Magnesium alloy corrosion-resistant coating and preparation method thereof

Abstract

The invention belongs to the technical field of magnesium alloy product manufacturing, and discloses a magnesium alloy corrosion-resistant coating and a preparation method thereof.The corrosion-resistant coating comprises an Al < x > Mg < 1-x > inner layer, an Al < x > Mg < 1-x > / Al < y > Ti < 1-y > nanometer multilayer and an Al < y > Ti < 1-y > O amorphous layer which are sequentially deposited, the Al < x > Mg < 1-x > inner layer is adjacent to a magnesium alloy, x is the mass ratio of aluminum to the total amount of aluminum and magnesium in the Al < x > Mg < 1-x >, and y is the total amount of the aluminum and magnesium in the Al < x > Mg < 1-x >; and y is the mass ratio of the aluminum element to the total amount of aluminum and magnesium elements in AlyTi1-y or AlyTi1-yO. The Al < x > Mg < 1-x >, Al < x > Mg < 1-x > / Al < y > Ti < 1-y > and Al < y > Ti < 1-y > O composite coatings are deposited on the surface of the magnesium alloy by adopting a magnetron sputtering method, so that the corrosion resistance of the magnesium alloy can be greatly improved, the problem of low coating binding force in an existing magnesium alloy surface coating technology is solved, and the aluminum-rich composite coating which is close to a magnesium alloy matrix in potential and has excellent corrosion resistance is obtained.

Description

Technical Field

[0001] This application belongs to the technical field of manufacturing magnesium alloy products, and particularly relates to a corrosion-resistant coating for magnesium alloy and a preparation method thereof. Background Art

[0002] Magnesium alloy is recognized as a "green and environmentally friendly new material in the 21st century" and can be widely used in many fields such as aerospace, automotive, biomedical, and oil and gas production. However, due to the low electrode potential and high chemical activity of magnesium, the corrosion resistance of magnesium alloy is very poor, and its application in the field of oil and gas exploration and development is limited.

[0003] The methods for improving the corrosion resistance of magnesium alloy are mainly divided into two categories: one is alloying. Adding appropriate amounts of Mn and Re elements to magnesium alloy can improve its corrosion resistance, but the effect of this method is very limited; the other method is to prepare a corrosion-resistant coating on the surface of magnesium alloy. This method can multiply the corrosion resistance of magnesium alloy and has good economy. The preparation methods of the surface coating of magnesium alloy include thermal spraying, physical vapor deposition, sol-gel method, electroplating, electroless plating, chemical conversion film, etc. Among many surface coating methods, physical vapor deposition is a truly pollution-free green surface coating technology. Among them, magnetron sputtering technology is pure atom / ion deposition, and the prepared coating has a dense structure and a flat surface. Therefore, magnetron sputtering is an important method for the surface coating of magnesium alloy.

[0004] The magnetron sputtering coating on the surface of magnesium alloy includes elemental coatings (Al, Ti, Zn, Zr, Cr, Cu, Si, diamond-like coatings, etc.) and compound coatings (TiN, CrN, TiAlN, AlO x etc.). Whether it is an elemental coating or a compound coating, the coating deposited by magnetron sputtering is usually columnar in structure. Due to the gaps between the columnar crystals, these gap defects provide an access channel for the corrosive medium, thereby weakening the protective effect of the coating. In addition, the difference in the thermal expansion coefficients between these coatings and magnesium alloy is relatively large, resulting in poor bonding strength between the coating and magnesium alloy, and it is difficult to fully exert the protective effect of the coating. Therefore, it is urgent to develop a new type of protective coating with high bonding strength and excellent corrosion resistance to magnesium alloy. Summary of the Invention

[0005] In order to overcome the defects existing in the above-mentioned prior art, the purpose of this application is to provide a corrosion-resistant coating for magnesium alloy and a preparation method thereof.

[0006] To achieve the above purpose, this application provides the following technical solutions:

[0007] A corrosion-resistant coating for magnesium alloy, the corrosion-resistant coating is a composite coating, including sequentially deposited Al x Mg 1-x inner layer, Al x Mg1-x / Al y Ti 1-y nanometer multi - layer and Al y Ti 1-y O amorphous layer,

[0008] wherein, Al x Mg 1-x the inner layer is adjacent to the magnesium alloy, and x is the mass ratio of aluminum element to the total amount of aluminum and magnesium elements in Al x Mg 1-x and y is the mass ratio of aluminum element to the total amount of aluminum and magnesium elements in Al y Ti 1-y or Al y Ti 1-y O.

