Magnesium alloy ultrahigh frequency synergistic hard particle micro-arc oxidation treatment method

Abstract

The invention discloses a magnesium alloy ultrahigh frequency and hard particle micro-arc oxidation treatment method. The method comprises the following steps: carrying out oil removal treatment on a magnesium alloy; washing the deoiled magnesium alloy with water; a micro-arc oxidation electrolyte is prepared, wherein the micro-arc oxidation electrolyte comprises at least one of 5-20 g / L of sodium silicate, 1-10 g / L of sodium hexametaphosphate, 1-10 g / L of sodium phosphate, 1-10 g / L of sodium hydroxide, 1-5 g / L of sodium fluoride, 1-2 g / L of lauryl sodium sulfate and 8-10 g / L of hard particles; ultrahigh-frequency micro-arc oxidation is conducted, specifically, micro-arc oxidation electrolyte is poured into a solution tank and cooled through a titanium alloy plate heat exchanger till the solution temperature is not higher than 40 DEG C, a stainless steel plate serves as a cathode, the washed magnesium alloy serves as an anode, and micro-arc oxidation is conducted for 10-100 min in a constant-current mode under the conditions that the current density is 1-20 A / dm < 2 >, the duty ratio is 20% and the frequency is 10000-20000 Hz; and finally, washing and drying.

Description

Technical Field

[0001] The present invention relates to the field of metal surface treatment, and in particular to a treatment method of magnesium alloy by ultra-high frequency coordinated hard particle micro-arc oxidation. Background Art

[0002] Micro-arc oxidation is an electrochemical treatment method developed from anodic oxidation. It induces plasma discharge on the metal surface by applying high voltage, thereby forming a modified ceramic coating on the surface of valve metals such as aluminum, magnesium, and titanium. It performs well in improving the corrosion resistance, wear resistance, insulation and decorative properties of magnesium alloys. However, the formation process of the micro-arc oxidation film is accompanied by strong plasma discharge, which greatly affects the morphology and composition of the coating, presenting a typical structure with a dense inner layer and a loose and porous outer layer. On the one hand, the porous structure of the micro-arc oxidation film provides a possible channel for the invasion of corrosive media, and on the other hand, it is not conducive to the wear resistance of the coating. Therefore, it is necessary to prepare a high-performance micro-arc oxidation film layer to improve the overall wear resistance.

[0003] In recent years, research on micro-arc oxidation coatings on magnesium alloys has focused on adjusting electrolyte composition, oxidation parameters, and the addition of nanoparticles. These efforts have yielded some improvements in the coating's microstructure and phase composition, particularly in corrosion resistance. However, relatively little research has focused on wear resistance, and the improvements have been limited, resulting in a lack of robust results in this area. Summary of the Invention

[0004] In view of the defects of the prior art, the purpose of the present invention is to provide a treatment method of magnesium alloy by ultra-high frequency coordinated hard particle micro-arc oxidation.

[0005] The technical solution of the present invention is: In a first aspect, the present invention provides a method for treating magnesium alloy by ultra-high frequency coordinated hard particle micro-arc oxidation, comprising the following steps: (1) Degreasing the magnesium alloy; (2) Washing the degreased magnesium alloy with water; (3) preparing a micro-arc oxidation electrolyte: the micro-arc oxidation electrolyte comprises at least one of 5-20 g / L sodium silicate, 1-10 g / L sodium hexametaphosphate, 1-10 g / L sodium phosphate, 1-10 g / L sodium hydroxide, 1-5 g / L sodium fluoride, 1-2 g / L sodium lauryl sulfate, and 8-10 g / L hard particles; (4) Ultra-high frequency micro-arc oxidation: pour the micro-arc oxidation electrolyte in step (3) into the solution tank, cool it to a temperature of no more than 40°C using a titanium alloy plate heat exchanger, use the stainless steel plate as the cathode and the magnesium alloy washed in step (2) as the anode, adopt a constant current mode, and operate at a current density of 1-20A / dm 2, micro-arc oxidation is carried out for 10-100 min at a duty cycle of 20% and a frequency of 10000-20000 Hz; (5) Water washing: washing the magnesium alloy after micro-arc oxidation in step (4); (6) Drying: Drying the magnesium alloy after washing in step (5).

[0006] Further preferably, in step (1), the deoiling temperature is 20-50° C., and the deoiling time is 10-30 s.

[0007] Further preferably, in step (1), the magnesium alloy degreasing agent includes at least one of 1-8 g / L sodium bicarbonate, 1-5 g / L sodium hydroxide, 5-10 g / L phosphate, and 0.2-1 g / L sodium dodecylbenzene sulfonate.

[0008] Further preferably, the magnesium alloy degreasing agent includes at least one of 3 g / L sodium bicarbonate, 3 g / L sodium hydroxide, 5 g / L phosphate, and 0.5 g / L sodium dodecylbenzene sulfonate.

[0009] Further preferably, in step (3), the micro-arc oxidation electrolyte includes at least one of 3-10 g / L sodium silicate, 1-5 g / L sodium hexametaphosphate, 5-10 g / L sodium phosphate, 2-4 g / L sodium hydroxide and 1-3 g / L sodium fluoride, 1-2 g / L sodium lauryl sulfate, and 8-10 g / L hard particles.

[0010] More preferably, the hard particles are zirconium oxide particles.

[0011] More preferably, the particle size of the zirconium oxide particles is 20-500 nm.

[0012] More preferably, the particle size of the zirconium oxide particles is 20 nm.

[0013] Further preferably, in step (4), a constant current mode is adopted, and the current density is 5A / dm 2 , micro-arc oxidation was carried out for 25 min under the conditions of a duty cycle of 20% and a frequency of 10000-20000 Hz.

[0014] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention breaks through the traditional conventional micro-arc oxidation technology and uses ultra-high frequency micro-arc oxidation to add hard particles in situ, which effectively improves the microstructure and phase composition of the film layer, increases the hardness of the film layer, and the prepared coating has better wear resistance.

