Manufacturing method and diffusion treatment method for high-performance sintered neodymium iron boron diffusion paint

Abstract

This invention discloses a method for manufacturing and diffusing high-performance sintered neodymium-iron-boron diffusion coatings. This method involves alloy powder manufacturing, adhesive manufacturing, diffusion coating manufacturing, pretreatment, coating application, surface drying, and heat treatment. By controlling the composition and particle size of the alloy powder and incorporating adhesives, anti-adhesive agents, and additives, it is possible to significantly improve coercivity and minimize or eliminate the loss of remanence even when using small amounts of diffusion heavy rare earth metals. Furthermore, it also solves the problems of coating peeling and adhesion between magnets after diffusion.

Description

[Technical Field]

[0001] The present invention relates to crystal boundary diffusion technology, and more particularly to the manufacturing and diffusion treatment method of high-performance sintered neodymium iron boron diffusion coating material. [Background technology]

[0002] Sintered neodymium-iron-boron diffusion paint originates from the grain boundary diffusion (GBD) technology, coined by Nakamura et al. in the early 21st century. The invention of this technology established the theoretical foundation for diffusion paints. Depending on the diffusion source, grain boundary diffusion can be divided into surface coating diffusion, surface sputtering diffusion, and vapor phase evaporation methods. The surface coating diffusion method involves mixing the diffusion source material, resin, additives, and solvent to create a diffusion paint. The coating is then applied by brushing or spraying, and the surface is dried at low temperature before being diffused at high temperature. The advantages of this method include improving the coercive force of magnets without significantly reducing remanence. It also effectively reduces the amount of heavy rare earth additives used, making it suitable for large-scale production, thereby bringing about a major leap forward in the magnetic materials industry. However, this method also has its shortcomings, such as insufficient diffusion depth, which gradually reduces the effective utilization rate as the amount of coating increases, resulting in not only wasted paint but also easy occurrence of adhesion (the phenomenon where magnets stick to each other) and coating peeling. Adhesion directly leads to scrapped products, and coating peeling causes the diffusion material to separate from the substrate, defeating the purpose of diffusion and resulting in insufficient performance. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention aims to solve the problems of the background art by providing a method for manufacturing and diffusing high-performance sintered neodymium iron boron diffusion coating material. [Means for solving the problem]

[0004] In order to solve the above problems, the present invention provides the following technical features. (a) Preparation of alloy powder: Three types of alloy powder, MOM1, M2H, and M3Fe, are mixed to obtain a composite alloy powder. (b) Preparation of adhesive: The resin is completely dissolved in the solvent under mechanical stirring to prepare the adhesive. (c) Preparation of diffusion coating material: Under inert gas protection, the composite alloy powder, adhesive, additives, and anti-adhesive agent are dispersed and stirred at high speed, and then removed from the inert gas protection environment and continued to stir at high speed to complete the preparation of diffusion coating material.

[0005] The present invention combines three different types (different elements) and sizes of alloy powders, allowing the alloys to work together to create a diffusion effect, significantly improving coercivity while minimizing remanence. This is more effective than using a single material and also improves the utilization rate of rare earths. Rare earths are generally not reduced, and because heavy rare earths are more expensive and rarer than the common light and medium rare earths, the heavy rare earths are primarily reduced.

[0006] The use of adhesives, anti-adhesive agents and additives can effectively prevent the adhesion phenomenon between magnets after heat treatment, without peeling off the coating after diffusion.

[0007] The three alloy powders of the present invention are as follows: M0 is one or a combination of two of praseodymium (Pr) or neodymium (Nd); M1 is one or a combination of more than one of cobalt (Co), nickel (Ni), aluminum (Al), copper (Cu), zinc (Zn), gallium (Ga), and molybdenum (Mo); M2H is one or a combination of two of dysprosium (Dy) or terbium (Tb), and H is hydrogen; and M3Fe is one or a combination of more than one of gadolinium (Gd), holmium (Ho), lanthanum (La), and cerium (Ce). The alloy powders are produced through melting, hydrogen destruction, and air jet milling processes. The composite alloy powder is a combination of three types of alloy powders: M0M1, M2H, and M3Fe. Through melting, hydrogen destruction, and air jet milling, the average particle size of M0M1 is controlled to 0.5-1 μm, M2H to 1-3 μm, and M3Fe to 0.5-1.5 μm.

