A method for preparing a corrosion-resistant coating on a magnesium alloy surface by hot rolling

Abstract

The application relates to a preparation method of a magnesium alloy surface corrosion-resistant coating through a hot-rolling composite process, and belongs to the technical field of magnesium alloy surface treatment. The application aims to solve the problems of poor corrosion resistance of an existing magnesium alloy plate and high protection treatment cost. The method comprises the following steps: one, pretreatment of the plate; two, spraying of an isolating agent; three, combined sealing and welding; four, vacuum extraction; five, hot rolling; and six, stripping of the plate. The application is based on the hot-rolling composite method, the alloy contact surface is subjected to great pressure through rolling to tightly combine the magnesium alloy plate and the aluminum plate, the magnesium-aluminum reaction is activated at high temperature, a reaction layer is formed on the alloy composite surface, and the reaction layer is broken from the aluminum plate side during mechanical stripping, so that a corrosion-resistant coating with a certain thickness is formed on the magnesium alloy plate side. The method provided by the application can realize vacuum protection during rolling, avoid oxidation of the magnesium alloy plate during thermal deformation, retain the mechanical properties of the rolled magnesium alloy plate, and besides, the aluminum plate can be reused after stripping, so that the cost is greatly reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of magnesium alloy surface treatment, and particularly relates to a method for preparing a magnesium alloy surface corrosion-resistant coating in a hot rolling composite process. BACKGROUND

[0002] Magnesium alloy is one of the lightest metal structural materials known at present, and its density is only 1.7 g / cm 3 , which is 2 / 3 of that of aluminum and 1 / 4 of that of steel, and has high specific strength and specific stiffness, good cutting property and other characteristics. At the same time, magnesium is the eighth most abundant element on earth, and its alloy is considered as the most potential lightweight material in the world. Since magnesium has the lowest standard electrode potential among metal structural materials, and its oxide film is loose and porous and cannot form a stable and effective protective film, it is prone to galvanic corrosion, environmental corrosion and other corrosion problems in most environments, and cannot be used continuously. In order to overcome the limitations of magnesium alloy application, the common method for improving the corrosion resistance of magnesium alloy at present is surface treatment and surface alloying, and the surface protection technology is the most effective method for protecting magnesium alloy.

[0003] At present, a variety of methods have been applied to the surface protection of magnesium alloy, including electrochemical plating, chemical conversion film, anodic oxidation treatment, chemical vapor deposition, micro-arc oxidation, sol-gel method, physical vapor deposition, thermal spraying and the like. However, these methods have their own advantages and disadvantages, for example, the hydrothermal method needs specific experimental conditions, including high temperature and high pressure, which leads to high equipment cost and long reaction time; the chemical vapor deposition method needs expensive equipment and raw materials, and has complex process and high preparation cost, which is not suitable for large-scale production of magnesium-based materials; the chemical conversion treatment generates a stable compound film on the surface of magnesium alloy through chemical reaction with the treatment liquid, but the reagent required by this process is toxic, and has great environmental pollution in the treatment process; the anodic oxidation treatment can deposit thin film on a large area and treat parts with complex shape, but the mechanical property of the thin film is poor; the magnetron sputtering technology, as a deposition method of physical vapor deposition, has the advantages of fast deposition rate and strong bonding force with the substrate, but the required equipment is expensive, the overall process is time-consuming, and skilled technicians are needed for operation, so the production efficiency is relatively low and the cost is relatively high; thermal spraying is widely used, but the dust, smoke and light radiation generated during the preparation of the coating pose hidden dangers to the health and safety of the operators. Therefore, many existing anticorrosion coating preparation methods are complex and high in cost, which limits their applicability in some fields. In order to solve this limitation, new coating technologies and more reliable and high-quality coating materials need to be developed, and factors such as coating performance, preparation cost and specific requirements of application scenarios need to be considered. SUMMARY

[0004] The present application aims to solve the problems of poor corrosion resistance of the surface of the existing magnesium alloy plate and high cost of protective treatment, and provides a preparation method of a magnesium alloy surface corrosion-resistant coating by a hot rolling compounding process.

