A high intrinsic coercivity, corrosion-resistant NdFeB magnet and its preparation method

Abstract

The present application relates to the field of NdFeB magnet preparation, and specifically to a high intrinsic coercivity, corrosion-resistant NdFeB magnet and its preparation method. The method comprises the following steps: melt spinning, hydrogen grinding, pressing, sintering, and phosphating, wherein the corrosion-resistant component comprises methylvinylsilazane and polysilazane resin; the phosphating solution comprises the following components at the following concentrations: 30-100 g / L potassium dihydrogen phosphate, 100-200 g / L phosphoric acid, and 5-10 g / L manganese nitrate; and the high-temperature phosphating temperature range is 85-98°C. The present application improves the corrosion resistance of NdFeB magnets containing Tb and Dy by sintering the corrosion-resistant components to form silicon nitride ceramics. Simultaneously, the sintered NdFeB magnet is phosphated, and the potassium ions in the phosphating solution form a highly adhesive phosphating film with the silicon nitride ceramic at high temperature, further improving the corrosion resistance of the NdFeB magnet, thereby preparing a high intrinsic coercivity, corrosion-resistant NdFeB magnet.

Description

Technical Field

[0001] The present application relates to the field of NdFeB magnet preparation, and in particular to a high intrinsic coercivity, corrosion-resistant NdFeB magnet and a preparation method thereof. Background Art

[0002] Neodymium iron boron (NdFeB) magnets are alloys composed of neodymium (Nd), iron (Fe), and boron (B). Developed and successfully implemented in the 1980s, NdFeB magnets are third-generation rare earth permanent magnets. Their high remanence, high coercivity, high magnetic energy product, and excellent dynamic recovery characteristics make them the most cost-effective magnetic material available. Known as the "King of Magnets" for their exceptional magnetic properties, NdFeB magnets play a vital role in the medical, automotive, home appliance, aerospace, and communications industries, boasting a broad range of applications.

[0003] Intrinsic coercivity is a key indicator used to measure a magnetic material's resistance to demagnetization. NdFeB magnets are often used in high-temperature environments. Magnetic materials with high intrinsic coercivity are effective in resisting thermally activated demagnetization, ensuring stable magnetic field strength even at high temperatures. Adding heavy rare earth elements (RLEs) is a common method for increasing the intrinsic coercivity of NdFeB magnets. However, the addition of RLEs reduces the corrosion resistance of NdFeB magnets, limiting their application. Summary of the Invention

[0004] In order to solve the problem that the corrosion resistance of NdFeB magnets added with heavy rare earth elements will decrease, the present application provides a preparation method of high intrinsic coercivity and corrosion-resistant NdFeB magnets. By combining the corrosion-resistant components with potassium dihydrogen phosphate in the phosphating solution at high temperature, the high intrinsic coercivity of the NdFeB magnet is ensured while maintaining high corrosion resistance.

[0005] In a first aspect, the present application provides a method for preparing a high intrinsic coercivity, corrosion-resistant NdFeB magnet, using the following technical solution:

[0006] A method for preparing a high intrinsic coercivity, corrosion-resistant NdFeB magnet comprises the following steps:

[0007] Melting strip throwing: Mix the metal raw materials according to the formula, and melt the mixture to obtain a molten liquid, which is then poured into a strip to obtain a strip throwing sheet;

[0008] Hydrogen grinding: The spun sheet is hydrogen-broken into coarse powder, and the coarse powder is jet-milled to obtain alloy powder;

[0009] Pressing and molding: placing the obtained alloy powder and corrosion-resistant components in a mold and pressing and molding to obtain a sintered green body;

[0010] Sintering process: The green compact is sintered under the protection of nitrogen. After sintering, it is rapidly cooled to room temperature in stages and tempered to obtain NdFeB magnets.

[0011] Phosphating treatment: After the surface of the NdFeB magnet is treated, it is placed in a phosphating solution for high-temperature phosphating treatment, and then taken out and rinsed to obtain the phosphide NdFeB magnet;

[0012] The metal raw material includes the following components in parts by weight: 6.5-7 parts of Pr, 19.5-21 parts of Nd, 0.90-1.03 parts of B, 4-6 parts of Tb, 0-1 parts of Dy, 1-2 parts of Co, and 64-68 parts of Fe;

[0013] The corrosion-resistant component includes at least one of methylvinylsilazane and polysilazane resin;

[0014] The phosphating solution includes the following components in concentrations: 30-100 g / L of potassium dihydrogen phosphate, 100-200 g / L of phosphoric acid, and 5-10 g / L of manganese nitrate;

[0015] The temperature range of the high-temperature phosphating treatment is 85-98°C.