[0008] As an improvement, the mass fractions of the three types of alloy powders, M0M1, M2H, and M3Fe, are set to 20% to 45%, 35% to 50%, and 15% to 20%, respectively.

[0009] Adhesive manufacturing involves completely dissolving the resin in a solvent under mechanical stirring conditions. The resin is typically selected from polyvinyl butyral, polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone. The solvent is typically selected from one or a combination of terpineol, n-butyl alcohol, propylene glycol methyl ether, propylene glycol butyl ether, ethylene glycol butyl ether, ethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, and propylene glycol butyl ether acetate. As an improvement, the viscosity of the resin described in step (b) is controlled to 2-10 seconds. The resin viscosity of the present invention is the Say viscosity, or Sagbolt viscosity. Say viscosity is the number of seconds (in seconds) it takes for 60 milliliters of a fixed sample to flow through a Say viscometer at a particular temperature (e.g., 100°F, 210°F, or 122°F). As an improvement, the mass fraction of resin in the adhesive in the present invention is set to 60% to 85%.

[0010] As an improvement, step (c) uses an additive selected from the group consisting of one or more combinations of primarily γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. As an improvement, the anti-adhesion agent in step (c) is used to prevent adhesion between the neodymium iron boron magnets during high-temperature treatment, and is mainly selected from one or more of aluminum oxide, silicon carbide, barium sulfate, titanium oxide, and titanium nitride, and its particle size is controlled to be 80-120 μm.

[0011] As an improvement, the diffusion paint is composed of composite alloy powder, adhesive, additives, and anti-adhesive agent, with the composite alloy powder accounting for 60% to 85% of the total, the mass fraction of adhesive being 13% to 35%, the mass fraction of additives being controlled at 0.5% to 1.5%, and the mass fraction of anti-adhesive powder being set at 2% to 5%.

[0012] The diffusion treatment method for high performance sintered neodymium iron boron diffusion coating includes the following steps: (1) Pretreatment: The sintered neodymium iron boron substrate is ultrasonically degreased, washed with water, ultrasonically cleaned, pickled, washed with water, washed with pure water, and washed with ethanol, and then washed with water again and dried to clean the surface. (2) Paint application: The treated sintered neodymium iron boron substrate is placed in a fixture and the appropriate diffusion paint is applied to the substrate surface by spray, brush, or roller. (3) Surface drying: After spraying, the sintered neodymium iron boron substrate is leveled and dried at 80 to 130°C for 15 to 45 minutes, and then cooled to room temperature before removing the material. (4) Heat treatment: The surface-dried sintered neodymium iron boron substrate is tempered at 850-950°C for 5-35 hours, cooled to room temperature, and then tempered again at 450-680°C for 5-10 hours. After cooling to room temperature, the material is removed and the diffusion treatment is completed. [Effects of the Invention]

[0013] The present invention can provide the following effects. By combining three alloy powders with different structures and components, the diffusion path can be optimized and the diffusion depth can be increased. This not only improves the effective utilization rate of the paint, but also optimizes the microstructure of the substrate and improves the anisotropy of the overall hard magnetic crystal grains. As a result, even with the use of a small amount of diffusion paint (heavy rare earth metal), the coercive force is significantly improved and there is almost no or very little decrease in remanence. The use of adhesives, anti-adhesive agents and additives can also solve the problems of coating peeling after diffusion and adhesion between magnets. By controlling the composition and particle size of the alloy powder and adding adhesives, anti-adhesive agents, and additives, the high-performance diffusion coating of the present invention can significantly improve coercivity even when using a small amount of diffusion heavy rare earth metal, with little or no decrease in remanence.Furthermore, it can also solve the problems of coating peeling after diffusion and adhesion between magnets. DETAILED DESCRIPTION OF THE INVENTION