[0005] The preparation method of a magnesium alloy surface corrosion-resistant coating by a hot rolling compounding process is specifically completed by the following steps:

[0006] I. Pretreatment of the plate:

[0007] Based on the actual processing requirements, cut the magnesium alloy plate and the aluminum plate to appropriate sizes, polish the cut plates to be flat, and clean and dry the surfaces to be combined to obtain the pretreated magnesium alloy plate and the pretreated aluminum plate.

[0008] II. Paste the peelable glue in the middle region of the surfaces to be combined of the pretreated magnesium alloy plate and the pretreated aluminum plate, and then spray the isolating agent on the edges of the four surfaces of the pretreated magnesium alloy plate and the pretreated aluminum plate, peel off the peelable glue after the spraying is completed, and obtain the magnesium alloy plate and the aluminum plate with the edges of the four surfaces sprayed with the isolating agent.

[0009] III. Arrange two aluminum plates with one surface sprayed with the isolating agent on the top layer and the bottom layer of the plate to be compounded respectively, arrange the surfaces sprayed with the isolating agent on the inner side, weld the edges of the four surfaces of the aluminum plates on the top layer and the bottom layer, and weld the air pipe with the valve to form the group-welded cover with the sealed cavity.

[0010] The plate to be compounded in step III is the magnesium alloy plate with the edges of the four surfaces sprayed with the isolating agent or the compounded plate material obtained by alternately stacking the magnesium alloy plate with the edges of the four surfaces sprayed with the isolating agent and the aluminum plate with the edges of the four surfaces sprayed with the isolating agent, and the number of layers of the magnesium alloy plate is one more than that of the aluminum plate in the compounded plate material.

[0011] IV. Extract vacuum from the group-welded cover with the sealed cavity, close the valve on the air pipe after the vacuum extraction is completed to 10 -3 Pa, and finally close the vacuum pump to obtain the cover after the vacuum extraction.

[0012] V. Put the cover after the vacuum extraction into the heating furnace, heat to the rolling temperature, keep the temperature for a period of time at the rolling temperature, and then perform hot rolling, so that the surfaces of the magnesium alloy plate and the aluminum plate are in close contact and react at high temperature to obtain the hot-rolled plate material.

[0013] VI. Cool the hot-rolled plate material in a certain way, cut off the welded edges, then peel off the aluminum plates on the top layer and the bottom layer, and then peel off the magnesium alloy plate, so that the peeled surface of the magnesium alloy plate forms a coating with a certain thickness, cut off the process area of the magnesium alloy plate, and then flatten the magnesium alloy plate with the surface containing the coating to obtain the magnesium alloy plate with the surface containing the corrosion-resistant coating, that is, the preparation method of the magnesium alloy surface corrosion-resistant coating by the hot rolling compounding process is completed.

[0014] The present application has the following advantages:

[0015] The present application proposes a magnesium alloy surface corrosion-resistant coating preparation technology based on hot rolling compounding process. The magnesium and aluminum are tightly contacted and reacted at high temperature by rolling method to form a compound layer with a certain thickness. Since the compound is hard and brittle and the aluminum plate used is relatively soft, when the outer aluminum plate is peeled off by mechanical method, the interface will be torn from the surface of the aluminum plate or broken from the middle of the intermetallic compound layer, and then a corrosion-resistant coating is formed on the surface of the magnesium plate. The present application also has the following advantages:

[0016] (1) The present application uses a vacuum self-sealing structure for rolling. The vacuum protection of the rolling process can be realized by using a common rolling mill, effectively solving the oxidation problem of magnesium alloy under thermal deformation. At the same time, the aluminum and aluminum alloy plate used in the coating preparation process can be recycled and reused after peeling, greatly reducing the production cost.

