Corrosion-resistant rare earth magnesium alloy composite material and preparation method thereof

Abstract

The invention relates to the field of metal materials, in particular to a corrosion-resistant rare earth magnesium alloy composite material and a preparation method thereof. The composite material sequentially comprises a magnesium alloy matrix, a transition layer and a functional layer, wherein the functional layer comprises the following components in parts by weight: 100 parts of modified yttria-stabilized zirconia powder and 0.5-2.0 parts of carbon nanotubes. According to the corrosion-resistant rare earth magnesium alloy composite material, through material modification (rare earth doping / nano coating / carbon nano tube grafting), the corrosion resistance, the interface bonding strength, the mechanical property and the like of the magnesium alloy composite material are improved, the problems that a traditional magnesium alloy coating is prone to stripping, high in brittleness, short in service life and the like are solved, and the remarkable industrial application value is achieved. The preparation method disclosed by the invention is simple and convenient to operate, easy to control, favorable for reducing the production cost and improving the production efficiency, and convenient for large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the field of metal materials, and in particular to a corrosion-resistant rare earth magnesium alloy composite material and a preparation method thereof. Background Art

[0002] Magnesium alloys, due to their low density, high specific strength, and excellent shock absorption, hold broad application prospects in aerospace, automotive manufacturing, electronics, and other fields. However, magnesium alloys are highly chemically active and readily react with oxygen, water vapor, and other environmental factors, resulting in poor corrosion resistance, which significantly limits their further application. To improve the corrosion resistance of magnesium alloys, researchers have explored various surface treatment methods, such as chemical conversion coatings, electrochemical treatments, and coating technologies. Coating technologies, among others, have garnered widespread attention due to their ease of use and significant effectiveness.

[0003] In coating technology, composite coatings, due to their unique structure and properties, can better meet various requirements, including corrosion resistance. Rare earth elements, with their unique electronic structure and physicochemical properties, interact well with magnesium alloys, enhancing coating performance. For example, rare earth elements can improve the coating's microstructure, increasing its density and bonding strength, thereby enhancing its corrosion resistance. Furthermore, rare earth elements possess excellent chemical and thermal stability, enabling the coating to maintain its performance even in harsh environments, such as high temperatures.

[0004] Although various methods have been developed to improve the corrosion resistance of magnesium alloys, some challenges remain. For example, some coating technologies lack sufficient bonding strength between the coating and the magnesium alloy substrate, making them susceptible to detachment during use. Other coatings, while offering excellent corrosion resistance, are complex to prepare and difficult to apply on a large scale. Therefore, developing a magnesium alloy composite material with excellent corrosion resistance, high bonding strength, and good impact resistance is crucial for promoting the application of magnesium alloys. Summary of the Invention

[0005] To address the above-mentioned issues, the present invention provides a corrosion-resistant rare earth magnesium alloy composite material and a method for preparing the same. The corrosion-resistant rare earth magnesium alloy composite material of the present invention, through material modification (rare earth doping / nanocoating / carbon nanotube grafting), improves the corrosion resistance, interfacial bonding strength, and mechanical properties of the magnesium alloy composite material, thereby resolving the problems of easy flaking, high brittleness, and short life of conventional magnesium alloy coatings, and thus has significant industrial application value. The preparation method of the present invention is simple to operate and easy to control, which helps reduce production costs, improve production efficiency, and facilitates large-scale industrial production.

[0006] The technical solutions adopted by the present invention to achieve the above-mentioned purpose are:

[0007] A corrosion-resistant rare earth magnesium alloy composite material comprises, in order, a magnesium alloy matrix, a transition layer, and a functional layer. The functional layer comprises, by weight, 100 parts of modified yttria-stabilized zirconia powder and 0.5 to 2.0 parts of carbon nanotubes. The preparation method of the modified yttria-stabilized zirconia powder is as follows:

[0008] Step 1: Take yttria-stabilized zirconia powder and dry it to remove adsorbed moisture;

[0009] Step 2: ball milling the dried yttria-stabilized zirconia powder with cerium oxide and lanthanum oxide;

[0010] Step 3: Place the chemically doped powder in an atomic layer deposition device, use trimethylaluminum and water as precursors, and coat it with an aluminum oxide nanofilm at 170-190°C with a film thickness of 10-20nm.

[0011] Preferably, in step 2, the weight proportions of the yttria-stabilized zirconia powder, cerium oxide, and lanthanum oxide are 92 to 95 parts, 2.0 to 5.0 parts, and 1.0 to 3.0 parts, respectively, and the weight-to-volume ratio of the total amount of the yttria-stabilized zirconia powder, cerium oxide, and lanthanum oxide solid powders to anhydrous ethanol is 1 g: 1 to 2 ml.