[0014] The effects of the present invention will be described in detail below with reference to each example. [Example]

[0015] Example 1 The manufacturing method of high performance sintered neodymium iron boron diffusion paint includes the following steps: (S1) Preparation of alloy powder: Three types of alloy powder, MOM1, M2H, and M3Fe, are mixed to obtain composite alloy powder. (S2) Preparation of adhesive: The resin is completely dissolved in the solvent while being mechanically stirred to prepare the adhesive. (S3) Preparation of diffusion coating material: Under nitrogen gas protection and oxygen concentration ≦ 0.005%, the composite alloy powder, adhesive, additives, and anti-adhesive agent are stirred and dispersed in a high-speed disperser (1000 rpm) for 30 minutes, then removed from the nitrogen gas protection environment and continued to stir in the high-speed disperser at 1500 rpm for another 2 hours to complete the preparation of the diffusion coating material.

[0016] The three alloy powders are: M0 is a combination of one or more of praseodymium (Pr) or neodymium (Nd); M1 is a combination of one or more of cobalt (Co), nickel (Ni), aluminum (Al), copper (Cu), zinc (Zn), gallium (Ga), and molybdenum (Mo); M2H is a combination of one or more of dysprosium (Dy) or terbium (Tb), and H is hydrogen; and M3Fe is a combination of one or more of gadolinium (Gd), holmium (Ho), lanthanum (La), and cerium (Ce).

[0017] The composite alloy powder is a combination of three types of alloy powders: M0M1, M2H, and M3Fe. Through melting, hydrogen destruction, and air jet milling, the average particle size is controlled to 0.5 μm for M0M1, 1 μm for M2H, and 0.5 μm for M3Fe. The mass fractions of the three types of alloy powders, M0M1, M2H, and M3Fe, are set at 20%, 35%, and 15%, respectively.

[0018] The resin is primarily polyvinyl butyral, and the solvent is primarily selected from one or a combination of terpineol, n-butyl alcohol, propylene glycol methyl ether, propylene glycol butyl ether, ethylene glycol butyl ether, ethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, and propylene glycol butyl ether acetate. The viscosity of the resin is 2 seconds, and the mass fraction of the resin in the adhesive is controlled to 60%.

[0019] The additives used are primarily one or a combination of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

[0020] The anti-adhesion agent is used to prevent adhesion between the neodymium iron boron magnets during high-temperature treatment, and is mainly selected from one or more of aluminum oxide, silicon carbide, barium sulfate, titanium oxide, and titanium nitride, and its average particle size is controlled to 80 μm.

[0021] The diffusion paint is composed of composite alloy powder, adhesive, additives, and anti-adhesive agent, with the composite alloy powder accounting for 60% of the total, the mass fraction of adhesive being 13%, the mass fraction of additives being controlled at 0.5%, and the mass fraction of anti-adhesive powder being set at 2%. The diffusion treatment method for high performance sintered neodymium iron boron diffusion coating includes the following steps: (1) Pretreatment: The sintered neodymium iron boron substrate is ultrasonically degreased, washed with water, ultrasonically cleaned, pickled, washed with water, washed with pure water, and washed with ethanol, and then washed with water again and dried to clean the surface. (2) Paint application: The treated sintered neodymium iron boron substrate is placed in a fixture and the appropriate diffusion paint is applied to the substrate surface by spray, brush, or roller. (3) Surface drying: After spraying, the sintered neodymium iron boron substrate is leveled and dried at 80°C for 15 minutes, cooled to room temperature, and then the material is removed. (4) Heat treatment: The surface-dried sintered neodymium iron boron substrate is tempered at 850°C for 5 hours, cooled to room temperature, and then tempered again at 450°C for 5 hours. After cooling to room temperature, the material is removed and the diffusion process is completed. A comparison of the performance of neodymium iron boron before and after diffusion in this Example 1 is shown in Table 1. [Example]