[0017] (2) Based on the hot rolling compounding process, the instantaneous contact pressure of the magnesium-aluminum plate material is extremely large when it is compounded. The formed coating is dense and tightly combined with the magnesium plate. At the same time of forming the magnesium alloy surface corrosion-resistant coating, the mechanical properties of the magnesium alloy plate are ensured to a certain extent through work hardening.

[0018] (3) The present application can be combined with multiple layers of magnesium-aluminum structure. The surface coating of multiple magnesium alloy plates can be prepared at one time of rolling compounding. At the same time, the tools and chemical reagents used in the preparation method based on the rolling process are simple, solving the problems of complex technology and high cost of existing magnesium alloy surface treatment methods. The present application has the advantages of simple process, easy operation, high production efficiency, green and friendly to the environment, etc. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a stage schematic diagram of the magnesium alloy plate surface coating preparation method of the hot rolling compounding process in Example 1. In the figure, 1 is the top layer of 2219 aluminum alloy plate, 2 is AZ31 magnesium alloy plate, 3 is the outer layer of 2219 aluminum alloy plate welding sealing edge, 4 is the core of 2219 aluminum alloy plate, 5 is boron nitride release agent, 6 is rolling roller, and 7 is the magnesium alloy plate with corrosion-resistant coating on the surface finally obtained.

[0020] Figure 2 It is a schematic diagram of the aluminum plate surface release agent spraying in Example 1.

[0021] Figure 3 It is a real object diagram of the magnesium alloy plate surface after rolling and peeling in Example 1.

[0022] Figure 4 It is an XRD diagram of the coating formed on the surface of the magnesium alloy plate in Example 1.

[0023] Figure 5 Polarization curves of the treated samples for the coating formed on the magnesium alloy substrate and the surface of the magnesium alloy plate in a 3.5wt.% NaCl solution;

[0024] Figure 6 The surface of the sample after potentiodynamic polarization test;

[0025] Figure 7 Changes in the surface of the sample under different immersion times in a 3.5wt.% NaCl solution, where (a) is 0h, (b) is 2h, (c) is 24h, and (d) is 48h. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0027] The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art unless otherwise specified, and can be obtained by commercial channels by those skilled in the art.

[0028] DETAILED DESCRIPTION The present embodiment is a method for preparing a corrosion-resistant coating on the surface of a magnesium alloy by hot rolling, which is completed by the following steps:

[0029] I. Pretreatment of the plate

[0030] Based on the actual processing needs, cut the magnesium alloy plate and aluminum plate to the appropriate size, polish the cut plate to be flat, and clean and dry the surface to be combined to obtain the pretreated magnesium alloy plate and the pretreated aluminum plate.

[0031] II. Paste the peelable adhesive in the middle region of the surface to be combined of the pretreated magnesium alloy plate and the pretreated aluminum plate, and then spray the release agent around the edges of the surface to be combined of the pretreated magnesium alloy plate and the pretreated aluminum plate. After the spraying is completed, peel off the peelable adhesive to obtain a magnesium alloy plate and an aluminum plate with the edges of the surface sprayed with the release agent.

[0032] III. Place two aluminum plates with the edges of the surface sprayed with the release agent on the top layer and the bottom layer of the plate to be combined respectively, with the surface sprayed with the release agent on the inside, then weld the edges of the top layer and the bottom layer of the aluminum plate, and weld the air pipe with the valve to form a group welding cover with a sealed cavity.