[0015] (2) The micro-arc oxidation technology used in the present invention effectively promotes the deposition of hard particles by synergizing ultra-high frequency technology with hard particles, closes the discharge holes in the micro-arc oxidation film, and improves the corrosion resistance of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings: Figure 1 The scanning electron microscope images of the surface of the micro-arc oxidation film of the first embodiment, the first comparative example, the second comparative example, and the third comparative example provided in the experimental examples of the present invention ( Figure 1 (a1) is a scanning electron microscope image of the surface of the micro-arc oxidation film provided in the first comparative example; Figure 1 (a2) is a scanning electron microscope image of discharge holes on the surface of the micro-arc oxidation film provided in the first comparative example; Figure 1 (b1) is a scanning electron microscope image of the surface of the micro-arc oxidation film provided in the second comparative example; Figure 1 (b2) is a scanning electron microscope image of discharge holes on the surface of the micro-arc oxidation film provided in the second comparative example; Figure 1 (c1) is a scanning electron microscope image of the surface of the micro-arc oxidation film provided in the third comparative example; Figure 1 Middle (c2) is a scanning electron microscope image of discharge holes on the surface of the micro-arc oxidation film provided in the third comparative example; Figure 1 (d1) is a scanning electron microscope image of the surface of the micro-arc oxidation film provided in the first embodiment; Figure 1 (d2) is a scanning electron microscope image of discharge holes on the surface of the micro-arc oxidation film provided in the first embodiment); Figure 2 The scanning electron microscope images of the cross sections of the micro-arc oxidation films of the first embodiment, the first comparative example, the second comparative example, and the third comparative example provided in the experimental examples of the present invention ( Figure 2 (a) is a scanning electron microscope image of the cross section of the micro-arc oxidation film provided in the first comparative example; Figure 2 (b) is a scanning electron microscope image of the cross section of the micro-arc oxidation film provided in the second comparative example; Figure 2 Middle (c) is a scanning electron microscope image of the cross section of the micro-arc oxidation film provided in the third comparative example; Figure 2 (d) is a scanning electron microscope image of a cross section of the micro-arc oxidation film provided in the first embodiment); Figure 3Schematic diagram of XRD analysis results of the micro-arc oxidation films of the first embodiment, first comparative example, second comparative example, and third comparative example provided in the experimental examples of the present invention (PEO-20k-Z: the micro-arc oxidation film provided in the first embodiment; PEO-500: the micro-arc oxidation film provided in the first comparative example; PEO-20k: the micro-arc oxidation film provided in the second comparative example; PEO-500-Z: the micro-arc oxidation film provided in the third comparative example); Figure 4 Schematic diagram of the hardness results of the micro-arc oxidation films of the magnesium alloy substrate, the first embodiment, the first comparative example, the second comparative example, and the third comparative example provided in the experimental examples of the present invention (GW83 alloy: magnesium alloy substrate; PEO-20K-Z: micro-arc oxidation film provided in the first embodiment; PEO-500: micro-arc oxidation film provided in the first comparative example; PEO-20k: micro-arc oxidation film provided in the second comparative example; PEO-500-Z: micro-arc oxidation film provided in the third comparative example); Figure 5 Schematic diagram of the results of friction and wear tests of the micro-arc oxidation films of the magnesium alloy substrate, the first embodiment, the first comparative example, the second comparative example, and the third comparative example provided in the experimental examples of the present invention ( Figure 5 (a) is a fluctuation diagram of the friction coefficient of the micro-arc oxidation film of the magnesium alloy substrate, the first embodiment, the first comparative example, the second comparative example, and the third comparative example; Figure 5 (b) is a schematic diagram of the average friction coefficients of the micro-arc oxidation films provided by the magnesium alloy substrate, the first embodiment, the first comparative example, the second comparative example, and the third comparative example; GW83 alloy: magnesium alloy substrate; PEO-20K-Z: micro-arc oxidation film provided by the first embodiment; PEO-500: micro-arc oxidation film provided by the first comparative example; PEO-20k: micro-arc oxidation film provided by the second comparative example; PEO-500-Z: micro-arc oxidation film provided by the third comparative example); Figure 6 The three-dimensional morphology diagram, wear scar width statistical diagram and surface morphology observation diagram of the friction and wear traces of the micro-arc oxidation film of the magnesium alloy substrate, the first embodiment, the first comparative example, the second comparative example and the third comparative example provided in the experimental example of the present invention ( Figure 6 (a) is a three-dimensional morphology of the friction and wear traces of the micro-arc oxidation film; Figure 6 Middle (b) is the wear scar width statistics of the friction and wear traces of the micro-arc oxidation film; Figure 6(c) is a schematic diagram of the surface morphology observation of the friction and wear traces of the micro-arc oxidation film; GW83 alloy: magnesium alloy substrate; PEO-20K-Z: micro-arc oxidation film provided by the first embodiment; PEO-500: micro-arc oxidation film provided by the first comparative example; PEO-20k: micro-arc oxidation film provided by the second comparative example; PEO-500-Z: micro-arc oxidation film provided by the third comparative example); Figure 7 Schematic diagram of polarization curve results of the magnesium alloy substrate, the first embodiment, the first comparative example, the second comparative example, and the third comparative example provided in the experimental examples of the present invention (GW83 alloy: magnesium alloy substrate; PEO-20K-Z: micro-arc oxidation film provided in the first embodiment; PEO-500: micro-arc oxidation film provided in the first comparative example; PEO-20k: micro-arc oxidation film provided in the second comparative example; PEO-500-Z: micro-arc oxidation film provided in the third comparative example). DETAILED DESCRIPTION

[0017] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are for describing specific embodiments rather than for limiting the scope of protection of the present invention.

[0018] A method for treating magnesium alloy by ultra-high frequency coordinated hard particle micro-arc oxidation, comprising the following steps: (1) The magnesium alloy is subjected to degreasing treatment, the degreasing temperature is 20-50°C, the degreasing time is 10-30s, and in some embodiments, the degreasing temperature is preferably 40°C and the degreasing time is 20s; the magnesium alloy degreasing agent includes at least one of 1-8g / L sodium bicarbonate, 1-5g / L sodium hydroxide, 5-10g / L phosphate, and 0.2-1g / L sodium dodecylbenzene sulfonate. In some embodiments, the magnesium alloy degreasing agent is a mixed solution consisting of 3g / L sodium bicarbonate, 3g / L sodium hydroxide, 5g / L phosphate, and 0.5g / L sodium dodecylbenzene sulfonate. (2) Washing the degreased magnesium alloy with water; (3) Preparing a micro-arc oxidation electrolyte: The micro-arc oxidation electrolyte includes at least one of 5-20 g / L sodium silicate, 1-10 g / L sodium hexametaphosphate, 1-10 g / L sodium phosphate, 1-10 g / L sodium hydroxide, 1-5 g / L sodium fluoride, 1-2 g / L sodium lauryl sulfate, and 8-10 g / L hard particles. In some embodiments, the micro-arc oxidation electrolyte is preferably a mixed solution consisting of 3-10 g / L sodium silicate, 1-5 g / L sodium hexametaphosphate, 5-10 g / L sodium phosphate, 2-4 g / L sodium hydroxide and 1-3 g / L sodium fluoride, 1-2 g / L sodium lauryl sulfate, and 8-10 g / L hard particles. In some embodiments, the hard particles are preferably zirconia particles, and the particle size of the zirconia particles is 20-500 nm, and the particle size is preferably 20 nm. (4) Ultra-high frequency micro-arc oxidation: pour the micro-arc oxidation electrolyte in step (3) into the solution tank, cool it to a temperature of no more than 40°C using a titanium alloy plate heat exchanger, use the stainless steel plate as the cathode and the magnesium alloy washed in step (2) as the anode, adopt a constant current mode, and operate at a current density of 1-20A / dm 2 , a duty cycle of 20% and a frequency of 10000-20000 Hz for 10-100 min; in some embodiments, a constant current mode is used, preferably with a current density of 5 A / dm 2 , micro-arc oxidation was carried out for 25 min at a duty cycle of 20% and a frequency of 10000-20000 Hz; (5) Water washing: washing the magnesium alloy after micro-arc oxidation in step (4); (6) Drying: Drying the magnesium alloy after washing in step (5).