[0022] Example 2 The manufacturing method of high performance sintered neodymium iron boron diffusion paint includes the following steps: (S1) Preparation of alloy powder: Three types of alloy powder, MOM1, M2H, and M3F e, are mixed to obtain composite alloy powder. (S2) Preparation of adhesive: The resin is completely dissolved in the solvent while being mechanically stirred to prepare the adhesive. (S3) Preparation of diffusion coating material: Under the condition of nitrogen gas protection and oxygen concentration ≦ 0.005%, the composite alloy powder, adhesive, additives, and anti-adhesive agent are stirred and dispersed in a high-speed disperser (1500 rpm) for 20 minutes, then removed from the nitrogen gas protection environment and continued to stir in the high-speed disperser at 2000 rpm for another hour to complete the preparation of the diffusion coating material.

[0023] The three alloy powders are: M0 is a combination of one or more of praseodymium (Pr) or neodymium (Nd); M1 is a combination of one or more of cobalt (Co), nickel (Ni), aluminum (Al), copper (Cu), zinc (Zn), gallium (Ga), and molybdenum (Mo); M2H is a combination of one or more of dysprosium (Dy) or terbium (Tb), and H is hydrogen; and M3Fe is a combination of one or more of gadolinium (Gd), holmium (Ho), lanthanum (La), and cerium (Ce).

[0024] The composite alloy powder is a combination of three types of alloy powders: M0M1, M2H, and M3Fe. Through melting, hydrogen destruction, and air jet milling, the average particle size is controlled to 1 μm for M0M1, 3 μm for M2H, and 1.5 μm for M3Fe. The mass fractions of the three types of alloy powders, M0M1, M2H, and M3Fe, are set at 45%, 50%, and 20%, respectively.

[0025] The resin is primarily polyethylene glycol, and the solvent is primarily selected from one or more of terpineol, n-butyl alcohol, propylene glycol methyl ether, propylene glycol butyl ether, ethylene glycol butyl ether, ethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, and propylene glycol butyl ether acetate. The viscosity of the resin is 10 seconds, and the mass fraction of the resin in the adhesive is controlled to 85%.

[0026] The additives used are primarily one or a combination of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. The anti-adhesion agent is used to prevent adhesion between the neodymium iron boron magnets during high-temperature treatment, and is mainly selected from one or more of aluminum oxide, silicon carbide, barium sulfate, titanium oxide, and titanium nitride, and its average particle size is controlled to 120 μm.

[0027] The diffusion paint is composed of composite alloy powder, adhesive, additives, and anti-adhesive agent, with the composite alloy powder accounting for 60% of the total, the mass fraction of adhesive being controlled at 35%, the mass fraction of additives being controlled at 1.5%, and the mass fraction of anti-adhesive powder being set at 5%.

[0028] The diffusion treatment method for high performance sintered neodymium iron boron diffusion coating includes the following steps: (1) Pretreatment: The sintered neodymium iron boron substrate is ultrasonically degreased, washed with water, ultrasonically cleaned, pickled, washed with water, washed with pure water, and washed with ethanol, and then washed with water again and dried to clean the surface. (2) Paint application: The treated sintered neodymium iron boron substrate is placed in a fixture and the appropriate diffusion paint is applied to the substrate surface by spray, brush, or roller. (3) Surface drying: After spraying, the sintered neodymium iron boron substrate is leveled and dried at 130°C for 45 minutes, cooled to room temperature, and then the material is removed. (4) Heat treatment: The surface-dried sintered neodymium iron boron substrate is tempered at 950°C for 35 hours, cooled to room temperature, and then tempered again at 680°C for 10 hours. After cooling to room temperature, the material is removed and the diffusion treatment is completed. [Example]