[0016] The present application generates silicon nitride ceramics by sintering corrosion-resistant components, thereby improving the corrosion resistance and intrinsic coercivity of NdFeB magnets added with Tb and Dy; at the same time, the sintered NdFeB magnets are phosphated, and the potassium ions in the phosphating solution form a high-adhesion phosphating film with the silicon nitride ceramics at high temperature, thereby further improving the corrosion resistance of the NdFeB magnets, thereby preparing high intrinsic coercivity and corrosion-resistant NdFeB magnets.

[0017] The aforementioned technical solution involves adding heavy rare earth metals such as Tb and Dy to NdFeB magnets primarily to increase the magnet's intrinsic coercivity, thereby improving its performance stability in high-temperature environments. However, the addition of these heavy rare earth metals does reduce the NdFeB magnet's corrosion resistance.

[0018] Methylvinylsilazane and polysilazane resins form a temporary bonding network at low temperatures. This network provides additional support during the green stage of the magnet, enhancing its mechanical strength. By reducing crack formation, these resins help improve green compact density and molding accuracy, thereby ensuring the structural integrity and consistent performance of the final magnet. During the sintering process, methylvinylsilazane and polysilazane resins decompose at high temperatures to produce silicon nitride ceramic. Silicon nitride ceramic coats the grain boundaries and surfaces of the NdFeB magnet, forming a dense physical barrier. This barrier effectively inhibits the penetration of oxygen and corrosive media, thereby improving the magnet's corrosion resistance.

[0019] Phosphating forms a dense phosphate film on the magnet surface. This film effectively covers micropores and defects on the magnet surface, reducing direct contact between corrosive media and the magnet substrate, thereby preventing these defects from becoming the starting point of corrosion. The formation of the phosphate film also makes the magnet surface smoother and reduces surface roughness, which helps reduce friction and wear between the magnet and the surrounding environment during use, thereby extending the magnet's service life.

[0020] Potassium dihydrogen phosphate is a key component in the phosphating solution. After sintering, the corrosion-resistant component produces silicon nitride ceramics. Potassium ions form coordination bonds with nitrogen atoms on the silicon nitride ceramics at temperatures between 85 and 98°C, creating a stable complex. The resulting phosphating film has stronger adhesion, further protecting the magnet substrate from corrosive media and improving the corrosion resistance of NdFeB magnets.

[0021] The present application improves the corrosion resistance of NdFeB magnets to which Tb and Dy are added by sintering corrosion-resistant components to generate silicon nitride ceramics; at the same time, the sintered NdFeB magnets are subjected to phosphating treatment, and potassium ions in the phosphating solution form a highly adhesive phosphating film with the silicon nitride ceramics at high temperature, thereby further improving the corrosion resistance of the NdFeB magnets, thereby preparing corrosion-resistant NdFeB magnets with high intrinsic coercivity.

[0022] Preferably, the corrosion-resistant component is polysilazane resin.

[0023] By adopting the above technical solution, methylvinylsilazane and polysilazane resins may release gases such as ammonia and carbon dioxide during high-temperature sintering, which in turn increases the porosity of the NdFeB magnet. When the porosity is too high, defects such as micropores and surface roughness are likely to appear inside and on the surface of the magnet. These defects can easily become the starting point of corrosion in high-temperature and high-humidity environments, accelerating the corrosion process. In comparison, NdFeB magnets incorporating polysilazane resin have better corrosion resistance than NdFeB magnets incorporating methylvinylsilazane, possibly because polysilazane resin releases less gas.

[0024] Preferably, the weight portion of the corrosion-resistant component is 0.2-0.5 parts.

[0025] Preferably, the weight portion of the corrosion-resistant component is 0.4 parts.

[0026] By adopting the above technical solution, when the content of the corrosion-resistant component is too low, the effect of improving the corrosion resistance of the NdFeB magnet is not obvious; when the content of the corrosion-resistant component is too high, the corrosion-resistant component will produce more gas during high-temperature sintering, and defects such as micropores and surface roughness are likely to appear inside and on the surface of the magnet, which in turn reduces the corrosion resistance of the NdFeB magnet; for this reason, the applicant finally determined after a lot of research and experimental verification that the weight of the corrosion-resistant component in this application should be as above.