[0033] The to-be-combined plate in step three is a magnesium alloy plate with isolation agent sprayed on the edges of the four sides of the two surfaces or a composite plate obtained by alternately stacking a magnesium alloy plate with isolation agent sprayed on the edges of the four sides of the two surfaces and an aluminum plate with isolation agent sprayed on the edges of the four sides of the two surfaces, and the number of layers of the magnesium alloy plate in the composite plate is one more than the number of layers of the aluminum plate;

[0034] Four, the sealed cavity is extracted to 10 -3 Pa, the valve on the air pipe is closed, and finally the vacuum pump is closed to obtain the vacuumized package;

[0035] Five, the vacuumized package is placed in a heating furnace, heated to a rolling temperature, and hot-rolled after being kept at the rolling temperature for a period of time. The magnesium alloy plate and the aluminum plate are in close contact and react at high temperature to obtain a hot-rolled plate;

[0036] Six, the hot-rolled plate is cooled in a certain way, the welded edge is cut off, then the top and bottom aluminum plates are peeled off, and then the magnesium alloy plate is peeled off. The peeled surface of the magnesium alloy plate forms a coating of a certain thickness. The process area of the magnesium alloy plate is cut off, and the magnesium alloy plate with the surface containing the coating is leveled to obtain a magnesium alloy plate with a surface containing a corrosion-resistant coating, i.e. the preparation method of the magnesium alloy surface corrosion-resistant coating in the hot-rolled composite process is completed.

[0037] Specific implementation method two: the difference between this implementation method and specific implementation method one is that: in step one, the polishing process needs to ensure that the plate is smooth and has no obvious deformation; in step one, anhydrous ethanol or acetone is used to clean the surface to be combined to be clean; the aluminum plate in step one is a pure aluminum plate or an aluminum alloy plate; the aluminum alloy plate is 2219 aluminum alloy. The other steps are the same as specific implementation method one.

[0038] Specific implementation method three: the difference between this implementation method and specific implementation method one or two is that: the state of the aluminum plate in step one is O state; the magnesium alloy plate in step one is AZ31 magnesium alloy. The other steps are the same as specific implementation method one or two.

[0039] Specific implementation method four: the difference between this implementation method and any one of specific implementation methods one to three is that: the isolation agent in step two is boron nitride. The other steps are the same as specific implementation methods one to three.

[0040] Specific implementation five: the difference between this embodiment and one of the first to fourth specific implementations is that the four peripheral edge sprayed release agent magnesium alloy plate and the four peripheral edge sprayed release agent aluminum plate in step three are the same size, the top layer and bottom layer aluminum plates are the same size, and the length of the top layer and bottom layer aluminum plates is 15mm-30mm larger than the length of the four peripheral edge sprayed release agent magnesium alloy plate, and the width of the top layer and bottom layer aluminum plates is 15mm-30mm larger than the width of the four peripheral edge sprayed release agent magnesium alloy plate. The other steps are the same as the first to fourth specific implementations.

[0041] Specific implementation six: the difference between this embodiment and one of the first to fifth specific implementations is that the top layer and bottom layer aluminum plates form a cavity after sealing around in step three, and the cavity size can ensure that the internal to-be-combined plate is fixed. The other steps are the same as the first to fifth specific implementations.

[0042] Specific implementation seven: the difference between this embodiment and one of the first to sixth specific implementations is that the rolling temperature in step five is 350℃-550℃; and the holding time in step five is 10min-30min. The other steps are the same as the first to sixth specific implementations.

[0043] Specific implementation eight: the difference between this embodiment and one of the first to seventh specific implementations is that the hot rolling reduction in step five is 10%-50% of the total thickness. The other steps are the same as the first to seventh specific implementations.

[0044] Specific implementation nine: the difference between this embodiment and one of the first to eighth specific implementations is that the cooling in step six is water cooling. The other steps are the same as the first to eighth specific implementations.

[0045] Specific implementation ten: the difference between this embodiment and one of the first to ninth specific implementations is that the stripping in step six is using hand tools or using mechanical equipment, and the stripping direction is parallel to the rolling direction or perpendicular to the rolling direction. The other steps are the same as the first to ninth specific implementations.

