CN115863040A - Diffusion method for improving performance of sintered NdFeB magnet - Google Patents
Diffusion method for improving performance of sintered NdFeB magnet Download PDFInfo
- Publication number
- CN115863040A CN115863040A CN202211626912.0A CN202211626912A CN115863040A CN 115863040 A CN115863040 A CN 115863040A CN 202211626912 A CN202211626912 A CN 202211626912A CN 115863040 A CN115863040 A CN 115863040A
- Authority
- CN
- China
- Prior art keywords
- diffusion
- magnet
- hcj
- pressure
- rare earth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Landscapes
- Hard Magnetic Materials (AREA)
Abstract
本发明公开了一种提高烧结NdFeB磁体性能的扩散方法：烧结NdFeB磁体基体用酸洗液进行酸洗刻蚀，所述酸洗液是将氯化铁水溶液和硝酸酒精溶液混合制备得到，酸洗液中FeCl3的质量分数为1.5～3.5％，硝酸的质量分数为1.5～3.5％，然后在酸洗刻蚀后的磁体表面沉积重稀土元素扩散层；再进行扩散处理：扩散温度为800℃～1000℃，保温时间为0.5h～48h，通入氩气至压力在1～10MPa之间，冷却后再进行回火处理，制得扩散后的高性能烧结NdFeB磁体。本发明首次提供了Hcj增量的可控条件和公式，并且通入氩气在一定压力下进行扩散，通过对压力和温度的控制，以及前期酸洗刻蚀前处理，提高了烧结NdFeB磁体的扩散效果，制备得到高Hcj、Br的扩散磁体。
The invention discloses a diffusion method for improving the performance of sintered NdFeB magnets: the sintered NdFeB magnet substrate is pickled and etched with pickling solution, the pickling solution is prepared by mixing ferric chloride aqueous solution and nitric acid alcohol solution, pickling The mass fraction of FeCl3 in the solution is 1.5-3.5%, the mass fraction of nitric acid is 1.5-3.5%, and then deposit a heavy rare earth element diffusion layer on the surface of the magnet after pickling and etching; then carry out diffusion treatment: the diffusion temperature is 800 °C ~1000℃, holding time is 0.5h~48h, argon gas is introduced until the pressure is between 1~10MPa, after cooling, tempering treatment is performed to obtain a high-performance sintered NdFeB magnet after diffusion. The present invention provides controllable conditions and formulas for the Hcj increment for the first time, and argon gas is introduced to diffuse under a certain pressure, and the sintered NdFeB magnet is improved by controlling the pressure and temperature, as well as the pre-treatment of pickling and etching. Diffusion effect, the preparation of high Hcj, Br diffusion magnet.
Description
Technical Field
The invention relates to a diffusion method for improving the performance of a sintered NdFeB magnet, and mainly relates to a diffusion method which is used for directly exposing a grain boundary phase on the surface through acid cleaning and etching, and controlling the diffusion degree of the magnet by changing the internal pressure of a furnace body and the diffusion temperature so as to control and improve the Hcj increment of the magnet.
Background
Sintered NdFeB has been developed for 30 years so far, and is still widely used in various fields of various industries so far due to higher magnetic properties and lower price.
For sintered NdFeB, the diffusion technology is a novel mode for improving the Hcj of the magnet, the operation is simple and convenient, the cost is low, and the Hcj improving amount is large. The principle of the diffusion technology is that a diffusion source diffuses from the surface of a magnet to the inside along an Nd-rich phase, and due to the uncontrollable nature of grain boundary diffusion, the Nd-rich phase may be replaced too much sometimes, and the Br reduction amount is too large, so how to control the diffusion degree is important to improve Hcj and reduce Br reduction amount.
