Nd-Fe-B magnet two-dimensional composite corrosion-resistant coating and preparation method thereof

Abstract

The application provides a neodymium-iron-boron magnet two-dimensional composite corrosion-resistant plating layer and a preparation method thereof, and belongs to the technical field of rare earth permanent magnet material plating layer preparation. The method comprises the following steps: neodymium-iron-boron magnet pretreatment, to obtain a magnet to be electroplated with a clean and rough surface; the magnet to be electroplated is soaked in a deposition solution, and ion exchange electrodeposition is carried out by applying a pulse electric field, and under the synergistic action of electrostatic assembly and the pulse electric field, a two-dimensional composite plating layer is deposited on the surface of the magnet to be electroplated; wherein the deposition solution comprises a nickel-based electroplating solution, a complexing agent and two-dimensional Ti3C2T x ; the complexing agent is selected from ammonia, EDTA-2Na or ammonium citrate. The application provides a method for applying two-dimensional Ti3C2T x to an alloy plating layer, which further improves the corrosion resistance of the electrodeposited plating layer on the surface of the neodymium-iron-boron magnet.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of rare earth permanent magnet material coating preparation, and particularly relates to a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet and a preparation method thereof. BACKGROUND

[0002] Neodymium-iron-boron permanent magnets are known as "the king of magnets" due to their excellent magnetic properties. They have high magnetic energy product, high cost performance, and are easy to process into various sizes, and are widely used in aerospace, wind power generation, energy-saving home appliances, electronic appliances, and new energy vehicles. However, due to their special multiphase structure and differences in chemical properties between the phases, neodymium-iron-boron rare earth permanent magnets exhibit inherent insufficient corrosion resistance. Especially in the application of new energy vehicles, the service life of the motor is often more than ten years, which puts higher demands on the corrosion resistance of neodymium-iron-boron rare earth permanent magnets. At present, one of the strategies to improve the corrosion resistance of neodymium-iron-boron rare earth permanent magnets is to add corrosion-resistant two-dimensional materials to the surface protective layer to improve corrosion resistance. Studies have shown that Ti3C2T x As a corrosion-resistant two-dimensional material, it can effectively improve the corrosion resistance of the coating. However, this material is rarely used in the modification of alloy coatings. The main reason is that the material is easily adsorbed with metal cations in the solution, leading to material aggregation, resulting in a decrease in the corrosion resistance of the final coating. SUMMARY

[0003] In view of this, the present application aims to provide a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet and a preparation method thereof, which aims to solve at least one technical problem in the background art.

[0004] The present application is implemented as follows:

[0005] The present application provides a preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, which comprises the following steps:

[0006] The neodymium-iron-boron magnet is pretreated to obtain a clean and rough surface for electroplating;

[0007] The electroplating magnet is immersed in a deposition solution, and ion exchange electrodeposition is carried out under the action of a pulse electric field. Under the synergistic action of electrostatic assembly and pulse electric field, a two-dimensional composite coating is deposited on the surface of the electroplating magnet;

[0008] The deposition solution comprises a nickel-based electroplating solution, a complexing agent, and a two-dimensional Ti3C2T x The complexing agent is selected from ammonia, EDTA-2Na, or ammonium citrate.

[0009] Furthermore, the preparation method of the deposition solution is as follows: a complexing agent is added to a nickel-based electroplating solution, and after sufficient reaction, the pH of the solution is adjusted to 4-6, and then Ti3C2T is added. x The powder was ultrasonically dispersed to obtain a sedimentation solution.

[0010] Furthermore, the two-dimensional Ti3C2T x The addition amount is 0.1g / L to 0.3g / L.

[0011] Furthermore, when the complexing agent is ammonia, its dosage is 5 ml / L to 20 ml / L; when the complexing agent is EDTA-2Na or ammonium citrate, its dosage is 0.2 g / L to 2 g / L.

[0012] Furthermore, the nickel-based electroplating solution comprises the following components at mass concentrations: nickel sulfate 180 g / L to 280 g / L; nickel chloride 20 g / L to 40 g / L; boric acid 30 g / L to 40 g / L; and sodium dodecyl sulfate 0.05 g / L to 0.1 g / L.