[0019] The present invention is described in detail below with reference to specific embodiments.

[0020] First embodiment This embodiment provides a micro-arc oxidation film suitable for the surface of GW83 magnesium alloy and a preparation method thereof. The preparation method in this embodiment combines ultra-high frequency technology with a method for collaborative processing of hard particles, and includes the following steps: (1) Degreasing: Prepare a magnesium alloy degreasing agent, the main components of which are 3 g / L sodium bicarbonate, 3 g / L sodium hydroxide, 5 g / L phosphate, and 0.5 g / L sodium dodecylbenzene sulfonate. The solvent is deionized water, and the temperature is adjusted to 40 °C. Immerse the GW83 magnesium alloy workpiece (hereinafter referred to as "magnesium alloy") in the magnesium alloy degreasing agent and degrease for 20 seconds to remove surface grease.

[0021] (2) Water washing: The magnesium alloy after degreasing in step (1) is washed with deionized water, and the washing is repeated until no magnesium alloy degreasing agent remains on the surface of the magnesium alloy.

[0022] (3) Preparation of Micro-arc Oxidation Electrolyte: Analytically pure chemicals are used to prepare the micro-arc oxidation electrolyte. The micro-arc oxidation electrolyte consists of a main solution and a sodium dodecyl sulfate solution containing hard particles. In this embodiment, the hard particles are zirconium oxide particles. In other embodiments, the particle size of the zirconium oxide particles is 20-500 nm. In this embodiment, the particle size of the zirconium oxide particles is preferably 20 nm. Those skilled in the art may select the particle size based on actual conditions, and this embodiment does not limit the selection.

[0023] The main solution is a mixed solution consisting of sodium silicate, sodium hexametaphosphate, sodium phosphate, sodium hydroxide and sodium fluoride, the solvent is deionized water, and the mixture is mixed under magnetic stirring and then stirred evenly using compressed air from an air compressor.

[0024] The preparation method of the sodium dodecyl sulfate solution containing zirconium oxide particles is as follows: first prepare the sodium dodecyl sulfate solution, the solvent is deionized water, and then add the zirconium oxide particles, mix them under magnetic stirring conditions, and then use compressed air from an air compressor to stir them evenly.

[0025] The main solution prepared above was mixed with a sodium dodecyl sulfate solution containing zirconium oxide particles, and dispersed evenly using an ultrasonic generator at 90 kHz for 30 minutes to obtain a micro-arc oxidation electrolyte.

[0026] In the micro-arc oxidation electrolyte, the concentrations of the components are 10 g / L sodium silicate, 5 g / L sodium hexametaphosphate, 5 g / L sodium phosphate, 2 g / L sodium hydroxide, 3 g / L sodium fluoride, 1 g / L sodium dodecyl sulfate solution, and 8 g / L zirconium oxide particles.

[0027] (4) Ultra-high frequency micro-arc oxidation: Pour the micro-arc oxidation electrolyte prepared in step (3) into the solution tank, cool the electrolyte with a titanium alloy plate heat exchanger to a temperature not higher than 40°C, use the stainless steel plate as the cathode and the magnesium alloy washed in step (2) as the anode, adopt a constant current mode, and at a current density of 5A / dm 2 , duty cycle of 20% and frequency of 20000 Hz for 25 min, and turn off the power after the oxidation is completed.

[0028] (5) Water washing: The magnesium alloy after micro-arc oxidation in step (4) is washed with deionized water, and the washing is repeated until no micro-arc oxidation electrolyte remains on the surface of the magnesium alloy.

[0029] (6) Drying: Use 0.3 MPa compressed air to blow the surface, gaps, and holes of the magnesium alloy after washing in step (5) from different directions (maintaining a distance of 10 to 20 cm), focusing on the treatment of concave or complex structure areas.

[0030] Second embodiment This embodiment provides a micro-arc oxidation film suitable for the surface of GW83 magnesium alloy and a preparation method thereof. The preparation method in this embodiment combines ultra-high frequency technology with a method for collaborative processing of hard particles, and includes the following steps: (1) Degreasing: Prepare a special degreasing agent for magnesium alloy, the main ingredients of which are 3g / L sodium bicarbonate, 3g / L sodium hydroxide, 5g / L phosphate and 0.5g / L sodium dodecylbenzene sulfonate. The solvent is deionized water, and the temperature is adjusted to 40°C. Immerse the GW83 magnesium alloy specimen (hereinafter referred to as "magnesium alloy") in the magnesium alloy degreasing agent and degrease for 20s to remove surface grease.

[0031] (2) Water washing: The magnesium alloy after degreasing in step (1) is washed with deionized water, and the washing is repeated until no magnesium alloy-specific degreasing agent remains on the surface of the magnesium alloy.

[0032] (3) Preparation of Micro-arc Oxidation Electrolyte: Analytically pure chemicals are used to prepare the micro-arc oxidation electrolyte. The micro-arc oxidation electrolyte consists of a main solution and a sodium dodecyl sulfate solution containing hard particles. In this embodiment, the hard particles are zirconium oxide particles. In other embodiments, the particle size of the zirconium oxide particles is 20-500 nm. In this embodiment, the particle size of the zirconium oxide particles is 20 nm. Those skilled in the art may select the particle size based on actual conditions, and this embodiment does not limit the selection.

[0033] The main solution is a mixed solution consisting of sodium silicate, sodium hexametaphosphate, sodium phosphate, sodium hydroxide and sodium fluoride, the solvent is deionized water, and the mixture is mixed under magnetic stirring and then stirred evenly using compressed air from an air compressor.

[0034] The preparation method of the sodium dodecyl sulfate solution containing zirconium oxide particles is as follows: first prepare the sodium dodecyl sulfate solution, the solvent is deionized water, and then add the zirconium oxide particles, mix them under magnetic stirring conditions, and then use compressed air from an air compressor to stir them evenly.