[0012] Preferably, in step 3, the specific method for depositing the aluminum oxide nanofilm is: introducing trimethylaluminum with a pulse time of 0.05 to 0.1 s, a dosage of 1.5 to 2.5 mg, and a chamber pressure of 100 to 200 Pa, then purging with nitrogen for 30 to 60 s with a flow rate of 20 to 30 L / min, then introducing water vapor with a pulse time of 0.05 to 0.1 s, a dosage of 1.5 to 3.0 mg, and finally purging with nitrogen again for 30 to 60 seconds. This is one cycle, and a total of 60-70 cycles are performed.

[0013] Yttria-stabilized zirconia is a high-performance ceramic material widely used in thermal barrier coatings, solid oxide fuel cells, corrosion-resistant coatings and other fields. The present invention modifies it by rare earth doping (CeO2 / La2O3) and atomic layer deposition (ALD) alumina nanofilm coating, so that it can play a better performance in magnesium alloy composite materials. The specific advantages are as follows: CeO2 has a higher oxygen vacancy concentration, which can improve the oxygen ion conductivity of the coating and inhibit the grain coarsening caused by high-temperature sintering. La2O3 can reduce the grain boundary energy of yttria-stabilized zirconia and improve the thermal shock resistance of the coating. The alumina nanofilm coating forms a dense barrier effect, and Al2O3 is chemically inert and can effectively block Cl -, H2O and other corrosive media. The ALD process can form a uniform coating on the surface of yttria-stabilized zirconia particles, reduce the porosity of the coating, and reduce the risk of electrochemical corrosion. The alumina nanofilm can reduce the van der Waals force between yttria-stabilized zirconia particles, avoid agglomeration, and improve the fluidity during the spraying process. Enhanced high-temperature stability: The Al2O3 film can prevent yttria-stabilized zirconia from over-sintering during HVOF spraying and maintain the uniformity of the coating microstructure. CeO2 can release Ce in a corrosive environment. 3+ / Ce 4+ , forming a passivation film and delaying the corrosion process.

[0014] Preferably, the carbon nanotubes are modified carbon nanotubes, and the preparation method of the modified carbon nanotubes is as follows:

[0015] Step S1, acidification pretreatment: take multi-walled carbon nanotubes and perform pre-oxidation treatment in a tube furnace with an air flow rate of 50-100 mL / min and a temperature of 350-400°C for 30-45 minutes. After naturally cooling to room temperature, the carbon nanotubes are transferred to a reactor, nitric acid solution is added, and the carbon nanotubes are heated in a water bath at 60-80°C with stirring for 1-2 hours. After the reaction is completed, the carbon nanotubes are washed and dried.

[0016] Step S2, mixed acid treatment: mixing the pretreated carbon nanotubes with concentrated sulfuric acid and concentrated nitric acid, ultrasonically treating them at 40-60° C. for 1-2 hours, and then neutralizing, washing, and drying.

[0017] Step S3, double silane grafting: the acidified carbon nanotubes are mixed with anhydrous ethanol, KH-550 silane coupling agent and acetic acid are added, and the mixture is reacted at 73-78°C under reflux condensation for 1.5-2.5 hours. After washing with ethanol, KH-570 silane coupling agent is added, the temperature is adjusted to 60-70°C, the mixture is reacted for 1-1.5 hours, washed, and dried.

[0018] Step S4: Plasma activation: Place the carbon nanotubes grafted in step S3 in a plasma reaction chamber, evacuate to 10-50 Pa, and then introduce a mixed gas of argon and hydrogen to maintain the chamber pressure at 80-120 Pa, the pulse frequency is 10-15 kHz, the power is 600-800 W, and the treatment time is 3-5 minutes. After the treatment is completed, cool to room temperature under nitrogen protection.

[0019] Carbon nanotubes are often used as composite material reinforcements due to their ultra-high strength, high aspect ratio and electrical conductivity. The present invention modifies carbon nanotubes through acid treatment, silane coupling agent grafting (KH-550 / KH-570) and plasma activation, so that they can play the following advantages in the yttria-stabilized zirconia-based functional layer: Acid treatment (HNO3 / H2SO4) introduces functional groups such as -COOH and -OH on the surface of carbon nanotubes, enhancing the chemical compatibility with the ceramic matrix and improving the interface bonding strength. Double silane coupling agent grafting: KH-550 forms hydrogen bonds or covalent bonds (Si-O-Zr) with the hydroxyl groups (-OH) on the surface of yttria-stabilized zirconia to enhance the interface bonding force. The interface bonding causes the cracks to bypass (rather than penetrate) when encountering carbon nanotubes, consuming more energy and effectively improving the fracture toughness. The dense Si-O-Zr interface reduces the pores in the coating and blocks Cl - / H2O penetration improves corrosion resistance. KH-570 provides hydrophobicity and free radical reaction sites, reducing water molecule adsorption, avoiding moisture-induced pores during the spraying process, and further improving the thermal stability of the carbon nanotubes. Argon-hydrogen plasma treatment removes impurities from the carbon nanotube surface and introduces active sites, further promoting chemical bonding with yttria-stabilized zirconia and preventing interfacial delamination. The modified carbon nanotubes significantly improve their dispersibility in ethanol, allowing for better uniform mixing with the modified yttria-stabilized zirconia, preventing agglomeration during the spraying process.

