Magnesium alloy with silicon-sodium functional layer and preparation method thereof

Abstract

The invention discloses a magnesium alloy with a silicon-sodium functional layer and a preparation method of the magnesium alloy, and belongs to the technical field of metal material surface processing. The invention provides a preparation method of a magnesium alloy with a silicon-sodium functional layer, which comprises the following steps: carrying out anodic oxidation treatment on the magnesium alloy in an electrolyte containing a silicon source, a boron source and a sodium source to obtain the magnesium alloy subjected to anodic oxidation treatment; the magnesium alloy subjected to anodic oxidation treatment is placed in a solution A containing a silicon source and a sodium source to be subjected to a hydrothermal reaction, and magnesium alloy subjected to the hydrothermal reaction is obtained; and grinding the magnesium alloy subjected to the hydrothermal reaction, putting the magnesium alloy into a solution B containing a silicon source and a sodium source, and obtaining the magnesium alloy with the silicon-sodium functional layer by adopting a micro-arc oxidation method. According to the magnesium alloy with the silicon-sodium functional layer prepared through the preparation method, the corrosion resistance and the wear resistance of the magnesium alloy are effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of metal material surface processing, and more specifically to a magnesium alloy with a silicon-sodium functional layer and a preparation method thereof. Background Art

[0002] Magnesium alloy is an alloy composed of magnesium and other elements. It has many excellent properties such as low density, high specific stiffness, strong shock absorption, good electrical and thermal conductivity, and easy recycling. In order to achieve the purpose of lightweighting, magnesium alloy is often used as a key component material in portable equipment and engineering. It is now widely used in aerospace engineering, transportation industry, military defense, petrochemical industry, and biomedical equipment materials. With the transformation and upgrading of my country's automobile industry and 3C industries and the significant improvement of China's economic status, the promotion and application of magnesium alloy plays a vital role in solving the lightweight problem of my country's key equipment and major projects.

[0003] However, magnesium alloys are very active in chemical properties and are easily corroded when in contact with water or in certain acidic environments. In addition, magnesium alloys have poor corrosion resistance, are easy to oxidize and burn, have poor heat resistance, and are severely worn in environments with friction. As key parts materials in some engineering fields, they are limited. These performance defects of magnesium alloys have seriously restricted its wide application and development space. Anodizing, a surface treatment method for magnesium alloys, has become the most promising surface treatment technology for magnesium alloys due to its simple process, large film forming area, convenient processing of complex workpieces, and low cost. However, the surface of anodized magnesium alloys has a double-layer structure, with a thin and dense inner layer and a thick and porous outer layer. At present, the sealing technology of anodized film of magnesium alloys is not mature, and the porous structure reduces its corrosion resistance and wear resistance. Therefore, it is of great significance to explore effective methods to improve the corrosion resistance and wear resistance of magnesium alloys. Summary of the invention

[0004] In view of the above problems, the present invention provides a magnesium alloy with a silicon-sodium functional layer and a preparation method thereof. The magnesium alloy with a silicon-sodium functional layer prepared by the preparation method of the present invention effectively improves the corrosion resistance and wear resistance of the magnesium alloy.

[0005] In a first aspect, the present invention provides a method for preparing a magnesium alloy having a silicon-sodium functional layer, comprising the following steps:

[0006] In an electrolyte containing a silicon source, a boron source and a sodium source, an anodized magnesium alloy is subjected to an anodic oxidation treatment to prepare micropores on the surface of the magnesium alloy to form a spatial network framework structure, thereby obtaining an anodized magnesium alloy;

[0007] The magnesium alloy after anodization treatment is placed in a solution A of an electrolyte containing a silicon source and a sodium source for hydrothermal reaction to form a silicon-sodium film layer, and silicon-sodium micro-nano particles are filled into the spatial network framework structure on the surface of the magnesium alloy to obtain a magnesium alloy after hydrothermal reaction;

[0008] The magnesium alloy after the hydrothermal reaction is polished and then placed in a solution B of an electrolyte containing a silicon source and a sodium source. The silicon source is used to seal the pores and reconstruct the surface of the magnesium alloy by a micro-arc oxidation method to obtain a magnesium alloy with a silicon-sodium functional layer.

[0009] In an exemplary embodiment of the present invention, the voltage of the anodizing treatment is 20-50V, and the oxidation time is 20-30min.

[0010] For example, the voltage is 20V, 22V, 24V, 26V, 28V, 30V, 32V, 34V, 36V, 38V, 40V, 42V, 44V, 46V, 48V, 50V; the oxidation time is 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min, 30min; but it is not limited to the listed values, other values ​​not listed within the above numerical range are also applicable.