[0013] Furthermore, the pretreatment of the NdFeB magnet specifically includes:

[0014] First, place the neodymium iron boron magnet in an alkaline cleaning solution at 65℃±5℃, stir to remove the oil stains from the neodymium iron boron magnet, and then rinse it clean with water; the alkaline cleaning solution includes NaOH, Na2CO3, Na3PO4, emulsifier and sodium dodecyl sulfate;

[0015] Then, the neodymium iron boron magnets were immersed in HNO3 solution for 30s±5s, and then rinsed with water.

[0016] The neodymium iron boron magnet was then immersed in H2SO4 solution for 30s±5s, rinsed with water, and then ultrasonically cleaned with anhydrous ethanol to obtain a clean and rough magnet for electroplating.

[0017] Furthermore, the parameters for ion exchange electrodeposition are: forward current density of 5 A / dm³. 2 ~15A / dm 2 The operating frequency is 400Hz to 1000Hz, and the duty cycle is 20% to 60%; the reverse current density is 0A / dm³. 2 ~1A / dm 2 The operating frequency is 400Hz to 1000Hz, and the duty cycle is 20% to 60%.

[0018] Furthermore, the temperature for ion exchange electrodeposition is 45±5℃.

[0019] The present invention also provides a two-dimensional composite corrosion-resistant coating for neodymium iron boron magnets prepared by the above-described preparation method.

[0020] Compared with the prior art, the present application comprises the following beneficial effects:

[0021] 1、 The present application provides a two-dimensional Ti3C2T x The method applied to the alloy coating further improves the corrosion resistance of the electrodeposited coating on the surface of the neodymium-iron-boron magnet.

[0022] 2、 The present application adds a complexing agent and two-dimensional Ti3C2T x , Ti3C2T x to the nickel-based electroplating solution. 2+ The Ni x preferentially forms a stable complex with the complexing agent, thereby avoiding the agglomeration of Ti3C2T x with the electroplating solution.

[0023] 3、 The present application electrostatically assembles and cooperates with ion exchange electrodeposition to prepare a composite coating with strong corrosion resistance. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 SEM images of the two-dimensional composite coating prepared for Example 1, Example 4, Example 5, and Comparative Example 2 of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with examples. It should be understood that the specific implementation cases described herein are only used to explain the present application and do not limit the present application.

[0026] A preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, the method comprising the following steps S11-S113:

[0027] S11, first place the neodymium-iron-boron magnet in an alkali cleaning solution at 65℃±5℃, stir to remove the oil stains on the neodymium-iron-boron magnet, and then clean with water; the alkali cleaning solution comprises NaOH, Na2CO3, Na3PO4, an emulsifier and sodium dodecyl sulfate; then immerse the neodymium-iron-boron magnet in an HNO3 solution for 30s±5s, and then clean with water; then immerse the neodymium-iron-boron magnet in an H2SO4 solution for 30s±5s, clean with water, and then ultrasonically clean with anhydrous ethanol to obtain a clean and rough surface of the magnet to be electroplated.

[0028] S12, immerse the magnet to be electroplated in a deposition solution, apply a pulse electric field for ion exchange electrodeposition, and deposit a two-dimensional composite coating on the surface of the magnet to be electroplated under the synergistic action of electrostatic assembly and the pulse electric field; wherein the deposition solution comprises a nickel-based electroplating solution, a complexing agent and two-dimensional Ti3C2T xThe preparation method of the deposition solution is: adding a complexing agent into a nickel-based electroplating solution, fully reacting, adjusting the pH of the solution, and then adding Ti3C2T x powder and ultrasonic dispersion to obtain the deposition solution.

[0029] When the complexing agent is ammonia water, the ammonia water generally has a mass concentration of 60% of ammonia content, and the amount of ammonia water is 5ml / L-20ml / L, for example, it can be 5ml / L, 10ml / L, 20ml / L; but not limited to the listed values, other values not listed within the value range are also applicable; when the complexing agent is EDTA-2Na or ammonium citrate, the amount is 0.2g / L-2g / L, for example, it can be 1.2g / L; but not limited to the listed values, other values not listed within the value range are also applicable;

[0030] Ti3C2T x The amount of Ti3C2T

[0031] The pH of the deposition solution is controlled to be 4-6, for example, it can be 4, 5, 6; but not limited to the listed values, other values not listed within the value range are also applicable;