[0020] Preferably, in step S1, the concentration of the nitric acid solution is 3-5 mol / L, and the mass-to-volume ratio of the carbon nanotubes to the nitric acid solution is 1 g:50-100 mL.

[0021] Preferably, in step S2, the mass volume ratio of the pretreated carbon nanotubes to the total amount of concentrated sulfuric acid and concentrated nitric acid solution is 1 g: 100-150 mL, the volume ratio of the concentrated sulfuric acid and concentrated nitric acid is 3-5:1, and the concentrations of the concentrated sulfuric acid and concentrated nitric acid are 95%-98% and 65%-68%, respectively.

[0022] Preferably, in step S3, the weight-to-volume ratio of the acidified carbon nanotubes to anhydrous ethanol is 1 g: 50-80 mL, the amounts of KH-550 silane coupling agent and acetic acid are 5%-8% and 0.1% of the mass of the acidified carbon nanotubes, respectively, and the amount of KH-570 silane coupling agent is 20%-30% of the mass of KH-550.

[0023] Preferably, in step S4, the flow rate of the argon gas is 80-120 mL / min, and the volume ratio of the argon gas to the hydrogen gas is 10:1.

[0024] The preparation method of the above-mentioned corrosion-resistant rare earth magnesium alloy composite material, wherein the preparation method of the functional layer is:

[0025] Step a: mixing carbon nanotubes with modified yttria-stabilized zirconia powder, adding anhydrous ethanol, performing ultrasonic dispersion treatment, and then spray drying to obtain a composite powder;

[0026] Step b: Plasma activation treatment of the composite powder using a mixture of argon and hydrogen followed by sieving;

[0027] Step c: spraying the powder treated in step b using a high-speed oxygen-fuel spraying method.

[0028] Preferably, the transition layer is made of nickel-chromium-aluminum-yttrium alloy powder sprayed by supersonic flame.

[0029] The present invention has the following beneficial effects:

[0030] The corrosion-resistant rare earth magnesium alloy composite material provided by the present invention forms a dense and chemically inert ceramic coating by compounding modified yttria-stabilized zirconia and carbon nanotubes in the functional layer, which significantly blocks corrosive media (such as Cl - , H2O) penetration, improving corrosion resistance. The introduction of cerium oxide and lanthanum oxide refines the grain size and enhances the coating's self-healing ability, forming a passivation film in corrosive environments and slowing the corrosion process. Aluminum oxide nanofilms formed on the surface of yttria-stabilized zirconia by atomic layer deposition (ALD) fill grain boundary defects, further reducing the coating's porosity and electrochemical activity, and improving corrosion resistance.

[0031] Furthermore, the modified carbon nanotubes are evenly dispersed in the functional layer, and their high aspect ratio and strength enhance the coating's ability to resist crack propagation, while also improving the coating's impact resistance and toughness. By modifying the carbon nanotubes with KH-550 / KH-570 bisilane, their chemical bonding with the ceramic matrix is enhanced, avoiding local corrosion caused by weak interfacial bonding. The modified carbon nanotubes and yttria-stabilized zirconia are covalently bridged to enhance the interfacial bonding between the two. The Al2O3 nanofilm fills the pores at the grain boundaries of yttria-stabilized zirconia, reducing the permeability of the coating. Rare earth doping (CeO2 / La2O3) refines the grains and enhances density. The modified carbon nanotubes and modified yttria-stabilized zirconia grains form a "fiber-toughened" network, enhancing fracture toughness.

[0032] Furthermore, supersonic flame spraying of nickel-chromium-aluminum-yttrium alloy is used as a transition layer to alleviate the thermal stress mismatch between the magnesium alloy substrate (large thermal expansion coefficient) and the ceramic functional layer (high brittleness) and avoid coating peeling.

[0033] Through material modification (rare earth doping / nano-coating / carbon nanotube grafting), the present invention achieves breakthroughs in the corrosion resistance, interface bonding strength, mechanical properties and process stability of magnesium alloy composite materials, and solves the problems of easy peeling, high brittleness and short life of traditional magnesium alloy coatings, and has significant industrial application value.

[0034] The preparation methods of the present invention, such as supersonic flame spraying, plasma activation treatment, high-speed oxygen fuel spraying, atomic layer deposition, etc., have high reliability and repeatability. For example, supersonic flame spraying technology can produce high-quality metal ceramic coatings with high production efficiency and coating performance; atomic layer deposition technology can accurately control the thickness and uniformity of the nanofilm, ensuring the quality of the modified yttria-stabilized zirconia powder. By rationally combining these process technologies, it is possible to ensure that the preparation process of the composite material is stable and reliable, and the product quality consistency is high. The preparation method of the present invention is simple to operate and easy to control, which is conducive to reducing production costs, improving production efficiency, and facilitating large-scale industrial production. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] Yttria-stabilized zirconia powder (15-53 μm, Qinghe County Tebo Metal Materials Co., Ltd.; cerium oxide 1-30 μm, Shanghai Yingfeng Ruihuang Metal Materials Co., Ltd.; lanthanum oxide 1-10 μm, Hebei Wenlun Metal Materials Co., Ltd.; nickel-chromium-aluminum-yttrium alloy powder 15-45 μm, Qinghe County Xingxin New Material Technology Co., Ltd. The raw materials used in the following examples are all common commercially available products.