[0011] In an exemplary embodiment of the present invention, the electrolyte containing a silicon source, a boron source and a sodium source is composed of a sodium source, a silicon source and a boron source in a molar concentration ratio of 1-1.5:0.1-1:0.8-1.

[0012] In an exemplary embodiment of the present invention, the temperature of the hydrothermal reaction is 150-190° C. and the time is 2-4 hours.

[0013] For example, the temperature of the hydrothermal reaction is 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, and 190°C; the time is 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h, and 4h; but it is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0014] In an exemplary embodiment of the present invention, the solution A containing a silicon source and a sodium source is composed of a sodium source and a silicon source in a mass concentration ratio of 5-6:14-16.

[0015] For example, in solution A containing a silicon source and a sodium source, the mass concentration ratio of the sodium source to the silicon source is 5:14, 5:15, 5:16, 5.5:14, 5.5:15, 5.5:16, 6:14, 6:15, and 6:16; but it is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0016] In an exemplary embodiment of the present invention, the voltage of the micro-arc oxidation method is 380-400V, and the oxidation time is 10-15 minutes.

[0017] For example, the voltage of the micro-arc oxidation method is 380V, 382V, 384V, 386V, 388V, 390V, 392V, 394V, 396V, 398V, and 400V; the oxidation time is 10min, 11min, 12min, 13min, 14min, and 15min; but it is not limited to the listed values, and other unlisted values ​​within the above numerical range are also applicable.

[0018] In an exemplary embodiment of the present invention, the solution B containing a silicon source and a sodium source is composed of a sodium source and a silicon source in a mass concentration ratio of 1-3:2.

[0019] For example, in solution B containing a silicon source and a sodium source, the mass concentration ratio of the sodium source to the silicon source is 1:2, 1.5:2, 2:2, 2.5:2, 3:2. However, the above values ​​are not limited thereto, and other values ​​not listed within the above range are also applicable.

[0020] In an exemplary embodiment of the present invention, the sodium source in the electrolyte, solution A and solution B is independently selected from one or more of NaOH, Na2CO3, and NaAlO2;

[0021] It will be appreciated that the sodium source may be NaOH, Na2CO3, NaAlO2, a combination of NaOH and Na2CO3, a combination of NaOH and NaAlO2, a combination of Na2CO3 and NaAlO2, a combination of NaOH, Na2CO3, NaAlO2, and the like.

[0022] In an exemplary embodiment of the present invention, the silicon source in the electrolyte, solution A and solution B is independently selected from one or more of sodium silicate, white carbon black and sodium metasilicate nonahydrate;

[0023] It is understood that the silicon source can be sodium silicate, white carbon, sodium metasilicate nonahydrate, a combination of sodium silicate and sodium metasilicate nonahydrate, a combination of sodium silicate and white carbon, a combination of white carbon and sodium metasilicate nonahydrate, a combination of sodium silicate, white carbon, sodium metasilicate nonahydrate, etc.;

[0024] The boron source in the electrolyte is Na2B4O7.

[0025] In a second aspect, the present invention provides a magnesium alloy having a sodium-silicon functional layer prepared by the preparation method described in the first aspect.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention adopts a method for preparing a magnesium alloy with a silicon-sodium functional layer, and uses an anodic oxidation method to control and prepare uniform micropores on the surface of the magnesium alloy to form a spatial network framework structure. Subsequently, a hydrothermal method is used to prepare a layer of silicon-sodium film on the surface of each magnesium alloy with a microporous structure, so that silicon-sodium micro-nano particles are effectively filled into the spatial network framework structure on the surface of the magnesium alloy. During the micro-arc oxidation treatment process, the silicon source plays a role in sealing the pores. The micro-arc oxidation method is used to control the preparation of a microstructure functional layer of a composite of silicon-sodium and magnesium alloy, and the surface is reconstructed. Finally, a functional layer surface structure with the characteristics of "interlacing + papillae" is formed.

[0028] The process of the invention is simple, and the prepared magnesium alloy surface functional layer has good super-hydrophobicity and excellent corrosion resistance and wear resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention provides a flow chart of the preparation process.

[0030] Figure 2 This is the water contact angle test result of Example 1 of the present invention.

[0031] Figure 3 It is a schematic diagram of the actual friction performance testing method of the present invention.