[0032] The nickel-based electroplating solution can use any nickel-containing electroplating solution allowed in the art that can form a corrosion-resistant plating layer, preferably, the nickel-based electroplating solution includes the following components with the following mass concentrations: nickel sulfate 180g / L-280g / L; nickel chloride 20g / L-40g / L; boric acid 30g / L-40g / L; sodium dodecyl sulfate 0.05g / L-0.1g / L; for example, it can be nickel sulfate 220g / L; nickel chloride 30g / L; boric acid 35g / L; sodium dodecyl sulfate 0.08g / L, but not limited to the listed values, other values not listed within the value range are also applicable;

[0033] The temperature of the ion exchange electrodeposition is 45±5°C; the reaction parameters are: the forward current density is 5A / dm 2 -15A / dm 2 , the working frequency is 400Hz-1000Hz, and the duty cycle is 20%-60%; the reverse current density is 0A / dm 2 -1A / dm 2 , the working frequency is 400Hz-1000Hz, and the duty cycle is 20%-60%. For example, the forward current density can be 8A / dm 2 , the working frequency is 800Hz, and the duty cycle is 40%; the reverse current density is 0.2A / dm 2, the working frequency is 400 Hz, and the duty cycle is 20%, but is not limited to the listed values, and other values not listed within the value range are also applicable.

[0034] The method is prepared by two-dimensional Ti3C2T x As the reinforcing phase of the Ni-based coating, the corrosion resistance of the commercial magnet is obviously improved, and the two-dimensional Ti3C2T x The surface has abundant functional groups and good dispersibility in the plating solution. The electrostatic assembly and electric field strengthening technology used in the method make the Ni 2+ Preferentially form stable complexes with complexing agents, thereby regulating Ti3C2T x The electrostatic effect of Ni 2+ , and under the synergistic effect of the electric field, the controllable Ni and Ti3C2T x Composite coating is prepared.

[0035] S13, after ion exchange electrodeposition, the Nd-Fe-B magnet is taken out, washed with water and dried, and the Nd-Fe-B magnet with corrosion-resistant coating on the surface is obtained.

[0036] Example 1

[0037] A method for preparing a two-dimensional composite corrosion-resistant coating of a Nd-Fe-B magnet, using an un-magnetized N40 commercial sintered Nd-Fe-B magnet as a prepared magnet, specifically comprising the following steps:

[0038] 1. Preparation of deposition solution: first, prepare a nickel-based electroplating solution according to the following formula: nickel sulfate 220 g / L; nickel chloride 30 g / L; boric acid 35 g / L; sodium dodecyl sulfate 0.08 g / L; add ammonia water containing 60% ammonia and adjust the pH value to 4 by sulfuric acid, stir for 10 min to fully complex the nickel ions (ammonia water reacts with sulfuric acid to form ammonium sulfate, and ammonium ions also play a complexing role); then add single-layer Ti3C2T x The two-dimensional material is uniformly dispersed by ultrasonic to form a deposition solution, and the amount of complexing agent ammonia water added is 10 ml / L, and the amount of Ti3C2T x in the deposition solution is 0.2 g / L.

[0039] 2. Nd-Fe-B magnet pretreatment: place the magnet in an alkali cleaning solution at 65℃±5℃ and stir for 10 min to remove oil, wherein the alkali cleaning formula is NaOH 7.5 g / L, Na2CO3 45 g / L, Na3PO4 50 g / L, emulsifier OP-10 2 g / L, and sodium dodecyl sulfate 0.2 g / L. After cleaning and removing oil, wash with deionized water, then immerse in a 6wt% HNO3 solution for 30s, then wash with deionized water; then immerse in a 3wt% H2SO4 solution for 30s, then ultrasonically clean with anhydrous ethanol for 3 min to obtain a pretreated sintered Nd-Fe-B magnet;

[0040] 3, Put the sintered Nd-Fe-B magnet pretreated in step 2 into the deposition solution prepared in step 1, and make Ti3C2T x The metal ions ionized on the surface of the magnet are electrostatically assembled; meanwhile, the magnet is connected to the negative electrode, the graphite sheet is used as the positive electrode, the temperature of the electrolyte is controlled to be 45℃±5℃, a pulse electric field is applied, and the parameters of the pulse electric field are as follows: the current density is 8A / dm 2 , the working frequency is 600Hz, the duty cycle is 40%, and the processing time is 20min, so that the two-dimensional composite coating is deposited on the magnet under the synergistic action of electrostatic assembly and the pulse electric field.