[0009] Furthermore, Al x Mg 1-x the inner layer, Al x Mg 1-x / Al y Ti 1-y nanometer multi - layer and Al y Ti 1-y O amorphous layer are deposited on the surface of the magnesium alloy by magnetron sputtering method.

[0010] Furthermore, 0.3 ≤ x ≤ 0.7, 0.5 ≤ y ≤ 0.95.

[0011] Furthermore, Al x Mg 1-x the thickness of the inner layer is 0.15 - 0.5 μm.

[0012] Furthermore, Al x Mg 1-x / Al y Ti 1-y the thickness of the nanometer multi - layer is 2 - 10 μm.

[0013] Furthermore, Al y Ti 1-y the thickness of the O amorphous layer is 0.5 - 2 μm.

[0014] On the other hand, the present application discloses a preparation method of a corrosion - resistant coating for magnesium alloy, which is used to prepare the above - mentioned corrosion - resistant coating for magnesium alloy, and includes:

[0015] Performing surface pretreatment on the magnesium alloy to remove contaminants and oxide layers on the surface of the magnesium alloy;

[0016] Cleaning and drying the magnesium alloy after surface pretreatment;

[0017] Heating and etching the magnesium alloy after cleaning and drying;

[0018] Deposit Al on the surface of the magnesium alloy after heating and etching x Mg 1-x Inner layer;

[0019] Perform thermal diffusion treatment on the magnesium alloy after depositing Al x Mg 1-x Inner layer;

[0020] Perform Al x Mg 1-x / Al y Ti 1-y Nanomultilayer deposition;

[0021] Perform Al x Mg 1-x / Al y Ti 1-y Perform Al y Ti 1-y Amorphous Al-Ti-O layer deposition.

[0022] Furthermore, heat and etch the magnesium alloy after cleaning and drying, including:

[0023] Heat the magnesium alloy using a magnetron sputtering coating device;

[0024] Etch the heated magnesium alloy with ions generated by argon plasma discharge;

[0025] Further etch the magnesium alloy etched with argon with aluminum metal ions.

[0026] Furthermore, heat the magnesium alloy using a magnetron sputtering coating device, including:

[0027] Control the heating temperature to 100 - 120 °C and the heating time to 30 - 60 minutes.

[0028] Furthermore, etch the heated magnesium alloy with ions generated by argon plasma discharge, including:

[0029] Control the etching bias voltage to -80 - -200 V, the etching time to 15 - 20 minutes, and the pressure to 1 - 2×10 -1 Pa.

[0030] Furthermore, further etch the magnesium alloy etched with argon with aluminum metal ions, including:

[0031] Set the current magnitude of the aluminum target to 4 - 5 A and the etching time to 10 - 20 minutes.

[0032] Furthermore, deposit Al on the surface of the magnesium alloy after heating and etching x Mg1-x The inner layer includes:

[0033] Deposit Al x Mg 1-x When depositing the inner layer, adjust the pressure of the magnetron sputtering coating equipment to 3 - 4×10 -1 Pa, adjust the temperature to 200 - 250 °C, adjust the bias voltage of the bias power supply to -150 - -200 V, set the current of the aluminum target to 3 - 4 A, and the deposition time is 10 - 20 minutes. During the deposition process, reduce the bias voltage at a rate of 6 - 10 V / minute.

[0034] Furthermore, perform heat diffusion treatment on the magnesium alloy after depositing Al x Mg 1-x The inner layer, including:

[0035] Heat the magnesium alloy after depositing Al x Mg 1-x The inner layer to 300 - 350 °C and keep it warm for 10 - 20 minutes.

[0036] Furthermore, perform Al x Mg 1-x / Al y Ti 1-y nanomultilayer deposition on the heat diffusion treated magnesium alloy, including:

[0037] Set the current of the aluminum - titanium target of the magnetron sputtering coating equipment to 4 - 6 A, adjust the current of the aluminum target to 4 - 6 A, adjust the substrate bias voltage to -30 - -60 V, and periodically deposit Al x Mg 1-x layers and Al y Ti 1-y layers on the magnesium alloy to obtain a 2 - 10 μm thick Al x Mg 1-x / Al y Ti 1-y nanomultilayer.