[0035] The main solution prepared above was mixed with a sodium dodecyl sulfate solution containing zirconium oxide particles, and dispersed evenly using an ultrasonic generator at 90 kHz for 30 minutes to obtain a micro-arc oxidation electrolyte.

[0036] In the micro-arc oxidation electrolyte, the concentrations of the components are 10 g / L sodium silicate, 5 g / L sodium hexametaphosphate, 5 g / L sodium phosphate, 2 g / L sodium hydroxide and 3 g / L sodium fluoride, 1 g / L sodium dodecyl sulfate solution, and 10 g / L zirconium oxide particles.

[0037] (4) Ultra-high frequency micro-arc oxidation: Pour the micro-arc oxidation electrolyte prepared in step (3) into the solution tank, cool the electrolyte with a titanium alloy plate heat exchanger to a temperature not higher than 40°C, use the stainless steel plate as the cathode and the magnesium alloy washed in step (2) as the anode, adopt a constant current mode, and at a current density of 5A / dm 2 , duty cycle of 20% and frequency of 10000 Hz for 25 min, and turn off the power after the oxidation is completed.

[0038] (5) Water washing: The magnesium alloy after micro-arc oxidation in step (4) is washed with deionized water, and the washing is repeated until no micro-arc oxidation electrolyte remains on the surface of the magnesium alloy.

[0039] (6) Drying: Use 0.3 MPa compressed air to blow the surface, gaps, and holes of the magnesium alloy after washing in step (5) from different directions (maintaining a distance of 10 to 20 cm), focusing on the treatment of concave or complex structure areas.

[0040] Third embodiment This embodiment provides a micro-arc oxidation film suitable for the surface of GW83 magnesium alloy and a preparation method thereof. The preparation method in this embodiment combines ultra-high frequency technology with a method for collaborative processing of hard particles, and includes the following steps: (1) Degreasing: Prepare a special degreasing agent for magnesium alloy, the main ingredients of which are 3g / L sodium bicarbonate, 3g / L sodium hydroxide, 5g / L phosphate and 0.5g / L sodium dodecylbenzene sulfonate. The solvent is deionized water, and the temperature is adjusted to 40°C. Immerse the GW83 magnesium alloy specimen (hereinafter referred to as "magnesium alloy") in the magnesium alloy degreasing agent and degrease for 20s to remove surface grease.

[0041] (2) Water washing: The magnesium alloy after degreasing in step (1) is washed with deionized water, and the washing is repeated until no magnesium alloy-specific degreasing agent remains on the surface of the magnesium alloy.

[0042] (3) Preparation of Micro-arc Oxidation Electrolyte: Analytically pure chemicals are used to prepare the micro-arc oxidation electrolyte. The micro-arc oxidation electrolyte consists of a main solution and a sodium dodecyl sulfate solution containing hard particles. In this embodiment, the hard particles are zirconium oxide particles. In other embodiments, the particle size of the zirconium oxide particles is 20-500 nm. In this embodiment, the particle size of the zirconium oxide particles is 20 nm. Those skilled in the art may select the particle size based on actual conditions, and this embodiment does not limit the selection.

[0043] The main solution is a mixed solution consisting of sodium silicate, sodium hexametaphosphate, sodium phosphate, sodium hydroxide and sodium fluoride, the solvent is deionized water, and the mixture is mixed under magnetic stirring and then stirred evenly using compressed air from an air compressor.

[0044] The preparation method of the sodium dodecyl sulfate solution containing zirconium oxide particles is as follows: first prepare the sodium dodecyl sulfate solution, the solvent is deionized water, and then add the zirconium oxide particles, mix them under magnetic stirring conditions, and then use compressed air from an air compressor to stir them evenly.

[0045] The main solution prepared above was mixed with a sodium dodecyl sulfate solution containing zirconium oxide particles, and dispersed evenly using an ultrasonic generator at 90 kHz for 30 minutes to obtain a micro-arc oxidation electrolyte.

[0046] In the micro-arc oxidation electrolyte, the concentrations of the components are 3 g / L sodium silicate, 5 g / L sodium hexametaphosphate, 10 g / L sodium phosphate, 4 g / L sodium hydroxide, 1 g / L sodium fluoride, 2 g / L sodium dodecyl sulfate solution, and 8 g / L zirconium oxide particles.

[0047] (4) Ultra-high frequency micro-arc oxidation: Pour the micro-arc oxidation electrolyte prepared in step (3) into the solution tank, cool the electrolyte with a titanium alloy plate heat exchanger to a temperature not higher than 40°C, use the stainless steel plate as the cathode and the magnesium alloy washed in step (2) as the anode, adopt a constant current mode, and at a current density of 5A / dm 2 , duty cycle of 20% and frequency of 20000 Hz for 25 min, and turn off the power after the oxidation is completed.

[0048] (5) Water washing: The magnesium alloy after micro-arc oxidation in step (4) is washed with deionized water, and the washing is repeated until no micro-arc oxidation electrolyte remains on the surface of the magnesium alloy.

[0049] (6) Drying: Use 0.3 MPa compressed air to blow the surface, gaps, and holes of the magnesium alloy after washing in step (5) from different directions (maintaining a distance of 10 to 20 cm), focusing on the treatment of concave or complex structure areas.

[0050] Fourth embodiment This embodiment provides a micro-arc oxidation film suitable for the surface of GW83 magnesium alloy and a preparation method thereof. The preparation method in this embodiment combines ultra-high frequency technology with a method for collaborative processing of hard particles, and includes the following steps: (1) Degreasing: Prepare a special degreasing agent for magnesium alloy, the main ingredients of which are 3g / L sodium bicarbonate, 3g / L sodium hydroxide, 5g / L phosphate and 0.5g / L sodium dodecylbenzene sulfonate. The solvent is deionized water, and the temperature is adjusted to 40°C. Immerse the GW83 magnesium alloy specimen (hereinafter referred to as "magnesium alloy") in the magnesium alloy degreasing agent and degrease for 20s to remove surface grease.

[0051] (2) Water washing: The magnesium alloy after degreasing in step (1) is washed with deionized water, and the washing is repeated until no magnesium alloy-specific degreasing agent remains on the surface of the magnesium alloy.

[0052] (3) Preparation of Micro-arc Oxidation Electrolyte: Analytically pure chemicals are used to prepare the micro-arc oxidation electrolyte. The micro-arc oxidation electrolyte consists of a main solution and a sodium dodecyl sulfate solution containing hard particles. In this embodiment, the hard particles are zirconium oxide particles. In other embodiments, the particle size of the zirconium oxide particles is 20-500 nm. In this embodiment, the particle size of the zirconium oxide particles is 20 nm. Those skilled in the art may select the particle size based on actual conditions, and this embodiment does not limit the selection.

