Corrosion-resistant magnesium alloy material and preparation method and application thereof

Abstract

The application discloses a kind of corrosion-resistant magnesium alloy material and preparation method thereof, it is related to alloy material technical field.The application is when preparing corrosion-resistant magnesium alloy material, pure magnesium, pure zinc, pure aluminum, magnesium gadolinium intermediate alloy and magnesium calcium intermediate alloy are fused and refined to obtain as-cast magnesium alloy;As-cast magnesium alloy is sequentially subjected to solid solution treatment, aging treatment, is extruded and is spun to obtain fine-grained magnesium alloy;After fine-grained magnesium alloy is cut and sampled, micro-arc oxidation is carried out, and then treated by 3-aminopropyl triethoxysilane alcoholysis solution to obtain pretreated magnesium alloy;Urea, formaldehyde are wrapped 2-mercapto benzothiazole to carry out in-situ polymerization to prepare corrosion-inhibiting microcapsule;Dimethyl imidazole, corrosion-inhibiting microcapsule and epoxy resin are spin-coated on the surface of pretreated magnesium alloy to prepare corrosion-resistant magnesium alloy material.The corrosion-resistant magnesium alloy material prepared by the application has excellent corrosion resistance, tensile strength and wear resistance.

Description

Technical Field

[0001] This invention relates to the field of alloy materials technology, specifically to a corrosion-resistant magnesium alloy material and its preparation method. Background Technology

[0002] With the rapid development of modern industry, structural materials required for modern industries such as aerospace and transportation are trending towards lightweight, high-speed, and high-power applications. Magnesium and magnesium alloys are the lightest metallic structural materials in industrial production, possessing not only high specific strength but also specific stiffness comparable to aluminum alloys and steel. They also exhibit excellent casting and machining properties and are environmentally friendly and recyclable. These superior comprehensive properties make magnesium and magnesium alloys promising for applications in various fields such as defense technology, automobiles, and electronic communications.

[0003] Pure magnesium struggles to meet high performance requirements in industrial applications, while the development of magnesium alloy applications has lagged significantly, suffering from problems such as poor plasticity and formability, low absolute strength, poor high-temperature resistance, and poor corrosion resistance. These shortcomings greatly limit the application range of magnesium alloys. Solving the performance applicability issues of magnesium alloys and expanding their application range is the only way to enhance their competitiveness in industry. Therefore, this invention prepares a corrosion-resistant magnesium alloy material with excellent corrosion resistance, tensile strength, and wear resistance. Summary of the Invention

[0004] The purpose of this invention is to provide a corrosion-resistant magnesium alloy material and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A corrosion-resistant magnesium alloy material, characterized in that the corrosion-resistant magnesium alloy material is obtained by spin-coating dimethylimidazole, corrosion-inhibiting microcapsules and epoxy resin onto the surface of a pretreated magnesium alloy.

[0007] As an optimization, the epoxy resin is model E44, sourced from Wanqing Chemical Technology Co., Ltd.

[0008] As an optimization, the corrosion-inhibiting microcapsules are prepared by in-situ polymerization of 2-mercaptobenzothiazole encapsulated in urea and formaldehyde.

[0009] As an optimization, the pretreated magnesium alloy is prepared by cutting and sampling fine-grained magnesium alloy, performing micro-arc oxidation, and then treating it with 3-aminopropyltriethoxysilane alcoholysis solution.

[0010] As an optimization, the refined magnesium alloy is obtained by melting and refining pure magnesium, pure zinc, pure aluminum, magnesium-gadolinium master alloy and magnesium-calcium master alloy, followed by solution treatment, aging treatment and extrusion spinning.

[0011] A method for preparing a corrosion-resistant magnesium alloy material includes the following preparation steps:

[0012] (1) In a protective gas environment, heat the pit-type resistance furnace to 720–740°C, add pure magnesium and 0.091–0.093 times the mass of pure magnesium gadolinium master alloy, sprinkle a covering agent with 0.01–0.03 times the mass of pure magnesium on the surface, keep it at this temperature for 15–25 minutes, cool it to 715–725°C, remove surface impurities with a slag skimmer, and add 0.011–0.013 times the mass of pure magnesium zinc, 0.002–0.004 times the mass of pure magnesium aluminum, and 0.027–0.029 times the mass of pure magnesium calcium master alloy. The alloy is coated with a covering agent at a ratio of 0.02 to 0.03 times the mass of pure magnesium. The temperature is raised to 725 to 735°C and held for 25 to 35 minutes. Surface impurities are removed with a slag skimmer. The mixture is stirred for 4 to 6 minutes. A refining agent at a ratio of 0.005 to 0.015 times the mass of pure magnesium and a covering agent at a ratio of 0.02 to 0.03 times the mass of pure magnesium are added. The mixture is stirred for another 5 to 15 minutes. Surface impurities are removed with a slag skimmer. The mixture is allowed to stand for 10 to 20 minutes and then cast into a steel mold preheated to 200 to 250°C. The mixture is allowed to solidify naturally to obtain a cast magnesium alloy.

[0013] (2) The cast magnesium alloy is wrapped in aluminum foil and embedded in dried graphite powder. It is heated in a box-type high-temperature resistance furnace from 150-250℃ to 450-550℃ at a rate of 4-6℃ / min, held for 9-11 hours, air-cooled to room temperature, and then reheated to 300-400℃ and held for 1-2 hours. It is then upsetting 3-5 times with a hydraulic press, transferred to a compression device, and subjected to a heating rate of 5-15℃ / s and a strain rate of 0.4-0.6s. -1 Under the condition of engineering strain of 0.7 to 0.9, the temperature is raised to 460 to 480℃, held for 2 to 4 minutes, air-cooled and quenched to room temperature, a pre-pressure of 450 to 550 N is applied, and the temperature is heated to 350 to 450℃ at a rate of 0.93 to 0.95℃ / sec. The die is fed 5 to 7 mm in the axial direction at an extrusion speed of 0.01 to 0.03 mm / s, and the punch is rotated clockwise 900 to 1100 N at a rate of 1.255 to 1.257 rad / s. The temperature is held for 7 to 9 minutes, and the furnace is cooled to room temperature at a rate of 20 to 50℃ per hour to obtain a fine-grained magnesium alloy.

[0014] (3) Cut the fine-grained magnesium alloy into samples of 30mm×10mm×5mm, mechanically polish them with 600-1200 mesh silicon carbide sandpaper for 1-3 minutes, wash them with anhydrous ethanol 3-5 times, air dry them at 20-30℃, micro-arc oxidation them with plasma electrolytic oxidation equipment for 7-9 minutes, take them out, wash them with deionized water 3-5 times, dry them at 130-150℃ for 1-3 hours, transfer them into 3-aminopropyltriethoxysilane alcoholysis solution, ultrasonically impregnate them at 77-79℃ for 1-3 hours, take them out and dry them at 190-210℃ for 1-3 hours to obtain pretreated magnesium alloy;

[0015] (4) Mix urea, a 4-6% polyvinyl alcohol solution, ammonium chloride, resorcinol, and deionized water in a mass ratio of 1:(2-4):(0.05-0.07):(0.05-0.07):(23-25). Adjust the pH to 7-8 with a 9-11% sodium hydroxide solution. Add 0.1-0.3 times the mass of urea of ​​2-mercaptobenzothiazole and 4-6 times the mass of urea of ​​xylene. Stir at 20-30℃ and 100-200 rpm for 20-40 min. Add 2-3 times the mass of urea of ​​formaldehyde. Heat to 55-65℃ and stir at 450-550 rpm for 2-4 h. Add a 9-11% sodium hydroxide solution of 2-mercaptobenzothiazole and 4-6 times the mass of urea of ​​xylene. The pH was adjusted to 3-4 with 4-6% hydrochloric acid solution, and the mixture was allowed to cool naturally to room temperature. The upper layer product was filtered, washed 3-5 times with deionized water, and dried at 55-65℃ for 8-10 hours to obtain corrosion-inhibiting microcapsules. Dimethylimidazole, corrosion-inhibiting microcapsules, and epoxy resin were mixed at a mass ratio of 1:(1-2):(13-15), stirred at 200-300 rpm for 10-20 minutes, sonicated for 10-20 minutes, and allowed to stand for 4-6 minutes to obtain a spin-coating solution. The solution was spin-coated onto the pretreated magnesium alloy surface at a speed of 700-900 rpm, with a coating thickness of 40-50 μm. The solution was then allowed to stand for 6-8 hours to air dry naturally to obtain a corrosion-resistant magnesium alloy material.