In the conventional magnet preparation process, if the magnet is circulated and placed for a long time in the midway, the rare earth on the surface is enriched, the rare earth content on the surface is too high, and in the subsequent diffusion process, heavy rare earth performs a large amount of replacement reaction on the surface, so that a large amount of shell layers are formed on the edge of a main phase on the surface. Along with gradual consumption of a diffusion source, the concentration of the heavy rare earth of the grain boundary on the surface is low, and the concentration of the heavy rare earth of the grain boundary can generate the back diffusion of the heavy rare earth of the grain boundary to form an anti-shell layer, so that the magnetic property is reduced.
In addition, because the grain boundary diffusion rate is greater than the grain diffusion rate, but unavoidable diffusion sources can enter the main phase, the reduction of the magnet Br is too large, the Hcj increase is not high, and the performance of the magnet is affected.
Disclosure of Invention
The invention aims to provide a diffusion method which can control the diffusion degree of a magnet to control and improve the increment of the Hcj of the magnet by changing the internal pressure of a furnace body and changing the diffusion temperature, and can effectively solve the problems of large Br reduction, anti-shell layer and the like in the diffusion.
The technical scheme adopted by the invention is as follows:
a diffusion method for improving the performance of a sintered NdFeB magnet, the method comprising the steps of:
(1) Carrying out acid-washing etching on the sintered NdFeB magnet matrix by using a pickling solution, wherein the pickling solution is prepared by mixing a ferric chloride aqueous solution and a nitric acid alcohol solution, and FeCl is contained in the pickling solution 3 The mass fraction of the nitric acid is 1.5-3.5%, the magnet after acid cleaning and etching is obtained, and then a heavy rare earth element diffusion layer is deposited on the surface of the magnet after acid cleaning and etching;
(2) Performing diffusion treatment on the magnet with the heavy rare earth element diffusion layer deposited on the surface: the diffusion temperature is 800-1000 ℃, the heat preservation time is 0.5-48 h, argon is introduced until the pressure is 1-10 MPa, and tempering treatment is carried out after cooling to prepare the high-performance sintered NdFeB magnet after diffusion.
In the step (1), the time of acid cleaning and etching is within 5s, generally 1-2 s.
The nitric acid alcohol solution is prepared by dissolving nitric acid in absolute ethyl alcohol with the mass fraction of more than 99.9%.
The mass fraction of the nital solution is preferably 4 to 5%, more preferably 5%.
The mass fraction of the iron chloride aqueous solution is preferably 4 to 5%, more preferably 5%.
Further, in the step (1), the weight loss ratio of the magnet after acid cleaning and etching is preferably 0.06% to 0.13%, and preferably 0.08% to 0.1%. The weight loss ratio is calculated according to the following formula: (magnet matrix mass-mass of magnet after acid-wash etching)/magnet matrix mass.
Further, in the step (1), the magnet base is etched by acid washing with an acid washing solution, and then preferably cleaned with clean water and dried.
In the step (1), a heavy rare earth element diffusion layer is preferably deposited on the surface of the magnet after acid cleaning and etching by adopting a coating method, a multi-arc sputtering method or an evaporation method.
The coating method is a conventional coating method, for example, a method of performing 1: after 1 mass percent, the alcohol concentration is 99 percent, and the substrate is uniformly coated in a fixed proportion by a wet film machine or a small spray gun, and other coating methods can be used.
The multi-arc sputtering method is a conventional magnetron sputtering method.
In the step (1), the heavy rare earth element diffusion layer preferably has a thickness of 10 to 30 μm (more preferably a thickness of 10 to 25 μm, and still more preferably 15 to 25 μm), and a weight ratio of 1.2 to 3.4% (more preferably 1.2 to 3%, and still more preferably 1.7 to 2.8%) of the weight of the magnet.
In the step (1), the heavy rare earth element diffusion source is pure heavy rare earth element metal, heavy rare earth element hydride, fluoride or oxide, or an alloy of the heavy rare earth element and other metal elements, the heavy rare earth element is at least one of Dy, tb or Ho, and more preferably the heavy rare earth element diffusion source is terbium fluoride, terbium hydride or dysprosium oxide.