[0053] The main solution is a mixed solution consisting of sodium silicate, sodium hexametaphosphate, sodium phosphate, sodium hydroxide and sodium fluoride, the solvent is deionized water, and the mixture is mixed under magnetic stirring and then stirred evenly using compressed air from an air compressor.

[0054] The preparation method of the sodium dodecyl sulfate solution containing zirconium oxide particles is as follows: first prepare the sodium dodecyl sulfate solution, the solvent is deionized water, and then add the zirconium oxide particles, mix them under magnetic stirring conditions, and then use compressed air from an air compressor to stir them evenly.

[0055] The main solution prepared above was mixed with a sodium dodecyl sulfate solution containing zirconium oxide particles, and dispersed evenly using an ultrasonic generator at 90 kHz for 30 minutes to obtain a micro-arc oxidation electrolyte.

[0056] In the micro-arc oxidation electrolyte, the concentration of each component is 3g / L sodium silicate, 5g / L sodium hexametaphosphate, 10g / L sodium phosphate, 4g / L sodium hydroxide, 1g / L sodium fluoride, 2g / L sodium dodecyl sulfate solution, and 8g / L zirconium oxide particles.

[0057] (4) Ultra-high frequency micro-arc oxidation: Pour the micro-arc oxidation electrolyte prepared in step (3) into the solution tank, cool the electrolyte with a titanium alloy plate heat exchanger to a temperature not higher than 40°C, use the stainless steel plate as the cathode and the magnesium alloy washed in step (2) as the anode, adopt a constant current mode, and at a current density of 5A / dm 2 , micro-arc oxidation was carried out for 25 min under the conditions of a duty cycle of 20% and a frequency of 10000 Hz, and the power was turned off after the oxidation was completed; (5) Water washing: washing the magnesium alloy after micro-arc oxidation in step (4) with deionized water, and repeating the water washing until no micro-arc oxidation electrolyte remains on the surface of the magnesium alloy; (6) Drying: Use 0.3 MPa compressed air to blow the surface, gaps, and holes of the magnesium alloy after washing in step (5) from different directions (maintaining a distance of 10 to 20 cm), focusing on the treatment of concave or complex structure areas.

[0058] The first comparison This comparative example provides a micro-arc oxidation film suitable for the surface of GW83 magnesium alloy and a preparation method thereof. The preparation method in this comparative example uses a normal pulse frequency (500 Hz) and does not add hard particles, and includes the following steps: (1) Degreasing: Prepare a magnesium alloy degreasing agent, the main components of which are 3 g / L sodium bicarbonate, 3 g / L sodium hydroxide, 5 g / L phosphate and 0.5 g / L sodium dodecylbenzene sulfonate. The solvent is deionized water, and the temperature is adjusted to 40 °C. Immerse the GW83 magnesium alloy specimen (hereinafter referred to as "magnesium alloy") in the magnesium alloy degreasing agent and degrease for 20 seconds to remove surface grease.

[0059] (2) Water washing: The magnesium alloy after degreasing in step (1) is washed with deionized water, and the washing is repeated until no magnesium alloy-specific degreasing agent remains on the surface of the magnesium alloy.

[0060] (3) Preparation of micro-arc oxidation electrolyte: Analytically pure chemicals were used to prepare the micro-arc oxidation electrolyte. The micro-arc oxidation electrolyte was a mixed solution consisting of 10 g / L sodium silicate, 5 g / L sodium hexametaphosphate, 5 g / L sodium phosphate, 2 g / L sodium hydroxide, 3 g / L sodium fluoride and 1 g / L sodium dodecyl sulfate. The solvent was deionized water. After mixing under magnetic stirring, the mixture was stirred evenly using compressed air from an air compressor. Then, an ultrasonic generator was used at 90 kHz for 30 min to disperse the mixture evenly to obtain the micro-arc oxidation electrolyte. (4) Micro-arc oxidation: Pour the micro-arc oxidation electrolyte prepared in step (3) into the solution tank, cool the electrolyte with a titanium alloy plate heat exchanger to a temperature not higher than 40°C, use the stainless steel plate as the cathode and the magnesium alloy washed in step (2) as the anode, adopt a constant current mode, and at a current density of 5A / dm 2 , duty cycle of 20% and frequency of 500 Hz for 25 min, and turn off the power after the oxidation is completed.

[0061] (5) Water washing: The magnesium alloy after micro-arc oxidation in step (4) is washed with deionized water, and the washing is repeated until no micro-arc oxidation electrolyte remains on the surface of the magnesium alloy.

[0062] (6) Drying: Use 0.3 MPa compressed air to blow the surface, gaps, and holes of the magnesium alloy after washing in step (5) from different directions (maintaining a distance of 10 to 20 cm), focusing on the treatment of concave or complex structure areas.

[0063] The second comparison This comparative example provides a micro-arc oxidation film suitable for the surface of GW83 magnesium alloy and a preparation method thereof. The preparation method in this comparative example uses an ultra-high frequency pulse frequency (20,000 Hz) without adding hard particles, and includes the following steps: (1) Degreasing: Prepare a magnesium alloy degreasing agent, the main components of which are 3 g / L sodium bicarbonate, 3 g / L sodium hydroxide, 5 g / L phosphate and 0.5 g / L sodium dodecylbenzene sulfonate. The solvent is deionized water, and the temperature is adjusted to 40 °C. Immerse the GW83 magnesium alloy specimen (hereinafter referred to as "magnesium alloy") in the magnesium alloy degreasing agent and degrease for 20 seconds to remove surface grease. (2) Water washing: The magnesium alloy after degreasing in step (1) is washed with deionized water, and the washing is repeated until no magnesium alloy special degreasing agent remains on the surface of the magnesium alloy; (3) Preparation of micro-arc oxidation electrolyte: Analytically pure chemicals were used to prepare the micro-arc oxidation electrolyte. The micro-arc oxidation electrolyte consisted of a mixed solution of 10 g / L sodium silicate, 5 g / L sodium hexametaphosphate, 5 g / L sodium phosphate, 2 g / L sodium hydroxide, 3 g / L sodium fluoride and 1 g / L sodium lauryl sulfate. The solvent was deionized water. After mixing under magnetic stirring, the mixture was stirred evenly using compressed air from an air compressor. The mixture was then dispersed evenly using an ultrasonic generator at 90 kHz for 30 min to obtain the micro-arc oxidation electrolyte. (4) Micro-arc oxidation: pour the micro-arc oxidation electrolyte prepared in step (3) into the solution tank, cool the electrolyte with a titanium alloy plate heat exchanger to a temperature not higher than 40°C, use the stainless steel plate as the cathode and the magnesium alloy washed in step (2) as the anode, adopt a constant current mode, and carry out micro-arc oxidation for 25 minutes under the conditions of a current density of 5A / dm2, a duty cycle of 20%, and a frequency of 20,000Hz. After the oxidation is completed, turn off the power supply; (5) Water washing: washing the magnesium alloy after micro-arc oxidation in step (4) with deionized water, and repeating the water washing until no micro-arc oxidation electrolyte remains on the surface of the magnesium alloy; (6) Drying: Use 0.3 MPa compressed air to blow the surface, gaps, and holes of the magnesium alloy after washing in step (5) from different directions (maintaining a distance of 10 to 20 cm), focusing on the treatment of concave or complex structure areas.