[0032] Figure 4 The corrosion resistance test results of the magnesium alloy samples prepared in the present invention are shown in Figure a, where Figure a is the corrosion current density and Figure b is the semicircle diameter. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] As described in the background technology, in order to further improve the corrosion resistance and wear resistance of magnesium alloy, the present invention provides a method for preparing a magnesium alloy with a silicon-sodium functional layer, comprising the following steps:

[0035] In an electrolyte containing a silicon source, a boron source and a sodium source, an anodized magnesium alloy is subjected to an anodic oxidation treatment to prepare micropores on the surface of the magnesium alloy to form a spatial network framework structure, thereby obtaining an anodized magnesium alloy;

[0036] The magnesium alloy after anodization treatment is placed in a solution A containing a silicon source and a sodium source for hydrothermal reaction to form a silicon-sodium film layer, and silicon-sodium micro-nano particles are filled into the spatial network framework structure on the surface of the magnesium alloy to obtain a magnesium alloy after hydrothermal reaction;

[0037] The magnesium alloy after the hydrothermal reaction is polished and then placed in a solution B containing a silicon source and a sodium source. The silicon source is used to seal the pores and reconstruct the surface of the magnesium alloy using a micro-arc oxidation method to obtain a magnesium alloy with a silicon-sodium functional layer.

[0038] During the preparation of the present invention, the surface of the magnesium alloy is first cleaned, and an anodic oxidation method is used to control and prepare uniform micropores on the surface of the magnesium alloy to form a spatial network framework structure. Subsequently, a hydrothermal method is used to prepare a layer of sodium silicon film on the surface of each magnesium alloy with a microporous structure, so that the sodium silicon micro-nano particles are effectively filled into the spatial network framework structure of the surface of the magnesium alloy. The surface of the sodium silicon film is then mechanically modified. Specifically, some surfaces that are not tightly bonded are polished off to make the surface of the film layer denser and the "nipple" more obvious and regular. After the mechanical modification is completed, during the micro-arc oxidation treatment, the silicon source plays a role in sealing the pores. The micro-arc oxidation method is used to control the preparation of a microstructure functional layer of a composite of sodium silicon and a magnesium alloy, and the surface is reconstructed. Finally, a functional layer surface structure with the characteristics of "interlacing + nipple" is formed, such as Figure 1 shown.

[0039] The surface treated by conventional micro-arc oxidation has many small holes, and pitting corrosion easily occurs at these small holes. After the preparation method of the present invention forms a "penetrating + mastoid" structure, the small holes on the surface are filled, and the mastoid structure also prevents the erosion of the corrosive medium.

[0040] In order to better improve the anodizing effect of the present invention, preferably, the anodizing voltage is 20-50V and the oxidation time is 20-30min. The magnesium alloy is regulated by process parameters to form a spatial network framework structure. If the reaction parameters are not within this parameter range, the anodizing effect will be affected, thereby affecting the final performance of the magnesium alloy. More preferably, the anodizing voltage is 20V and the oxidation time is 30min.

[0041] When performing anodizing treatment, the electrolyte used in the present invention is an electrolyte containing a silicon source, a boron source and a sodium source. The addition of the sodium source makes the electrolyte alkaline. The setting of the alkaline environment can make the magnesium alloy more stable in an alkaline environment. The addition of the silicon source and the boron source is to improve the ionization of the solute and enhance the conductivity of the solution.

[0042] In order to further improve the effect of anodizing treatment, the electrolyte containing silicon source, boron source and sodium source is composed of sodium source, silicon source and boron source in a molar concentration ratio of 1-1.5:0.1-1:0.8-1. More preferably, the electrolyte containing silicon source, boron source and sodium source is composed of sodium source, silicon source and boron source in a molar concentration ratio of 1:1:1.

[0043] In order to better improve the treatment effect of the hydrothermal reaction, the present invention preferably has a hydrothermal reaction temperature of 150-190°C and a time of 2-4h. When the above parameter range is exceeded, the coating will have poor performance. For example, if the hydrothermal reaction temperature is 170°C and the time is less than 2h, the hydrothermal coating grows very thin. If it is greater than 4h, the coating is easy to fall off, affecting the final performance of the magnesium alloy. More preferably, the hydrothermal reaction temperature is 170°C and the time is 3h.

[0044] When the hydrothermal reaction is carried out, the reaction solution is a solution A containing a silicon source and a sodium source. The addition of the sodium source makes the reaction solution alkaline. The setting of the alkaline environment can make the magnesium alloy more stable in the alkaline environment. The addition of the silicon source (such as white carbon black) is to obtain a stable silicon-containing coating.