[0037] Example 1

[0038] A corrosion-resistant rare earth magnesium alloy composite material comprises, in order, a magnesium alloy matrix, a transition layer, and a functional layer. The functional layer comprises, by weight, 100 parts of modified yttria-stabilized zirconia powder and 1.2 parts of carbon nanotubes (diameter 8-15 nm, length 50 μm). The preparation method of the modified yttria-stabilized zirconia powder is as follows:

[0039] Step 1: Raw material pretreatment: Place yttria-stabilized zirconia powder in a vacuum drying oven and dry at 110°C for 2.5 hours to remove adsorbed moisture;

[0040] Step 2: Chemical doping modification: 95 parts of pretreated yttria-stabilized zirconia powder, 2.0 parts of cerium oxide, and 3.0 parts of lanthanum oxide were mixed and wet-milled using a planetary ball mill. The ball milling medium was anhydrous ethanol, and the ball-to-material ratio was 8:1. The weight-to-volume ratio of the total amount of the three solid powders of yttria-stabilized zirconia powder, cerium oxide, and lanthanum oxide to anhydrous ethanol was 1g:1ml. A step-type ball mill was used, first coarse grinding at 280rpm for 2h, then fine grinding at 320rpm for 1.5h. After the ball milling was completed, the slurry was dried at 120°C for 10h.

[0041] Step 3: Nano-coating treatment: The chemically doped powder is placed in an atomic layer deposition device, and trimethylaluminum and water are used as precursors to coat the aluminum oxide nanofilm at 180°C, with a film thickness of 14 nm. The specific method for depositing the aluminum oxide nanofilm is as follows: trimethylaluminum is introduced with a pulse time of 0.08s and an amount of 2mg. The chamber pressure is maintained at 100-200Pa. Trimethylaluminum reacts with the hydroxyl groups on the surface of the powder to form a single layer of aluminum precursor adsorption. Nitrogen is introduced for 45s at a flow rate of 25L / min to remove unreacted trimethylaluminum and by-products. Water vapor is then introduced in an amount of 2.2mg and a pulse time of 0.08s to react with the adsorbed trimethylaluminum to form aluminum oxide. Nitrogen is purged again for 45 seconds to remove residual reactants. This is one cycle, and a total of 66 cycles are performed.

[0042] The preparation method of the above-mentioned corrosion-resistant rare earth magnesium alloy composite material is as follows:

[0043] First, the magnesium alloy substrate was pretreated by sandblasting with 130 μm alumina sand particles at a pressure of 0.4 MPa until the surface roughness was 4.0-5.0 μm, and then ultrasonically cleaned.

[0044] Then, the transition layer is sprayed. The transition layer is sprayed with nickel-chromium-aluminum-yttrium alloy powder using supersonic flame spraying. The powder particle size is 15-45μm. The process parameters are: propane flow rate 90L / min, oxygen flow rate 200L / min, spraying distance 125mm, powder feeding rate 20-25g / min, and coating thickness 40μm.

[0045] Finally, a functional layer is prepared, and the preparation method of the functional layer is as follows:

[0046] Step a: carbon nanotubes and modified yttria-stabilized zirconia powder are mixed, anhydrous ethanol is added to obtain a mixed solution, wherein the solid content of the mixed solution is 25%, ultrasonic dispersion is performed at an ultrasonic power of 300 W and a dispersion time of 60 minutes. After dispersion is completed, the mixture is spray-dried at an inlet temperature of 95°C and an outlet temperature of 70°C to obtain a composite powder;

[0047] Step b: Plasma activation treatment: The composite powder is placed in a plasma treatment device, using a mixed gas of argon and hydrogen (volume ratio of 4:1), a chamber pressure of 75 Pa, a gas flow rate of 25 L / min, a power of 1000 W, and a treatment time of 5 min. The powder is then sieved through a 250-mesh sieve to remove agglomerated particles.

[0048] Step c: The composite powder treated in step b is sprayed with high-speed oxygen fuel (HVOF) using propane as fuel, a flow rate of 80 L / min, an oxygen flow rate of 200 L / min, a spraying distance of 180-220 mm, a powder feeding rate of 20-25 g / min, and a coating thickness of 160 μm.

