阅读说明：本技术 一种烧结钕铁硼永磁体的防腐蚀处理方法 (Anti-corrosion treatment method for sintered neodymium-iron-boron permanent magnet ) 是由 白晓刚 于海华 潘广麾 仉新功 聂源航 韩雪 胡蝶 于 2021-12-08 设计创作，主要内容包括：本发明提供一种烧结钕铁硼永磁体的防腐蚀处理方法,所述防腐蚀处理方法是采用粉末热渗锌的方式,包括以下步骤：基体前处理→渗锌→渗锌后处理,其中,所述渗锌步骤中添加的渗锌剂不含有任何氯离子。所述渗锌剂包括锌粉和稀土粉末混合物。由于采用上述技术方案,经本发明的防腐蚀处理方法处理后的烧结钕铁硼永磁体,渗锌层均匀、致密、防腐蚀性能好,且对磁体无损失,可以持续使用。(The invention provides an anti-corrosion treatment method of a sintered neodymium iron boron permanent magnet, which adopts a powder hot zincification mode and comprises the following steps: matrix pretreatment → zincification → post-treatment of zincification, wherein the zincification agent added in the zincification step does not contain any chloride ion. The zinc impregnation agent comprises a mixture of zinc powder and rare earth powder. By adopting the technical scheme, the sintered neodymium iron boron permanent magnet treated by the anti-corrosion treatment method has the advantages of uniform and compact zinc impregnation layer, good anti-corrosion performance, no loss to the magnet and continuous use.)

1. The anti-corrosion treatment method of the sintered neodymium iron boron permanent magnet is characterized by adopting a powder hot zincification mode.

2. The anti-corrosion treatment method of the sintered neodymium-iron-boron permanent magnet according to claim 1, comprising the following steps: matrix pretreatment → zincification → zinc impregnation post-treatment, which is characterized in that the zincification agent added in the zincification step does not contain any chloride ion.

3. The anti-corrosion treatment method for the sintered neodymium-iron-boron permanent magnet according to claim 2, characterized in that: the zinc impregnation agent comprises zinc powder.

4. The anti-corrosion treatment method for the sintered neodymium-iron-boron permanent magnet according to claim 3, characterized in that: the rare earth powder mixture is one or more of terbium, dysprosium and gallium.

5. The anti-corrosion treatment method for the sintered NdFeB permanent magnet according to claim 4, characterized in that: the surface roughness RA of the base body before the surface roughness zincification of the sintered Nd-Fe-B permanent magnet is more than 0.3 mu m.

6. The anti-corrosion treatment method for the sintered neodymium-iron-boron permanent magnet according to claim 2, characterized in that: the formula of the zinc impregnation agent comprises, by weight, 0-4 parts of rare earth powder mixture and 96-100 parts of zinc powder.

7. The anti-corrosion treatment method for the sintered neodymium-iron-boron permanent magnet according to claim 2, characterized in that: the D50 of the zinc impregnation agent is between 0.02 and 3.0 microns.

8. The anti-corrosion treatment method for the sintered neodymium-iron-boron permanent magnet according to claim 2, characterized in that: and in the step of zincification, the sintered neodymium iron boron permanent magnet body is mixed with a zincification agent, then the temperature is raised to 350-380 ℃, the temperature is kept for 15-60 minutes, then the temperature is lowered to below 60 ℃, the magnetic powder and the magnet are separated, and the material is discharged.

9. The anti-corrosion treatment method for the sintered neodymium-iron-boron permanent magnet according to claim 2, characterized in that: the pretreatment step of the matrix comprises surface oil removal → surface rust removal → ultrasonic washing → antirust drying; and the post-treatment step is to polish and passivate the surface of the galvanized magnet by using galvanized steel balls.

10. The anti-corrosion treatment method for the sintered neodymium-iron-boron permanent magnet according to claim 9, characterized in that: in the surface rust removal process in the base body pretreatment step, the sintered neodymium iron boron permanent magnet is treated by a steel grit grinding machine or a resin grinding wheel or sand blasting, so that the surface roughness RA = 0.3-0.6 μm.

Technical Field

The invention belongs to the technical field of anticorrosive treatment of neodymium iron boron permanent magnets, and particularly relates to an anticorrosive treatment method of a sintered neodymium iron boron permanent magnet.