[0016] As an optimization, the pure magnesium, pure zinc, pure aluminum, magnesium gadolinium master alloy and magnesium calcium master alloy mentioned in step (1) are obtained by washing with deionized water 3 to 5 times, drying at 190 to 210°C for 6 to 8 hours, and then transferring them into a box-type resistance furnace and preheating at 190 to 210°C for 25 to 35 minutes.

[0017] As an optimization, the magnesium-gadolinium master alloy is designated as Mg-30%Gd and is sourced from Suzhou Chuanmao Metal Materials Co., Ltd.

[0018] As an optimization, the magnesium-calcium master alloy is designated as Mg-30%Ga and is sourced from Suzhou Haichuan Rare Metals Products Co., Ltd.

[0019] As an optimization, the protective gas in step (1) is obtained by mixing carbon dioxide and sulfur hexafluoride in a volume ratio of 100:1.

[0020] As an optimization, the covering agent in step (1) is obtained by mixing sodium chloride, calcium chloride, barium chloride, potassium chloride and sodium hexafluoroaluminate in a mass ratio of 1:20:6:5.3:1.

[0021] As an optimization, the refining agent in step (1) is obtained by mixing sodium chloride, calcium chloride, barium chloride, potassium chloride, chlorine chloride, sodium hexafluoroaluminate and calcium fluoride in a mass ratio of 1:16.3:6:5.3:2:1:1.6.

[0022] As an optimization, the conditions for micro-arc oxidation in step (3) are: power supply frequency 500Hz, pulse ratio 10:1, and current density 6.5A / dm³. 2 The electrolyte consists of sodium silicate, sodium stannate, and sodium hydroxide in a molar ratio of 1:1:2. The anode is a fine-grained magnesium alloy sample, and the cathode is a stainless steel plate.

[0023] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0024] In preparing corrosion-resistant magnesium alloy materials, this invention involves melting and refining pure magnesium, pure zinc, pure aluminum, magnesium-gadolinium master alloy, and magnesium-calcium master alloy to obtain a cast magnesium alloy; sequentially subjecting the cast magnesium alloy to solution treatment, aging treatment, and upsetting and spinning to obtain a fine-grained magnesium alloy; cutting and sampling the fine-grained magnesium alloy and subjecting it to micro-arc oxidation, followed by treatment with 3-aminopropyltriethoxysilane hydrolysis solution to obtain a pretreated magnesium alloy; encapsulating 2-mercaptobenzothiazole with urea and formaldehyde and performing in-situ polymerization to obtain corrosion-inhibiting microcapsules; and then spin-coating dimethylimidazole, the corrosion-inhibiting microcapsules, and epoxy resin onto the surface of the pretreated magnesium alloy to produce a corrosion-resistant magnesium alloy material.

[0025] First, pure magnesium, pure zinc, pure aluminum, gadolinium magnesium master alloy, and magnesium-calcium master alloy are melt-refined to obtain a cast magnesium alloy. The cast magnesium alloy is then subjected to solution treatment, aging treatment, and upsetting and spinning to obtain a fine-grained magnesium alloy. During the forging process, gadolinium and zinc elements are introduced to promote alloy strengthening. During solution treatment and aging treatment, a long-period ordered granulated structure is formed as a strengthening phase, improving the tensile strength of the corrosion-resistant magnesium alloy. The introduction of aluminum can form a dense oxide film with magnesium and can also promote the transformation of the long-period ordered granulated structure from the 18R type to the 14H type during solution treatment, reducing grain boundary energy and improving the corrosion resistance of the corrosion-resistant magnesium alloy. Through upsetting and spinning, the lamellar and blocky long-period ordered granulated structure phases are elongated and broken to form fine lamellar and short rod-shaped long-period ordered granulated structure phases. At the same time, a large number of nano-precipitates are precipitated, which assists strain-induced grain boundary migration, producing grain boundary bowing, forming ultrafine grains, and enhancing the wear resistance of the corrosion-resistant magnesium alloy.

[0026] Secondly, after cutting and sampling the fine-grained magnesium alloy, micro-arc oxidation was performed, followed by treatment with 3-aminopropyltriethoxysilane hydrolysate to obtain a pretreated magnesium alloy. Urea and formaldehyde were then used to encapsulate 2-mercaptobenzothiazole in situ for polymerization to prepare corrosion-inhibiting microcapsules. Dimethylimidazole, the corrosion-inhibiting microcapsules, and epoxy resin were then spin-coated onto the surface of the pretreated magnesium alloy to create a corrosion-resistant magnesium alloy material. Micro-arc oxidation with a silicate electrolyte was then performed to form a uniform porous ceramic oxide layer containing oxides such as silicon dioxide on the surface of the fine-grained magnesium alloy, improving the corrosion resistance of the magnesium alloy material. The coating improves wear resistance and corrosion resistance. Modification of the film layer with 3-aminopropyltriethoxysilane allows for chemical bonding between the epoxy resin coating and the alloy, enhancing the corrosion resistance of the magnesium alloy material. Adding corrosion-inhibiting microcapsules loaded with 2-mercaptobenzothiazole to the epoxy resin coating allows for the release of 2-mercaptobenzothiazole when the surface is damaged. The thiol groups form coordination or covalent bonds with the magnesium surface, creating a protective adsorption film that reduces contact between the magnesium alloy and corrosive media, further improving the corrosion resistance of the magnesium alloy material. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The test methods for various indicators of the corrosion-resistant magnesium alloy material prepared in the following embodiments are as follows:

[0029] Corrosion resistance: The corrosion-resistant magnesium alloy materials obtained in each embodiment and the comparative example were immersed in a 3.5% sodium chloride solution for 30 min. The corrosion current density was measured using a Gamry 3000 instrument under an open circuit potential of 1 mV / min to determine the corrosion resistance.

[0030] Tensile properties: The corrosion-resistant magnesium alloy materials obtained in each embodiment and the comparative example were made into tensile specimens according to GB / T228.1, and the tensile strength was tested using a SANSDNS100 universal tensile testing machine at 150℃ and a tensile speed of 0.2 mm / min.

[0031] Wear resistance: The corrosion-resistant magnesium alloy materials obtained in each embodiment and the comparative example were tested for wear loss using a microcomputer-controlled end-face friction and wear tester of model MMU-10, under the conditions of silicon nitride small balls with a friction pair diameter of 5mm, load of 5N, rotation speed of 150r / min and friction time of 800s, to determine the wear resistance.