[0038] Furthermore, perform Al x Mg 1-x / Al y Ti 1-y nanomultilayer deposition on the magnesium alloy after Al y Ti 1-y O amorphous layer deposition, including:

[0039] Perform Al x Mg 1-x / Al y Ti 1-yAfter the nano-multilayer deposition, turn off the power supply of the aluminum target and stop introducing argon gas. Then introduce oxygen into the magnetron sputtering coating equipment, and adjust the pressure to 2 - 3.5×10 -1 Pa, adjust the substrate bias voltage to -50 - -100 V, and control the thickness of the Al y Ti 1-y O amorphous layer to be 0.5 - 2 μm by adjusting the deposition time.

[0040] Technical effects and advantages of this application:

[0041] This application uses the magnetron sputtering method to deposit Al x Mg 1-x 、Al x Mg 1-x / Al y Ti 1-y and Al y Ti 1-y O composite coatings on the surface of magnesium alloys. The composite coatings are all Al-rich coatings from the inside to the outside. The purpose is to give full play to the excellent corrosion resistance of Al, and moreover, the electrode potential of Al is close to that of magnesium alloys, and the galvanic corrosion effect is small. Adjacent to the magnesium alloy is the Al x Mg 1-x inner layer. Al and Mg can form intermetallic compounds, and using Al as the inner layer can enhance the overall bonding performance of the coating; in the middle is the nano-multilayer structure of Al x Mg 1-x / Al y Ti 1-y layer. The nano-multilayer structure can break the columnar growth of the coating, eliminate the fast atomic diffusion channels formed by the gaps between the columnar crystals of the coating, improve the density of the coating, and block the penetration of atomic diffusion; the outermost layer is the amorphous structure of Al y Ti 1-y O layer. On the one hand, the amorphous structure coating has no fast atomic diffusion channels and can better resist the inward diffusion of corrosive medium atoms. On the other hand, oxide ceramics have relatively poor conductivity compared to metals or alloys. Even if the corrosive solution reaches the magnesium alloy substrate, the galvanic corrosion effect can also be weakened. In addition, before depositing the composite coating on the surface of the magnesium alloy, the magnesium alloy is subjected to surface pretreatment, argon ion etching, and aluminum ion etching. The purpose is to remove the oxide layer and contamination on the surface of the magnesium alloy, expose the fresh surface of the magnesium alloy, and facilitate the bonding between the coating and the magnesium alloy. Using a relatively large bias voltage at the beginning stage of depositing the Al x Mg 1-x inner layer is also to enable aluminum ions to enter the surface of the magnesium alloy substrate and improve the bonding performance of the coating.

[0042] Other features and advantages of the present application will be set forth in the following description, and in part will be obvious from the description, or may be learned by practice of the present application. The objectives and other advantages of the present application may be realized and attained by the structure particularly pointed out in the specification, claims as well as the drawings. Description of the Drawings

[0043] Figure 1 It is a flowchart of a preparation method of a corrosion-resistant coating for a magnesium alloy of the present application. Detailed Embodiments

[0044] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0045] The present application provides a corrosion-resistant coating for a magnesium alloy. The corrosion-resistant coating is a composite coating, including successively deposited Al x Mg 1-x inner layer, Al x Mg 1-x / Al y Ti 1-y nanomultilayer and Al y Ti 1-y O amorphous layer.

[0046] Among them, the Al x Mg 1-x inner layer is adjacent to the magnesium alloy, x is the mass ratio of aluminum element to the total amount of aluminum and magnesium elements in Al x Mg 1-x , and y is the mass ratio of aluminum element to the total amount of aluminum and magnesium elements in Al y Ti 1-y or Al y Ti 1-y O.

[0047] In some embodiments of the present invention, the Al x Mg 1-x inner layer, Al x Mg 1-x / Al y Ti 1-y nanomultilayer and Al y Ti 1-y O amorphous layer are deposited on the surface of the magnesium alloy by magnetron sputtering method.

[0048] In some embodiments of the present invention, 0.3 ≤ x ≤ 0.7, 0.5 ≤ y ≤ 0.95. For example, x = 0.3, 0.4, 0.5, 0.6 or 0.7, and y = 0.5, 0.6, 0.7, 0.8, 0.9 or 0.95.

[0049] In some embodiments of the present invention, Al x Mg 1-x The thickness of the inner layer is 0.15 - 0.5 μm, such as 0.15 μm, 0.2 μm, 0.3 μm, 0.4 μm or 0.5 μm.