Background

In recent years, the application and development of neodymium iron boron (NdFeB) permanent magnet materials are very rapid, and the success of the protection of the neodymium iron boron permanent magnet materials is related to one of the key technologies of popularization and application of the materials. The material is mainly prepared from rare earth metal elements such as Nd, iron, boron and the like by a powder metallurgy process. As the strongest magnetic material at present, the magnetic material is widely applied to the fields of electroplating devices, machinery, medical treatment, automobiles and the like, and has very wide application prospect.

The application of the neodymium iron boron permanent magnet material is premised on solving the problem of corrosion resistance of the neodymium iron boron permanent magnet material. As a porous material prepared by a powder metallurgy process, the neodymium-rich phase, the main phase and the boundary phase of the neodymium iron boron are easy to form intergranular corrosion. The rare earth element neodymium in the neodymium-iron-boron powder alloy has active property, so that the corrosion resistance of the whole neodymium-iron-boron alloy is very poor, the neodymium-iron-boron powder alloy is very easy to rust and corrode in a damp and hot environment, the magnetic property is reduced or damaged due to corrosion failure, the service life of the neodymium-iron-boron permanent magnet is seriously influenced, and the stability and the reliability of the product are reduced. The magnetic performance of the Nd-Fe-B permanent magnetic material has a great relationship with the organization structure. The main phase of the ndfeb permanent magnet is the main source of magnetic performance of the magnet. The most contributing to the coercive force is the neodymium-rich phase. When the neodymium iron boron permanent magnet material is corroded, the magnetic performance of the material is greatly changed. Therefore, the problem of corrosion prevention of the ndfeb permanent magnet material has been a major problem to be solved.

At present, the corrosion prevention methods of the neodymium iron boron permanent magnet material are many. Among them are various methods such as nickel electroplating, zinc electroplating (CN 1421547A, CN 1056133A), multi-layer nickel electroplating, copper plating (CN 1514889A), phosphating, electrophoretic paint, passivation, etc. There are many passivation applications, and 5 related patents (CN 200980125595, CN200980134446, CN200880109023, CN201080062182, and CN 201180032708) are applied by hitachi metal strain corporation. However, no relevant report is found about the way of processing the neodymium iron boron permanent magnet material by adopting the zinc impregnation way.

Disclosure of Invention

The invention aims to provide an anti-corrosion treatment method of a sintered neodymium iron boron permanent magnet, which is used for improving the anti-corrosion performance of the sintered neodymium iron boron permanent magnet. The specific scheme is as follows: an anti-corrosion treatment method for a sintered neodymium iron boron permanent magnet adopts a powder hot zincification mode.

Further, the anti-corrosion treatment method of the sintered neodymium iron boron permanent magnet comprises the following steps: matrix pretreatment → zincification → post-treatment of zincification, wherein the zincification agent added in the zincification step does not contain any chloride ion.

Further, the zincizing agent comprises zinc powder.

Furthermore, the rare earth powder mixture also comprises one or more of terbium dysprosium gallium.

Further, the surface roughness RA of the base body before the surface roughness zincification of the sintered NdFeB permanent magnet is more than 0.3 mu m.

Furthermore, the formula of the zinc impregnation agent comprises, by weight, 0-4 parts of rare earth powder mixture and 96-100 parts of zinc powder.

Furthermore, in order to ensure safe operation in the zincizing process, the D50 of the zincizing agent is between 0.02 and 3.0 microns.

Further, the step of zincification is to mix the sintered neodymium iron boron permanent magnet body with a zincification agent, then heat the mixture to 350-380 ℃, keep the temperature for 15-60 minutes, then cool the mixture to below 60 ℃, separate the magnetic powder from the magnet and discharge the material.

Further, the pretreatment step of the matrix is surface oil removal → surface rust removal → ultrasonic water washing → antirust drying; and the post-treatment step is to polish and passivate the surface of the galvanized magnet by using galvanized steel balls.

Further, in the surface rust removal process in the base body pretreatment step, the sintered neodymium iron boron permanent magnet is treated by a steel grit grinding machine or a resin grinding wheel or sand blasting, so that the surface roughness RA = 0.3-0.6 μm.

Due to the adoption of the technical scheme, the invention has the following advantages and positive effects:

1. the sintered neodymium-iron-boron permanent magnet porous material is treated by the zincification process, and no additional iron powder is needed, so that the operation process is simple, energy is saved, the efficiency is high, and the popularization and the application are convenient;

2. the method does not add any activating agent in the zincizing process, does not generate harmful substances, does not discharge waste water, and is environment-friendly and safe.

