] 1) Find the weak position of the film layer of the aluminum alloy workpiece, mark it with a red circle, and measure the diameter of the smallest circle that can cover the position, and make the area inside the smallest circle the area to be repaired;

[0080] 2) Measure the film thickness at the marked position and the surrounding film thickness: Use an eddy current thickness gauge to measure the film thickness at the weak position and the film thickness around the weak position to obtain an average film thickness of 105.2μm, where there are 5-8 measuring points in the marked circle and 5-8 measuring points around the marked circle.

[0081] 3) Use an angle grinder to grind the area to be repaired on the aluminum alloy workpiece to reveal the metallic luster, and then polish it.

[0082] 4) Use deionized water to clean the residue from the polished area of ​​the product.

[0083] 5) Cold spraying was performed on the polished area. The first cold spraying process was as follows: stainless steel powder with a particle size of 100 μm was transported to the cold spraying device through a powder feeder, and the surface of the aluminum alloy to be repaired was subjected to cold spraying roughening treatment. The spraying distance was controlled to be 30 mm, the sandblasting rate was 25 mm / s, and the particle incident angle was 70°; the second cold spraying process was as follows: compressed nitrogen was used as the gas, the main gas flow rate was 300 L / min, the spraying pressure was 5 MPa, the temperature of the cold spraying working gas was 500 °C, the spraying distance was 20 mm, and the sandblasting rate was 15 mm / s; the powder spraying component was pure Al, and the powder feeding rate was 6 g / min.

[0084] 6) Prepare an electrolyte for local micro-arc oxidation of an aluminum alloy workpiece. The electrolyte formula of the aluminum alloy is: 10 g / L sodium silicate, 2 g / L sodium tungstate, 3 g / L KOH, 5 g / L borax, 0.5 g / L nano titanium dioxide, and the solvent is deionized water.

[0085] 7) On-site processing of a local micro-arc oxidation film repair device that matches the area to be repaired: Measure the size of the area to be repaired and process a matching sealing ring according to the size to ensure that the sealing ring can be sealed after installation without leaking electrolyte, such as Figure 2 The matching state of the workpiece 2 and the conical insulating tube 3 is shown in FIG. Figure 1 The assembled device for repairing local micro-arc oxidation film on a light alloy workpiece is shown.

[0086] 8) Install the local micro-arc oxidation repair device for light alloy workpieces on the aluminum alloy workpiece for local micro-arc oxidation: follow the steps below: Figure 2As shown, the micro-arc oxidation device is installed and micro-arc oxidation is carried out. The process parameters of micro-arc oxidation are: frequency is 800Hz, duty cycle is 30%, number of positive pulses is 3, number of negative pulses is 1, and negative voltage is 150V; when the micro-arc oxidation film thickness h≤30mm, the positive voltage is 300V, when the micro-arc oxidation film layer is 100mm>h>30mm, the positive voltage is 400V, and when the micro-arc oxidation film layer h≥100mm, the micro-arc oxidation positive voltage is 500V; after a large spark is generated at the grinding position, the local micro-arc oxidation of the aluminum alloy workpiece is stopped to measure the film layer. After measurement, the film thickness is 101.5μm, which satisfies the equation |hm|=3.7μm<5μm, and the appearance has no color difference with the original film layer and is defect-free.

[0087] Example 3

[0088] like Figure 3 As shown, the method for repairing a local micro-arc oxidation film layer of a titanium alloy workpiece in this embodiment comprises the following steps in sequence:

[0089] 1) Find the weak position of the film layer of the titanium alloy workpiece, mark it with a red circle, and measure the diameter of the smallest circle that can cover the position, and make the area inside the smallest circle the area to be repaired;

[0090] 2) Measure the film thickness at the marked position and the surrounding film thickness: Use an eddy current thickness gauge to measure the film thickness at the weak position and the film thickness around the weak position, and the average film thickness is 65.6μm, among which there are 5-8 measuring points in the marked circle and 5-8 measuring points around the marked circle.

[0091] 3) Use an angle grinder polishing pad to grind the area to be repaired on the titanium alloy workpiece to reveal the metallic luster, and then polish it.

[0092] 4) Use deionized water to clean the residue from the polished area of ​​the product.

[0093] 5) Cold spraying is performed on the polished area. The first cold spraying process is: stainless steel powder with a particle size of 150μm is transported to the cold spraying device through a powder feeder, and the surface of the titanium alloy to be repaired is cold sprayed for roughening treatment. The spraying distance is controlled to be 40mm, the sandblasting rate is 35mm / s, and the particle incident angle is 90°; the second cold spraying process is: compressed nitrogen is used as the gas, the gas flow rate is 320L / min, the spraying pressure is 3.2MPa, the temperature of the cold spraying working gas is 600℃, the spraying distance is 40mm, and the sandblasting rate is 30mm / s; the powder spraying component is pure Ti, and the powder feeding rate is 10g / min.