[0027] Preferably, the concentration of potassium dihydrogen phosphate is 50-90 g / L.

[0028] Preferably, the concentration of potassium dihydrogen phosphate is 75 g / L.

[0029] By adopting the above technical solution, when the potassium dihydrogen phosphate content is low, the number of potassium ions may not be sufficient to fully form a complex with the silicon-nitrogen bonds on the silicon nitride ceramic, resulting in low adhesion of the phosphating film, and thus the corrosion resistance of the NdFeB magnet is not significantly improved. When the potassium dihydrogen phosphate content in the phosphating solution is too high, it will lead to an excessively high potassium ion concentration in the solution. Excessive potassium ions may form excessive intermetallic compounds or potassium-rich phases in the phosphating film. These phases may reduce the hardness and wear resistance of the phosphating film, and in turn reduce the corrosion resistance of the NdFeB magnet.

[0030] Preferably, the high-temperature phosphating treatment lasts for 8-15 minutes.

[0031] By adopting the above technical solution, when the phosphating treatment time is too short, the phosphating reaction is not sufficient, and the concentration of the film-forming ions does not reach the solubility product, resulting in the phosphating film being too thin and difficult to form a dense protective layer; when the phosphating treatment time is too long, the phosphating reaction continues, resulting in the phosphating film being too thick, the roughness increases, and the adhesion is affected; for this reason, the applicant finally determined after a lot of research and experimental verification that the time for high-temperature phosphating treatment in this application is appropriate to be the above.

[0032] In a second aspect, the present application provides a high intrinsic coercivity, corrosion-resistant NdFeB magnet, which adopts the following technical solution:

[0033] A high intrinsic coercivity and corrosion-resistant neodymium iron boron magnet is prepared by the above-mentioned preparation method of the high intrinsic coercivity and corrosion-resistant neodymium iron boron magnet.

[0034] In summary, this application has the following beneficial effects:

[0035] The present application improves the corrosion resistance of NdFeB magnets to which Tb and Dy are added by sintering corrosion-resistant components to generate silicon nitride ceramics; at the same time, the sintered NdFeB magnets are subjected to phosphating treatment, and potassium ions in the phosphating solution form a highly adhesive phosphating film with the silicon nitride ceramics at high temperature, thereby further improving the corrosion resistance of the NdFeB magnets, thereby preparing corrosion-resistant NdFeB magnets with high intrinsic coercivity. DETAILED DESCRIPTION

[0036] The raw materials in this application include the following parts:

[0037] Methylvinylsilazane: 1,1,3,3-tetramethyl-1,3-divinyldisilazane, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasilazane, etc. can be selected. This application uses 1,1,3,3-tetramethyl-1,3-divinyldisilazane (hereinafter referred to as tetramethyldivinyldisilazane) with CAS No. 7691-02-3 as an example for illustration;

[0038] Polysilazane resin: a commercially available product with CAS number 475645-84-2;

[0039] The present application is further described in detail below with reference to the following examples and comparative examples.

[0040] Example 1

[0041] A method for preparing a neodymium iron boron magnet comprises the following steps:

[0042] Melting strip: 68g Pr, 205g Nd, 9.5g B, 50g Tb, 5g Dy, 15g Co, and 660g Fe were mixed and placed in a vacuum melting furnace for melting to obtain a molten liquid, which was then cast into a strip to obtain a strip sheet;

[0043] Hydrogen grinding: The spun sheet is hydrogen-broken into coarse powder, and the coarse powder is jet-milled to obtain alloy powder;

[0044] Pressing: The obtained alloy powder and 4 g of polysilazane resin were placed in a mold and pressed to obtain a sintered green body;

[0045] Sintering process: The green compact is sintered under nitrogen protection at a temperature of 1100°C for 3 hours. After sintering, it is rapidly cooled to room temperature in stages and tempered to obtain NdFeB magnets.

[0046] Phosphating treatment: After the surface of the NdFeB magnet is treated, heat 10L of phosphating solution to 93°C, then put the NdFeB magnet into the phosphating solution for phosphating treatment for 12 minutes, then take it out and rinse it to obtain the phosphated NdFeB magnet.