[0029] Example 3 The manufacturing method of high performance sintered neodymium iron boron diffusion paint includes the following steps: (S1) Preparation of alloy powder: Three types of alloy powder, MOM1, M2H, and M3Fe, are mixed to obtain composite alloy powder. (S2) Preparation of adhesive: The resin is completely dissolved in the solvent while being mechanically stirred to prepare the adhesive. (S3) Preparation of diffusion coating material: Under nitrogen gas protection and oxygen concentration ≦0.005%, the composite alloy powder, adhesive, additives, and anti-adhesive agent are stirred and dispersed in a high-speed disperser (1250 rpm) for 25 minutes, then removed from the nitrogen gas protection environment and continued to stir in the high-speed disperser at 1750 rpm for another 1.5 hours to complete the preparation of the diffusion coating material.

[0030] The three alloy powders are: M0 is a combination of one or more of praseodymium (Pr) or neodymium (Nd); M1 is a combination of one or more of cobalt (Co), nickel (Ni), aluminum (Al), copper (Cu), zinc (Zn), gallium (Ga), and molybdenum (Mo); M2H is a combination of one or more of dysprosium (Dy) or terbium (Tb), and H is hydrogen; and M3Fe is a combination of one or more of gadolinium (Gd), holmium (Ho), lanthanum (La), and cerium (Ce).

[0031] The composite alloy powder is a combination of three types of alloy powders: M0M1, M2H, and M3Fe. Through melting, hydrogen destruction, and air jet milling, the average particle size is controlled to 0.7 μm for M0M1, 2 μm for M2H, and 1 μm for M3Fe. The mass fractions of the three types of alloy powders, M0M1, M2H, and M3Fe, are set at 33%, 43%, and 17%, respectively.

[0032] The resin is primarily polyvinylpyrrolidone, and the solvent is primarily selected from one or more of terpineol, n-butyl alcohol, propylene glycol methyl ether, propylene glycol butyl ether, ethylene glycol butyl ether, ethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, and propylene glycol butyl ether acetate. The viscosity of the resin is 6 seconds, and the mass fraction of the resin in the adhesive is controlled to 73%.

[0033] The additives used are primarily one or a combination of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

[0034] The anti-adhesion agent is used to prevent adhesion between neodymium iron boron magnets during high-temperature treatment, and is mainly selected from one or more of aluminum oxide, silicon carbide, barium sulfate, titanium oxide, and titanium nitride, and its average particle size is controlled to 100 μm.

[0035] The diffusion paint is composed of composite alloy powder, adhesive, additives, and anti-adhesive agent, with the composite alloy powder accounting for 73% of the total, the mass fraction of adhesive being 24%, the mass fraction of additives being controlled at 1%, and the mass fraction of anti-adhesive agent powder being set at 3.5%.

[0036] The diffusion treatment method for high performance sintered neodymium iron boron diffusion coating includes the following steps: (1) Pretreatment: The sintered neodymium iron boron substrate is ultrasonically degreased, washed with water, ultrasonically cleaned, pickled, washed with water, washed with pure water, and washed with ethanol, and then washed with water again and dried to clean the surface. (2) Paint application: The treated sintered neodymium iron boron substrate is placed in a fixture, and the diffusion paint is applied to the substrate surface by spray, brush, or roller. (3) Surface drying: After spraying, the sintered neodymium iron boron substrate is leveled and dried at 105°C for 30 minutes, cooled to room temperature, and then the material is removed. (4) Heat treatment: The surface-dried sintered neodymium-iron-boron substrate is tempered at 900°C for 20 hours, cooled to room temperature, and then tempered again at 565°C for 7.5 hours. After cooling to room temperature, the material is removed and the diffusion process is completed. [Example]

[0037] Example 4 The manufacturing method of high performance sintered neodymium iron boron diffusion paint includes the following steps: (S1) Preparation of alloy powder: Three types of alloy powder, MOM1, M2H, and M3Fe, are mixed to obtain composite alloy powder. (S2) Preparation of adhesive: The resin is completely dissolved in the solvent while being mechanically stirred to prepare the adhesive. (S3) Preparation of diffusion coating material: Under the protection of inert gas, the composite alloy powder, adhesive, additives, and anti-adhesive agent are stirred and dispersed in a high-speed disperser for 15 minutes, then removed from the inert gas protective environment and continued to stir in the high-speed disperser for another 30 minutes to complete the preparation of diffusion coating material.