[0050] In some embodiments of the present invention, Al x Mg 1-x / Al y Ti 1-y The thickness of the nano - multilayer is 2 - 10 μm, such as 2 μm, 4 μm, 6 μm, 8 μm or 10 μm.

[0051] In some embodiments of the present invention, Al y Ti 1-y The thickness of the Al

[0052] On the other hand, as Figure 1 shown, the present application discloses a method for preparing a corrosion - resistant coating for a magnesium alloy, which is used to prepare the above - mentioned corrosion - resistant coating for a magnesium alloy, and includes:

[0053] Performing surface pretreatment on the magnesium alloy to remove contaminants and oxide layers on the surface of the magnesium alloy;

[0054] Cleaning and drying the magnesium alloy after surface pretreatment;

[0055] Heating and etching the magnesium alloy after cleaning and drying;

[0056] Depositing an Al x Mg 1-x inner layer on the surface of the magnesium alloy after heating and etching;

[0057] Performing thermal diffusion treatment on the magnesium alloy after depositing the Al x Mg 1-x inner layer;

[0058] Performing Al x Mg 1-x / Al y Ti 1-y nano - multilayer deposition on the magnesium alloy after thermal diffusion treatment;

[0059] For Al x Mg 1-x / Aly Ti 1-y After the magnesium alloy is deposited with nano-multilayers, Al y Ti 1-y O amorphous layer is deposited.

[0060] It is worth mentioning that the composite coating is an Al-rich coating from the inside to the outside. The purpose is to give full play to the excellent corrosion resistance of Al. Moreover, the electrode potential of Al is close to that of the magnesium alloy, and the galvanic corrosion effect is small. Adjacent to the magnesium alloy is the Al x Mg 1-x inner layer. Al and Mg can form intermetallic compounds. Using Al as the inner layer can enhance the overall bonding performance of the coating; the middle is the nano-multilayer structure of Al x Mg 1-x / Al y Ti 1-y layer. The nano-multilayer structure can break the columnar growth of the coating, eliminate the fast atomic diffusion channels formed by the gaps between the columnar crystals of the coating, improve the denseness of the coating, and block the penetration of atomic diffusion; the outermost layer is the amorphous structure of Al y Ti 1-y O layer. On the one hand, the amorphous structure coating has no fast atomic diffusion channels and can better resist the inward diffusion of corrosive medium atoms. On the other hand, compared with metals or alloys, oxide ceramics have poor conductivity. Even if the corrosive solution reaches the magnesium alloy substrate, the galvanic corrosion effect can be weakened. In addition, before depositing the composite coating on the surface of the magnesium alloy in this application, the magnesium alloy is subjected to surface pretreatment, argon ion etching, and aluminum ion etching. The purpose is to remove the oxide layer and contamination on the surface of the magnesium alloy, expose the fresh surface of the magnesium alloy, and facilitate the bonding between the coating and the magnesium alloy.

[0061] In some embodiments of the present invention, the magnesium alloy after cleaning and drying is heated and etched, including:

[0062] Heating the magnesium alloy using a magnetron sputtering coating device;

[0063] Etching the heated magnesium alloy with ions generated by argon plasma discharge;

[0064] Further etching the magnesium alloy etched with argon with aluminum metal ions.

[0065] In some embodiments of the present invention, when heating the magnesium alloy using a magnetron sputtering coating device, the heating temperature is controlled to be 100-120°C, and the heating time is 30-60 minutes.

[0066] In some embodiments of the present invention, when etching the heated magnesium alloy with ions generated by argon plasma discharge, the etching bias voltage is controlled to be -80 to -200V, the etching time is 15-20 minutes, and the pressure is 1-2×10 -1 Pa.

[0067] In some embodiments of the present invention, when the magnesium alloy after argon etching is further etched with aluminum metal ions, the current magnitude of the aluminum target is set to 4 - 5 A, and the etching time is 10 - 20 minutes.