[0094] 6) Prepare the local micro-arc oxidation electrolyte for titanium alloy workpiece: sodium silicate 30g / L, KOH 3g / L, NaF 0.5g / L, disodium ethylenediaminetetraacetic acid 15g / L, and the solvent is deionized water.

[0095] 7) On-site processing of a local micro-arc oxidation film repair device that matches the area to be repaired: Measure the size of the area to be repaired and process a matching sealing ring according to the size to ensure that the sealing ring can be sealed after installation without leaking electrolyte, such as Figure 2 The matching state of the workpiece 2 and the conical insulating tube 3 is shown in FIG. Figure 1 The assembled device for repairing local micro-arc oxidation film on a light alloy workpiece is shown.

[0096] 8) Install the local micro-arc oxidation repair device for light alloy workpieces on the titanium alloy workpiece for local micro-arc oxidation: Figure 2 As shown, the micro-arc oxidation device is installed and micro-arc oxidation is carried out. The micro-arc oxidation process parameters are: frequency of 300 Hz, duty cycle of 40%, number of positive pulses of 3, number of negative pulses of 1, and negative voltage of 150 V; when the micro-arc oxidation film thickness h≤30 mm, the positive voltage is 300 V, and when the micro-arc oxidation film layer is 100 mm>h>30 mm, the positive voltage is 400 V; after a large spark is generated at the grinding position, the local micro-arc oxidation of the titanium alloy workpiece is stopped to measure the film layer. After measurement, the film thickness is 69.8 μm, which satisfies the equation |hm|=4.2 μm<5 μm, and the appearance has no color difference with the original film layer and is defect-free.

Claims

1. A method for repairing local micro-arc oxidation film on light alloy workpieces. It is characterized in that The following steps are included in sequence: Step 1: Determine the area to be repaired on the workpiece: mark the weak part of the film layer on the workpiece, and measure the diameter of the smallest circle that can cover the weak part, and make the area inside the smallest circle the area to be repaired; Step 2, measuring the average film thickness m of the workpiece: the average film thickness m of the workpiece is obtained from the film thickness of the area to be repaired on the workpiece and the film thickness outside the area to be repaired; Step 3: pre-treat the area to be repaired on the workpiece: including grinding, polishing, cleaning, and two cold spraying treatments in sequence, wherein the spraying component of the first cold spraying treatment is stainless steel powder, and the spraying component of the second cold spraying treatment is the basic element powder or main element powder of the light alloy workpiece; Among them, if the workpiece is a magnesium alloy workpiece, the first cold spraying process is: using stainless steel powder with a particle size of 50-150 μm as the powder spraying component, controlling the spraying distance to be 20-50 mm, the sandblasting rate to be 15-35 mm / s, and the particle incident angle to be 50°-90°. The second cold spraying process is: using compressed nitrogen as the gas, the gas flow rate to be 275-320 L / min, the spraying pressure to be 2.8-3.2 MPa, the temperature of the cold spraying working gas to be 200-300°C, the spraying distance to be 40-70 mm, the sandblasting rate to be 30-60 mm / s, the powder spraying component to be Mg 10-25%, Zn 0.3-0.5%, Mn 0.3-0.5%, the balance to be Al, and the powder feeding rate to be 3-10 g / min; Step 4: Prepare the micro-arc oxidation electrolyte according to the alloy type of the workpiece; Among them, if the workpiece is a magnesium alloy workpiece, the electrolyte formula is: Film-forming agent: at least one of silicate 10-30 g / L, aluminate 8-30 g / L, phosphate 8-10 g / L, acid zirconate 5-20 g / L, At least one of the pH adjusting reagents KOH 1-5 g / L and NaOH 1-5 g / L, At least one of the first additives NaF 0.5-3 g / L and KF 0.5-3 g / L, The second additive is at least one of 5-15 ml / L glycerol, 5-15 ml / L triethanolamine, and 5-15 g / L sodium citrate. The third additive is at least one of nano-aluminum oxide 0.5-3g / L and nickel acetate 0.3-0.8g / L. Solvent: deionized water; Step 5: On-site processing of a local micro-arc oxidation film repair device adapted to the area to be repaired; Step 6. Install a local micro-arc oxidation film repair device on the workpiece, and set the micro-arc oxidation parameters according to the type of workpiece alloy to perform micro-arc oxidation reaction on the area to be repaired. When the film thickness h of the repaired area and the average film thickness m of the workpiece satisfy |hm|≤5µm, the micro-arc oxidation reaction process can be stopped, and the local micro-arc oxidation film repair of the light alloy workpiece is completed.