3. The sintered Nd-Fe-B permanent magnet treated by the anti-corrosion treatment method has the advantages of uniform and compact zinc impregnation layer, good anti-corrosion performance, no loss to the magnet and continuous use.

Detailed Description

The invention discloses an anti-corrosion treatment method of a sintered neodymium iron boron permanent magnet, which comprises the following steps: matrix pretreatment → zincification post-treatment, wherein the matrix pretreatment comprises the following steps: surface oil removal, surface rust removal, water washing and rust prevention drying; the surface oil removal can adopt common organic solvent oil removal, chemical oil removal, mechanical oil removal and wiping oil removal; the surface rust removing method adopts a common chemical acid washing method or a mechanical rust removing method, such as a mechanical method of rolling, brushing, sand blasting or shot blasting and the like. The surface of the deoiled and derusted magnet is cleaned and dried after ultrasonic water washing and antirust drying.

And the step of zincizing is to fill the magnet with the surface roughness reaching the standard and the prepared zincizing agent into a zincizing device (during specific operation, the zincizing magnet is required to be completely embedded into the zincizing agent), then the filled zincizing device is placed into a heating device to be heated and heated, when the temperature reaches 350-380 ℃, the temperature is kept for 15-60 minutes, zinc-iron intermetallic compounds are formed on the surface of the magnet, after the zincizing treatment is finished, the temperature is cooled to below 60 ℃, the zincizing device is taken out, the magnet is separated from the zincizing agent, and the material is discharged. It should be noted that, in the zincizing process, in order to ensure safety, after the magnet and the prepared zincizing agent are filled, an isolation treatment needs to be performed before sealing, for example, a filler such as quartz sand or alumina is added to prevent potential danger caused by oxidation of zinc powder in the zincizing process.

The post-treatment step is to adopt galvanized steel balls to carry out surface polishing and passivation on the galvanized magnet.

The present invention is further illustrated by the following examples, which are only for illustrating the technical solutions of the present invention and are not to be construed as limiting the present invention.

Example 1

3.5 kg of ¢ 24 x ¢ 15 x 18mm nd fe-b permanent magnet material was first ground in a vibrating mill for 2 hours. After degreasing and deoiling by 20 g/L of sodium phosphate, 10 g/L of sodium carbonate and 10 g/L of sodium hydroxide, blasting sand to remove rust by using 60-mesh white corundum, cleaning the surface (in an ultrasonic washing mode) and performing rust prevention and drying to obtain a permanent magnet material with the surface roughness RA =0.6 mu m, and performing high-energy ball milling treatment on 96 parts of zinc powder (by weight ratio) and 4 parts of rare earth powder dysprosium, wherein D50 is 0.15 mu m. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping the temperature for 15 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

Example 2

Polishing 3.5 kilograms of ¢ 24 × ¢ 15 × 18mm neodymium iron boron permanent magnet material for 2 hours according to the method of example 1, using 60-mesh carborundum and nitric acid for rust removal, then carrying out surface cleaning (ultrasonic washing mode) and rust prevention drying to obtain the permanent magnet material with the surface roughness RA =0.35 μm, and carrying out high-energy ball milling treatment on 99 parts of zinc powder (by weight) and 1 part of rare earth powder terbium, wherein D50 is 0.5 micrometer. Mixing the mixture evenly, putting the mixture together with a magnet, heating the mixture to 350 ℃, keeping the temperature for 60 minutes, taking out the mixture, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the properties shown in Table 1.

Example 3

Polishing 3.5 kilograms of ¢ 24 × ¢ 15 × 18mm neodymium iron boron permanent magnet material according to the method of example 1, performing sand blasting rust removal, using 80-mesh brown corundum, performing surface cleaning (ultrasonic washing mode) and performing rust prevention drying to obtain the permanent magnet material with the surface roughness RA =0.4 μm, and performing high-energy ball milling treatment on 98 parts of zinc powder (by weight), 1 part of rare earth powder dysprosium and 1 part of metal terbium, wherein D50 is 3 micrometers. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping for 45 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