[0049] Example 2

[0050] A corrosion-resistant rare earth magnesium alloy composite material comprises, in order, a magnesium alloy matrix, a transition layer, and a functional layer. The functional layer comprises, by weight, 100 parts of modified yttria-stabilized zirconia powder and 2.0 parts of carbon nanotubes. The preparation method of the modified yttria-stabilized zirconia powder is as follows:

[0051] Step 1: Raw material pretreatment: Place yttria-stabilized zirconia powder in a vacuum drying oven and dry at 100°C for 3.0 hours to remove adsorbed moisture;

[0052] Step 2: Chemical doping modification: 93 parts of pretreated yttria-stabilized zirconia powder, 3 parts of cerium oxide, and 2 parts of lanthanum oxide were mixed and wet-milled using a planetary ball mill. The ball milling medium was anhydrous ethanol, and the ball-to-material ratio was 10:1. The weight-to-volume ratio of the total amount of the three solid powders of yttria-stabilized zirconia powder, cerium oxide, and lanthanum oxide to anhydrous ethanol was 1g:1.5ml. Step-type ball milling was used, first coarse grinding at 290rpm for 1.5h, then fine grinding at 310rpm for 2h. After the ball milling was completed, the slurry was dried at 130°C for 8h.

[0053] Step 3: Nano-coating treatment: The chemically doped powder is placed in an atomic layer deposition device, and trimethylaluminum and water are used as precursors to coat the aluminum oxide nanofilm at 170°C, with a film thickness of 10-20nm; the specific method for depositing the aluminum oxide nanofilm is as follows: trimethylaluminum is introduced with a pulse time of 0.1s and an amount of 2.5mg, and the chamber pressure is maintained at 100-200Pa. Trimethylaluminum reacts with the hydroxyl groups on the surface of the powder to form a single layer of aluminum precursor adsorption, and nitrogen is introduced for 30s at a flow rate of 30L / min to remove unreacted trimethylaluminum and by-products, and then water vapor is introduced with an amount of 3.0mg and a pulse time of 0.1s to react with the adsorbed trimethylaluminum to form aluminum oxide, and nitrogen is purged again for 30 seconds to remove residual reactants. This is one cycle, and a total of 60 cycles are performed.

[0054] The carbon nanotubes are modified carbon nanotubes, and the preparation method of the modified carbon nanotubes is as follows:

[0055] Step S1, acidification pretreatment: multi-walled carbon nanotubes were pre-oxidized in a tube furnace at an air flow rate of 50 mL / min and a temperature of 400°C for 30 minutes. After naturally cooling to room temperature, the carbon nanotubes were transferred to a reactor, nitric acid solution was added, and the mixture was heated in a water bath at 80°C and stirred for 1 hour. After the reaction was completed, the mixture was washed with deionized water until neutral, and vacuum dried at 100°C for 6 hours. The concentration of the nitric acid solution was 5 mol / L, and the mass volume ratio of the carbon nanotubes to the nitric acid solution was 1 g:50 mL.

[0056] Step S2, mixed acid treatment: the pretreated carbon nanotubes are mixed with concentrated sulfuric acid and concentrated nitric acid, and ultrasonically treated at 50°C, 400W power, and 40kHz frequency for 1.5 hours, and then neutralized with 0.3mol / L sodium hydroxide solution until neutral, and then washed with deionized water, and finally vacuum dried at 90°C to constant weight; wherein the mass volume ratio of the pretreated carbon nanotubes to the total amount of concentrated sulfuric acid and concentrated nitric acid solution is 1g:120mL, the volume ratio of the concentrated sulfuric acid and concentrated nitric acid is 4:1, and the concentrations of the concentrated sulfuric acid and concentrated nitric acid are 96% and 66%, respectively;

[0057] Step S3, double silane grafting: mixing the acidified carbon nanotubes with anhydrous ethanol, adding KH-550 silane coupling agent and acetic acid, reacting at 75°C under reflux condensation conditions for 2 hours, washing with ethanol, adding KH-570 silane coupling agent, adjusting the temperature to 65°C, reacting for 1.2 hours, washing with ethanol four times, and vacuum drying at 70°C to constant weight; wherein the weight-to-volume ratio of the acidified carbon nanotubes to anhydrous ethanol is 1 g:70 mL, the amounts of KH-550 silane coupling agent and acetic acid are 7% and 0.1% of the mass of the acidified carbon nanotubes, respectively, and the amount of KH-570 silane coupling agent is 25% of the mass of KH-550;

[0058] Step S4: plasma activation: Place the carbon nanotubes grafted in step S3 in a plasma reaction chamber, evacuate to 30 Pa, and then introduce a mixed gas of argon and hydrogen to maintain the chamber pressure at 100 Pa, the pulse frequency is 12 kHz, the power is 700 W, and the treatment time is 4 minutes. After the treatment, cool to room temperature under nitrogen protection to obtain the product, wherein the argon flow rate is 100 mL / min, and the volume ratio of the argon and hydrogen is 10:1.

[0059] The preparation method of the above-mentioned corrosion-resistant rare earth magnesium alloy composite material, wherein the preparation method of the functional layer is:

[0060] Step a: carbon nanotubes and modified yttria-stabilized zirconia powder were mixed, and anhydrous ethanol was added to obtain a mixed solution with a solid content of 20%. Ultrasonic dispersion was performed at an ultrasonic power of 320 W for 45 minutes. After dispersion, the mixture was spray-dried at an inlet temperature of 98° C. and an outlet temperature of 73° C. to obtain a composite powder.