[0047] The cooling of the green compact after sintering is carried out in three stages. In the first stage, the sintering temperature is reduced from 1100°C to 800°C at a cooling rate of 7°C / min for 3 hours. In the second stage, the sintering temperature is further reduced from 800°C to room temperature at a cooling rate of 4°C / min. The tempering treatment consists of two stages. The first stage is tempered at 800°C for 2 hours. After the end, the magnetic material is cooled to room temperature using argon gas. Then the second stage of tempering treatment begins. The second tempering temperature is 500°C for 3 hours. After the end, the magnetic material is cooled to room temperature using argon gas.

[0048] The surface treatment involves cleaning the NdFeB magnets with an alkaline cleaning solution (a mixture of 100g / L potassium hydroxide solution and 50g sodium silicate solution, with a volume ratio of 1:3). The magnets are then cleaned with alcohol and a non-woven fabric and air-dried for later use. The cleaned NdFeB magnets are then soaked in molten potassium nitrate for 4 minutes, removed, dissolved in 35°C water, and rinsed and dried.

[0049] The phosphating solution includes the following components in concentrations: 75 g / L potassium dihydrogen phosphate, 150 g / L phosphoric acid, and 8 g / L manganese nitrate.

[0050] Example 2-3

[0051] In Example 2-3, based on the preparation method of Example 1, the component ratio of the NdFeB magnet is adjusted. The specific adjustments are shown in Table 1.

[0052] Comparative Examples 1-4

[0053] Comparative Example 1 is based on the preparation method of Example 1, except that 4 g of polysilazane resin is not added, and phosphating treatment is not performed, and other conditions remain unchanged.

[0054] Comparative Example 2 is based on the preparation method of Comparative Example 1, except that Tb and Dy are not added, and other conditions remain unchanged.

[0055] Comparative Example 3 is based on the preparation method of Example 1, except that 4 g of polysilazane resin is not added, and other conditions remain unchanged.

[0056] Comparative Example 4 Based on the preparation method of Example 1, the potassium dihydrogen phosphate in the phosphating solution was replaced with zinc dihydrogen phosphate, and the other conditions remained unchanged.

[0057] Performance testing

[0058] The NdFeB magnets of Examples 1-3 and Comparative Examples 1-4 were analyzed, and the specific detection method was as follows:

[0059] Magnetic properties

[0060] The comprehensive magnetic properties are tested according to GB / T3217-2013 "Magnetic Test Methods for Permanent Magnetic (Hard Magnetic) Materials".

[0061] Corrosion resistance

[0062] A neutral salt spray test was conducted using a 5wt% sodium chloride aqueous solution on the magnetic material samples at a test temperature of 35°C. Since the corrosion reaction of NdFeB magnets in neutral salt spray is mainly oxidation and spalling, the weight loss rate is used as the basis for testing the corrosion resistance of the magnetic material samples. Weight loss rate = (mass before immersion - mass after immersion) / mass before immersion.

[0063] According to the above detection method, the test results of Examples 1-3 and Comparative Examples 1-4 were obtained, as shown in Table 1 below:

[0064] Table 1 Component ratios and performance test table of NdFeB magnets of Examples 1-3 and Comparative Examples 1-4 (unit: g)

[0065]

[0066] As shown in Table 1, by comparing Examples 1-3 with Comparative Examples 1-4, the addition of heavy rare earth elements such as Tb and Dy to the NdFeB magnet formula significantly increases the intrinsic coercivity of the NdFeB magnet compared to Example 1 and Comparative Examples 1-2. This is likely because Tb and Dy, as heavy rare earth elements, possess unique magnetic properties in magnets, effectively enhancing the magnet's intrinsic coercivity.

[0067] It can also be found that when more heavy rare earth elements (Tb and Dy) are added to the NdFeB magnet formula, the corrosion resistance of the NdFeB magnet will be reduced. This may be because when Tb and Dy replace part of the neodymium, the main phase Nd2Fe 14 There is an electrochemical potential difference between B and the neodymium-rich phase Nd-rich, which makes the magnet more susceptible to corrosion in an electrochemical environment.

[0068] Compared with Example 1 and Comparative Examples 3-4, only phosphating treatment has limited effect on the improvement of the corrosion resistance of the NdFeB magnet. In addition, replacing potassium dihydrogen phosphate with zinc dihydrogen phosphate in the phosphating solution will also affect the corrosion resistance of the NdFeB magnet. This may be because the polysilazane resin produces silicon nitride ceramics after sintering, and the silicon nitride ceramics can cover the grain boundaries and surfaces of the NdFeB magnet to form a dense physical barrier. This barrier effectively inhibits the penetration of oxygen and corrosive media, thereby improving the corrosion resistance of the magnet. In addition, potassium ions form coordination bonds with nitrogen atoms on the silicon nitride ceramics at 85-98°C, thereby generating a stable complex. The phosphating film thus generated has stronger adhesion, further protecting the magnet substrate from erosion by corrosive media and improving the corrosion resistance of the NdFeB magnet.