The sintered NdFeB magnet matrix in the step (1) is preferably a magnet matrix with the rare earth content of less than 30.5wt%, and can be in any shape or brand, and the composition ratio of the magnet matrix has no influence on the diffusion method of the invention.
In the step (2), the diffusion temperature is preferably 860 to 980 ℃, more preferably 860 to 950 ℃, more preferably 890 to 920 ℃, the heat preservation time is preferably 6 to 12 hours (more preferably 6 to 10 hours, more preferably 8 to 10 hours), and the pressure is preferably 1 to 5.8MPa, more preferably 1 to 5MPa.
In the invention, argon is introduced to ensure the pressure in the furnace during diffusion.
In the step (2), the tempering temperature is 400-600 ℃ (preferably 400-480 ℃), and the tempering time is 1-24 h (preferably 3-6 h).
In the step (2), after the diffusion heat preservation is finished, the vacuum air cooling is preferably performed at a cooling rate of 3 to 8 ℃/min (more preferably 4 to 6 ℃/min).
In the step (2), after the tempering and heat preservation are finished, the vacuum air cooling is preferably carried out at a cooling rate of 3-8 ℃/min (more preferably 5 ℃/min).
The vacuum air cooling is to vacuumize to the absolute vacuum degree of 1.0 multiplied by 10 -3 After Pa or less, air cooling is performed.
In the step (2), the diffusion treatment is preferably carried out in a high-temperature high-pressure sintering furnace, and the highest pressure can reach 10MPa.
After the surface oxide is removed, the performance and the component of the diffused high-performance sintered NdFeB magnet are tested.
The performance test equipment is an NIM-15000 permanent magnet tester, and the component test is iCP-OES.
The magnet surface oxide removal is preferably performed by sandblasting or pickling.
The improved principle of the method of the invention is as follows:
the magnet is placed the magnet surface and can produce the rare earth enrichment after a period of time, if directly carry out diffusion treatment, can lead to the heavy tombarthite on surface and the production of surperficial PrNd to replace in a large number, to the main phase diffusion in-process, form a large amount of shells at the superficial layer major phase, along with diffusion time increases, the diffusion source consumption of coating is totally done, heavy tombarthite diffusion source in the surface grain boundary phase continues the diffusion to inside, lead to surface grain boundary phase heavy tombarthite concentration to be less than surface major phase heavy tombarthite concentration, main phase heavy tombarthite is to grain boundary phase back diffusion, form anti-shell, lead to Hcj to reduce.
The invention adopts an etching and acid-washing method and uses FeCl 3 Dissolving the surface-enriched rare earth with the nital solution, and simultaneously corroding the surface to directly expose a grain boundary phase on the surface of the magnet, wherein the diffusion rate of the grain boundary is far greater than that of the surface, so that the diffusion efficiency is greatly increased by the method; simultaneous addition of FeCl 3 Can protect the main phase and prevent the main phase from being greatly corroded to cause great reduction of Br.
After the Nd-rich phase is melted, the diffusion source diffuses towards the inside of the magnet along the melting channel, and because the diffusion rate of the grain boundary is far higher than that of the crystal grains, the diffusion source diffuses to the grain boundary inside the magnet along the external grain boundary, and only a small amount of the diffusion source enters the crystal grains of the magnet.
The deeper the diffusion depth of the diffusion source, the greater the Hcj lift. The kinetics of diffusion from diffusion sources are mainly due to concentration differences and pressure. The concentration difference can be controlled manually and is easy to realize, but the conventional diffusion pressure mainly comes from gravity, the diffusion depth is insufficient due to small pressure, diffusion of a diffusion source to crystal grains is caused, the main phase structure is damaged, br and Hcj are reduced, and the like, so that the pressure needs to be applied from the outside, and the diffusion depth and the diffusion amount are controlled manually by pressurizing.