[0064] The third comparison This comparative example provides a micro-arc oxidation film suitable for the surface of GW83 magnesium alloy and a preparation method thereof. The preparation method in this comparative example uses a normal pulse frequency (500 Hz) and adds hard particles, and includes the following steps: (1) Degreasing: Prepare a magnesium alloy degreasing agent, the main components of which are 3 g / L sodium bicarbonate, 3 g / L sodium hydroxide, 5 g / L phosphate and 0.5 g / L sodium dodecylbenzene sulfonate. The solvent is deionized water, and the temperature is adjusted to 40 °C. Immerse the GW83 magnesium alloy specimen (hereinafter referred to as "magnesium alloy") in the magnesium alloy degreasing agent and degrease for 20 seconds to remove surface grease.

[0065] (2) Water washing: The magnesium alloy after degreasing in step (1) is washed with deionized water, and the washing is repeated until no magnesium alloy-specific degreasing agent remains on the surface of the magnesium alloy.

[0066] (3) Preparation of micro-arc oxidation electrolyte: Use analytically pure chemicals to prepare the micro-arc oxidation electrolyte, which consists of a main solution and a sodium dodecyl sulfate solution containing hard particles.

[0067] The main solution is a mixed solution consisting of sodium silicate, sodium hexametaphosphate, sodium phosphate, sodium hydroxide and sodium fluoride, the solvent is deionized water, and the mixture is mixed under magnetic stirring and then stirred evenly using compressed air from an air compressor.

[0068] The preparation method of the sodium dodecyl sulfate solution containing zirconium oxide particles is as follows: first prepare the sodium dodecyl sulfate solution, the solvent is deionized water, and then add the zirconium oxide particles, mix them under magnetic stirring conditions, and then use compressed air from an air compressor to stir them evenly.

[0069] The main solution prepared above was mixed with a sodium dodecyl sulfate solution containing zirconium oxide particles, and dispersed evenly using an ultrasonic generator at 90 kHz for 30 minutes to obtain a micro-arc oxidation electrolyte.

[0070] In the micro-arc oxidation electrolyte, the concentration of each component is 10g / L sodium silicate, 5g / L sodium hexametaphosphate, 5g / L sodium phosphate, 2g / L sodium hydroxide, 3g / L sodium fluoride, 1g / L sodium dodecyl sulfate solution, and 10g / L zirconium oxide particles.

[0071] (4) Micro-arc oxidation: pour the micro-arc oxidation electrolyte prepared in step (3) into the solution tank, cool the electrolyte with a titanium alloy plate heat exchanger to a temperature not higher than 40°C, use the stainless steel plate as the cathode and the magnesium alloy washed in step (2) as the anode, adopt a constant current mode, and carry out micro-arc oxidation for 25 minutes under the conditions of a current density of 5A / dm2, a duty cycle of 20% and a frequency of 500Hz. After the oxidation is completed, turn off the power supply; (5) Water washing: washing the magnesium alloy after micro-arc oxidation in step (4) with deionized water, and repeating the water washing until no micro-arc oxidation electrolyte remains on the surface of the magnesium alloy; (6) Drying: Use 0.3 MPa compressed air to blow the surface, gaps, and holes of the magnesium alloy after washing in step (5) from different directions (maintaining a distance of 10 to 20 cm), focusing on the treatment of concave or complex structure areas.

[0072] Experimental example This experimental example employed the following experiments to verify the excellent wear and corrosion resistance of the micro-arc oxidation film obtained using the ultra-high frequency (UHF) and hard particle micro-arc oxidation method provided by the present invention. Hardness testing, friction coefficient testing, and friction and wear trace testing demonstrated excellent wear resistance, while polarization curve corrosion current density testing demonstrated excellent corrosion resistance.

[0073] 1) EDS analysis experiment The film surface was observed using a field emission scanning electron microscope at a magnification of 200 times, and the main components of the micro-arc oxidation film on the surface of GW83 magnesium alloy were analyzed using an energy dispersive X-ray spectrometer equipped with the instrument.

[0074] The main component results of the micro-arc oxidation films on the surface of the GW83 magnesium alloy provided by the first comparative example, the second comparative example, the third comparative example and the first embodiment are shown in Table 1: The micro-arc oxidation film of the first embodiment (PEO-20k-Z) is mainly composed of Mg, O, Si, P and Zr elements, among which the mass percentages of Mg, O, Si, P and Zr are 13.7%, 33.1%, 5.4%, 1.4% and 46.2% respectively.

[0075] Table 1 EDS analysis of GW83 magnesium alloy The micro-arc oxidation film on the surface of the GW83 magnesium alloy provided by the first comparative example (PEO-500) is mainly composed of Mg, O, Si, and P elements, wherein the mass percentages of Mg, O, Si, and P are 42.7%, 40.2%, 12.7%, and 4.4%, respectively.

[0076] The micro-arc oxidation film on the surface of the GW83 magnesium alloy provided by the second comparative example (PEO-20k) is mainly composed of Mg, O, Si, and P elements, wherein the mass percentages of Mg, O, Si, and P are 48.8%, 39.2%, 8.5%, and 3.5%, respectively.

[0077] The micro-arc oxidation film on the surface of the GW83 magnesium alloy provided by the third comparative example (PEO-500-Z) is mainly composed of Mg, O, Si, P and Zr elements, among which the mass percentages of Mg, O, Si, P and Zr are 27.1%, 35.2%, 5.0%, 3.3% and 29.4%, respectively.

[0078] The main component difference of the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided by the first embodiment and the first, second and third comparative examples is the presence of the Zr element. The Zr element does not exist in the first and second comparative examples, and the Zr element exists in the third comparative example and the first embodiment. However, the Zr element content in the first embodiment is higher than the Zr element content in the third comparative example. The results show that the added zirconia hard particles participate in the film layer composition process, and under the action of ultra-high frequency pulses, more hard particles participate in the composition process of the micro-arc oxidation film layer.

[0079] 2) SEM morphology observation The morphology of the micro-arc oxidation film on the surface of GW83 magnesium alloy was observed using a field emission scanning electron microscope. The surface morphology results are as follows: Figure 1 The cross-sectional morphology results are shown in Figure 2 shown.