[0068] In some embodiments of the present invention, Al is deposited on the surface of the magnesium alloy after heating and etching x Mg 1-x Inner layer, including:

[0069] When depositing Al x Mg 1-x inner layer, the pressure of the magnetron sputtering coating equipment is adjusted to 3 - 4×10 -1 Pa, the temperature is adjusted to 200 - 250 °C, the bias voltage magnitude of the bias power supply is adjusted to -150 - -200 V, the current magnitude of the aluminum target is set to 3 - 4 A, the deposition time is 10 - 20 minutes, and the bias voltage magnitude is decreased at a rate of 6 - 10 V / minute during the deposition process. At the beginning stage of depositing Al x Mg 1-x inner layer, a larger bias voltage is adopted, which can enable aluminum ions to enter the surface of the magnesium alloy matrix and improve the bonding performance of the coating.

[0070] In some embodiments of the present invention, the magnesium alloy after depositing Al x Mg 1-x inner layer is subjected to thermal diffusion treatment, including:

[0071] The magnesium alloy after depositing Al x Mg 1-x inner layer is heated to 300 - 350 °C and held for 10 - 20 minutes. At a higher temperature, the diffusion of Al atoms in the Al x Mg 1-x inner layer into the magnesium alloy can be accelerated to ensure that more Mg 17 Al2 intermetallic compounds are formed near the layer / substrate interface, and the metallurgical bonding interface is beneficial to improving the bonding strength between the coating and the substrate.

[0072] In some embodiments of the present invention, the magnesium alloy after thermal diffusion treatment is subjected to Al x Mg 1-x / Al y Ti 1-y nanomultilayer deposition, including:

[0073] The current magnitude of the aluminum-titanium target of the magnetron sputtering coating equipment is set to 4 - 6 A, the current magnitude of the aluminum target is adjusted to 4 - 6 A, the substrate bias voltage is adjusted to -30 - -60 V, and 10 - 50 nm thick Al x Mg 1-x layers and Aly Ti 1-y layer to obtain Al with a thickness of 2 - 10 μm x Mg 1-x / Al y Ti 1-y nanomultilayer. The nanomultilayer structure can break the columnar growth of the coating, eliminate the fast atomic diffusion channels formed by the gaps between columnar crystals in the coating, improve the densification of the coating, and block the penetration of atomic diffusion.

[0074] In some embodiments of the present invention, after depositing the Al x Mg 1-x / Al y Ti 1-y nanomultilayer on the magnesium alloy, perform the deposition of an Al y Ti 1-y O amorphous layer, including:

[0075] After performing the deposition of the Al x Mg 1-x / Al y Ti 1-y nanomultilayer, turn off the power supply of the aluminum target and stop introducing argon gas, introduce oxygen into the magnetron sputtering coating equipment, adjust the pressure to 2 - 3.5×10 -1 Pa, adjust the substrate bias voltage to -50 - -100 V, and control the thickness of the Al y Ti 1-y O amorphous layer to be 0.5 - 2 μm by adjusting the deposition time. The amorphous structure coating has no channels for fast atomic diffusion, can better resist the inward diffusion of corrosive medium atoms. On the other hand, compared with metals or alloys, oxide ceramics have poor electrical conductivity. Even if the corrosive solution reaches the magnesium alloy substrate, the galvanic corrosion effect can also be weakened.

[0076] To better illustrate this solution, the following examples and comparative examples are provided.

[0077] Example 1

[0078] S1: Place a magnesium alloy block with dimensions of 5 mm × 12 mm × 15 mm in a sandblasting machine for dry sandblasting treatment to remove contaminants and oxide layers on the surface of the magnesium alloy.

[0079] S2: Place the magnesium alloy block treated in S1 in absolute ethanol and clean it for 10 minutes. Immediately after cleaning, place the magnesium alloy in a vacuum drying oven and dry it for 10 minutes.

[0080] S3: Place the dried magnesium alloy block in a magnetron sputtering coating equipment, turn on the auxiliary heating system to heat the magnesium alloy block to 120 °C, and the heating time is 60 minutes. Then, introduce argon gas into the vacuum chamber, and control the pressure in the vacuum chamber to be 1.5×10 - 1Pa, the magnesium alloy was etched with ions generated by argon plasma discharge. A bias voltage of -100 V was applied to the magnesium alloy, and the etching time was 20 minutes. Then, the power supply of the magnetron sputtering target was turned on, the current of the aluminum target was set to 5 A, and the magnesium alloy was further etched with aluminum metal ions for 20 minutes.