[0045] In order to further improve the treatment effect of the hydrothermal reaction, the solution A containing silicon source and sodium source is composed of sodium source and silicon source in a mass concentration ratio of 5-6:14-16. Preferably, the alkaline solution A containing silicon source is composed of sodium source and silicon source in a mass concentration ratio of 6:16.

[0046] In order to better improve the treatment effect of the micro-arc oxidation method, the present invention preferably has a voltage of 380-400V and an oxidation time of 10-15min. If the reaction parameters are not within this parameter range, the final properties of the magnesium alloy will be affected. More preferably, the voltage of the micro-arc oxidation method is 380V and the oxidation time is 10min.

[0047] When performing micro-arc oxidation treatment, the solution used is solution B containing a silicon source and a sodium source. The addition of the sodium source is used to adjust the pH. The setting of the alkaline environment can make the magnesium alloy more stable in an alkaline environment, and the silicon source plays a role in sealing the pores.

[0048] In order to further improve the treatment effect of the micro-arc oxidation method, the solution B containing the silicon source and the sodium source is composed of the sodium source and the silicon source in a mass concentration ratio of 1-3:2. Preferably, the solution B containing the silicon source and the sodium source is composed of the sodium source and the silicon source in a mass concentration ratio of 3:2.

[0049] The sodium source is not particularly limited in the present invention. Any sodium source known to those skilled in the art can be used. As long as the environment system during the reaction can be adjusted to an alkaline environment and sodium can be provided, those skilled in the art can select and adjust it according to the actual application. The reason for selecting the sodium source in the present invention is that sodium is in the form of Na + More preferably, the sodium source in the electrolyte, solution A and solution B is independently selected from one or more of NaOH, Na2CO3 and NaAlO2.

[0050] The present invention has no particular limitation on the silicon source, and any silicon source known to those skilled in the art can be used, and those skilled in the art can select and adjust it according to the actual application. Preferably, the silicon source in the electrolyte, solution A and solution B is independently selected from one or more of sodium silicate (NaO·nSiO), white carbon black, and sodium metasilicate nonahydrate (Na2SiO3·9H2O).

[0051] The present invention has no particular limitation on the boron source, and any boron source known to those skilled in the art can be used, and those skilled in the art can select and adjust it according to actual application conditions. Preferably, the boron source in the electrolyte is Na2B4O7.

[0052] In principle, the present invention has no particular limitation on the magnesium alloy used. Those skilled in the art can select and adjust the type of magnesium alloy according to the actual application. Preferably, the magnesium alloy used in the present invention is AZ91D magnesium alloy. It can be understood that before processing the magnesium alloy, the magnesium alloy needs to be polished and cleaned in order to remove the oxide film on the surface of the magnesium alloy.

[0053] The following experimental methods and detection methods, unless otherwise specified, are conventional methods; the following reagents and raw materials, unless otherwise specified, are commercially available reagents and raw materials, and the present invention is not particularly limited herein.

[0054] Example 1

[0055] (1) Select AZ91D magnesium alloy with a size of 40 mm × 20 mm × 5 mm.

[0056] (2) The surface of the magnesium alloy was first polished with 360-mesh silicon carbide sandpaper, then placed in an ultrasonic cleaner and cleaned with deionized water for 15 minutes, and then the surface of the magnesium alloy substrate was cleaned with an alkaline cleaning solution and an acid cleaning solution in turn, and finally placed in an oven for drying.

[0057] (3) The pretreated magnesium alloy was used as the anode and a brass sheet of the same size was used as the cathode. The pretreated magnesium alloy was placed in a mixed electrolyte of NaOH, Na2O·nSiO2 and Na2B4O7 with a concentration of 0.5 mol / L. The distance between the cathode and the cathode was 25 mm. The voltage was set to 20 V and the magnesium alloy was treated by anodization for 30 minutes.

[0058] (4) 0.50 g of sodium hydroxide (analytical grade) and 2.50 g of sodium carbonate (analytical grade) were added to 80 g of deionized water and stirred until completely dissolved. 8 g of white carbon black particles were slowly added to the solution under sufficient stirring conditions. After ultrasonic treatment for 10 minutes, magnetic stirring was performed for 20 minutes to ensure uniform mixing.

[0059] (5) The AZ91D magnesium alloy treated in step (3) was placed in a polytetrafluoroethylene liner, and then placed in the solution prepared in step (4). The reaction kettle containing polytetrafluoroethylene was heated and kept warm at 150°C for 3 hours in an oven. After the reaction was completed, it was rinsed with deionized water and then placed in a 50°C constant temperature oven for drying for 30 minutes.

[0060] (6) Use 200-grit sandpaper to fully polish the surface sodium silicon film.