[0080] The SEM morphology observation results of the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided in the first embodiment are as follows: Figure 1 (d1), 1(d2) and Figure 2 As shown in (d), the surface of the micro-arc oxidation film is covered with discharge holes, the diameter of the discharge holes is less than 3.2μm, the thickness of the micro-arc oxidation film is between 25-32μm, and the micro-arc oxidation film is metallurgically bonded to the magnesium alloy substrate in a jagged shape, indicating that the micro-arc oxidation film has good bonding with the GW83 magnesium alloy. When subjected to external forces (such as friction, impact, bending), temperature changes or environmental factors (such as corrosive media), the film layer is not easy to fall off, bubble or peel off from the substrate, and has a protective effect on the substrate.

[0081] The SEM morphology observation results of the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided in the first comparative example are as follows: Figure 1 (a1), 1(a2) and Figure 2 As shown in (a), the surface of the micro-arc oxidation film is covered with discharge holes, and the diameter of the discharge holes is less than 6.2μm. The thickness of the micro-arc oxidation film is between 20-30μm. The micro-arc oxidation film and the magnesium alloy substrate are metallurgically bonded in a jagged pattern, indicating that the micro-arc oxidation film has good bonding with the GW83 magnesium alloy. When subjected to external forces (such as friction, impact, bending), temperature changes or environmental factors (such as corrosive media), the film layer is not easy to fall off, bubble or peel off from the substrate, and has a protective effect on the substrate.

[0082] The SEM morphology observation results of the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided in the second comparative example are as follows: Figure 1 (b1), 1(b2) and Figure 2As shown in (b), the surface of the micro-arc oxidation film is covered with discharge holes, the diameter of the discharge holes is less than 4.5μm, the thickness of the micro-arc oxidation film is between 23-32μm, and the micro-arc oxidation film and the magnesium alloy substrate are metallurgically bonded in a jagged shape, indicating that the micro-arc oxidation film has good bonding with the GW83 magnesium alloy. When subjected to external forces (such as friction, impact, bending), temperature changes or environmental factors (such as corrosive media), the film layer is not easy to fall off, bubble or peel off from the substrate, and has a protective effect on the substrate.

[0083] The SEM morphology observation results of the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided in the third comparative example are as follows: Figure 1 (c1), 1(c2) and Figure 2 As shown in (c), the surface of the micro-arc oxidation film is covered with discharge holes, the diameter of the discharge holes is less than 6.0μm, the thickness of the micro-arc oxidation film is between 20-30μm, and the micro-arc oxidation film is metallurgically bonded to the magnesium alloy substrate in a jagged shape, indicating that the micro-arc oxidation film has good bonding with the GW83 magnesium alloy. When subjected to external forces (such as friction, impact, bending), temperature changes or environmental factors (such as corrosive media), the film layer is not easy to fall off, bubble or peel off from the substrate, and has a protective effect on the substrate.

[0084] The main difference between the micro-arc oxidation films on the surface of the GW83 magnesium alloy provided by the first embodiment and the first, second and third comparative examples lies in the size of the discharge hole diameter. From the above data, it can be seen that the discharge hole diameter of the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided by the first embodiment is the smallest (less than 3.2 μm), indicating that the ultra-high frequency and hard particle micro-arc oxidation treatment method effectively promotes the deposition of hard particles, closes the discharge holes of the micro-arc oxidation film layer, and is beneficial to improving the corrosion resistance of the film layer.

[0085] 3) XRD analysis Cu Kα radiation was used at 4° min -1 The crystalline material composition of the micro-arc oxidation film on the surface of GW83 magnesium alloy was analyzed by X-ray diffraction (XRD) with a scanning rate in the 2θ range of 10° to 80°.

[0086] The XRD analysis results are as follows Figure 3 As shown in the figure, the micro-arc oxidation film on the surface of GW83 magnesium alloy provided by the first embodiment (PEO-20k-Z) is mainly composed of MgO, Mg2Zr5O 12 , Mg2SiO4 and other crystalline substances; the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided by the first comparative example (PEO-500) and the second comparative example (PEO-20k) is mainly composed of MgO, Mg2SiO4 and other crystalline substances; the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided by the third comparative example is mainly composed of MgO, Mg2Zr5O12 , Mg2SiO4 and other crystalline substances.

[0087] XRD analysis results show that the zirconium oxide particles added to the micro-arc oxidation solution are Mg2Zr5O 12 The composite oxide crystal material form participates in the film composition.

[0088] 4) Hardness test The hardness of the micro-arc oxidation film prepared on GW83 magnesium alloy was measured using a nanoindenter. The nanoindenter setting parameters were: depth of 0.1 mm, duration of 15 s, and the results were as follows: Figure 4 shown.

[0089] The test result of the magnesium alloy substrate (GW83 alloy) using a nanoindenter was 1.4 GPa; the test result of the micro-arc oxidation film (PEO-20K-Z) on the surface of the GW83 magnesium alloy provided in the first embodiment using a nanoindenter was 11.4 GPa; the test result of the micro-arc oxidation film (PEO-500) on the surface of the GW83 magnesium alloy provided in the first comparative example using a nanoindenter was 8.6 GPa; the test result of the micro-arc oxidation film (PEO-20k) on the surface of the GW83 magnesium alloy provided in the second comparative example using a nanoindenter was 8.8 GPa; and the test result of the micro-arc oxidation film (PEO-500-Z) on the surface of the GW83 magnesium alloy provided in the third comparative example using a nanoindenter was 10.6 GPa.

[0090] Comparing the test results of the first embodiment with the first, second and third comparative examples and the test results of the magnesium alloy substrate, it is shown that the micro-arc oxidation film prepared by the preparation method of ultra-high frequency coordinated hard particle micro-arc oxidation has the highest microhardness and its wear resistance is correspondingly improved.

[0091] 5) Friction and wear test The tribological properties of the micro-arc oxidation film on the surface of GW83 magnesium alloy were tested using a multifunctional wear tester. The test conditions were: load 10N, linear speed 10 mm / s, oscillation amplitude 5 mm, duration 15 min, and the friction pair was an alumina ceramic ball with a diameter of 6.35 mm. The average friction coefficient test results are shown in Figure 2. Figure 5 shown.

[0092] like Figure 5As shown in (a), the CFO value of the GW83 magnesium alloy substrate rises rapidly initially, then fluctuates around 0.4 as the friction process continues. The friction coefficient characteristics of the four PEO micro-arc oxidation films (provided in the first embodiment, the first comparative example, the second comparative example, and the third comparative example) are similar. The friction coefficient rises slowly initially, eventually approaching the horizontal fluctuation state of the magnesium alloy substrate, with a small fluctuation amplitude.