[0041] 4, Finally, the sintered Nd-Fe-B magnet plated with nickel on the surface is put into deionized water at 50℃ for cleaning, and then dried in an environment at 60℃, and the SEM image of the two-dimensional composite coating after drying is shown in Figure 1 (a).

[0042] Example 2

[0043] The embodiment provides a preparation method of a two-dimensional composite corrosion-resistant coating of a Nd-Fe-B magnet, which is only different from that of example 1 in that the addition amount of ammonia water in step 1 is 5ml / L, and the remaining parameters and conditions are the same as those of example 1.

[0044] Example 3

[0045] The embodiment provides a preparation method of a two-dimensional composite corrosion-resistant coating of a Nd-Fe-B magnet, which is only different from that of example 1 in that the addition amount of ammonia water in step 1 is 20ml / L, and the remaining parameters and conditions are the same as those of example 1.

[0046] Example 4

[0047] The embodiment provides a preparation method of a two-dimensional composite corrosion-resistant coating of a Nd-Fe-B magnet, which is only different from that of example 1 in that the addition amount of Ti3C2T x in step 1 is 0.1g / L, and the remaining parameters and conditions are the same as those of example 1. The SEM image of the two-dimensional composite coating prepared in example 4 is shown in Figure 1 (b).

[0048] Example 5

[0049] The embodiment provides a preparation method of a two-dimensional composite corrosion-resistant coating of a Nd-Fe-B magnet, which is only different from that of example 1 in that the addition amount of Ti3C2T x in step 1 is 0.3g / L, and the remaining parameters and conditions are the same as those of example 1. The SEM image of the two-dimensional composite coating prepared in example 5 is shown in Figure 1 (c).

[0050] Example 6

[0051] The embodiment provides a preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, which is different from the embodiment 1 only in that a complexing agent of step 1 is EDTA-2Na, and the amount is 1.2 g / L, and the remaining parameters and conditions are the same as those of the embodiment 1.

[0052] Embodiment 7

[0053] The embodiment provides a preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, which is different from the embodiment 1 only in that a complexing agent of step 1 is ammonium citrate, and the amount is 1.2 g / L, and the remaining parameters and conditions are the same as those of the embodiment 1.

[0054] Embodiment 8

[0055] The embodiment provides a preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, which is different from the embodiment 1 only in that, when the deposition solution is prepared in step 1, the pH value is adjusted to 5, and the remaining parameters and conditions are the same as those of the embodiment 1.

[0056] Embodiment 9

[0057] The embodiment provides a preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, which is different from the embodiment 1 only in that, when the deposition solution is prepared in step 1, the pH value is adjusted to 6, and the remaining parameters and conditions are the same as those of the embodiment 1.

[0058] Comparative example 1

[0059] The comparative example provides a preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, which is different from the embodiment 1 only in that no complexing agent is used in step 1, and the remaining parameters and conditions are the same as those of the embodiment 1.

[0060] Comparative example 2

[0061] The comparative example provides a preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, which is different from the embodiment 1 only in that no complexing agent and Ti3C2T x is used in step 1, and the remaining parameters and conditions are the same as those of the embodiment 1, and the SEM diagram of the prepared two-dimensional composite coating is shown in (d) of FIG. 1. Figure 1

[0062] Comparative example 3

[0063] The comparative example provides a preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, which is different from the embodiment 1 only in that the amount of Ti3C2T x is 0.4 g / L in step 1, and the remaining parameters and conditions are the same as those of the embodiment 1.

[0064] Comparative example 4

[0065] ​The comparative example provides a preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, which is only different from example 1 in that the pH value is adjusted to 3 when the deposition solution is prepared in step 1, and the remaining parameters and conditions are the same as those of example 1.

[0066] Comparative example 5

[0067] The comparative example provides a preparation method of a two-dimensional composite corrosion-resistant coating of a neodymium-iron-boron magnet, which is only different from example 1 in that the pH value is adjusted to 7 when the deposition solution is prepared in step 1, and the remaining parameters and conditions are the same as those of example 1.