2. The method for repairing a local micro-arc oxidation film layer of a light alloy workpiece according to claim 1, It is characterized in that In step three, ① if the average film thickness of the workpiece m ≥ 100mm, use an angle grinder grinding wheel to grind the area to be repaired to reveal the metallic luster; ② if 100mm>the average film thickness of the workpiece m>30mm, use an angle grinder polishing sheet to grind to reveal the metallic luster; ③ if the average film thickness of the workpiece m ≤ 30mm, use 80-grit sandpaper to manually grind out the metallic luster, and then polish.

3. The method for repairing a local micro-arc oxidation film layer of a light alloy workpiece according to claim 1, It is characterized in that In step five, for the workpiece being a magnesium alloy workpiece, the micro-arc oxidation process parameters are: frequency of 800-1200 Hz, duty cycle of 10-20%, number of positive pulses of 3, number of negative pulses of 1, negative voltage of 50-150 V, and the positive voltage follows the following rules: when the film thickness h ≥ 100 mm, the micro-arc oxidation positive voltage is 450-500 V, when 100 mm>h>30 mm, the micro-arc oxidation positive voltage is 350-400 V, and when the film thickness h ≤ 30 mm, the micro-arc oxidation positive voltage is 250-300 V.

4. A method for repairing local micro-arc oxidation film on light alloy workpieces. It is characterized in that The following steps are included in sequence: Step 1: Determine the area to be repaired on the workpiece: mark the weak part of the film layer on the workpiece, and measure the diameter of the smallest circle that can cover the weak part, and make the area inside the smallest circle the area to be repaired; Step 2, measuring the average film thickness m of the workpiece: the average film thickness m of the workpiece is obtained from the film thickness of the area to be repaired on the workpiece and the film thickness outside the area to be repaired; Step 3: pre-treat the area to be repaired on the workpiece: including grinding, polishing, cleaning, and two cold spraying treatments in sequence, wherein the spraying component of the first cold spraying treatment is stainless steel powder, and the spraying component of the second cold spraying treatment is the basic element powder or main element powder of the light alloy workpiece; Among them, if the workpiece is an aluminum alloy workpiece, the first cold spraying process is: using stainless steel powder with a particle size of 50-150μm as the powder spraying component, controlling the spraying distance to be 15-40mm, the sandblasting rate to be 15-35mm / s, and the particle incident angle to be 50-90°. The second cold spraying process is: using compressed nitrogen as the gas, the main gas flow rate to be 275-320L / min, the spraying pressure to be 4-7MPa, the temperature of the cold spraying working gas to be 400-600℃, the spraying distance to be 20-40mm, the sandblasting rate to be 15-45mm / s, the powder spraying component to be Al, and the powder feeding rate to be 3-10g / min. Step 4: Prepare the micro-arc oxidation electrolyte according to the alloy type of the workpiece; Among them, if the workpiece is an aluminum alloy workpiece, the electrolyte formula is: Film-forming agents: at least two of silicate 3-20 g / L, tungstate 1-5 g / L, aluminate 1-5 g / L, At least one of the pH adjusting reagents KOH 1-5 g / L and NaOH 1-5 g / L, The first additive is borax 3-10g / L, The second additive is at least one of nano titanium dioxide 0.3-0.8 g / L, nano silicon dioxide 0.5-1.5 g / L, and nano aluminum oxide 0.5-1.5 g / L. Solvent: deionized water; Step 5: On-site processing of a local micro-arc oxidation film repair device adapted to the area to be repaired; Step 6. Install a local micro-arc oxidation film repair device on the workpiece, and set the micro-arc oxidation parameters according to the type of workpiece alloy to perform micro-arc oxidation reaction on the area to be repaired. When the film thickness h of the repaired area and the average film thickness m of the workpiece satisfy |hm|≤5µm, the micro-arc oxidation reaction process can be stopped, and the local micro-arc oxidation film repair of the light alloy workpiece is completed.

5. The method for repairing a local micro-arc oxidation film layer of a light alloy workpiece according to claim 4, It is characterized in that In step three, ① if the average film thickness of the workpiece m ≥ 100mm, use an angle grinder grinding wheel to grind the area to be repaired to reveal the metallic luster; ② if 100mm>the average film thickness of the workpiece m>30mm, use an angle grinder polishing sheet to grind to reveal the metallic luster; ③ if the average film thickness of the workpiece m ≤ 30mm, use 80-grit sandpaper to manually grind out the metallic luster, and then polish.