[0093] like Figure 5 As shown in (b), the average friction coefficient of the magnesium alloy substrate (GW83 alloy) is 0.35. The average friction coefficients of the micro-arc oxidation film (PEO-20K-Z) on the surface of the GW83 magnesium alloy provided by the first embodiment, the first comparative example (PEO-500), the second comparative example (PEO-20k), and the third comparative example (PEO-500-Z) are 0.3, 0.5, 0.4, and 0.4, respectively. The friction coefficient test results demonstrate that both ultrahigh frequency pulses and hard particles reduce the friction coefficient. Therefore, through the synergistic effect of ultrahigh frequency and hard particles, the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided by the first embodiment has the lowest friction coefficient.

[0094] At the same time, the profile and surface morphology of the wear marks on the micro-arc oxidation film on the surface of GW83 magnesium alloy were tested using a surface profiler and a scanning electron microscope. Figure 6 shown.

[0095] The wear scar width of the magnesium alloy substrate (GW83 alloy) is 1018.3 μm, with obvious grooves and deep wear marks parallel to the sliding direction. The wear scar width of the micro-arc oxidation film (PEO-20K-Z) on the surface of the GW83 magnesium alloy provided by the first embodiment is 368.3 μm, with less debris shedding and a flatter wear scar. The wear scar widths of the first comparative example (PEO-500), the second comparative example (PEO-20k), and the third comparative example (PEO-500-Z) are 736.7 μm, 563.3 μm, and 628.3 μm, respectively, and obvious ceramic fragments fall off on the worn surface.

[0096] The friction and wear mark test shows that the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided by the first embodiment has the best wear resistance.

[0097] 6) Potentiodynamic polarization curve test At a scan rate of 1 mV / s, a potentiodynamic polarization test was performed from −0.25 V vsOCP to 1.2 V vsOCP with the open circuit potential as the reference. The results are shown in the figure. Figure 7 As shown. The corrosion potential (E corr) and corrosion current density (i corr ) and other electrochemical parameters, and the results are shown in Table 2.

[0098] Table 2 Corrosion potential (E corr ) and corrosion current density (i corr ) Electrochemical parameters The corrosion current density of the magnesium alloy substrate is 4.1 × 10 -5 A / cm 2 The corrosion current density of the micro-arc oxidation film on the surface of the GW83 magnesium alloy provided by the first embodiment (PEO-20K-Z), the first comparative example (PEO-500), the second comparative example (PEO-20k), and the third comparative example (PEO-500-Z) is 4.8 × 10 -7 A / cm2 , 3.3 × 10 -6 A / cm 2、5.7 × 10-7 A / cm 2 , 1.9 × 10 -6A / cm2 .

[0099] The micro-arc oxidation film on the surface of the GW83 magnesium alloy provided in the first embodiment has the smallest corrosion current density and the largest corrosion potential, indicating that the micro-arc oxidation film prepared by ultra-high frequency and hard particles provided by the present invention has excellent corrosion resistance.

[0100] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A method for treating magnesium alloy by ultra-high frequency coordinated micro-arc oxidation of hard particles, characterized in that: The following steps are involved: (1) Degreasing the magnesium alloy; (2) Washing the degreased magnesium alloy with water; (3) preparing a micro-arc oxidation electrolyte: the micro-arc oxidation electrolyte comprises at least one of 5-20 g / L sodium silicate, 1-10 g / L sodium hexametaphosphate, 1-10 g / L sodium phosphate, 1-10 g / L sodium hydroxide, 1-5 g / L sodium fluoride, 1-2 g / L sodium lauryl sulfate, and 8-10 g / L hard particles; (4) Ultra-high frequency micro-arc oxidation: pour the micro-arc oxidation electrolyte in step (3) into the solution tank, cool it to a temperature of no more than 40°C using a titanium alloy plate heat exchanger, use the stainless steel plate as the cathode and the magnesium alloy washed in step (2) as the anode, adopt a constant current mode, and operate at a current density of 1-20A / dm 2 , micro-arc oxidation is carried out for 10-100 min at a duty cycle of 20% and a frequency of 10000-20000 Hz; (5) Water washing: washing the magnesium alloy after micro-arc oxidation in step (4); (6) Drying: Drying the magnesium alloy after washing in step (5).

2. The method for treating magnesium alloy by ultra-high frequency coordinated hard particle micro-arc oxidation according to claim 1, characterized in that: In step (1), the degreasing temperature is 20-50° C., and the degreasing time is 10-30 seconds.

3. The method for treating magnesium alloy by ultra-high frequency coordinated hard particle micro-arc oxidation according to claim 1, characterized in that: In step (1), the magnesium alloy degreasing agent includes at least one of 1-8 g / L sodium bicarbonate, 1-5 g / L sodium hydroxide, 5-10 g / L phosphate, and 0.2-1 g / L sodium dodecylbenzene sulfonate.

4. The method for treating magnesium alloy by ultra-high frequency coordinated micro-arc oxidation of hard particles according to claim 3, characterized in that: The magnesium alloy degreasing agent includes at least one of 3g / L sodium bicarbonate, 3g / L sodium hydroxide, 5g / L phosphate, and 0.5g / L sodium dodecylbenzene sulfonate.

5. The method for treating magnesium alloy by ultra-high frequency coordinated micro-arc oxidation of hard particles according to claim 1, characterized in that: In step (3), the micro-arc oxidation electrolyte includes at least one of 3-10 g / L sodium silicate, 1-5 g / L sodium hexametaphosphate, 5-10 g / L sodium phosphate, 2-4 g / L sodium hydroxide, 1-3 g / L sodium fluoride, 1-2 g / L sodium lauryl sulfate, and 8-10 g / L hard particles.

6. The method for treating magnesium alloy by ultra-high frequency coordinated micro-arc oxidation of hard particles according to claim 5, characterized in that: The hard particles are zirconium oxide particles.

7. The method for treating magnesium alloy by ultra-high frequency coordinated micro-arc oxidation of hard particles according to claim 6, characterized in that: The particle size of the zirconium oxide particles is 20-500 nm.

8. The method for treating magnesium alloy by ultra-high frequency coordinated micro-arc oxidation of hard particles according to claim 6, characterized in that: The particle size of the zirconium oxide particles is 20 nm.

9. The method for treating magnesium alloy by ultra-high frequency coordinated hard particle micro-arc oxidation according to claim 1, characterized in that: In step (4), the constant current mode is adopted, and the current density is 5A / dm 2 , micro-arc oxidation was carried out for 25 min under the conditions of a duty cycle of 20% and a frequency of 10000-20000 Hz.

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