Example 4

3.5 kilograms of ¢ 24- ¢ 15-18 mm neodymium iron boron permanent magnet material is polished according to the method of example 1, degreased, sand-blasted and derusted, 60-mesh white corundum is used, and then the permanent magnet material with the surface roughness RA =0.6 mu m is obtained after surface cleaning (ultrasonic washing mode) and rust prevention drying, 96 parts of zinc powder (weight ratio) and 4 parts of rare earth powder gallium are treated by high-energy ball milling, wherein D50 is 0.02 micron. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping the temperature for 40 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

Example 5

3.5 kilograms of ¢ 24 × ¢ 15 × 18mm neodymium iron boron permanent magnet material is polished according to the method of the embodiment 1, sand blasting is carried out to remove rust, 80-mesh brown corundum is used, and then the permanent magnet material with the surface roughness RA =0.5 μm is obtained after surface cleaning (ultrasonic washing mode) and rust prevention drying, 97 parts of zinc powder (weight ratio), 1 part of rare earth powder dysprosium, 1 part of gallium and 1 part of terbium are processed through high-energy ball milling, wherein D50 is 2.0 micrometers. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 370 ℃, keeping for 45 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium iron boron permanent magnet material with the properties shown in table 1.

EXAMPLE 6 (best mode)

Polishing 3.5 kilograms of ¢ 24 × ¢ 15 × 18mm neodymium iron boron permanent magnet material according to the method of example 1, performing sand blasting rust removal, using 60-mesh white corundum, performing surface cleaning (ultrasonic washing mode) and performing rust prevention and drying to obtain the permanent magnet material with the surface roughness RA =0.6 μm, and performing high-energy ball milling treatment on 96 parts of zinc powder (by weight ratio), 2 parts of rare earth powder terbium, 1 part of dysprosium and 1 part of gallium, wherein D50 is 1.3 micrometers. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping the temperature for 60 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

Example 7

Polishing 3.5 kilograms of ¢ 24 × ¢ 15 × 18mm neodymium iron boron permanent magnet material according to the method of example 1, performing sand blasting rust removal, using 80-mesh white corundum, performing surface cleaning (ultrasonic washing way) and performing rust prevention and drying to obtain the permanent magnet material with the surface roughness RA =0.5 μm, and performing high-energy ball milling treatment on 96 parts of zinc powder (by weight ratio), 2 parts of rare earth powder dysprosium, 1 part of terbium and 1 part of gallium, wherein D50 is 1.0 micrometer. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping the temperature for 15 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

Example 8

Polishing 3.5 kilograms of ¢ 24 × ¢ 15 × 18mm neodymium iron boron permanent magnet material according to the method of example 1, performing sand blasting rust removal, using 60-mesh white corundum, performing surface cleaning (ultrasonic washing way) and performing rust prevention and drying to obtain the permanent magnet material with the surface roughness RA =0.6 μm, and performing high-energy ball milling treatment on 96 parts of zinc powder (by weight ratio), 2 parts of rare earth powder dysprosium, 1 part of terbium and 1 part of gallium, wherein D50 is 0.05 micrometers. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping for 45 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

And (4) conclusion: as can be seen from table 1, in the anti-corrosion permanent magnet materials obtained in the above embodiments 1 to 8, the performance parameters in embodiment 6 are the best, so that embodiment 6 is the best embodiment, that is, the optimal process of the zincizing process of the neodymium iron boron permanent magnet is as follows: mixing a magnet with the roughness RA (surface roughness) of more than 0.3 micrometer and a zincizing agent together, heating to 380 ℃, carrying out constant temperature treatment for 1 hour, polishing the surface by using a galvanized steel ball, separating magnetic powder from the magnet, cooling to below 60 ℃, discharging, and obtaining the magnet with the zincizing layer of 1-10 micrometers in thickness. Wherein the adopted zincizing agent is a mixture of zinc powder and at least one rare earth powder.

TABLE 1

The obtained experimental data are measured, wherein the high subtraction is (normal temperature magnetic flux-magnet is raised to 150 ℃ for 1 hour and then is reduced to normal temperature magnetic flux)/normal temperature magnetic flux is 100%, wherein the residual magnetism (Br), the coercive force (Hcb) and the magnetic energy product (BHm) are the magnetic performance parameters of the sintered NdFeB permanent magnet.