[0061] Step b: Plasma activation treatment: The composite powder is placed in a plasma treatment device, using a mixed gas of argon and hydrogen (volume ratio of 3:1), a chamber pressure of 100 Pa, a gas flow rate of 30 L / min, a power of 900 W, and a treatment time of 6 min. The powder is then sieved through a 200-mesh sieve to remove agglomerated particles.

[0062] Step c: The composite powder treated in step b was sprayed with high-speed oxygen fuel (HVOF) using propane as fuel, a flow rate of 90 L / min, an oxygen flow rate of 190 L / min, a spraying distance of 220 mm, a powder feeding rate of 20 g / min, and a coating thickness of 120 μm.

[0063] The rest is the same as in Example 1.

[0064] Example 3

[0065] A corrosion-resistant rare earth magnesium alloy composite material comprises, in order, a magnesium alloy matrix, a transition layer, and a functional layer. The functional layer comprises, by weight, 100 parts of modified yttria-stabilized zirconia powder and 0.5 parts of carbon nanotubes. The preparation method of the modified yttria-stabilized zirconia powder is as follows:

[0066] Step 1: Raw material pretreatment: Place yttria-stabilized zirconia powder in a vacuum drying oven and dry at 120°C for 2.0 hours to remove adsorbed moisture;

[0067] Step 2: Chemical doping modification: 92 parts of pretreated yttria-stabilized zirconia powder, 5.0 parts of cerium oxide, and 1.0 parts of lanthanum oxide were mixed and wet-milled using a planetary ball mill. The ball milling medium was anhydrous ethanol, and the ball-to-material ratio was 12:1. The weight-to-volume ratio of the total amount of the three solid powders of yttria-stabilized zirconia powder, cerium oxide, and lanthanum oxide to anhydrous ethanol was 1g:2ml. Step-type ball milling was used, first coarse grinding at 270rpm for 2.5h, then fine grinding at 330rpm for 1h. After the ball milling was completed, the slurry was dried at 110°C for 12h.

[0068] Step 3: Nano-coating treatment: The chemically doped powder is placed in an atomic layer deposition device, and trimethylaluminum and water are used as precursors to coat the aluminum oxide nanofilm at 190°C, with a film thickness of 10-20nm; the specific method for depositing the aluminum oxide nanofilm is as follows: trimethylaluminum is introduced with a pulse time of 0.05s and an amount of 1.5mg, and the chamber pressure is maintained at 100-200Pa. Trimethylaluminum reacts with the hydroxyl groups on the surface of the powder to form a single layer of aluminum precursor adsorption, and nitrogen is introduced for 60s at a flow rate of 20L / min to remove unreacted trimethylaluminum and by-products, and then water vapor is introduced with an amount of 1.5mg and a pulse time of 0.05s to react with the adsorbed trimethylaluminum to form aluminum oxide, and nitrogen is purged again for 60 seconds to remove residual reactants. This is one cycle, and a total of 70 cycles are performed.

[0069] The carbon nanotubes are modified carbon nanotubes, and the preparation method of the modified carbon nanotubes is as follows:

[0070] Step S1, acidification pretreatment: multi-walled carbon nanotubes were pre-oxidized in a tube furnace at an air flow rate of 75 mL / min and a temperature of 380°C for 36 minutes. After naturally cooling to room temperature, the carbon nanotubes were transferred to a reactor, nitric acid solution was added, and the mixture was heated in a water bath at 60°C and stirred for 2 hours. After the reaction was completed, the mixture was washed with deionized water until neutral, and vacuum dried at 80°C for 12 hours. The concentration of the nitric acid solution was 3 mol / L, and the mass volume ratio of the carbon nanotubes to the nitric acid solution was 1 g:100 mL.

[0071] Step S2, during the mixed acid treatment, the mass volume ratio of the pretreated carbon nanotubes to the total amount of the concentrated sulfuric acid and concentrated nitric acid solution is 1 g:100 mL, the volume ratio of the concentrated sulfuric acid and concentrated nitric acid is 3:1, and the concentrations of the concentrated sulfuric acid and concentrated nitric acid are 96% and 66%, respectively; the rest is the same as in Example 2;

[0072] Step S3, during the double silane grafting process, the weight-to-volume ratio of the acidified carbon nanotubes to anhydrous ethanol is 1 g:80 mL, the amounts of KH-550 silane coupling agent and acetic acid used are 8% and 0.1% of the mass of the acidified carbon nanotubes, respectively, and the amount of KH-570 silane coupling agent used is 20% of the mass of KH-550. The rest of the process is the same as in Example 2;

[0073] Step S4: Same as Example 2.

[0074] The preparation method of the above-mentioned corrosion-resistant rare earth magnesium alloy composite material is the same as that of Example 1.