[0046] The beneficial effects of the present application are verified by the following examples:

[0047] Example 1: a preparation method of a hot-rolled composite process magnesium alloy surface corrosion-resistant coating, specifically completed by the following steps:

[0048] I. Pretreatment of the plate:

[0049] Based on the actual processing requirements, laser cutting magnesium alloy plate and aluminum plate, using #180, #400 silicon carbide sandpaper in turn to the surface of the cut plate polishing to flat, remove the surface of the pollutants, expose clean metal matrix, increase its roughness, facilitate to promote subsequent rolling interface metallurgical bonding, then use anhydrous ethanol to clean the plate after polishing, finally cold air dry, get pretreated magnesium alloy plate and pretreated aluminum plate;

[0050] The aluminum plate in step one is 2219 aluminum alloy plate, the thickness is 1mm, and the state is O state;

[0051] The magnesium alloy plate in step one is AZ31 magnesium alloy plate, the thickness is 1mm;

[0052] II. Paste the peelable adhesive in the middle region of the surface to be combined of the pretreated magnesium alloy plate and the pretreated aluminum plate, then spray the release agent (the width of the release agent is 20mm) on the four edges of the pretreated magnesium alloy plate or the pretreated aluminum plate, peel off the peelable adhesive after the spraying is completed, and get the magnesium alloy plate with the four edges of the surface sprayed with the release agent and the aluminum plate with the four edges of the surface sprayed with the release agent;

[0053] The release agent in step two is boron nitride;

[0054] III. Place two aluminum plates with the four edges of one surface sprayed with the release agent on the top layer and the bottom layer of the to-be-combined plate respectively, place the surface sprayed with the release agent on the inner side, then weld the four edges of the top layer and the bottom layer of the aluminum plate, and weld the air pipe with the valve, so as to form a group welding package with a sealed cavity;

[0055] The to-be-combined plate in step three is a composite plate obtained by alternately stacking two magnesium alloy plates with the four edges of two surfaces sprayed with the release agent and two aluminum plates with the four edges of two surfaces sprayed with the release agent, and the number of layers of the magnesium alloy plate is one more than that of the aluminum plate, that is, magnesium alloy plate-aluminum plate-magnesium alloy plate;

[0056] The size of the magnesium alloy plate with the four edges of the surface sprayed with the release agent and the aluminum plate with the four edges of the surface sprayed with the release agent is the same, the size of the top layer and the bottom layer of the aluminum plate is the same, and the length of the top layer and the bottom layer of the aluminum plate is 30mm longer than that of the magnesium alloy plate with the four edges of the surface sprayed with the release agent, and the width of the top layer and the bottom layer of the aluminum plate is 30mm wider than that of the magnesium alloy plate with the four edges of the surface sprayed with the release agent;

[0057] After the four edges of the top layer and the bottom layer of the aluminum plate are welded in step three, a cavity is formed, and the size of the cavity can ensure that the to-be-combined plate inside is fixed;

[0058] IV. Extract vacuum from the group welding package with a sealed cavity, and extract vacuum to 10 -3After Pa, close the valve on the gas tube, and finally turn off the vacuum pump to obtain the vacuum-evacuated casing.

[0059] 5. After vacuuming, the cladding is placed in a heating furnace and heated to the rolling temperature. After holding at the rolling temperature for a period of time, hot rolling is performed. The surfaces of the magnesium alloy plate and the aluminum plate are in close contact and react at high temperature. At this time, a reaction layer of suitable thickness is formed between the magnesium alloy plate and the aluminum plate. This reaction layer has high hardness and high brittleness. When the magnesium and aluminum alloy plates are mechanically peeled off later, they will break preferentially from the reaction layer; thus, hot-rolled plates are obtained.

[0060] The rolling temperature mentioned in step five is 450℃;

[0061] The heat preservation time mentioned in step five is 20 minutes;

[0062] In step five, the hot rolling reduction is 40% of the total thickness, and the hot rolling speed is 30 mm / s.