[0061] (7) The magnesium alloy treated in step (6) is connected to the positive electrode of the micro-arc oxidation equipment, and the stainless steel plate is connected to the negative electrode, and it is completely immersed in a mixed electrolyte of NaAlO2 (concentration 10g / L), Na2SiO3 (concentration 10g / L) and NaOH (concentration 5g / L) for micro-arc oxidation surface treatment. The voltage of micro-arc oxidation is 380V constant voltage, and the oxidation time is 15min. After completion, the sample is removed, rinsed with deionized water, and dried with hot air to obtain a magnesium alloy with a silicon-sodium functional layer. The obtained sample is recorded as C150H3.

[0062] Example 2

[0063] (1) Select AZ91D magnesium alloy with a size of 40 mm × 20 mm × 5 mm.

[0064] (2) The surface of the magnesium alloy was first polished with 360-mesh silicon carbide sandpaper, then placed in an ultrasonic cleaner and cleaned with deionized water for 15 minutes, and then the surface of the magnesium alloy substrate was cleaned with an alkaline cleaning solution and an acid cleaning solution in turn, and finally placed in an oven for drying.

[0065] (3) The pretreated magnesium alloy was used as the anode and a brass sheet of the same size was used as the cathode. The pretreated magnesium alloy was placed in a mixed electrolyte of NaOH, Na2O·nSiO2 and Na2B4O7 with a concentration of 0.5 mol / L. The distance between the cathode and the cathode was 25 mm. The voltage was set to 20 V and the magnesium alloy was treated by anodization for 30 minutes.

[0066] (4) 0.50 g of sodium hydroxide (analytical grade) and 2.50 g of sodium carbonate (analytical grade) were added to 80 g of deionized water and stirred until completely dissolved. 8 g of white carbon black particles were slowly added to the solution under sufficient stirring conditions. After ultrasonic treatment for 10 minutes, magnetic stirring was performed for 20 minutes to ensure uniform mixing.

[0067] (5) The AZ91D magnesium alloy treated in step (3) was placed in a polytetrafluoroethylene liner, and then placed in the solution prepared in step (4), and the reaction kettle filled with polytetrafluoroethylene was heated and kept warm at 170°C for 3 hours in an oven. After the reaction was completed, it was rinsed with deionized water and then placed in a 50°C constant temperature oven for drying for 30 minutes.

[0068] (6) Use 200-grit sandpaper to fully polish the surface sodium silicon film.

[0069] (7) The magnesium alloy treated in step (6) is connected to the positive electrode of the micro-arc oxidation equipment, and the stainless steel plate is connected to the negative electrode, and it is completely immersed in a mixed electrolyte of NaAlO2 (concentration 10g / L), Na2SiO3 (concentration 10g / L) and NaOH (concentration 5g / L) for micro-arc oxidation surface treatment. The voltage of micro-arc oxidation is 380V constant voltage, and the oxidation time is 15min. After completion, the sample is removed, rinsed with deionized water, and dried with hot air to obtain a magnesium alloy with a silicon-sodium functional layer. The obtained sample is recorded as C170H3.

[0070] Example 3

[0071] (1) Select AZ91D magnesium alloy with a size of 40 mm × 20 mm × 5 mm.

[0072] (2) The surface of the magnesium alloy was first polished with 360-mesh silicon carbide sandpaper, then placed in an ultrasonic cleaner and cleaned with deionized water for 15 minutes, and then the surface of the magnesium alloy substrate was cleaned with an alkaline cleaning solution and an acid cleaning solution in turn, and finally placed in an oven for drying.

[0073] (3) The pretreated magnesium alloy was used as the anode and a brass sheet of the same size was used as the cathode. The pretreated magnesium alloy was placed in a mixed electrolyte of NaOH, Na2O·nSiO2 and Na2B4O7 with a concentration of 0.5 mol / L. The distance between the cathode and the cathode was 25 mm. The voltage was set to 20 V and the magnesium alloy was treated by anodization for 30 minutes.

[0074] (4) 0.50 g of sodium hydroxide (analytical grade) and 2.50 g of sodium carbonate (analytical grade) were added to 80 g of deionized water and stirred until completely dissolved. 8 g of white carbon black particles were slowly added to the solution under sufficient stirring conditions. After ultrasonic treatment for 10 minutes, magnetic stirring was performed for 20 minutes to ensure uniform mixing.