The invention adopts the mode of filling argon to a certain pressure for sintering, and because the argon is relatively stable, the reaction can not occur even under the high temperature of 1700 ℃, therefore, the argon is filled to the internal pressure of 1-5 Mpa during sintering, the sintering temperature and time are adjusted, the Hcj increased by the magnet can be controlled, and a large amount of experiments show that the calculation formula of the theoretical value of the increment of the Hcj in a certain condition range is as follows:
increment of Hcj = (T-860)/30 + (P +4 MPa)/MPa + K,1 formula;
hcj increment =22.4- { (T-860)/30 + (P +4 MPa)/MPa + K },2, when Hcj increment calculated by formula 1 is greater than 11.5KOe, calculated by formula 2; wherein T is temperature (DEG C), P is pressure, K is a numerical value which changes along with the pressure, the constant is 2.2 when the pressure is 1-5 MPa, and the K is greatly reduced when the pressure is higher than 5MPa or lower than 1MPa, which is not suitable for the calculation of the formula.
The applicant proves that the theoretical increment of Hcj is calculated by adopting the formula when the pressure is 1-5 MPa, the diffusion temperature is 860-980 ℃, the diffusion time is 8-12 h and the thickness of the heavy rare earth element diffusion layer is 10-25 mu m, and the experimental result shows that the difference value of the actual increment of Hcj and the theoretical increment of Hcj obtained by the formula is within 0.25KOe, and the rare earth proportion in the magnet after diffusion is less than 31%.
However, when the gas pressure is lower than 1Mpa, the increment of Hcj obtained by the conventional diffusion process is insufficient, the diffusion amount of a diffusion source is insufficient, and when the gas pressure is higher than 5.8Mpa, the pressure is too high, so that the diffusion source enters the interior of the magnet in a large amount, the Nd-rich phase is replaced in a large amount, the grain boundary phase is damaged in a large amount, the densification of the magnet is reduced during sintering, and the reduction amount of Br is further increased. Meanwhile, the diffusion source which has overlarge diffusion amount and enters the crystal grains is increased, so that the main phase is damaged, and the Hcj lifting amount is not high.
Similarly, the regulated temperature is also at the regulated pressure, the gas has an expansion/contraction effect, and the pressure of the diffusion source of the gas pair changes when the high temperature is regulated according to the formula PV = nRT (P is the pressure, V is the volume, n is the amount of the gas substance, R is the gas constant, and T is the temperature). Meanwhile, different phases can be precipitated from the sintered NdFeB by adjusting the temperature, the grain boundary phase can be more continuous by proper temperature, and the diffusion quantity of the diffusion source along the inner part of the main phase is less.
Before diffusion, the surface of the matrix is pickled and etched, so that the grain boundary phase on the surface of the magnet is corroded to form fine cracks, thereby facilitating the better diffusion of a diffusion source.
The diffusion source adopts a magnetron sputtering mode for diffusion source deposition, and has the advantages of high deposition rate, good adhesive force, high vacuum state during film coating, few film impurities and the like.
After diffusion, a vacuum air cooling mode is preferably adopted, and the problem that the diffusion source still depends on gas pressure and retained high temperature to perform secondary diffusion and other uncontrollable diffusion in a temperature reduction stage after diffusion is solved.
In the diffused magnet prepared by the invention, the mass fraction of the diffusion source entering the magnet is 0.28-0.83%, and the increment range of Hcj is 3-11.5 KOe.
The method is characterized in that the amount of the diffusion source entering the magnet can be in a certain range by adjusting the flushing amount and the temperature of the argon, and a certain rule is met; meanwhile, for the performance of the magnet, under a certain diffusion condition, the Hcj lifting amount can accord with a range formula
Increment of Hcj = (T-860)/30 + (P +4 MPa)/MPa + K, formula 1;
the increment of Hcj is =22.4- { (T-860)/30 + (P +4 MPa)/MPa + K }, and the formula 2 is used for calculating the increment of Hcj by using the formula 2 (wherein T is temperature, P is pressure, K is a numerical value changing along with pressure, a constant is 2.2 when the pressure is 1-5 MPa, and the K is greatly reduced when the pressure is higher than 5MPa or lower than 1 MPa) when the increment of Hcj calculated by the formula 1 is larger than 11.5 KOe), the difference between the actual increment of Hcj and the increment obtained by the formula is within 0.25KOe, the rare earth proportion of the magnet after diffusion is below 31%, and the diffusion depth of the invention can reach 10mm.