[0032] Example 1

[0033] A method for preparing a corrosion-resistant magnesium alloy material, the method comprising the following steps:

[0034] (1) In a protective gas environment, the temperature of the pit-type resistance furnace is raised to 720℃. Pure magnesium and magnesium-gadolinium master alloy with a mass of 0.091 times that of pure magnesium are added. Covering agent with a mass of 0.01 times that of pure magnesium is sprinkled on the surface. The temperature is kept for 25 minutes. The temperature is lowered to 715℃. Surface impurities are removed with a slag scraper. Pure zinc with a mass of 0.011 times that of pure magnesium, pure aluminum with a mass of 0.002 times that of pure magnesium, and magnesium-calcium master alloy with a mass of 0.027 times that of pure magnesium are added. Covering agent with a mass of 0.02 times that of pure magnesium is sprinkled on the surface. The temperature is raised to 725℃ and kept for 35 minutes. Surface impurities are removed with a slag scraper. The mixture is stirred for 6 minutes. Refining agent with a mass of 0.005 times that of pure magnesium and covering agent with a mass of 0.02 times that of pure magnesium are added. The mixture is stirred for another 15 minutes. Surface impurities are removed with a slag scraper. The mixture is allowed to stand for 20 minutes. The mixture is then poured into a steel mold with a preheated temperature of 200℃ and allowed to solidify naturally to obtain a cast magnesium alloy.

[0035] (2) The cast magnesium alloy was wrapped in aluminum foil and embedded in dried graphite powder. It was heated from 150°C to 450°C in a box-type high-temperature resistance furnace at a rate of 4°C / min, held for 11 hours, air-cooled to room temperature, and then reheated to 300°C and held for 2 hours. It was then upsetting three times with a hydraulic press, transferred to a compression device, and subjected to a heating rate of 5°C / s and a strain rate of 0.4s. -1 Under the condition of engineering strain 0.7, the temperature is raised to 460℃, held for 4 min, air-cooled and quenched to room temperature, a pre-pressure of 450N is applied, and the temperature is heated to 350℃ at a rate of 0.93℃ / sec. The die is fed 5mm in the axial direction at an extrusion speed of 0.01mm / s, and the punch is rotated 900N clockwise at a rate of 1.255rad / s. The temperature is held for 9 min, and the temperature is cooled to room temperature in the furnace at a rate of 20℃ per hour to obtain a fine-grained magnesium alloy.

[0036] (3) The fine-grained magnesium alloy was cut into samples of 30mm×10mm×5mm, mechanically polished with 600-mesh silicon carbide sandpaper for 3min, washed with anhydrous ethanol 3 times, air-dried at 20℃, micro-arc oxidized with plasma electrolytic oxidation equipment for 9min, taken out, washed with deionized water 3 times, dried at 130℃ for 3h, transferred into 3-aminopropyltriethoxysilane alcoholysis solution, ultrasonically impregnated at 77℃ for 3h, taken out and dried at 190℃ for 3h to obtain pretreated magnesium alloy;

[0037] (4) Mix urea, a 4% polyvinyl alcohol solution, ammonium chloride, resorcinol, and deionized water in a mass ratio of 1:2:0.05:0.05:23. Adjust the pH to 7 with a 9% sodium hydroxide solution. Add 0.1 times the mass of urea of ​​2-mercaptobenzothiazole and 4 times the mass of urea of ​​xylene. Stir at 20°C and 100 rpm for 40 min. Add 2 times the mass of urea of ​​formaldehyde. Heat to 55°C and stir at 450 rpm for 4 h. Adjust the pH to 7 with a 4% hydrochloric acid solution. Adjust the pH to 3, allow it to cool naturally to room temperature, filter the supernatant, wash it three times with deionized water, and dry it at 55℃ for 10 hours to obtain corrosion-inhibiting microcapsules; mix dimethylimidazole, corrosion-inhibiting microcapsules and epoxy resin at a mass ratio of 1:1:13, stir at 200 rpm for 20 minutes, sonicate for 20 minutes, and let it stand for 6 minutes to obtain a spin-coating solution; spin-coat the pretreated magnesium alloy surface at a speed of 700 rpm, with a coating thickness of 40 μm, and let it stand for 6 hours to air dry naturally to obtain corrosion-resistant magnesium alloy material.

[0038] Example 2

[0039] A method for preparing a corrosion-resistant magnesium alloy material, the method comprising the following steps:

[0040] (1) In a protective gas environment, the temperature of the pit-type resistance furnace is raised to 730℃. Pure magnesium and magnesium gadolinium master alloy with a mass of 0.092 times that of pure magnesium are added. Covering agent with a mass of 0.02 times that of pure magnesium is sprinkled on the surface. The temperature is kept for 20 minutes. The temperature is lowered to 720℃. Surface impurities are removed with a slag scraper. Pure zinc with a mass of 0.012 times that of pure magnesium, pure aluminum with a mass of 0.003 times that of pure magnesium, and magnesium calcium master alloy with a mass of 0.028 times that of pure magnesium are added. Covering agent with a mass of 0.025 times that of pure magnesium is sprinkled on the surface. The temperature is raised to 730℃ and kept for 30 minutes. Surface impurities are removed with a slag scraper. The mixture is stirred for 5 minutes. Refining agent with a mass of 0.01 times that of pure magnesium and covering agent with a mass of 0.025 times that of pure magnesium are added. The mixture is stirred for another 10 minutes. Surface impurities are removed with a slag scraper. The mixture is allowed to stand for 15 minutes. The mixture is then poured into a steel mold with a preheated temperature of 225℃ and allowed to solidify naturally to obtain a cast magnesium alloy.

[0041] (2) The cast magnesium alloy was wrapped in aluminum foil and embedded in dried graphite powder. It was heated from 200°C to 500°C in a box-type high-temperature resistance furnace at a rate of 5°C / min, held for 10 hours, air-cooled to room temperature, and then reheated to 350°C and held for 1.5 hours. It was then upsetting four times with a hydraulic press and transferred to a compression device at a heating rate of 10°C / s and a strain rate of 0.5s. -1Under the condition of engineering strain 0.8, the temperature is raised to 470℃, held for 3 min, air-cooled and quenched to room temperature, a pre-pressure of 500N is applied, and the temperature is heated to 400℃ at a rate of 0.94℃ / sec. The die is fed 6mm in the axial direction at an extrusion speed of 0.02mm / s, and the punch is rotated clockwise by 1000N at a rate of 1.256rad / s. The temperature is held for 8 min, and the temperature is cooled to room temperature in the furnace at a rate of 35℃ per hour to obtain a fine-grained magnesium alloy.

[0042] (3) The fine-grained magnesium alloy was cut into samples of 30mm×10mm×5mm, mechanically polished with 900-mesh silicon carbide sandpaper for 2min, washed with anhydrous ethanol 4 times, air-dried at 25℃, micro-arc oxidation with plasma electrolytic oxidation equipment for 8min, washed with deionized water 4 times, dried at 140℃ for 2h, transferred into 3-aminopropyltriethoxysilane alcoholysis solution, ultrasonically impregnated at 78℃ for 2h, and then dried at 200℃ for 2h to obtain the pretreated magnesium alloy.

[0043] (4) Mix urea, 5% polyvinyl alcohol solution, ammonium chloride, resorcinol, and deionized water in a mass ratio of 1:3:0.06:0.06:24. Adjust the pH to 7.5 with 10% sodium hydroxide solution. Add 0.2 times the mass of urea of ​​2-mercaptobenzothiazole and 5 times the mass of urea of ​​xylene. Stir at 25°C and 150 rpm for 30 min. Add 2.5 times the mass of urea of ​​formaldehyde. Heat to 60°C and stir at 500 rpm for 3 h. Add 5% hydrochloric acid solution. Adjust the pH to 3.5, allow it to cool naturally to room temperature, filter the supernatant, wash it four times with deionized water, and dry it at 60℃ for 9 hours to obtain corrosion-inhibiting microcapsules; mix dimethylimidazole, corrosion-inhibiting microcapsules and epoxy resin at a mass ratio of 1:1.5:14, stir at 250 rpm for 15 minutes, sonicate for 15 minutes, and let it stand for 5 minutes to obtain a spin-coating solution; spin-coat the pretreated magnesium alloy surface at a speed of 800 rpm, with a coating thickness of 45 μm, and let it stand for 7 hours to air dry naturally to obtain corrosion-resistant magnesium alloy material.