[0069] Therefore, it is necessary to add heavy rare earth elements such as Tb and Dy to increase the intrinsic coercivity of NdFeB magnets. It is also necessary to add corrosion-resistant components such as polysilazane resins and perform a phosphating treatment. The phosphating solution includes potassium dihydrogen phosphate, which can significantly improve the corrosion resistance of NdFeB magnets.

[0070] Comparing the intrinsic coercive forces of Examples 1-3, Example 1 has the highest intrinsic coercive force and its corrosion resistance is substantially equivalent to that of Example 2, so it is preferred.

[0071] Examples 4-7

[0072] In Examples 4-6, based on the preparation method of Example 1, the amount of polysilazane resin added was adjusted. The specific adjustments are shown in Table 2.

[0073] Example 7 Based on the preparation method of Example 1, in the pressing step, the obtained alloy powder and 4 g of tetramethyldivinyldisilazane are placed in a mold and pressed to obtain a sintered green body.

[0074] According to the above detection method, the test results of Examples 4-7 were obtained, as shown in Table 2 below.

[0075] Table 2 Performance test data of Example 1 and Examples 4-7

[0076]

[0077] As shown in Table 2, a comparison of Example 1 with Examples 4-7 shows that the addition of tetramethyldivinyldisilazane or polysilazane resin can enhance the corrosion resistance of NdFeB magnets. This is likely due to the high-temperature decomposition of methylvinylsilazane and polysilazane resins during the sintering process, producing silicon nitride ceramics. Furthermore, the silicon nitride ceramics coat the grain boundaries and surfaces of the NdFeB magnets, forming a dense physical barrier. This barrier effectively inhibits the penetration of oxygen and corrosive media, significantly improving the magnet's corrosion resistance.

[0078] In comparison, the corrosion resistance of NdFeB magnets with polysilazane resin is better than that of NdFeB magnets with tetramethyldivinyldisilazane resin. This may be because polysilazane resin releases less gas, and there are fewer defects such as micropores and surface roughness inside and on the surface of the magnets, thus having higher corrosion resistance.

[0079] Examples 8-11

[0080] In Examples 8-11, based on the preparation method of Example 1, the concentrations of the components of the phosphating solution were adjusted. The specific adjustments are shown in Table 3.

[0081] Comparative Example 5

[0082] Comparative Example 5 Based on the preparation method of Example 1, the concentrations of the components of the phosphating solution were adjusted to 10 g / L of potassium dihydrogen phosphate, 350 g / L of phosphoric acid, and 10 g / L of potassium nitrate.

[0083] The NdFeB magnets of Examples 8-11 and Comparative Example 5 were subjected to the above performance tests, and the test results are shown in Table 3.

[0084] Table 3 Phosphating solution composition ratios and performance test data for Example 1, Examples 8-11, and Comparative Example 5

[0085]

[0086] Referring to Table 3, it can be seen from Comparative Example 1, Examples 8-11 and Comparative Example 5 that as the concentration of potassium dihydrogen phosphate increases, the 96h weight loss rate of the NdFeB magnet shows a trend of first decreasing and then increasing. This is probably because as the concentration of potassium dihydrogen phosphate increases, the potassium ion content increases, gradually and fully forming a complex with the silicon-nitrogen bond on the silicon nitride ceramic, so that the adhesion of the phosphating film is gradually improved, thereby continuously improving the corrosion resistance of the NdFeB magnet. When it exceeds a certain range, excessive potassium ions may form excessive intermetallic compounds or potassium-rich phases in the phosphating film, which may reduce the hardness and wear resistance of the phosphating film, but reduce the corrosion resistance of the NdFeB magnet.

[0087] Examples 12-13

[0088] In Examples 12-13, based on the preparation method of Example 1, the heating temperature in the phosphating step was adjusted. The specific adjustments are shown in Table 4.

[0089] Comparative Examples 6-7

[0090] Comparative Examples 6-7 are based on the preparation method of Example 1, except that the heating temperature in the phosphating step is adjusted. The specific adjustments are shown in Table 4.

[0091] The NdFeB magnets of Examples 12-13 were subjected to the above performance tests, and the test results are shown in Table 4.