Comparative Experimental example 1

¢ 24 g ¢ 15 g 18mm neodymium iron boron permanent magnet material 3.5 kg is polished according to the method of example 1, sand blasting is carried out to remove rust, 300 meshes of white corundum is used, and the permanent magnet material with surface roughness RA =0.2 μm is obtained after surface cleaning (ultrasonic washing way) and rust prevention drying, 96 parts by weight and 4 parts by weight of rare earth powder dysprosium are treated by high energy ball milling, wherein D50 is 0.15 μm. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping the temperature for 15 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

Comparative experiment example 2

¢ 24 g ¢ 15 g 18mm neodymium iron boron permanent magnet material 3.5 kg is polished according to the method of example 1, 60-mesh white corundum is used, and the permanent magnet material with the surface roughness RA =0.6 μm is obtained after surface cleaning (ultrasonic washing way) and rust-proof drying, 96 parts of zinc powder (weight ratio) and 4 parts of ammonium chloride are treated by high-energy ball milling, wherein D50 is 0.15 μm. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping the temperature for 15 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

Comparative experiment example 3

¢ 24 g ¢ 15 g 18mm neodymium iron boron permanent magnet material 3.5 kg is polished according to the method of the embodiment 1, sand blasting is carried out to remove rust, 60-mesh white corundum is used, and then the permanent magnet material with the surface roughness RA =0.6 μm is obtained after surface cleaning (ultrasonic washing way) and rust prevention drying, 96 parts of zinc powder (weight ratio) and 4 parts of rare earth powder dysprosium are processed by high energy ball milling, wherein D50 is 0.15 μm. Mixing the mixture evenly, putting the mixture together with a magnet, heating the mixture to 410 ℃, keeping the temperature for 15 minutes, taking out the mixture, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium iron boron permanent magnet material with the properties shown in Table 1.

Comparative experiment example 4

¢ 24 g ¢ 15 g 18mm neodymium iron boron permanent magnet material 3.5 kg is polished according to the method of example 1, sand blasting is carried out to remove rust, 60-mesh white corundum is used, and then the permanent magnet material with surface roughness RA =0.6 μm is obtained after surface cleaning (ultrasonic washing way) and rust prevention drying, 96 parts of zinc powder (weight ratio) and 4 parts of rare earth powder dysprosium are processed by high energy ball milling, wherein D50 is 3.5 microns. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping the temperature for 15 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

Comparative experiment example 5

¢ 24 g ¢ 15 g 18mm neodymium iron boron permanent magnet material 3.5 kg is polished according to the method of example 1, sand blasting is carried out to remove rust, 60-mesh white corundum is used, then surface cleaning (ultrasonic washing mode) and rust prevention drying are carried out to obtain the permanent magnet material with the surface roughness RA =0.6 μm, 100 parts of zinc powder (weight ratio) are treated by high-energy ball milling, wherein D50 is 0.15 μm. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping the temperature for 15 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

Comparative experiment example 6

¢ 24 g ¢ 15 g 18mm neodymium iron boron permanent magnet material 3.5 kg is polished according to the method of example 1, sand blasting is carried out to remove rust, 60-mesh white corundum is used, then surface cleaning (ultrasonic washing mode) and rust prevention drying are carried out to obtain the permanent magnet material with the surface roughness RA =0.2 μm, 100 parts of zinc powder (weight ratio) are treated by high-energy ball milling, wherein D50 is 0.15 μm. Mixing the mixture evenly, putting the mixture together with a magnet, heating to 380 ℃, keeping the temperature for 15 minutes, taking out, removing light in a vibration mill, and passivating to obtain the anticorrosive neodymium-iron-boron permanent magnet material with the performance shown in table 1.

And (4) conclusion: (1) by comparing the thickness, the salt spray test, the height reduction, the magnetic performance parameters and the like of the sintered neodymium-iron-boron permanent magnet obtained in the experimental examples 1 and 6, the addition of the rare earth not only promotes the uniformity and the compactness of a zinc layer of the magnet in the zincification process, but also inhibits the deterioration of the magnet;

(2) it can be seen from comparison of experimental examples 2 and 5 that the addition of a chlorine-containing activator can increase the thickness of the zincized layer, but has a very significant effect on deterioration of the magnet properties;

(3) compared with the experimental examples 1 and 3, the improvement of the roughness of the surface of the sintered neodymium iron boron permanent magnet is beneficial to improving the zinc impregnation effect;

(4) it can be seen from comparative examples 3 and 5 that the magnetic integrity is adversely affected by an excessively high zincizing temperature.

The present invention has been described in detail with reference to the above examples, but the description is only for the preferred examples of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.