[0081] S4: Adjust the argon flow rate to make the working pressure of the vacuum chamber 3.5×10 -1 Pa. Set the target temperature for heating the magnesium alloy to 250 °C. After the actual temperature of the magnesium alloy reaches the target temperature, adjust the bias voltage of the bias voltage power supply to -200 V. At the same time, set the current of the aluminum target to 4 A, the deposition time is 10 minutes, and the deposition thickness is 0.15 μm. During the deposition process, the bias voltage is reduced at a rate of 10 V / minute.

[0082] S5: Heat the magnesium alloy block treated in S4 to 350 °C and keep it warm for 15 minutes. At a higher temperature, accelerate the diffusion of Al atoms in the inner layer into the magnesium alloy to ensure that more Mg 17 Al2 intermetallic compounds are formed near the layer / substrate interface, and the metallurgical bonding interface is beneficial to improving the bonding strength between the coating and the substrate.

[0083] S6: Turn on the power supply of the aluminum-titanium target, set the current of the aluminum-titanium target to 5 A, adjust the current of the aluminum target to 5 A, and adjust the substrate bias voltage to -60 V. The magnesium alloy block rotates in the vacuum chamber and alternately passes through the sputtering areas of the Al target and the AlTi target to achieve periodic deposition of a 10-thick Al 0.3 Mg 0.7 layer and Al 0.5 Ti 0.5 layer. The deposition time is 120 minutes to obtain a 2-μm-thick Al 0.3 Mg 0.7 / Al 0.5 Ti 0.5 nanomultilayer.

[0084] S7: Introduce oxygen into the vacuum chamber, and at the same time turn off the power supply of the aluminum target and the argon valve to make the working pressure of the vacuum chamber 3.5×10 -1 Pa. Adjust the substrate bias voltage to -75 V, and the deposition time is 60 minutes to obtain an Al 0.5 Ti 0.5 O amorphous layer with a thickness of 0.5 μm.

[0085] The performance of the prepared corrosion-resistant coating was tested. The bonding strength grade of the corrosion-resistant coating was measured to be HF2, and no corrosion spots appeared on the surface after 168 h of neutral salt spray corrosion.

[0086] Example 2

[0087] S1: Place a magnesium alloy block with dimensions of 5 mm × 12 mm × 15 mm into a sandblasting machine for dry sandblasting to remove surface contaminants and oxide layers on the magnesium alloy.

[0088] S2: Place the magnesium alloy block treated in S1 into anhydrous ethanol for 5 minutes of cleaning. Immediately after cleaning, put the magnesium alloy into a vacuum drying oven for 5 minutes of drying.

[0089] S3: Place the dried magnesium alloy block into a magnetron sputtering coating device. Turn on the auxiliary heating system to heat the magnesium alloy block to 100 °C for 45 minutes. Then, introduce argon gas into the vacuum chamber, control the pressure in the vacuum chamber to be 1.8×10 - 1 Pa, and use the ions generated by argon plasma discharge to etch the magnesium alloy. The bias voltage applied to the magnesium alloy is -150 V, and the etching time is 15 minutes. Then, turn on the magnetron sputtering target power supply, set the current of the aluminum target to 4 A, and use aluminum metal ions to further etch the magnesium alloy for 10 minutes.

[0090] S4: Adjust the argon gas flow rate to make the working pressure in the vacuum chamber 3.8×10 -1 Pa. Set the target temperature for heating the magnesium alloy to 200 °C. After the actual temperature of the magnesium alloy reaches the target temperature, adjust the bias voltage of the bias voltage power supply to -150 V. At the same time, set the current of the aluminum target to 3 A, and the deposition time is 20 minutes with a deposition thickness of 0.5 μm. During the deposition process, reduce the bias voltage at a rate of 6 V / minute.

[0091] S5: Heat the magnesium alloy block treated in S4 to 300 °C and keep it warm for 10 minutes to accelerate the diffusion of Al atoms in the inner layer into the magnesium alloy at a higher temperature, so as to ensure the formation of more Mg 17 Al2 intermetallic compounds near the layer / substrate interface, and the metallurgical bonding interface is beneficial to improving the bonding strength between the coating and the substrate.

[0092] S6: Turn on the aluminum-titanium target power supply, set the current of the aluminum-titanium target to 4 A, adjust the current of the aluminum target to 4 A, and adjust the substrate bias voltage to -30 V. The magnesium alloy block rotates in the vacuum chamber and alternately passes through the sputtering areas of the Al target and the AlTi target to achieve periodic deposition of a 50-nm-thick Al 0.7 Mg 0.3 layer and an Al 0.95 Ti 0.05 layer. The deposition time is 180 minutes to obtain a 10-μm-thick Al 0.7 Mg 0.3 / Al 0.95 Ti 0.05 nanomultilayer.