[0075] (5) The AZ91D magnesium alloy treated in step (3) was placed in a polytetrafluoroethylene liner, and then placed in the solution prepared in step (4). The reaction kettle filled with polytetrafluoroethylene was heated and kept warm at 190°C for 3 hours in an oven. After the reaction was completed, it was rinsed with deionized water and then placed in a 50°C constant temperature oven for drying for 30 minutes.

[0076] (6) Use 200-grit sandpaper to fully polish the surface sodium silicon film.

[0077] (7) The magnesium alloy treated in step (6) is connected to the positive electrode of the micro-arc oxidation equipment, and the stainless steel plate is connected to the negative electrode, and it is completely immersed in a mixed electrolyte of NaAlO2 (concentration 10g / L), Na2SiO3 (concentration 10g / L) and NaOH (concentration 5g / L) for micro-arc oxidation surface treatment. The voltage of micro-arc oxidation is 380V constant voltage, and the oxidation time is 15min. After completion, the sample is removed, rinsed with deionized water, and dried with hot air to obtain a magnesium alloy with a silicon-sodium functional layer. The obtained sample is recorded as C190H3.

[0078] Example 4

[0079] (1) Select AZ91D magnesium alloy with a size of 40 mm × 20 mm × 5 mm.

[0080] (2) The surface of the magnesium alloy was first polished with 360-mesh silicon carbide sandpaper, then placed in an ultrasonic cleaner and cleaned with deionized water for 15 minutes, and then the surface of the magnesium alloy substrate was cleaned with an alkaline cleaning solution and an acid cleaning solution in turn, and finally placed in an oven for drying.

[0081] (3) The pretreated magnesium alloy was used as the anode and a brass sheet of the same size was used as the cathode. The anode and the cathode were placed in a mixed electrolyte consisting of NaOH (concentration 50 g / L), Na2B4O7·10H2O (concentration 40 g / L) and NaSiO3 (concentration 100 g / L). The distance between the cathode and the cathode was 25 mm. The voltage was set to 50 V and the magnesium alloy was treated by anodization for 20 minutes.

[0082] (4) 0.70 g of sodium hydroxide (analytical grade) and 2.50 g of sodium carbonate (analytical grade) were added to 80 g of deionized water and stirred until completely dissolved. 8 g of white carbon black particles were slowly added to the solution under sufficient stirring conditions. After ultrasonic treatment for 10 minutes, magnetic stirring was performed for 20 minutes to ensure uniform mixing.

[0083] (5) Place the AZ91D magnesium alloy treated in step (2) into a polytetrafluoroethylene liner, and then place it into the solution prepared in step (3), and use an oven to heat and insulate the reactor containing polytetrafluoroethylene. After the reaction is completed, rinse the AZ91D magnesium alloy with deionized water, and then place it in a 50°C constant temperature oven to dry for 30 minutes.

[0084] (6) Use 200-grit sandpaper to fully polish the surface sodium silicon film.

[0085] (7) The magnesium alloy treated in step (6) is connected to the positive electrode of the micro-arc oxidation equipment, and the stainless steel plate is connected to the negative electrode, and it is completely immersed in a mixed electrolyte of NaAlO2 (concentration 10g / L), Na2SiO3 (concentration 10g / L) and NaOH (concentration 5g / L) for micro-arc oxidation surface treatment. The voltage of micro-arc oxidation is 380V constant voltage, and the oxidation time is 15min. After completion, the sample is removed, rinsed with deionized water, and dried with hot air to obtain a magnesium alloy with a silicon-sodium functional layer.

[0086] Example 5

[0087] (1) Select AZ91D magnesium alloy with a size of 40 mm × 20 mm × 5 mm.

[0088] (2) The surface of the magnesium alloy was first polished with 360-mesh silicon carbide sandpaper, then placed in an ultrasonic cleaner and cleaned with deionized water for 15 minutes, and then the surface of the magnesium alloy substrate was cleaned with an alkaline cleaning solution and an acid cleaning solution in turn, and finally placed in an oven for drying.

[0089] (3) The pretreated magnesium alloy was used as the anode and a brass sheet of the same size was used as the cathode. The pretreated magnesium alloy was placed in a mixed electrolyte of NaOH, Na2O·nSiO2 and Na2B4O7 with a concentration of 0.5 mol / L. The distance between the cathode and the cathode was 25 mm. The voltage was set to 50 V and the magnesium alloy was treated by anodization for 20 minutes.

[0090] (4) 0.50 g of sodium hydroxide (analytical grade) and 2.25 g of sodium carbonate (analytical grade) were added to 80 g of deionized water and stirred until completely dissolved. 7 g of white carbon black particles were slowly added to the solution under sufficient stirring. After ultrasonic treatment for 10 minutes, magnetic stirring was performed for 20 minutes to ensure uniform mixing.