[0044] Example 3

[0045] A method for preparing a corrosion-resistant magnesium alloy material, the method comprising the following steps:

[0046] (1) In a protective gas environment, the temperature of the pit-type resistance furnace is raised to 740℃. Pure magnesium and magnesium-gadolinium master alloy with a mass of 0.093 times that of pure magnesium are added. Covering agent with a mass of 0.03 times that of pure magnesium is sprinkled on the surface. The temperature is kept for 15 minutes. The temperature is lowered to 725℃. Surface impurities are removed with a slag scraper. Pure zinc with a mass of 0.013 times that of pure magnesium, pure aluminum with a mass of 0.004 times that of pure magnesium, and magnesium-calcium master alloy with a mass of 0.029 times that of pure magnesium are added. Covering agent with a mass of 0.03 times that of pure magnesium is sprinkled on the surface. The temperature is raised to 735℃ and kept for 25 minutes. Surface impurities are removed with a slag scraper. The mixture is stirred for 4 minutes. Refining agent with a mass of 0.015 times that of pure magnesium and covering agent with a mass of 0.03 times that of pure magnesium are added. The mixture is stirred for another 5 minutes. Surface impurities are removed with a slag scraper. The mixture is allowed to stand for 10 minutes. The mixture is then poured into a steel mold with a preheated temperature of 250℃ and allowed to solidify naturally to obtain a cast magnesium alloy.

[0047] (2) The cast magnesium alloy was wrapped in aluminum foil and embedded in dried graphite powder. It was heated from 250°C to 550°C in a box-type high-temperature resistance furnace at a rate of 6°C / min, held for 9 hours, air-cooled to room temperature, and then reheated to 400°C and held for 1 hour. It was then upsetting 5 times with a hydraulic press and transferred to a compression device at a heating rate of 15°C / s and a strain rate of 0.6s. -1 Under the condition of engineering strain 0.9, the temperature is raised to 480℃, held for 2 min, air-cooled and quenched to room temperature, a pre-pressure of 550N is applied, and the temperature is heated to 450℃ at a rate of 0.95℃ / sec. The die is fed 7mm in the axial direction at an extrusion speed of 0.03mm / s, and the punch is rotated clockwise by 1100N at a rate of 1.257rad / s. The temperature is held for 7 min, and the temperature is cooled to room temperature in the furnace at a rate of 50℃ per hour to obtain a fine-grained magnesium alloy.

[0048] (3) The fine-grained magnesium alloy was cut into samples of 30mm×10mm×5mm, mechanically polished with 1200-mesh silicon carbide sandpaper for 1 minute, washed with anhydrous ethanol 5 times, air-dried at 30℃, micro-arc oxidized with plasma electrolytic oxidation equipment for 7 minutes, washed with deionized water 5 times, dried at 150℃ for 1 hour, transferred into 3-aminopropyltriethoxysilane alcoholysis solution, ultrasonically impregnated at 79℃ for 1 hour, and then dried at 210℃ for 1 hour to obtain the pretreated magnesium alloy.

[0049] (4) Mix urea, a 6% polyvinyl alcohol solution, ammonium chloride, resorcinol, and deionized water in a mass ratio of 1:4:0.07:0.07:25. Adjust the pH to 8 with an 11% sodium hydroxide solution. Add 0.3 times the mass of urea of ​​2-mercaptobenzothiazole and 6 times the mass of urea of ​​xylene. Stir at 30°C and 200 rpm for 20 min. Add 3 times the mass of urea of ​​formaldehyde. Heat to 65°C and stir at 550 rpm for 2 h. Add a 6% hydrochloric acid solution. Adjust the pH to 4, allow it to cool naturally to room temperature, filter the supernatant, wash it 5 times with deionized water, and dry it at 65℃ for 8 hours to obtain corrosion-inhibiting microcapsules; mix dimethylimidazole, corrosion-inhibiting microcapsules and epoxy resin at a mass ratio of 1:2:15, stir at 300 rpm for 10 min, sonicate for 10 min, and let it stand for 4 min to obtain a spin-coating solution; spin-coat the pretreated magnesium alloy surface at a speed of 900 rpm, with a coating thickness of 50 μm, and let it stand for 8 hours to air dry naturally to obtain corrosion-resistant magnesium alloy material.

[0050] Comparative Example 1

[0051] A method for preparing a corrosion-resistant magnesium alloy material, the method comprising the following steps:

[0052] (1) In a protective gas environment, the temperature of the pit-type resistance furnace is raised to 730℃. Pure magnesium is added and a covering agent of 0.02 times the mass of pure magnesium is sprinkled on the surface. The temperature is maintained for 20 minutes. The temperature is lowered to 720℃. Surface impurities are removed with a slag scraper. Pure aluminum of 0.003 times the mass of pure magnesium and magnesium-calcium intermediate alloy of 0.028 times the mass of pure magnesium are added. A covering agent of 0.025 times the mass of pure magnesium is sprinkled on the surface. The temperature is raised to 730℃ and maintained for 30 minutes. Surface impurities are removed with a slag scraper. The mixture is stirred for 5 minutes. Refining agent of 0.01 times the mass of pure magnesium and covering agent of 0.025 times the mass of pure magnesium are added. The mixture is stirred for another 10 minutes. Surface impurities are removed with a slag scraper. The mixture is allowed to stand for 15 minutes and then cast into a steel mold with a preheated temperature of 225℃. The mixture is allowed to solidify naturally to obtain a cast magnesium alloy.

[0053] (2) The cast magnesium alloy was wrapped in aluminum foil and embedded in dried graphite powder. It was heated from 200°C to 500°C in a box-type high-temperature resistance furnace at a rate of 5°C / min, held for 10 hours, air-cooled to room temperature, and then reheated to 350°C and held for 1.5 hours. It was then upsetting four times with a hydraulic press and transferred to a compression device at a heating rate of 10°C / s and a strain rate of 0.5s. -1Under the condition of engineering strain 0.8, the temperature is raised to 470℃, held for 3 min, air-cooled and quenched to room temperature, a pre-pressure of 500N is applied, and the temperature is heated to 400℃ at a rate of 0.94℃ / sec. The die is fed 6mm in the axial direction at an extrusion speed of 0.02mm / s, and the punch is rotated clockwise by 1000N at a rate of 1.256rad / s. The temperature is held for 8 min, and the temperature is cooled to room temperature in the furnace at a rate of 35℃ per hour to obtain a fine-grained magnesium alloy.

[0054] (3) The fine-grained magnesium alloy was cut into samples of 30mm×10mm×5mm, mechanically polished with 900-mesh silicon carbide sandpaper for 2min, washed with anhydrous ethanol 4 times, air-dried at 25℃, micro-arc oxidation with plasma electrolytic oxidation equipment for 8min, washed with deionized water 4 times, dried at 140℃ for 2h, transferred into 3-aminopropyltriethoxysilane alcoholysis solution, ultrasonically impregnated at 78℃ for 2h, and then dried at 200℃ for 2h to obtain the pretreated magnesium alloy.

[0055] (4) Mix urea, 5% polyvinyl alcohol solution, ammonium chloride, resorcinol, and deionized water in a mass ratio of 1:3:0.06:0.06:24. Adjust the pH to 7.5 with 10% sodium hydroxide solution. Add 0.2 times the mass of urea of ​​2-mercaptobenzothiazole and 5 times the mass of urea of ​​xylene. Stir at 25°C and 150 rpm for 30 min. Add 2.5 times the mass of urea of ​​formaldehyde. Heat to 60°C and stir at 500 rpm for 3 h. Add 5% hydrochloric acid solution. Adjust the pH to 3.5, allow it to cool naturally to room temperature, filter the supernatant, wash it four times with deionized water, and dry it at 60℃ for 9 hours to obtain corrosion-inhibiting microcapsules; mix dimethylimidazole, corrosion-inhibiting microcapsules and epoxy resin at a mass ratio of 1:1.5:14, stir at 250 rpm for 15 minutes, sonicate for 15 minutes, and let it stand for 5 minutes to obtain a spin-coating solution; spin-coat the pretreated magnesium alloy surface at a speed of 800 rpm, with a coating thickness of 45 μm, and let it stand for 7 hours to air dry naturally to obtain corrosion-resistant magnesium alloy material.