[0063] VI. After the hot-rolled sheet is cooled in a certain way, the welded edge is removed, then the top and bottom aluminum plates are peeled off, and then the magnesium alloy plate is peeled off. A coating of a certain thickness is formed on the peeled surface of the magnesium alloy plate. The process area of ​​the magnesium alloy plate is removed, and the magnesium alloy plate with the coating on the surface is leveled to obtain a magnesium alloy plate with a corrosion-resistant coating on the surface. This completes the preparation method of the corrosion-resistant coating on the surface of the magnesium alloy in the hot-rolled composite process.

[0064] The cooling described in step six is ​​water cooling;

[0065] The peeling described in step six is ​​done using hand tools, and the peeling direction is perpendicular to the rolling direction;

[0066] Figure 3 This is a photograph of the surface of the magnesium alloy plate after rolling and peeling in Example 1.

[0067] Figure 4 The image shows the XRD pattern of the coating formed on the surface of the magnesium alloy plate in Example 1.

[0068] Depend on Figure 4 It can be seen that the diffraction peaks of the phases on the surface of the rolled magnesium alloy plate are all Al2O3, indicating that its main component is dense alumina ceramic. Therefore, during peeling, the composite surface is torn from one side of the aluminum alloy plate, leaving the compound layer on the magnesium alloy plate and leaving a thin film of alumina.

[0069] To characterize the corrosion resistance of the coating, a CHI660E electrochemical workstation was used to test the electrochemical properties of the magnesium alloy substrate and the coating at room temperature. A 3.5wt.% NaCl solution was used as the electrolyte, the working electrode was the sample being tested, the counter electrode was a platinum electrode, and the reference electrode was a saturated AgCl electrode. The polarization curve was obtained by scanning from the cathode to the anode at a rate of 1 mV / s in a voltage range of 0.5 V relative to the open circuit potential, as shown in Figure 5 , and the surface of the sample after electrochemical accelerated corrosion is shown in Figure 6 . The Tafel extrapolation method was used to obtain the corrosion data, as shown in Table 1. The results show that, compared to the AZ31 magnesium alloy substrate, the corrosion current density of the sample after the coating is prepared by this method decreases by two orders of magnitude, the corrosion potential increases from about -1.52 V to -1.09 V, and the corrosion rate of the treated sample decreases significantly; at the same time, the polarization curve of the sample after coating treatment appears a passivation region, indicating that the coating has a certain corrosion resistance.

[0070] Table 1

[0071]

[0072] To more intuitively compare the corrosion resistance of the samples, the substrate sample and the sample after the coating were immersed in a 3.5wt.% NaCl solution, and the surface of the sample after immersion for different times is shown in Figure 7 . The magnesium alloy substrate corrodes obviously just after being immersed for 2h, and the surface of the substrate corrodes severely after 24h Figure 7 (c) left sample); the coating prepared by rolling and compounding still does not corrode obviously after 48h Figure 7 (d) right sample).