[0091] (5) The AZ91D magnesium alloy treated in step (3) was placed in a polytetrafluoroethylene liner, and then placed in the solution prepared in step (4), and the reaction kettle filled with polytetrafluoroethylene was heated and kept warm for 2 hours at 170°C in an oven. After the reaction was completed, it was rinsed with deionized water and then placed in a 50°C constant temperature oven for drying for 30 minutes.

[0092] (6) Use 200-grit sandpaper to fully polish the surface sodium silicon film.

[0093] (7) The magnesium alloy treated in step (6) is connected to the positive electrode of the micro-arc oxidation equipment, and the stainless steel plate is connected to the negative electrode, and it is completely immersed in a mixed electrolyte of Na2SiO3 (concentration 10g / L) and NaOH (concentration 5g / L) for micro-arc oxidation surface treatment. The voltage of micro-arc oxidation is 400V constant voltage, and the oxidation time is 10min. After completion, the sample is removed, rinsed with deionized water, and dried with hot air to obtain a magnesium alloy with a silicon-sodium functional layer.

[0094] Example 6

[0095] (1) Select AZ91D magnesium alloy with a size of 40 mm × 20 mm × 5 mm.

[0096] (2) The surface of the magnesium alloy was first polished with 360-mesh silicon carbide sandpaper, then placed in an ultrasonic cleaner and cleaned with deionized water for 15 minutes, and then the surface of the magnesium alloy substrate was cleaned with an alkaline cleaning solution and an acid cleaning solution in turn, and finally placed in an oven for drying.

[0097] (3) The pretreated magnesium alloy was used as the anode and a brass sheet of the same size was used as the cathode. The pretreated magnesium alloy was placed in a mixed electrolyte consisting of NaOH (concentration 0.45 mol / L), Na2B4O7·10H2O (concentration 0.27 mol / L) and NaSiO3 (concentration 0.15 mol / L). The distance between the cathode and the cathode was 25 mm. The voltage was set to 30 V and the magnesium alloy was treated by anodization for 25 minutes.

[0098] (4) 0.50 g of sodium hydroxide (analytical grade) and 2.00 g of sodium carbonate (analytical grade) were added to 80 g of deionized water and stirred until completely dissolved. 7.5 g of white carbon black particles were slowly added to the solution under sufficient stirring conditions. After ultrasonic treatment for 10 minutes, magnetic stirring was performed for 20 minutes to ensure uniform mixing.

[0099] (5) The AZ91D magnesium alloy treated in step (3) was placed in a polytetrafluoroethylene liner, and then placed in the solution prepared in step (4), and the reaction kettle filled with polytetrafluoroethylene was heated and kept warm at 170°C for 4 hours in an oven. After the reaction was completed, it was rinsed with deionized water and then placed in a 50°C constant temperature oven for drying for 30 minutes.

[0100] (6) Use 200-grit sandpaper to fully polish the surface sodium silicon film.

[0101] (7) The magnesium alloy treated in step (6) is connected to the positive electrode of the micro-arc oxidation equipment, and the stainless steel plate is connected to the negative electrode, and it is completely immersed in a mixed electrolyte of NaAlO2 (concentration 5g / L), Na2SiO3 (concentration 10g / L) and NaOH (concentration 5g / L) for micro-arc oxidation surface treatment. The voltage of micro-arc oxidation is 400V constant voltage, and the oxidation time is 10min. After completion, the sample is removed, rinsed with deionized water, and dried with hot air to obtain a magnesium alloy with a silicon-sodium functional layer.

[0102] The magnesium alloys with silicon-sodium functional layers prepared by the present invention all have excellent super-hydrophobicity and corrosion resistance and wear resistance. The performance of the magnesium alloys with silicon-sodium functional layers prepared in Examples 1-3 is tested below.

[0103] Depend on Figure 2 It can be seen that the water contact angle of the functional layer surface of the magnesium alloy with the sodium-silicon functional layer prepared in Example 1 reaches 164°, indicating that the surface of the magnesium alloy functional layer has excellent superhydrophobicity.

[0104] Friction performance: Test method diagram Figure 3 . Use 2000# silicon carbide sandpaper as the bottom friction medium, place the sample on the silicon carbide sand, place a 50g standard weight on the sample, use a tensile gauge to hook the sample and pull it at a constant speed, each pulling of 23cm is counted as one friction number, and every 5 friction numbers are a group.