[0068] The neodymium-iron-boron magnets prepared in examples 1 to 9 and comparative examples 1 to 5 are subjected to electrochemical performance testing in a 3.5% NaCl solution at room temperature by using an electrochemical workstation, and the results are shown in Table 1.

[0069] Table 1

[0070] [R ct (Ω·cm 2 )]]> E corr (mV)]]> I corr (10 -6 A·cm -2 )]]> Example 1 14354 -474 5.13 Example 2 11352 -569 10.37 Example 3 24140 -442 4.40 Example 4 9198 -587 20.13 Example 5 5308 -653 16.56 Example 6 3217 -717 54.77 Example 7 16136 -708 49.69 Example 8 9740 -476 5.36 Example 9 9297 -439 9.54 Comparative Example 1 4201 -530 7.89 Comparative Example 2 1892 -831 43.12 Comparative Example 3 3147 -711 31.01 Comparative Example 4 4125 -704 28.93 Comparative Example 5 6314 -769 13.71

[0071] Self-corrosion potential E corr The more negative, the higher the activity, and the faster the electrochemical corrosion; the corrosion rate is proportional to the self-corrosion current density I corr The larger the self-corrosion current density, the faster the electrochemical corrosion; the coating impedance value is proportional to the charge transfer resistance R ct in the equivalent circuit, the larger the impedance value, the more excellent the corrosion resistance of the coating.

[0072] From the data in Table 1, the neodymium-iron-boron magnets prepared in examples 1 to 9 have a self-corrosion potential E corr that is increased, a self-corrosion current density I corr that is reduced, and a charge transfer resistance R ct that is increased, indicating that the coating prepared by electroplating with the deposition solution of the examples has excellent corrosion resistance.

[0073] Examples 1 to 3 differ in that the amount of the complexing agent ammonia is adjusted, and from the data in Table 1, with the increase of the complexing agent, the charge transfer resistance R ct is first increased, the self-corrosion potential E corr continuously increases, the self-corrosion current density I corr is first greatly reduced and then slightly increased; however, the overall corrosion resistance is better than that of a conventional electro-deposited coating.

[0074] Examples 1, 4 and 5 differ in that the amount of Ti3C2T x is adjusted, and from the data in Table 1, with the increase of Ti3C2T x , the charge transfer resistance R ctfirstly increased and then decreased, self-corrosion potential E corr firstly decreased and then increased, self-corrosion current density I corr firstly decreased and then increased; in terms of corrosion resistance, Example 1 > Example 4 > Example 5, but the overall corrosion resistance of the coatings prepared by the three examples is better than that of the coating prepared by conventional electrodeposition. Figure 1 As can be seen from (a), (b) and (c), when the dosage of Ti3C2T x is 0.2 g / L (Example 1), the two-dimensional composite coating prepared has the best flatness, followed by Example 4 (the dosage of Ti3C2T x is 0.1 g / L), and Example 5 (the dosage of Ti3C2T x is 0.3 g / L) has more small protrusions and its flatness is worse than that of Example 4, i.e., in terms of flatness, Example 1 > Example 4 > Example 5, which is consistent with the corrosion resistance.

[0075] The difference between Example 6, Example 7 and Example 1 is that the complexing agent is replaced by EDTA-2Na or ammonium citrate, respectively. As can be seen from the data in Table 1, the electrodeposited coating prepared by using the deposition solution with the complexing agent has good corrosion resistance.

[0076] The difference between Example 8, Example 9 and Example 1 is that the pH value in the preparation process of the deposition solution is adjusted. As can be seen from the data in Table 1, with the increase of the pH value, the charge transfer resistance R ct firstly increased and then decreased, self-corrosion potential E corr decreased, self-corrosion current density I corr increased.