[0093] S7: Introduce oxygen into the vacuum chamber, and at the same time, turn off the power supply of the aluminum target and the argon valve, so that the working pressure of the vacuum chamber is 3.3×10 -1 Pa, adjust the substrate bias voltage to -50V, and the deposition time is 80 minutes. The obtained thickness of the Al 0.95 Ti 0.05 O amorphous layer is 2μm.

[0094] Perform performance testing on the prepared corrosion-resistant coating. The measured bonding strength grade of the corrosion-resistant coating is HF2, and no corrosion spots appear on the surface after 168h of neutral salt spray corrosion.

[0095] Comparative Example 1

[0096] S1: Place a magnesium alloy block with dimensions of 5mm×12mm×15mm in a sandblasting machine for dry sandblasting to remove contaminants and oxide layers on the surface of the magnesium alloy.

[0097] S2: Then place the magnesium alloy block in absolute ethanol for cleaning for 5 minutes. Immediately after cleaning, place the magnesium alloy in a vacuum drying oven for drying for 5 minutes.

[0098] S3: Place the dried magnesium alloy block in a magnetron sputtering coating device, turn on the auxiliary heating system to heat the magnesium alloy to 120°C, and the heating time is 60 minutes. Then, introduce argon into the vacuum chamber, control the pressure of the vacuum chamber to be 1.9×10 - 1 Pa, use the ions generated by argon plasma discharge to etch the magnesium alloy, and the bias voltage applied to the magnesium alloy is -150V, and the etching time is 15 minutes.

[0099] S4: Adjust the argon flow rate so that the working pressure of the vacuum chamber is 3.6×10 -1 Pa, set the target temperature for heating the magnesium alloy to 250°C. After the actual temperature of the magnesium alloy reaches the target temperature, adjust the magnitude of the bias voltage of the bias voltage power supply to -50V. At the same time, set the current magnitude of the aluminum target to 5A, and the deposition time is 180 minutes.

[0100] Perform performance testing on the Al coating. The measured bonding strength grade of the Al coating is HF3, and corrosion spots appear on the surface after 24h of neutral salt spray corrosion.

[0101] Finally, it should be noted that the above are only the preferred embodiments of the present application and are not used to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A corrosion-resistant coating for magnesium alloy, characterized in that, The corrosion-resistant coating is a composite coating, including Al deposited successively x Mg 1-x inner layer, Al x Mg 1-x / Al y Ti 1-y nanomultilayer and Al y Ti 1-y O amorphous layer. Among them, the Al x Mg 1-x inner layer is adjacent to the magnesium alloy, and x is the mass ratio of aluminum element to the total amount of aluminum and magnesium elements in Al x Mg 1-x ; y is the mass ratio of aluminum element to the total amount of aluminum and magnesium elements in Al y Ti 1-y or Al y Ti 1-y O.

2. The corrosion-resistant coating for magnesium alloy according to claim 1, wherein The said Al x Mg 1-x Inner layer, Al x Mg 1-x / Al y Ti 1-y Nanometer multi - layer and Al y Ti 1-y The amorphous Al - Ti - O layer is deposited on the surface of the magnesium alloy by magnetron sputtering method.

3. The corrosion-resistant coating for magnesium alloy according to claim 1, wherein 0.3 ≤ x ≤ 0.7, 0.5 ≤ y ≤ 0.

95.

4. The corrosion-resistant coating for magnesium alloy according to claim 1, wherein The Al x Mg 1-x The thickness of the inner layer is 0.15 to 0.5 μm.

5. The corrosion-resistant coating for magnesium alloy according to claim 1, wherein The said Al x Mg 1-x / Al y Ti 1-y The thickness of the nano-multilayer is 2 to 10 μm.

6. The corrosion-resistant coating for magnesium alloy according to claim 1, wherein The Al y Ti 1-y The thickness of the amorphous layer is 0.5 to 2 μm.