[0038] The three alloy powders are: M0 is a combination of one or more of praseodymium (Pr) or neodymium (Nd); M1 is a combination of one or more of cobalt (Co), nickel (Ni), aluminum (Al), copper (Cu), zinc (Zn), gallium (Ga), and molybdenum (Mo); M2H is a combination of one or more of dysprosium (Dy) or terbium (Tb), and H is hydrogen; and M3Fe is a combination of one or more of gadolinium (Gd), holmium (Ho), lanthanum (La), and cerium (Ce).

[0039] The composite alloy powder is a combination of three types of alloy powders: M0M1, M2H, and M3Fe. Through melting, hydrogen destruction, and air jet milling, the average particle size is controlled to 0.5 μm for M0M1, 1 μm for M2H, and 0.5 μm for M3Fe. The mass fractions of the three types of alloy powders, M0M1, M2H, and M3Fe, are set at 20%, 35%, and 15%, respectively.

[0040] The resin is primarily polyvinyl alcohol, and the solvent is primarily selected from one or more of terpineol, n-butyl alcohol, propylene glycol methyl ether, propylene glycol butyl ether, ethylene glycol butyl ether, ethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, and propylene glycol butyl ether acetate. The viscosity of the resin is 2 seconds, and the mass fraction of the resin in the adhesive is controlled to 60%.

[0041] The additives used are primarily one or a combination of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

[0042] The anti-adhesion agent is used to prevent adhesion between the neodymium iron boron magnets during high-temperature treatment, and is mainly selected from one or more of aluminum oxide, silicon carbide, barium sulfate, titanium oxide, and titanium nitride, and its average particle size is controlled to 80 μm.

[0043] The diffusion paint is composed of composite alloy powder, adhesive, additives, and anti-adhesive agent, with the composite alloy powder accounting for 60% of the total, the mass fraction of adhesive being 13%, the mass fraction of additives being controlled at 0.5%, and the mass fraction of anti-adhesive powder being set at 2%.

[0044] The diffusion treatment method for high performance sintered neodymium iron boron diffusion coating includes the following steps: (1) Pretreatment: The sintered neodymium iron boron substrate is ultrasonically degreased, washed with water, ultrasonically cleaned, pickled, washed with water, washed with pure water, and washed with ethanol, and then washed with water again and dried to clean the surface. (2) Paint application: The treated sintered neodymium iron boron substrate is placed in a fixture, and the diffusion paint is applied to the substrate surface by spray, brush, or roller. (3) Surface drying: After spraying, the sintered neodymium iron boron substrate is leveled and dried at 80°C for 15 minutes, cooled to room temperature, and then the material is removed. (4) Heat treatment: The surface-dried sintered neodymium iron boron substrate is tempered at 850°C for 5 hours, cooled to room temperature, then tempered at 450°C for 5 hours, cooled to room temperature, and then removed from the material to complete the diffusion treatment. [Example]

[0045] Example 5 The manufacturing method of high performance sintered neodymium iron boron diffusion paint includes the following steps: (S1) Preparation of alloy powder: Three types of alloy powder, MOM1, M2H, and M3Fe, are mixed to obtain composite alloy powder. (S2) Preparation of adhesive: The resin is completely dissolved in the solvent while being mechanically stirred to prepare the adhesive. (S3) Preparation of diffusion coating material: Under the protection of inert gas, the composite alloy powder, adhesive, additives, and anti-adhesive agent are stirred and dispersed in a high-speed disperser for 15 minutes, then removed from the inert gas protective environment and continued to stir in the high-speed disperser for another 0.5 hours to complete the preparation of diffusion coating material.