[0075] Example 4

[0076] A corrosion-resistant rare earth magnesium alloy composite material, wherein the carbon nanotubes are modified carbon nanotubes, and the preparation method of the modified carbon nanotubes is as follows:

[0077] The carbon nanotubes are modified carbon nanotubes, and the preparation method of the modified carbon nanotubes is as follows:

[0078] Step S1, acidification pretreatment: multi-walled carbon nanotubes were pre-oxidized in a tube furnace at an air flow rate of 100 mL / min and a temperature of 350°C for 30 minutes. After naturally cooling to room temperature, the carbon nanotubes were transferred to a reactor, nitric acid solution was added, and the mixture was heated in a water bath at 70°C and stirred for 1.5 hours. After the reaction was completed, the mixture was washed with deionized water until neutral, and vacuum dried at 90°C for 8 hours. The concentration of the nitric acid solution was 4 mol / L, and the mass volume ratio of the carbon nanotubes to the nitric acid solution was 1 g:75 mL.

[0079] Step S2, during the mixed acid treatment, the mass volume ratio of the pretreated carbon nanotubes to the total amount of concentrated sulfuric acid and concentrated nitric acid solution is 1 g:150 mL, the volume ratio of the concentrated sulfuric acid and concentrated nitric acid is 5:1, and the concentrations of the concentrated sulfuric acid and concentrated nitric acid are 98% and 68%, respectively; the rest is the same as in Example 2;

[0080] Step S3, during the double silane grafting process, the weight volume ratio of the acidified carbon nanotubes to anhydrous ethanol is 1 g:50 mL, the amounts of KH-550 silane coupling agent and acetic acid are 5% and 0.1% of the mass of the acidified carbon nanotubes, respectively, and the amount of KH-570 silane coupling agent is 30% of the mass of KH-550. The rest of the process is the same as in Example 2;

[0081] Step S4 is the same as in Example 2.

[0082] A corrosion-resistant rare earth magnesium alloy composite material and a preparation method using the modified carbon nanotubes are the same as those in Example 2.

[0083] Example 5

[0084] A corrosion-resistant rare earth magnesium alloy composite material and a preparation method thereof, wherein the carbon nanotubes are the modified carbon nanotubes of Example 2, and the rest are the same as Example 1.

[0085] Comparative Example 1

[0086] A corrosion-resistant rare earth magnesium alloy composite material and a preparation method thereof, wherein the modified yttria-stabilized zirconia powder in the functional layer is replaced with unmodified ordinary yttria-stabilized zirconia powder, and the rest is the same as in Example 1.

[0087] Comparative Example 2

[0088] A corrosion-resistant rare earth magnesium alloy composite material and a preparation method thereof, wherein the modified yttria-stabilized zirconia powder in the functional layer is replaced with unmodified ordinary yttria-stabilized zirconia powder, and the rest is the same as in Example 5.

[0089] The corrosion resistance and mechanical properties of the material samples of Examples 1-5 and Comparative Examples 1 and 2 were tested respectively:

[0090] 1. Corrosion resistance: Salt spray test. The test method is based on the national standard GB / T10125-2012 "Artificial atmosphere corrosion test salt spray test". The salt spray solution is 5% NaCl solution, pH 6.5-7.2, and the temperature is (35±1)°C. The test time is 7 days, 14 days, one month, and three months respectively. The corrosion rate (i.e., the percentage of mass loss) is calculated by the weight difference before and after.

[0091] 2. Mechanical test: Tensile performance test is carried out according to GB / T16865-2013.

[0092] Table 1. Performance test results

[0093]

[0094] As can be seen in Table 1, the corrosion resistance and mechanical properties of the magnesium alloy composites of Examples 1-5 are superior to those of Comparative Examples 1 and 2. This indicates that the use of the modified yttria-stabilized zirconia powder of the present invention significantly improves the corrosion resistance and mechanical properties of the composites. Furthermore, the use of modified carbon nanotubes further enhances the corrosion resistance of the resulting composites.

[0095] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0096] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A corrosion-resistant rare earth magnesium alloy composite material, characterized in that: The invention sequentially comprises a magnesium alloy matrix, a transition layer, and a functional layer. The functional layer comprises 100 parts of modified yttria-stabilized zirconia powder and 0.5 to 2.0 parts of carbon nanotubes in parts by weight. The preparation method of the modified yttria-stabilized zirconia powder is as follows: Step 1: Take yttria-stabilized zirconia powder and dry it to remove adsorbed moisture; Step 2: ball milling the dried yttria-stabilized zirconia powder with cerium oxide and lanthanum oxide; Step 3: Place the chemically doped powder in an atomic layer deposition device, use trimethylaluminum and water as precursors, and coat it with an aluminum oxide nanofilm at 170-190°C with a film thickness of 10-20nm.