[0056] Comparative Example 2

[0057] A method for preparing a corrosion-resistant magnesium alloy material, the method comprising the following steps:

[0058] (1) In a protective gas environment, the temperature of the well-type electric resistance furnace is raised to 730℃. Pure magnesium and magnesium gadolinium master alloy with a mass of 0.092 times that of pure magnesium are added. Covering agent with a mass of 0.02 times that of pure magnesium is sprinkled on the surface. The temperature is kept for 20 minutes. The temperature is lowered to 720℃. Surface impurities are removed with a slag scraper. Pure zinc with a mass of 0.012 times that of pure magnesium and magnesium calcium master alloy with a mass of 0.028 times that of pure magnesium are added. Covering agent with a mass of 0.025 times that of pure magnesium is sprinkled on the surface. The temperature is raised to 730℃ and kept for 30 minutes. Surface impurities are removed with a slag scraper. The mixture is stirred for 5 minutes. Refining agent with a mass of 0.01 times that of pure magnesium and covering agent with a mass of 0.025 times that of pure magnesium are added. The mixture is stirred for another 10 minutes. Surface impurities are removed with a slag scraper. The mixture is allowed to stand for 15 minutes. The mixture is then poured into a steel mold with a preheated temperature of 225℃ and allowed to solidify naturally to obtain a cast magnesium alloy.

[0059] (2) The cast magnesium alloy was wrapped in aluminum foil and embedded in dried graphite powder. It was heated from 200°C to 500°C in a box-type high-temperature resistance furnace at a rate of 5°C / min, held for 10 hours, air-cooled to room temperature, and then reheated to 350°C and held for 1.5 hours. It was then upsetting four times with a hydraulic press and transferred to a compression device at a heating rate of 10°C / s and a strain rate of 0.5s. -1 Under the condition of engineering strain 0.8, the temperature is raised to 470℃, held for 3 min, air-cooled and quenched to room temperature, a pre-pressure of 500N is applied, and the temperature is heated to 400℃ at a rate of 0.94℃ / sec. The die is fed 6mm in the axial direction at an extrusion speed of 0.02mm / s, and the punch is rotated clockwise by 1000N at a rate of 1.256rad / s. The temperature is held for 8 min, and the temperature is cooled to room temperature in the furnace at a rate of 35℃ per hour to obtain a fine-grained magnesium alloy.

[0060] (3) The fine-grained magnesium alloy was cut into samples of 30mm×10mm×5mm, mechanically polished with 900-mesh silicon carbide sandpaper for 2min, washed with anhydrous ethanol 4 times, air-dried at 25℃, micro-arc oxidation with plasma electrolytic oxidation equipment for 8min, washed with deionized water 4 times, dried at 140℃ for 2h, transferred into 3-aminopropyltriethoxysilane alcoholysis solution, ultrasonically impregnated at 78℃ for 2h, and then dried at 200℃ for 2h to obtain the pretreated magnesium alloy.

[0061] (4) Mix urea, 5% polyvinyl alcohol solution, ammonium chloride, resorcinol, and deionized water in a mass ratio of 1:3:0.06:0.06:24. Adjust the pH to 7.5 with 10% sodium hydroxide solution. Add 0.2 times the mass of urea of ​​2-mercaptobenzothiazole and 5 times the mass of urea of ​​xylene. Stir at 25°C and 150 rpm for 30 min. Add 2.5 times the mass of urea of ​​formaldehyde. Heat to 60°C and stir at 500 rpm for 3 h. Add 5% hydrochloric acid solution. Adjust the pH to 3.5, allow it to cool naturally to room temperature, filter the supernatant, wash it four times with deionized water, and dry it at 60℃ for 9 hours to obtain corrosion-inhibiting microcapsules; mix dimethylimidazole, corrosion-inhibiting microcapsules and epoxy resin at a mass ratio of 1:1.5:14, stir at 250 rpm for 15 minutes, sonicate for 15 minutes, and let it stand for 5 minutes to obtain a spin-coating solution; spin-coat the pretreated magnesium alloy surface at a speed of 800 rpm, with a coating thickness of 45 μm, and let it stand for 7 hours to air dry naturally to obtain corrosion-resistant magnesium alloy material.

[0062] Comparative Example 3

[0063] A method for preparing a corrosion-resistant magnesium alloy material, the method comprising the following steps:

[0064] (1) In a protective gas environment, the temperature of the pit-type resistance furnace is raised to 730℃. Pure magnesium and magnesium gadolinium master alloy with a mass of 0.092 times that of pure magnesium are added. Covering agent with a mass of 0.02 times that of pure magnesium is sprinkled on the surface. The temperature is kept for 20 minutes. The temperature is lowered to 720℃. Surface impurities are removed with a slag scraper. Pure zinc with a mass of 0.012 times that of pure magnesium, pure aluminum with a mass of 0.003 times that of pure magnesium, and magnesium calcium master alloy with a mass of 0.028 times that of pure magnesium are added. Covering agent with a mass of 0.025 times that of pure magnesium is sprinkled on the surface. The temperature is raised to 730℃ and kept for 30 minutes. Surface impurities are removed with a slag scraper. The mixture is stirred for 5 minutes. Refining agent with a mass of 0.01 times that of pure magnesium and covering agent with a mass of 0.025 times that of pure magnesium are added. The mixture is stirred for another 10 minutes. Surface impurities are removed with a slag scraper. The mixture is allowed to stand for 15 minutes. The mixture is then poured into a steel mold with a preheated temperature of 225℃ and allowed to solidify naturally to obtain a cast magnesium alloy.

[0065] (2) The cast magnesium alloy is wrapped in aluminum foil and buried in dried graphite powder. It is heated from 200°C to 500°C at a rate of 5°C / min in a box-type high-temperature resistance furnace, held for 10 hours, cooled to room temperature by air, and then heated to 350°C and held for 1.5 hours. It is then cooled to room temperature with the furnace at a rate of 35°C per hour to obtain the pretreated magnesium alloy.

[0066] (3) The pretreated magnesium alloy was cut into samples of 30mm×10mm×5mm, mechanically polished with 900-mesh silicon carbide sandpaper for 2min, washed with anhydrous ethanol 4 times, air-dried at 25℃, micro-arc oxidation with plasma electrolytic oxidation equipment for 8min, washed with deionized water 4 times, dried at 140℃ for 2h, transferred into 3-aminopropyltriethoxysilane alcoholysis solution, ultrasonically impregnated at 78℃ for 2h, and then dried at 200℃ for 2h to obtain the pretreated magnesium alloy.

[0067] (4) Mix urea, 5% polyvinyl alcohol solution, ammonium chloride, resorcinol, and deionized water in a mass ratio of 1:3:0.06:0.06:24. Adjust the pH to 7.5 with 10% sodium hydroxide solution. Add 0.2 times the mass of urea of ​​2-mercaptobenzothiazole and 5 times the mass of urea of ​​xylene. Stir at 25°C and 150 rpm for 30 min. Add 2.5 times the mass of urea of ​​formaldehyde. Heat to 60°C and stir at 500 rpm for 3 h. Add 5% hydrochloric acid solution. Adjust the pH to 3.5, allow it to cool naturally to room temperature, filter the supernatant, wash it four times with deionized water, and dry it at 60℃ for 9 hours to obtain corrosion-inhibiting microcapsules; mix dimethylimidazole, corrosion-inhibiting microcapsules and epoxy resin at a mass ratio of 1:1.5:14, stir at 250 rpm for 15 minutes, sonicate for 15 minutes, and let it stand for 5 minutes to obtain a spin-coating solution; spin-coat the pretreated magnesium alloy surface at a speed of 800 rpm, with a coating thickness of 45 μm, and let it stand for 7 hours to air dry naturally to obtain corrosion-resistant magnesium alloy material.