[0046] The three alloy powders are: M0 is a combination of one or more of praseodymium (Pr) or neodymium (Nd); M1 is a combination of one or more of cobalt (Co), nickel (Ni), aluminum (Al), copper (Cu), zinc (Zn), gallium (Ga), and molybdenum (Mo); M2H is a combination of one or more of dysprosium (Dy) or terbium (Tb), and H is hydrogen; and M3Fe is a combination of one or more of gadolinium (Gd), holmium (Ho), lanthanum (La), and cerium (Ce).

[0047] The composite alloy powder is a combination of three types of alloy powders: M0M1, M2H, and M3Fe. Through melting, hydrogen destruction, and air jet milling, the average particle size is controlled to 0.5 μm for M0M1, 1 μm for M2H, and 0.5 μm for M3Fe. The mass fractions of the three types of alloy powders, M0M1, M2H, and M3Fe, are set at 20%, 35%, and 15%, respectively.

[0048] The resin is primarily polyvinyl alcohol, and the solvent is primarily selected from one or more of terpineol, n-butyl alcohol, propylene glycol methyl ether, propylene glycol butyl ether, ethylene glycol butyl ether, ethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, and propylene glycol butyl ether acetate. The viscosity of the resin is 2 seconds, and the mass fraction of the resin in the adhesive is controlled to 60%.

[0049] The additives used are primarily one or a combination of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

[0050] The anti-adhesion agent is used to prevent adhesion between the neodymium iron boron magnets during high-temperature treatment, and is mainly selected from one or more of aluminum oxide, silicon carbide, barium sulfate, titanium oxide, and titanium nitride, and its average particle size is controlled to 80 μm.

[0051] The diffusion paint is composed of composite alloy powder, adhesive, additives, and anti-adhesive agent, with the composite alloy powder accounting for 60% of the total, the mass fraction of adhesive being 13%, the mass fraction of additives being controlled at 0.5%, and the mass fraction of anti-adhesive powder being set at 2%.

[0052] The diffusion treatment method for high performance sintered neodymium iron boron diffusion coating includes the following steps: (1) Pretreatment: The sintered neodymium iron boron substrate is ultrasonically degreased, washed with water, ultrasonically cleaned, pickled, washed with water, washed with pure water, and washed with ethanol, and then washed with water again and dried to clean the surface. (2) Paint application: The treated sintered neodymium iron boron substrate is placed in a fixture and the appropriate diffusion paint is applied to the substrate surface by spray, brush, or roller. (3) Surface drying: After spraying, the sintered neodymium iron boron substrate is leveled and dried at 80°C for 15 minutes, cooled to room temperature, and then the material is removed. (4) Heat treatment: The surface-dried sintered neodymium iron boron substrate is tempered at 850°C for 5 hours, then cooled to room temperature, and then tempered at 450°C for 5 hours. After cooling to room temperature, the material is removed and the diffusion treatment is completed.

[0053] Table 1 is a comparison table of the performance of neodymium iron boron before diffusion in the present invention and after diffusion in Examples 1 to 3. [Table 1]

Claims

1. The manufacturing method of high performance sintered neodymium iron boron diffusion paint includes the following steps: (a) Preparation of alloy powder: Three types of alloy powder, M0M1, M2H, and M3Fe, are mixed to obtain a composite alloy powder. (b) Preparation of adhesive: The adhesive is prepared by completely dissolving the resin in the solvent under mechanical stirring conditions. (c) Preparation of diffusion coating material: Under the protection of inert gas, the composite alloy powder, adhesive, additives, and anti-adhesive agent are dispersed and stirred at high speed, and then removed from the inert gas protective environment and continued to stir at high speed to complete the preparation of diffusion coating material.