2. The corrosion-resistant rare earth magnesium alloy composite material according to claim 1, characterized in that: In step 2, the weight proportions of the yttria-stabilized zirconia powder, cerium oxide, and lanthanum oxide are 92 to 95 parts, 2.0 to 5.0 parts, and 1.0 to 3.0 parts, respectively. The weight-to-volume ratio of the total amount of the yttria-stabilized zirconia powder, cerium oxide, and lanthanum oxide solid powders to anhydrous ethanol is 1 g: 1 to 2 ml.

3. The corrosion-resistant rare earth magnesium alloy composite material according to claim 1, characterized in that: In step 3, the specific method for depositing the aluminum oxide nanofilm is: introducing trimethylaluminum with a pulse time of 0.05 to 0.1 s, a dosage of 1.5 to 2.5 mg, and a chamber pressure of 100 to 200 Pa, then purging with nitrogen for 30 to 60 s at a flow rate of 20 to 30 L / min, then introducing water vapor with a pulse time of 0.05 to 0.1 s, a dosage of 1.5 to 3.0 mg, and finally purging with nitrogen again for 30 to 60 seconds. This is one cycle, and a total of 60-70 cycles are performed.

4. The corrosion-resistant rare earth magnesium alloy composite material according to claim 1, characterized in that: The carbon nanotubes are modified carbon nanotubes, and the preparation method of the modified carbon nanotubes is as follows: Step S1, acidification pretreatment: taking multi-walled carbon nanotubes, pre-oxidizing them in a tube furnace at an air flow rate of 50-100 mL / min and a temperature of 350-400°C for 30-45 minutes. After cooling naturally to room temperature, the carbon nanotubes are transferred to a reactor, nitric acid solution is added, and the mixture is heated in a water bath at 60-80°C with stirring for 1-2 hours. After the reaction is completed, the mixture is washed and dried. Step S2, mixed acid treatment: mixing the pretreated carbon nanotubes with concentrated sulfuric acid and concentrated nitric acid, ultrasonically treating them at 40-60° C. for 1-2 hours, and then neutralizing, washing, and drying. Step S3, double silane grafting: the acidified carbon nanotubes are mixed with anhydrous ethanol, KH-550 silane coupling agent and acetic acid are added, and the mixture is reacted at 73-78°C under reflux condensation for 1.5-2.5 hours. After washing with ethanol, KH-570 silane coupling agent is added, the temperature is adjusted to 60-70°C, the mixture is reacted for 1-1.5 hours, washed, and dried. Step S4: Plasma activation: Place the carbon nanotubes grafted in step S3 in a plasma reaction chamber, evacuate to 10-50 Pa, introduce a mixture of argon and hydrogen, maintain the chamber pressure at 80-120 Pa, pulse frequency 10-15 kHz, power 600-800 W, treatment time 3-5 min, and cool to room temperature under nitrogen protection after treatment.

5. The corrosion-resistant rare earth magnesium alloy composite material according to claim 4, characterized in that: In step S1, the concentration of the nitric acid solution is 3-5 mol / L, and the mass-to-volume ratio of the carbon nanotubes to the nitric acid solution is 1 g:50-100 mL.

6. The corrosion-resistant rare earth magnesium alloy composite material according to claim 4, characterized in that: In step S2, the mass volume ratio of the pretreated carbon nanotubes to the total amount of concentrated sulfuric acid and concentrated nitric acid solution is 1 g: 100-150 mL, the volume ratio of the concentrated sulfuric acid and concentrated nitric acid is 3-5:1, and the concentrations of the concentrated sulfuric acid and concentrated nitric acid are 95%-98% and 65%-68%, respectively.

7. The corrosion-resistant rare earth magnesium alloy composite material according to claim 4, characterized in that: In step S3, the weight-to-volume ratio of the acidified carbon nanotubes to anhydrous ethanol is 1 g: 50-80 mL, the amounts of KH-550 silane coupling agent and acetic acid are 5%-8% and 0.1% of the mass of the acidified carbon nanotubes, respectively, and the amount of KH-570 silane coupling agent is 20%-30% of the mass of KH-550.

8. The corrosion-resistant rare earth magnesium alloy composite material according to claim 4, characterized in that: In step S4, the flow rate of the argon gas is 80-120 mL / min, and the volume ratio of the argon gas to the hydrogen gas is 10:

1.

9. The method for preparing the corrosion-resistant rare earth magnesium alloy composite material according to any one of claims 1 to 8, characterized in that: The preparation method of the functional layer is as follows: Step a: mixing carbon nanotubes with modified yttria-stabilized zirconia powder, adding anhydrous ethanol, performing ultrasonic dispersion treatment, and then spray drying to obtain a composite powder; Step b: Plasma activation treatment of the composite powder using a mixture of argon and hydrogen followed by sieving; Step c: spraying the powder treated in step b using a high-speed oxygen-fuel spraying method.

10. The method for preparing the corrosion-resistant rare earth magnesium alloy composite material according to claim 9, characterized in that: The transition layer is made of nickel-chromium-aluminum-yttrium alloy powder sprayed by supersonic flame.

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