[0068] Comparative Example 4

[0069] A method for preparing a corrosion-resistant magnesium alloy material, the method comprising the following steps:

[0070] (1) In a protective gas environment, the temperature of the pit-type resistance furnace is raised to 730℃. Pure magnesium and magnesium gadolinium master alloy with a mass of 0.092 times that of pure magnesium are added. Covering agent with a mass of 0.02 times that of pure magnesium is sprinkled on the surface. The temperature is kept for 20 minutes. The temperature is lowered to 720℃. Surface impurities are removed with a slag scraper. Pure zinc with a mass of 0.012 times that of pure magnesium, pure aluminum with a mass of 0.003 times that of pure magnesium, and magnesium calcium master alloy with a mass of 0.028 times that of pure magnesium are added. Covering agent with a mass of 0.025 times that of pure magnesium is sprinkled on the surface. The temperature is raised to 730℃ and kept for 30 minutes. Surface impurities are removed with a slag scraper. The mixture is stirred for 5 minutes. Refining agent with a mass of 0.01 times that of pure magnesium and covering agent with a mass of 0.025 times that of pure magnesium are added. The mixture is stirred for another 10 minutes. Surface impurities are removed with a slag scraper. The mixture is allowed to stand for 15 minutes. The mixture is then poured into a steel mold with a preheated temperature of 225℃ and allowed to solidify naturally to obtain a cast magnesium alloy.

[0071] (2) The cast magnesium alloy was wrapped in aluminum foil and embedded in dried graphite powder. It was heated from 200°C to 500°C in a box-type high-temperature resistance furnace at a rate of 5°C / min, held for 10 hours, air-cooled to room temperature, and then reheated to 350°C and held for 1.5 hours. It was then upsetting four times with a hydraulic press and transferred to a compression device at a heating rate of 10°C / s and a strain rate of 0.5s. -1 Under the condition of engineering strain 0.8, the temperature is raised to 470℃, held for 3 min, air-cooled and quenched to room temperature, a pre-pressure of 500N is applied, and the temperature is heated to 400℃ at a rate of 0.94℃ / sec. The die is fed 6mm in the axial direction at an extrusion speed of 0.02mm / s, and the punch is rotated clockwise by 1000N at a rate of 1.256rad / s. The temperature is held for 8 min, and the temperature is cooled to room temperature in the furnace at a rate of 35℃ per hour to obtain a fine-grained magnesium alloy.

[0072] (3) Cut the fine-grained magnesium alloy into samples of 30mm×10mm×5mm, mechanically polish them with 900-mesh silicon carbide sandpaper for 2 minutes, wash them 4 times with anhydrous ethanol, air dry them at 25℃, transfer them into 3-aminopropyltriethoxysilane alcoholysis solution, ultrasonically impregnate them at 78℃ for 2 hours, take them out and dry them at 200℃ for 2 hours to obtain the pretreated magnesium alloy.

[0073] (4) Mix urea, 5% polyvinyl alcohol solution, ammonium chloride, resorcinol, and deionized water in a mass ratio of 1:3:0.06:0.06:24. Adjust the pH to 7.5 with 10% sodium hydroxide solution. Add 0.2 times the mass of urea of ​​2-mercaptobenzothiazole and 5 times the mass of urea of ​​xylene. Stir at 25°C and 150 rpm for 30 min. Add 2.5 times the mass of urea of ​​formaldehyde. Heat to 60°C and stir at 500 rpm for 3 h. Add 5% hydrochloric acid solution. Adjust the pH to 3.5, allow it to cool naturally to room temperature, filter the supernatant, wash it four times with deionized water, and dry it at 60℃ for 9 hours to obtain corrosion-inhibiting microcapsules; mix dimethylimidazole, corrosion-inhibiting microcapsules and epoxy resin at a mass ratio of 1:1.5:14, stir at 250 rpm for 15 minutes, sonicate for 15 minutes, and let it stand for 5 minutes to obtain a spin-coating solution; spin-coat the pretreated magnesium alloy surface at a speed of 800 rpm, with a coating thickness of 45 μm, and let it stand for 7 hours to air dry naturally to obtain corrosion-resistant magnesium alloy material.

[0074] Comparative Example 5

[0075] A method for preparing a corrosion-resistant magnesium alloy material, the method comprising the following steps:

[0076] (1) In a protective gas environment, the temperature of the pit-type resistance furnace is raised to 730℃. Pure magnesium and magnesium gadolinium master alloy with a mass of 0.092 times that of pure magnesium are added. Covering agent with a mass of 0.02 times that of pure magnesium is sprinkled on the surface. The temperature is kept for 20 minutes. The temperature is lowered to 720℃. Surface impurities are removed with a slag scraper. Pure zinc with a mass of 0.012 times that of pure magnesium, pure aluminum with a mass of 0.003 times that of pure magnesium, and magnesium calcium master alloy with a mass of 0.028 times that of pure magnesium are added. Covering agent with a mass of 0.025 times that of pure magnesium is sprinkled on the surface. The temperature is raised to 730℃ and kept for 30 minutes. Surface impurities are removed with a slag scraper. The mixture is stirred for 5 minutes. Refining agent with a mass of 0.01 times that of pure magnesium and covering agent with a mass of 0.025 times that of pure magnesium are added. The mixture is stirred for another 10 minutes. Surface impurities are removed with a slag scraper. The mixture is allowed to stand for 15 minutes. The mixture is then poured into a steel mold with a preheated temperature of 225℃ and allowed to solidify naturally to obtain a cast magnesium alloy.

[0077] (2) The cast magnesium alloy was wrapped in aluminum foil and embedded in dried graphite powder. It was heated from 200°C to 500°C in a box-type high-temperature resistance furnace at a rate of 5°C / min, held for 10 hours, air-cooled to room temperature, and then reheated to 350°C and held for 1.5 hours. It was then upsetting four times with a hydraulic press and transferred to a compression device at a heating rate of 10°C / s and a strain rate of 0.5s. -1 Under the condition of engineering strain 0.8, the temperature is raised to 470℃, held for 3 min, air-cooled and quenched to room temperature, a pre-pressure of 500N is applied, and the temperature is heated to 400℃ at a rate of 0.94℃ / sec. The die is fed 6mm in the axial direction at an extrusion speed of 0.02mm / s, and the punch is rotated clockwise by 1000N at a rate of 1.256rad / s. The temperature is held for 8 min, and the temperature is cooled to room temperature in the furnace at a rate of 35℃ per hour to obtain a fine-grained magnesium alloy.

[0078] (3) Cut the fine-grained magnesium alloy into samples of 30mm×10mm×5mm, mechanically polish them with 900-mesh silicon carbide sandpaper for 2 minutes, wash them with anhydrous ethanol 4 times, air dry them at 25℃, micro-arc oxidation them with plasma electrolytic oxidation equipment for 8 minutes, take them out, wash them with deionized water 4 times, and dry them at 140℃ for 2 hours to obtain the pretreated magnesium alloy.