6. The method for repairing a local micro-arc oxidation film layer of a light alloy workpiece according to claim 4, It is characterized in that In step five, for the workpiece being an aluminum alloy workpiece, the micro-arc oxidation process parameters are: frequency of 500-1200 Hz, duty cycle of 10-30%, number of positive pulses of 3, number of negative pulses of 1, negative voltage of 50-150 V, and the positive voltage follows the following rules: when the film thickness h ≥ 100 mm, the micro-arc oxidation positive voltage is 500-550 V, when 100 mm>h>30 mm, the micro-arc oxidation positive voltage is 400-480 V, and when the film thickness h ≤ 30 mm, the micro-arc oxidation positive voltage is 300-350 V.

7. A method for repairing local micro-arc oxidation film on light alloy workpieces. It is characterized in that The following steps are included in sequence: Step 1: Determine the area to be repaired on the workpiece: mark the weak part of the film layer on the workpiece, and measure the diameter of the smallest circle that can cover the weak part, and make the area inside the smallest circle the area to be repaired; Step 2, measuring the average film thickness m of the workpiece: the average film thickness m of the workpiece is obtained from the film thickness of the area to be repaired on the workpiece and the film thickness outside the area to be repaired; Step 3: pre-treat the area to be repaired on the workpiece: including grinding, polishing, cleaning, and two cold spraying treatments in sequence, wherein the spraying component of the first cold spraying treatment is stainless steel powder, and the spraying component of the second cold spraying treatment is the basic element powder or main element powder of the light alloy workpiece; Among them, for the workpiece being a titanium alloy workpiece, the first cold spraying process is: using stainless steel powder with a particle size of 50 to 150 μm as the powder spraying component, controlling the spraying distance to be 10 to 40 mm, the sandblasting rate to be 15 to 35 mm / s, and the particle incident angle to be 50 to 90°; the second cold spraying process is: using compressed nitrogen as the gas, the gas flow rate to be 275 to 320 L / min, the spraying pressure to be 2.8 to 3.2 MPa, the temperature of the cold spraying working gas to be 500 to 600 °C, the spraying distance to be 15 to 40 mm, the sandblasting rate to be 10 to 30 mm / s, the powder spraying component to be Ti, and the powder feeding rate to be 3 to 10 g / min; Step 4: Prepare the micro-arc oxidation electrolyte according to the alloy type of the workpiece; Among them, if the workpiece is a titanium alloy workpiece, the electrolyte formula is: Film-forming agent: one of silicate 10-30 g / L, aluminate 8-30 g / L, phosphate 8-10 g / L, pH adjustment reagent: one of KOH 1-5g / L and NaOH 1-5g / L, The first additive is at least one of NaF 0.5 to 3 g / L and KF 0.5 to 3 g / L, The second additive is at least one of 5 to 15 g / L sodium citrate and 5 to 15 g / L disodium ethylenediaminetetraacetate, Solvent: deionized water; Step 5: On-site processing of a local micro-arc oxidation film repair device adapted to the area to be repaired; Step 6. Install a local micro-arc oxidation film repair device on the workpiece, and set the micro-arc oxidation parameters according to the type of workpiece alloy to perform micro-arc oxidation reaction on the area to be repaired. When the film thickness h of the repaired area and the average film thickness m of the workpiece satisfy |hm|≤5µm, the micro-arc oxidation reaction process can be stopped, and the local micro-arc oxidation film repair of the light alloy workpiece is completed.

8. The method for repairing a local micro-arc oxidation film layer of a light alloy workpiece according to claim 7, It is characterized in that In step three, ① if the average film thickness of the workpiece m ≥ 100mm, use an angle grinder grinding wheel to grind the area to be repaired to reveal the metallic luster; ② if 100mm>the average film thickness of the workpiece m>30mm, use an angle grinder polishing sheet to grind to reveal the metallic luster; ③ if the average film thickness of the workpiece m ≤ 30mm, use 80-grit sandpaper to manually grind out the metallic luster, and then polish.

9. The method for repairing a local micro-arc oxidation film layer of a light alloy workpiece according to claim 7, It is characterized in that In step five, for the workpiece being a titanium alloy workpiece, the micro-arc oxidation process parameters are: frequency of 300-800 Hz, duty cycle of 20-40%, number of positive pulses of 3, number of negative pulses of 1, negative voltage of 50-150 V, and the positive voltage follows the following rules: when the film thickness h ≥ 100 mm, the micro-arc oxidation positive voltage is 450-500 V, when 100 mm>h>30 mm, the micro-arc oxidation positive voltage is 400-420 V, and when the film thickness h ≤ 30 mm, the micro-arc oxidation positive voltage is 300-350 V.

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