Claims

1. A method for producing a corrosion resistant coating on a magnesium alloy surface by hot roll bonding, characterized by The preparation method is specifically completed according to the following steps: I. Pretreatment of the plate: Based on the actual processing requirements, the magnesium alloy plate and the aluminum plate are cut into appropriate sizes, the cut plates are polished flat, and the surfaces to be combined are cleaned and dried, thereby obtaining the pretreated magnesium alloy plate and the pretreated aluminum plate; II. In the middle region of the surfaces to be combined of the pretreated magnesium alloy plate and the pretreated aluminum plate, a peelable adhesive is pasted, and then an isolating agent is sprayed on the four peripheral edges of the pretreated magnesium alloy plate and the pretreated aluminum plate, after the spraying is completed, the peelable adhesive is peeled off, thereby obtaining a magnesium alloy plate and an aluminum plate with the four peripheral edges of one surface or two surfaces sprayed with the isolating agent; III. Two aluminum plates with the four peripheral edges of one surface sprayed with the isolating agent are arranged at the top layer and the bottom layer of the to-be-combined plate respectively, the surface sprayed with the isolating agent is arranged at the inner side, then the four peripheries of the aluminum plates at the top layer and the bottom layer are welded and sealed, and the air pipe with the valve is welded, thereby forming a group-welded cover with a sealed cavity; The to-be-combined plate in step III is a magnesium alloy plate with the four peripheral edges of one surface sprayed with the isolating agent or a composite plate obtained by alternately stacking the magnesium alloy plate with the four peripheral edges of one surface sprayed with the isolating agent and the aluminum plate with the four peripheral edges of one surface sprayed with the isolating agent, and the number of layers of the magnesium alloy plate in the composite plate is one more than that of the aluminum plate. IV. The assembly is evacuated to 10 -3 Pa and the valve on the gas line is closed. The vacuum pump is then turned off and the evacuated assembly is obtained. V. The cover after vacuumizing is placed into a heating furnace, the temperature is raised to the rolling temperature, the cover is kept at the rolling temperature for a period of time, and then hot rolling is performed, the magnesium alloy plate and the aluminum plate are in close contact and react at high temperature, thereby obtaining a hot-rolled plate; VI. After the hot-rolled plate is cooled in a certain way, the welded and sealed edge is cut off, then the aluminum plates at the top layer and the bottom layer are peeled off, and then the magnesium alloy plate is peeled off, the peeled surface of the magnesium alloy plate forms a coating with a certain thickness, the process area of the magnesium alloy plate is cut off, the magnesium alloy plate with the surface containing the coating is leveled, thereby obtaining a magnesium alloy plate with the surface containing the corrosion-resistant coating, and the preparation method of the magnesium alloy surface corrosion-resistant coating in the hot-rolling composite process is completed.

2. The method of claim 1, wherein the magnesium alloy surface corrosion resistant coating is prepared by a hot rolling process. In step I, the polishing process needs to ensure that the plate is smooth and has no obvious deformation; in step I, the surface to be combined is cleaned with anhydrous ethanol or acetone until it is clean; the aluminum plate in step I is a pure aluminum plate or an aluminum alloy plate; the aluminum alloy plate is 2219 aluminum alloy.

3. A method of producing a corrosion resistant coating on a magnesium alloy surface by hot rolling according to claim 2, characterized in that The aluminum plate in step I is in the O state; the magnesium alloy plate in step I is AZ31 magnesium alloy.

4. The method of claim 1, wherein the magnesium alloy surface corrosion resistant coating is prepared by a hot rolling process. The isolating agent in step II is boron nitride.

5. The method of claim 1, wherein the hot-rolled composite process is characterized by In step III, the size of the magnesium alloy plate with the four peripheral edges sprayed with the isolating agent and the aluminum plate with the four peripheral edges sprayed with the isolating agent is the same, the size of the aluminum plates at the top layer and the bottom layer is the same, and the length of the aluminum plates at the top layer and the bottom layer is 15mm-30mm larger than that of the magnesium alloy plate with the four peripheral edges sprayed with the isolating agent, and the width of the aluminum plates at the top layer and the bottom layer is 15mm-30mm larger than that of the magnesium alloy plate with the four peripheral edges sprayed with the isolating agent.

6. The method of claim 1, wherein the hot-rolled composite process is characterized by After the aluminum plates at the top layer and the bottom layer are welded and sealed in step III, a cavity is formed, and the size of the cavity can ensure that the to-be-combined plate inside is fixed.

7. The method of claim 1, wherein the hot-rolled composite process is characterized by The rolling temperature in step V is 350℃-550℃; the keeping time in step V is 10min-30min.

8. The method of claim 1, wherein the hot-rolled composite process is characterized by The reduction in step V is 10%-50% of the total thickness.

9. The method of claim 1, wherein the hot-rolled composite process is characterized by The cooling described in step six is water cooling.

10. The method of claim 1, wherein the magnesium alloy surface corrosion resistant coating is prepared by a hot rolling process. The stripping described in step six is stripping using hand tools or using mechanical equipment, the stripping direction being parallel to the rolling direction or perpendicular to the rolling direction.

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