2. The manufacturing method for high-performance sintered neodymium iron boron diffusion coating described in claim 1 uses three types of alloy powders: M0M1, M2H, and M3Fe, which have the following characteristics: M0 is a combination of one or more of praseodymium (Pr) or neodymium (Nd); M1 is a combination of one or more of cobalt (Co), nickel (Ni), aluminum (Al), copper (Cu), zinc (Zn), gallium (Ga), and molybdenum (Mo); in M2H, M2 is a combination of one or more of dysprosium (Dy) or terbium (Tb), and H is hydrogen; and in M3Fe, M3 is a combination of one or more of gadolinium (Gd), holmium (Ho), lanthanum (La), and cerium (Ce).

3. The manufacturing method of high-performance sintered neodymium iron boron diffusion paint according to claim 1 is characterized in that the mass fractions of the three types of alloy powders, M0M1, M2H and M3Fe, are 20%-45%, 35-50% and 15-20%, respectively, and the composite alloy powder is prepared by combining the three types of alloy powders, M0M1, M2H and M3Fe, and controlling the particle sizes of the M0M1, M2H and M3Fe to 0.5-1 μm, 1-3 μm and 0.5-1.5 μm, respectively, through melting, hydrogen destruction and airflow polishing.

4. In the manufacturing method of high-performance sintered neodymium iron boron diffusion paint according to claim 1, the diffusion paint is characterized in that the mass fraction of the composite alloy powder is controlled to 60-85%, the mass fraction of the adhesive is controlled to 13-35%, the mass fraction of the additive is controlled to 0.5-1.5%, and the mass fraction of the anti-adhesion agent is controlled to 2-5%.

5. The method for producing a high-performance sintered neodymium iron boron diffusion paint according to claim 1 is characterized in that in step (b), a resin mainly selected from polyvinyl butyral, polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone and a solvent mainly selected from one or more combinations of terpineol, n-butyl alcohol, propylene glycol methyl ether, propylene glycol butyl ether, ethylene glycol butyl ether, ethylene glycol butyl ether acetate, propylene glycol methyl ether acetate, and propylene glycol butyl ether acetate are used.

6. The method for producing high-performance sintered neodymium iron boron diffusion paint according to claim 1 is characterized in that the viscosity of the resin mentioned in step (b) is controlled to be 2-10 seconds, and the mass fraction of the resin is 60%-85%.

7. The method for producing a high-performance sintered neodymium iron boron diffusion coating according to claim 1 is characterized in that in step (c), an additive selected from one or a combination of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane is mainly used.

8. The method for producing a high-performance sintered NdFeB diffusion paint according to claim 1 is characterized in that the anti-adhesion agent in step (c) is used to prevent adhesion between NdFeB magnets during high-temperature treatment, and is mainly selected from one or more of aluminum oxide, silicon carbide, barium sulfate, titanium oxide, and titanium nitride, and its particle size is controlled to be 80-120 μm.

9. A diffusion treatment method for a diffusion paint manufactured by the manufacturing method of a high-performance sintered neodymium iron boron diffusion paint according to any one of claims 1 to 8, characterized by comprising the following steps: (1) Pretreatment: The sintered neodymium iron boron substrate is ultrasonically degreased, washed with water, ultrasonically cleaned, pickled, washed with water, washed with pure water, and washed with ethanol, and then washed with water again and dried to clean the surface. (2) Paint application: The treated sintered neodymium iron boron substrate is placed in a fixture, and the diffusion paint is applied to the substrate surface by spray, brush, or roller. (3) Surface drying: The sprayed sintered neodymium iron boron substrate is leveled and dried at 80-130°C for 15-45 minutes, and then cooled to room temperature before being removed. (4) Heat treatment: The surface-dried sintered neodymium-iron-boron substrate is tempered at 850-950°C for 5-35 hours, cooled to room temperature, and then tempered again at 450-680°C for 5-10 hours. After cooling to room temperature, the material is removed and the diffusion treatment is completed.

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