[0079] (4) Mix urea, 5% polyvinyl alcohol solution, ammonium chloride, resorcinol, and deionized water in a mass ratio of 1:3:0.06:0.06:24. Adjust the pH to 7.5 with 10% sodium hydroxide solution. Add 0.2 times the mass of urea of ​​2-mercaptobenzothiazole and 5 times the mass of urea of ​​xylene. Stir at 25°C and 150 rpm for 30 min. Add 2.5 times the mass of urea of ​​formaldehyde. Heat to 60°C and stir at 500 rpm for 3 h. Add 5% hydrochloric acid solution. Adjust the pH to 3.5, allow it to cool naturally to room temperature, filter the supernatant, wash it four times with deionized water, and dry it at 60℃ for 9 hours to obtain corrosion-inhibiting microcapsules; mix dimethylimidazole, corrosion-inhibiting microcapsules and epoxy resin at a mass ratio of 1:1.5:14, stir at 250 rpm for 15 minutes, sonicate for 15 minutes, and let it stand for 5 minutes to obtain a spin-coating solution; spin-coat the pretreated magnesium alloy surface at a speed of 800 rpm, with a coating thickness of 45 μm, and let it stand for 7 hours to air dry naturally to obtain corrosion-resistant magnesium alloy material.

[0080] Comparative Example 6

[0081] A method for preparing a corrosion-resistant magnesium alloy material, the method comprising the following steps:

[0082] (1) In a protective gas environment, the temperature of the pit-type resistance furnace is raised to 730℃. Pure magnesium and magnesium gadolinium master alloy with a mass of 0.092 times that of pure magnesium are added. Covering agent with a mass of 0.02 times that of pure magnesium is sprinkled on the surface. The temperature is kept for 20 minutes. The temperature is lowered to 720℃. Surface impurities are removed with a slag scraper. Pure zinc with a mass of 0.012 times that of pure magnesium, pure aluminum with a mass of 0.003 times that of pure magnesium, and magnesium calcium master alloy with a mass of 0.028 times that of pure magnesium are added. Covering agent with a mass of 0.025 times that of pure magnesium is sprinkled on the surface. The temperature is raised to 730℃ and kept for 30 minutes. Surface impurities are removed with a slag scraper. The mixture is stirred for 5 minutes. Refining agent with a mass of 0.01 times that of pure magnesium and covering agent with a mass of 0.025 times that of pure magnesium are added. The mixture is stirred for another 10 minutes. Surface impurities are removed with a slag scraper. The mixture is allowed to stand for 15 minutes. The mixture is then poured into a steel mold with a preheated temperature of 225℃ and allowed to solidify naturally to obtain a cast magnesium alloy.

[0083] (2) The cast magnesium alloy was wrapped in aluminum foil and embedded in dried graphite powder. It was heated from 200°C to 500°C in a box-type high-temperature resistance furnace at a rate of 5°C / min, held for 10 hours, air-cooled to room temperature, and then reheated to 350°C and held for 1.5 hours. It was then upsetting four times with a hydraulic press and transferred to a compression device at a heating rate of 10°C / s and a strain rate of 0.5s. -1Under the condition of engineering strain 0.8, the temperature is raised to 470℃, held for 3 min, air-cooled and quenched to room temperature, a pre-pressure of 500N is applied, and the temperature is heated to 400℃ at a rate of 0.94℃ / sec. The die is fed 6mm in the axial direction at an extrusion speed of 0.02mm / s, and the punch is rotated clockwise by 1000N at a rate of 1.256rad / s. The temperature is held for 8 min, and the temperature is cooled to room temperature in the furnace at a rate of 35℃ per hour to obtain a fine-grained magnesium alloy.

[0084] (3) The fine-grained magnesium alloy was cut into samples of 30mm×10mm×5mm, mechanically polished with 900-mesh silicon carbide sandpaper for 2min, washed with anhydrous ethanol 4 times, air-dried at 25℃, micro-arc oxidation with plasma electrolytic oxidation equipment for 8min, washed with deionized water 4 times, dried at 140℃ for 2h, transferred into 3-aminopropyltriethoxysilane alcoholysis solution, ultrasonically impregnated at 78℃ for 2h, and then dried at 200℃ for 2h to obtain the pretreated magnesium alloy.

[0085] (4) Mix dimethylimidazole and epoxy resin at a mass ratio of 1:14, stir at 250 rpm for 15 min, sonicate for 15 min, and let stand for 5 min to obtain spin coating liquid; spin coat on the pretreated magnesium alloy surface at a speed of 800 r / min, with a coating thickness of 45 μm, and let stand for 7 h to air dry naturally to obtain corrosion resistant magnesium alloy material.

[0086] Example of effect

[0087] Table 1 below shows the analysis results of the corrosion resistance, tensile strength and wear resistance of the corrosion-resistant magnesium alloy materials of Examples 1-3 and Comparative Examples 1-6 of the present invention.

[0088] Table 1

[0089] <![CDATA[Corrosion current density A·cm -2 > Tensile strength (MPa) Wear loss mg Example 1 <![CDATA[2.17×10 -7 ]]> 346 0.94 Example 2 <![CDATA[2.04×10 -7 ]]> 351 0.89 Example 3 <![CDATA[2.19×10 -7 ]]> 347 0.96 Comparative Example 1 <![CDATA[6.98×10 -7 ]]> 172 1.02 Comparative Example 2 <![CDATA[5.25×10 -5 ]]> 349 1.03 Comparative Example 3 <![CDATA[2.46×10 -7 ]]> 347 1.72 Comparative Example 4 <![CDATA[5.75×10 -5 ]]> 341 1.69 Comparative Example 5 <![CDATA[5.32×10 -6 ]]> 345 0.96 Comparative Example 6 <![CDATA[6.63×10 -5 ]]> 348 0.99

[0090] A comparison of the experimental data from Examples 1-3 and Comparative Examples 1-6 in Table 1 reveals that the corrosion-resistant magnesium alloy material prepared by this invention possesses excellent corrosion resistance, tensile strength, and wear resistance.

[0091] By comparison, Examples 1, 2, and 3 showed higher tensile strength than Comparative Example 1, indicating that the introduction of gadolinium and zinc elements during the forging process promoted alloy strengthening and formed a long-period ordered stacked structure during solution treatment and aging treatment, which served as a strengthening phase and improved the tensile properties of corrosion-resistant magnesium alloy materials.

[0092] By comparison, Examples 1, 2, and 3 showed lower corrosion current densities compared to Comparative Example 2, indicating that the introduction of aluminum can form a dense oxide film with magnesium, and can also promote the transformation of the long-period ordered stacked structure from the 18R type to the 14H type during the solution treatment process, reduce grain boundary energy, and improve the corrosion resistance of the corrosion-resistant magnesium alloy material.

[0093] By comparison, Examples 1, 2, and 3 showed less wear loss compared to Comparative Example 3, indicating that the lamellar and blocky long-period ordered stacked structure phases were elongated and broken by extrusion spinning to form fine lamellar and short rod-shaped long-period ordered stacked structure phases. At the same time, a large number of nano-precipitates were precipitated, which assisted strain-induced grain boundary migration, resulting in grain boundary bowing and the formation of ultrafine grains, thus enhancing the wear resistance of corrosion-resistant magnesium alloy materials.

[0094] By comparison, Examples 1, 2, and 3 showed lower corrosion current density and wear loss compared to Comparative Example 4, indicating that micro-arc oxidation with silicate electrolyte forms a uniform porous ceramic oxide layer containing oxides such as silicon dioxide on the surface of fine-grained magnesium alloy, thereby improving the wear resistance and corrosion resistance of the corrosion-resistant magnesium alloy material.

[0095] By comparison, Examples 1, 2, and 3 showed lower corrosion current densities compared to Comparative Example 5, indicating that modifying the film layer with 3-aminopropyltriethoxysilane allows for the formation of chemical bonds between the epoxy resin coating and the alloy, thereby enhancing the corrosion resistance of the corrosion-resistant magnesium alloy material.