[0077] The difference between Comparative Example 1, Comparative Example 2 and Example 1 is that no complexing agent is added in the deposition solution of Comparative Example 1, and no complexing agent and Ti3C2T x is added in the deposition solution of Comparative Example 2. As can be seen from the data in Table 1, the corrosion resistance of the coating prepared by Comparative Example 1 and Comparative Example 2 is much lower than that of Example 1, and the performance comparison results of the three are: Comparative Example 2 < Comparative Example 1 < Example 1. The reason is that: Comparative Example 2 uses a conventional electrodeposition to prepare the coating, and Comparative Example 1 adds Ti3C2T x , but the agglomeration of the deposition solution occurs without the complexing agent, which affects the electroplating effect. Figure 1 As can be seen from (d), the surface flatness of the coating prepared by Comparative Example 2 is very poor.

[0078] The difference between Comparative Example 3 and Example 1 is that an excessive amount of Ti3C2T x is added. As can be seen from the data in Table 1, the charge transfer resistance R ct decreased, self-corrosion potential E corr decreased, self-corrosion current density I corrThe ascending; the overall corrosion resistance performance is reduced.

[0079] The difference between Comparative Example 4, Comparative Example 5 and Example 1 is that the pH value in the preparation process of the deposition solution is adjusted to 3 and 7 respectively. As can be seen from the data in Table 1, the charge transfer resistance R ct of Comparative Example 4 and Comparative Example 5 is reduced, the self-corrosion potential E corr is reduced, the self-corrosion current density I corr is increased; that is, the overall corrosion resistance performance is reduced.

[0080] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A method for preparing a two-dimensional composite corrosion-resistant coating for neodymium iron boron magnets, characterized in that, The method includes the following steps: Neodymium iron boron magnet pretreatment is used to obtain a clean and rough magnet to be electroplated; The magnet to be electroplated is immersed in the deposition solution, and a pulsed electric field is applied to perform ion exchange electrodeposition. Under the synergistic effect of electrostatic assembly and pulsed electric field, a two-dimensional composite coating is deposited on the surface of the magnet to be electroplated. The deposition solution includes a nickel-based electroplating solution, a complexing agent, and two-dimensional Ti3C2T. x The complexing agent is selected from ammonia water; The preparation method of the deposition solution is as follows: a complexing agent is added to a nickel-based electroplating solution, and after the reaction is complete, the pH of the solution is adjusted to 4-5, and then Ti3C2T is added. x The powder was ultrasonically dispersed to obtain a sedimentation solution; The two-dimensional Ti3C2T x The addition amount is 0.2 g / L; When the complexing agent is ammonia, its dosage is 5 ml / L to 20 ml / L; The nickel-based electroplating solution comprises the following components in mass concentrations: nickel sulfate 180 g / L~280 g / L; nickel chloride 20 g / L~40 g / L; boric acid 30 g / L~40 g / L; sodium dodecyl sulfate 0.05 g / L~0.1 g / L.

2. The method for preparing a two-dimensional composite corrosion-resistant coating for a neodymium iron boron magnet according to claim 1, characterized in that, The pretreatment of the NdFeB magnet specifically includes: First, place the neodymium iron boron magnet in an alkaline cleaning solution at 65℃±5℃, stir to remove the oil stains from the neodymium iron boron magnet, and then rinse it clean with water; the alkaline cleaning solution includes NaOH, Na2CO3, Na3PO4, emulsifier and sodium dodecyl sulfate; Then, the neodymium iron boron magnets were immersed in HNO3 solution for 30s±5s, and then rinsed with water. The neodymium iron boron magnet was then immersed in H2SO4 solution for 30s±5s, rinsed with water, and then ultrasonically cleaned with anhydrous ethanol to obtain a clean and rough magnet for electroplating.

3. The method for preparing a two-dimensional composite corrosion-resistant coating for a NdFeB magnet according to claim 1, characterized in that, The parameters for ion exchange electrodeposition are: forward current density of 5 A / dm³. 2 ~15A / dm 2 The operating frequency is 400Hz to 1000Hz, and the duty cycle is 20% to 60%; the reverse current density is 0A / dm³. 2 ~1A / dm 2 The operating frequency is 400Hz to 1000Hz, and the duty cycle is 20% to 60%.

4. The method for preparing a two-dimensional composite corrosion-resistant coating for a neodymium iron boron magnet according to claim 1, characterized in that, The temperature for ion exchange electrodeposition is 45℃±5℃.

5. A two-dimensional composite corrosion-resistant coating for neodymium iron boron magnets prepared by the preparation method according to any one of claims 1 to 4.

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