7. A method for preparing a corrosion-resistant coating on a magnesium alloy, characterized in that, The method is used for preparing the corrosion-resistant coating for magnesium alloy according to any one of claims 1-6, and includes: Performing surface pretreatment on the magnesium alloy to remove contaminants and oxide layers on the surface of the magnesium alloy; Cleaning and drying the magnesium alloy after surface pretreatment; Heating and etching the magnesium alloy after cleaning and drying; Deposit Al on the surface of the magnesium alloy after heating and etching x Mg 1-x Inner layer; Perform thermal diffusion treatment on the magnesium alloy after depositing Al x Mg 1-x ; Aluminum is applied to the heat-diffusion treated magnesium alloy x Magnesium 1-x / Aluminum y Titanium 1-y Nano-multilayer deposition; For Al x Mg 1-x / Al y Ti 1-y After nano-multilayer deposition on the magnesium alloy, perform Al y Ti 1-y amorphous oxide layer deposition.

8. The preparation method of a corrosion-resistant coating for magnesium alloy according to claim 7, characterized in that, The heating and etching of the magnesium alloy after cleaning and drying includes: Heating the magnesium alloy by using a magnetron sputtering coating device; Etching the heated magnesium alloy with ions generated by argon plasma discharge; Further etching the magnesium alloy etched by argon with aluminum metal ions.

9. The preparation method of a corrosion-resistant coating for a magnesium alloy according to claim 8, characterized in that, The heating of the magnesium alloy by using a magnetron sputtering coating device includes: Controlling the heating temperature to be 100-120 °C and the heating time to be 30-60 minutes.

10. The preparation method of a corrosion-resistant coating for magnesium alloy according to claim 8, characterized in that, The etching of the heated magnesium alloy with ions generated by argon plasma discharge includes: Control the etching bias voltage to be -80 to -200 V, the etching time to be 15 to 20 minutes, and the pressure to be 1 to 2×10 -1 Pa.

11. The preparation method of a corrosion-resistant coating for magnesium alloy according to claim 8, characterized in that, The further etching of the magnesium alloy etched by argon with aluminum metal ions includes: Setting the current magnitude of the aluminum target to be 4-5 A and the etching time to be 10-20 minutes.

12. The preparation method of a magnesium alloy corrosion-resistant coating according to claim 7, characterized in that, Depositing Al on the surface of the magnesium alloy after heating and etching x Mg 1-x Inner layer, including: Depositing Al x Mg 1-x When depositing the inner layer, adjust the pressure of the magnetron sputtering coating equipment to 3 - 4×10 -1 Pa, adjust the temperature to 200 - 250 °C, adjust the bias voltage of the bias power supply to -150 - -200 V, set the current of the aluminum target to 3 - 4 A, and the deposition time is 10 - 20 minutes. During the deposition process, reduce the bias voltage at a rate of 6 - 10 V / minute.

13. The preparation method of a corrosion-resistant coating for a magnesium alloy according to claim 7, characterized in that, The described thermal diffusion treatment of the magnesium alloy after depositing Al x Mg 1-x includes: Deposit Al x Mg 1-x Heat the magnesium alloy after depositing the inner layer to 300 - 350 °C and keep it warm for 10 - 20 minutes.

14. The preparation method of a corrosion-resistant coating for magnesium alloy according to claim 7, characterized in that, The Al x Mg 1-x / Al y Ti 1-y nanomultilayer deposition on the heat-diffusion-treated magnesium alloy includes: Set the current of the aluminum-titanium target of the magnetron sputtering coating equipment to 4 - 6 A, adjust the current of the aluminum target to 4 - 6 A, adjust the substrate bias voltage to -30 - -60 V, and periodically deposit Al layers with a thickness of 10 - 50 nm on the magnesium alloy. x Mg 1-x layers and Al y Ti 1-y layers to obtain an Al x Mg 1-x / Al y Ti 1-y nanomultilayer.

15. A method for preparing a corrosion-resistant coating on a magnesium alloy according to claim 7, characterized in that, The described Al x Mg 1-x / Al y Ti 1-y After the nano-multilayer deposition on the magnesium alloy, Al y Ti 1-y amorphous oxide layer deposition is carried out, including: Perform Al x Mg 1-x / Al y Ti 1-y After the nano-multilayer deposition, turn off the power supply of the aluminum target and stop introducing argon gas. Introduce oxygen into the magnetron sputtering coating equipment, and adjust the pressure to 2 - 3.5×10 -1 Pa, adjust the substrate bias voltage to -50 - -100V, and control the thickness of the Al y Ti 1-y O amorphous layer to be 0.5 - 2μm by adjusting the deposition time.

Images