[0092] Table 4 Heating temperature and performance test data of Example 1, Examples 12-13 and Comparative Examples 6-7

[0093]

[0094] Referring to Table 4, it can be seen from the comparison of Example 1, Examples 12-13 and Comparative Examples 6-7 that as the heating temperature during the phosphating treatment continues to rise, the 96h weight loss rate of the NdFeB magnet shows a trend of first decreasing and then increasing. This may be because as the heating temperature during the phosphating treatment continues to rise, potassium ions and silicon nitride ceramics generated by the polysilazane resin continuously form coordination bonds, thereby enhancing the adhesion of the phosphating film, thereby enhancing the corrosion resistance of the NdFeB magnet; when exceeding a certain range, excessively high temperatures may cause the phosphating film structure to become loose, thereby reducing the corrosion resistance of the NdFeB magnet.

[0095] Examples 14-17

[0096] In Examples 14-17, based on the preparation method of Example 1, the phosphating treatment time in the phosphating treatment step was adjusted. The specific adjustments are shown in Table 5.

[0097] The NdFeB magnets of Examples 14-17 were subjected to the above performance tests, and the test results are shown in Table 5.

[0098] Table 5 Phosphating treatment time and performance test data of Example 1 and Examples 14-17

[0099]

[0100] Referring to Table 5, it can be seen from the comparison between Example 1 and Examples 14-17 that, as the phosphating treatment time during the phosphating treatment continues to increase, the 96h weight loss rate of the NdFeB magnet shows a trend of first decreasing and then increasing. This may be because as the phosphating treatment time during the phosphating treatment continues to increase, the phosphating reaction gradually becomes sufficient to form a dense protective layer, thereby enhancing the corrosion resistance of the NdFeB magnet; when it exceeds a certain range, the phosphating reaction continues, resulting in an excessively thick phosphating film, increased roughness, and affected adhesion, thereby reducing the corrosion resistance of the NdFeB magnet.

[0101] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing a high intrinsic coercivity, corrosion-resistant NdFeB magnet, characterized in that: The following steps are involved: Melting strip throwing: Mix the metal raw materials according to the formula, melt the mixture to obtain a molten liquid, and cast the molten liquid into a strip to obtain a strip throwing sheet; Hydrogen grinding: The spun sheet is hydrogen-broken into coarse powder, and the coarse powder is jet-milled to obtain alloy powder; Pressing and molding: placing the obtained alloy powder and corrosion-resistant components in a mold and pressing and molding to obtain a sintered green body; Sintering process: The green compact is sintered under the protection of nitrogen. After sintering, it is rapidly cooled to room temperature in stages and tempered to obtain NdFeB magnets. Phosphating treatment: After the surface of the NdFeB magnet is treated, it is placed in a phosphating solution for high-temperature phosphating treatment, and then taken out and rinsed to obtain a phosphated NdFeB magnet; the temperature range of the high-temperature phosphating treatment is 85-98°C, and the treatment time is 8-15 minutes; The corrosion-resistant component produces silicon nitride ceramics after sintering, wherein potassium ions form coordination bonds with nitrogen atoms on the silicon nitride ceramics at 85-98°C, thereby generating a stable complex; The metal raw material is composed of the following components in parts by weight: 6.5-7 parts of Pr, 19.5-21 parts of Nd, 0.90-1.03 parts of B, 4-6 parts of Tb, 0-1 parts of Dy, 1-2 parts of Co, and 64-68 parts of Fe; The corrosion-resistant component is a polysilazane resin, with a weight portion of 0.2-0.5 parts; The phosphating solution is composed of components with the following concentrations: 50-90 g / L of potassium dihydrogen phosphate, 100-200 g / L of phosphoric acid, and 5-10 g / L of manganese nitrate.

2. The method for preparing a high intrinsic coercivity, corrosion-resistant NdFeB magnet according to claim 1, wherein: The weight portion of the corrosion-resistant component is 0.4 parts.

3. The method for preparing a high intrinsic coercivity, corrosion-resistant NdFeB magnet according to any one of claims 1 or 2, characterized in that: The concentration of the potassium dihydrogen phosphate is 75 g / L.

4. A high intrinsic coercivity, corrosion-resistant NdFeB magnet, characterized by: The magnet is prepared by the method for preparing a high intrinsic coercivity and corrosion-resistant NdFeB magnet according to any one of claims 1 to 3.

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