[0105] Table 1 Mass of samples after friction of different samples

[0106] Initial weight (g) 5 times (g) 10 times (g) 15 times (g) 20 times (g) AZ91D pure sample 1.3818 1.3818 1.3817 1.3816 1.3812 Example 1 1.0846 1.0835 1.0833 1.0830 1.0827

[0107] It can be seen from Table 1 that the initial mass of the pure AZ91D sample is 1.3821g, and the masses of the sample after 5, 10, 15, and 20 frictions are 1.3818g, 1.3817g, 1.3816g, and 1.3812g, respectively. The initial mass of the sample with a functional layer surface prepared in Example 1 is 1.0846g, and the masses of the sample after 5, 10, 15, and 20 frictions are 1.0835g, 1.0833g, 1.0830g, and 1.0827g, respectively. Since there is solid deposition residue on the surface of the sample prepared in Example 1, it will fall off at the beginning of friction, resulting in a higher wear amount of the magnesium alloy after the modification treatment. After multiple frictions, the shedding is reduced and the wear amount becomes lower.

[0108] Figure 4 The corrosion properties of the magnesium alloy samples prepared in Examples 1 to 3 are shown in Table 1. The corrosion current density (I corr ) is 4.397×10 -4 A / cm 2 , corrosion rate (Vcorr ) reached 9.6184mm / a. Under different heating temperatures and the same holding time, the I corr and V corr They are 1.8402×10 - 6 A / cm 2 and 0.040251mm / a. The Stern-Geary coefficient is the largest among all samples, which is 123.02. The semicircular diameter of the C170H3 sample is about 200Ω·cm 2 Compared with the pure sample of AZ91D, the semicircular diameter of the C170H3 sample increased by about 20 times.

[0109] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0110] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a magnesium alloy having a sodium-silicon functional layer, characterized in that: The following steps are involved: In an electrolyte containing a silicon source, a boron source and a sodium source, an anodized magnesium alloy is subjected to an anodic oxidation treatment to prepare micropores on the surface of the magnesium alloy to form a spatial network framework structure, thereby obtaining an anodized magnesium alloy; The magnesium alloy after anodization treatment is placed in a solution A containing a silicon source and a sodium source for hydrothermal reaction to form a silicon-sodium film layer, and silicon-sodium micro-nano particles are filled into the spatial network framework structure on the surface of the magnesium alloy to obtain a magnesium alloy after hydrothermal reaction; The magnesium alloy after the hydrothermal reaction is polished and then placed in a solution B containing a silicon source and a sodium source. The silicon source is used to seal the pores and reconstruct the surface of the magnesium alloy using a micro-arc oxidation method to obtain a magnesium alloy with a silicon-sodium functional layer.

2. The method for preparing a magnesium alloy having a sodium-silicon functional layer according to claim 1, characterized in that: The voltage of anodizing treatment is 20-50V, and the oxidation time is 20-30min.

3. The method for preparing a magnesium alloy having a silicon-sodium functional layer according to claim 1, characterized in that: The electrolyte containing silicon source, boron source and sodium source is composed of sodium source, silicon source and boron source in a molar concentration ratio of 1-1.5:0.1-1:0.8-1.

4. The method for preparing a magnesium alloy having a sodium-silicon functional layer according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 150-190°C and the time is 2-4h.

5. The method for preparing a magnesium alloy having a sodium-silicon functional layer according to claim 1, characterized in that: Solution A containing a silicon source and a sodium source is composed of a sodium source and a silicon source in a mass concentration ratio of 5-6:14-16.

6. The method for preparing a magnesium alloy having a sodium-silicon functional layer according to claim 1, characterized in that: The voltage of the micro-arc oxidation method is 380-400V, and the oxidation time is 10-15min.

7. The method for preparing a magnesium alloy having a silicon-sodium functional layer according to claim 1, characterized in that: Solution B containing a silicon source and a sodium source is composed of a sodium source and a silicon source in a mass concentration ratio of 1-3:

2.

8. The method for preparing a magnesium alloy having a silicon-sodium functional layer according to claim 1, characterized in that: The sodium source in the electrolyte, solution A and solution B is independently selected from one or more of NaOH, Na2CO3, and NaAlO2.

9. The method for preparing a magnesium alloy having a sodium-silicon functional layer according to claim 1, characterized in that: The silicon source in the electrolyte, solution A and solution B is independently selected from one or more of sodium silicate, white carbon black and sodium metasilicate nonahydrate; The boron source in the electrolyte is Na2B4O7.

10. A magnesium alloy having a silicon-sodium functional layer prepared by the preparation method according to any one of claims 1 to 9.

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