[0096] By comparison, Examples 1, 2, and 3 showed lower corrosion current densities compared to Comparative Example 6, indicating that adding corrosion-inhibiting microcapsules loaded with 2-mercaptobenzothiazole to epoxy resin coatings can release 2-mercaptobenzothiazole when the surface is damaged. The mercapto groups form coordination or covalent bonds with the magnesium surface, forming a protective adsorption film, reducing the contact between the magnesium alloy and the corrosive medium, and further improving the corrosion resistance of the corrosion-resistant magnesium alloy material.

[0097] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A corrosion-resistant magnesium alloy material, characterized in that, The corrosion-resistant magnesium alloy material is obtained by spin-coating dimethylimidazolium, corrosion-inhibiting microcapsules, and epoxy resin onto the surface of a pretreated magnesium alloy. The corrosion-inhibiting microcapsules are prepared by in-situ polymerization of 2-mercaptobenzothiazole encapsulated in urea and formaldehyde. The pretreated magnesium alloy is prepared by cutting and sampling a fine-grained magnesium alloy, performing micro-arc oxidation, and then treating it with 3-aminopropyltriethoxysilane hydrolysis solution. The fine-grained magnesium alloy is obtained by melting and refining pure magnesium, pure zinc, pure aluminum, magnesium-gadolinium master alloy, and magnesium-calcium master alloy, followed by solution treatment, aging treatment, and extrusion spinning.

2. A method for preparing a corrosion-resistant magnesium alloy material, characterized in that, The preparation steps include the following: (1) In a protective gas environment, heat the pit-type resistance furnace to 720~740℃, add pure magnesium and 0.091~0.093 times the mass of pure magnesium gadolinium master alloy, sprinkle the surface with a covering agent of 0.01~0.03 times the mass of pure magnesium, keep it at the temperature for 15~25min, cool it down to 715~725℃, remove surface impurities with a slag scraper, add 0.011~0.013 times the mass of pure magnesium zinc, 0.002~0.004 times the mass of pure magnesium aluminum, and 0.027~0.029 times the mass of pure magnesium calcium master alloy. The alloy is coated with a covering agent at a ratio of 0.02 to 0.03 times the mass of pure magnesium. The temperature is raised to 725 to 735°C and held for 25 to 35 minutes. Surface impurities are removed with a slag skimmer. The mixture is stirred for 4 to 6 minutes. A refining agent at a ratio of 0.005 to 0.015 times the mass of pure magnesium and a covering agent at a ratio of 0.02 to 0.03 times the mass of pure magnesium are added. The mixture is stirred for another 5 to 15 minutes. Surface impurities are removed with a slag skimmer. The mixture is allowed to stand for 10 to 20 minutes and then cast into a steel mold at a preheated temperature of 200 to 250°C. The mixture is allowed to solidify naturally to obtain a cast magnesium alloy. (2) Wrap the cast magnesium alloy in aluminum foil, embed it in dried graphite powder, and heat it in a box-type high-temperature resistance furnace from 150~250℃ to 450~550℃ at a rate of 4~6℃ / min. Hold it at this temperature for 9~11h, air-cool it to room temperature, and then reheat it to 300~400℃ and hold it for 1~2h. Then, use a hydraulic press to reciprocate upsetting 3~5 times, transfer it to a compression device, and heat it at a rate of 5~15℃ / s and a strain rate of 0.4~0.6s. -1 Under the condition of engineering strain of 0.7~0.9, the temperature is raised to 460~480℃, held for 2~4min, air-cooled and quenched to room temperature, a pre-pressure of 450~550N is applied, and the temperature is heated to 350~450℃ at a rate of 0.93~0.95℃ / sec. The die is fed 5~7mm in the axial direction at an extrusion speed of 0.01~0.03mm / s, and the punch is rotated clockwise 900~1100N at a rate of 1.255~1.257rad / s. The temperature is held for 7~9min, and the furnace is cooled to room temperature at a rate of 20~50℃ per hour to obtain a fine-grained magnesium alloy. (3) Cut the fine-grained magnesium alloy into samples of 30mm×10mm×5mm, mechanically polish them with 600~1200 mesh silicon carbide sandpaper for 1~3min, wash them with anhydrous ethanol 3~5 times, air dry them at 20~30℃, micro-arc oxidation them with plasma electrolytic oxidation equipment for 7~9min, take them out, wash them with deionized water 3~5 times, dry them at 130~150℃ for 1~3h, transfer them into 3-aminopropyltriethoxysilane alcoholysis solution, ultrasonically impregnate them at 77~79℃ for 1~3h, take them out and dry them at 190~210℃ for 1~3h to obtain pretreated magnesium alloy; (4) Mix urea, a 4-6% polyvinyl alcohol solution, ammonium chloride, resorcinol, and deionized water in a mass ratio of 1:(2-4):(0.05-0.07):(0.05-0.07):(23-25). Adjust the pH to 7-8 with a 9-11% sodium hydroxide solution. Add 0.1-0.3 times the mass of urea of ​​2-mercaptobenzothiazole and 4-6 times the mass of urea of ​​xylene. Stir at 20-30℃ and 100-200 rpm for 20-40 min. Add 2-3 times the mass of urea of ​​formaldehyde. Heat to 55-65℃ and stir at 450-550 rpm for 2-4 h. Add a 9-11% sodium hydroxide solution of 2-mercaptobenzothiazole and 4-6 times the mass of urea of ​​xylene. Adjust the pH to 3-4 with 4-6% hydrochloric acid solution, allow to stand and cool naturally to room temperature, filter the supernatant, wash with deionized water 3-5 times, and dry at 55-65℃ for 8-10 hours to obtain corrosion-inhibiting microcapsules; mix dimethylimidazole, corrosion-inhibiting microcapsules and epoxy resin at a mass ratio of 1:(1-2):(13-15), stir at 200-300 rpm for 10-20 minutes, sonicate for 10-20 minutes, and let stand for 4-6 minutes to obtain a spin-coating solution; spin-coat the pretreated magnesium alloy surface at a speed of 700-900 rpm, with a coating thickness of 40-50 μm, and let stand for 6-8 hours to air dry naturally to obtain corrosion-resistant magnesium alloy material.

3. The method for preparing a corrosion-resistant magnesium alloy material according to claim 2, characterized in that, The pure magnesium, pure zinc, pure aluminum, magnesium gadolinium master alloy and magnesium calcium master alloy mentioned in step (1) are obtained by washing with deionized water 3 to 5 times, drying at 190 to 210°C for 6 to 8 hours, and then transferring them into a box-type resistance furnace and preheating at 190 to 210°C for 25 to 35 minutes.

4. The method for preparing a corrosion-resistant magnesium alloy material according to claim 2, characterized in that, The protective gas in step (1) is obtained by mixing carbon dioxide and sulfur hexafluoride in a volume ratio of 100:

1.

5. The method for preparing a corrosion-resistant magnesium alloy material according to claim 2, characterized in that, The covering agent in step (1) is obtained by mixing sodium chloride, calcium chloride, barium chloride, potassium chloride and sodium hexafluoroaluminate in a mass ratio of 1:20:6:5.3:

1.

6. The method for preparing a corrosion-resistant magnesium alloy material according to claim 2, characterized in that, The refining agent in step (1) is obtained by mixing sodium chloride, calcium chloride, barium chloride, potassium chloride, gadolinium chloride, sodium hexafluoroaluminate and calcium fluoride in a mass ratio of 1:16.3:6:5.3:2:1:1.

6.

7. The method for preparing a corrosion-resistant magnesium alloy material according to claim 2, characterized in that, The conditions for micro-arc oxidation in step (3) are: power supply frequency 500Hz, pulse ratio 10:1, and current density 6.5A / dm³. 2 The electrolyte consists of sodium silicate, sodium stannate, and sodium hydroxide in a molar ratio of 1:1:

2. The anode is a fine-grained magnesium alloy sample, and the cathode is a stainless steel plate.