The invention provides controllable conditions and formulas of the increment of Hcj for the first time, argon is introduced to carry out diffusion under certain pressure, the diffusion effect of the sintered NdFeB magnet is improved by controlling the pressure and the temperature and carrying out acid pickling and etching pretreatment in the early stage, and the high-Hcj and high-Br diffusion magnet is prepared.
Description of the drawings:
FIG. 1 gold phase diagram after acid etching with different acid solutions in example 1.
FIG. 2 Electron micrographs of the fourth set of experiments from example 2 after diffusion.
FIG. 3 Electron micrograph of eighth set of experiments from example 2 after diffusion.
The specific implementation mode is as follows:
the technical solution of the present invention is further described with specific examples, but the scope of the present invention is not limited thereto.
Example 1: after the matrix is subjected to magnetron sputtering coating treatment, the matrix is placed in a high-temperature high-pressure sintering furnace for diffusion treatment, and the specific implementation mode is as follows:
s1, selecting a magnet with a matrix of N48M, wherein the specific composition is R 1 R 2 M 1 M 2 A 1 T 1 ，R 1 Pr + Nd, content 22.90wt%, 7.40wt%, respectively, R 2 Dy is 0.1wt%, M 1 Al and Cu in an amount of 0.3wt% and 0.18wt%, respectively, and M 2 Is Co, ga or Zr, the contents are respectively 0.4wt%, 0.1wt% and 0.12wt%, A 1 B, content 0.95wt%, prevents the high Ga low B phenomenon from occurring, and reduces diffusion effect. The balance being T 1 And is Fe. The matrix is prepared by a conventional powder metallurgy process, and is generally processed into a cylindrical matrix phi 10mm x 10mm by smelting, crushing, press forming, sintering and linear cutting.
Carrying out acid cleaning and etching treatment on the magnet matrix, wherein acid cleaning solution for acid cleaning is the mixture ratio of five solutions, and FeCl with the concentration of 5 percent respectively 3 Solution 1g with 5% HNO 3 9g of mixed 5% FeCl alcohol solution (nitric acid in 99.9% alcohol) 3 Solution 3g with 5% HNO 3 Alcohol solution 7g mixed, concentration 5%FeCl 3 5g of solution with 5% HNO 3 5g of mixed ethanol solution, 5% FeCl 3 Solution 7g with 5% HNO 3 3g of mixed ethanol solution and 5% FeCl 3 9g of solution with 5% HNO 3 Mixing with 1g of alcohol solution.
The time of acid cleaning and etching is within 5 seconds, generally 1-2 seconds.
S2, depositing a diffusion source on the surface of the magnet after acid cleaning and etching by a multi-arc sputtering method, specifically performing magnetron sputtering physical vapor deposition in a plasma vacuum coating machine, wherein the diffusion source is terbium hydride. The thickness of the terbium hydride film layer is 20mm, and the weight ratio of the terbium hydride film layer to the magnet is 2.5 percent, so that the magnet with the terbium hydride film layer deposited on the surface is obtained.
S3, placing the new magnet into a high-temperature high-pressure sintering furnace for diffusion treatment, wherein the diffusion temperature is 905 ℃, the time is 9 hours, and before the diffusion starts, vacuumizing to the absolute vacuum degree of 1.0 multiplied by 10 -3 Pa, then argon is introduced into the reactor to 1.01X 10 5 Pa, namely diffusion under one atmosphere, and after the diffusion is finished, vacuumizing to 1.0 multiplied by 10 -3 Pa, and performing vacuum air cooling with the cooling rate of 5 ℃/min. Cooling to room temperature, tempering at 445 deg.C for 4.5h, vacuum air cooling at 5 deg.C/min, and cooling to room temperature.
And S4, performing surface treatment on the diffused magnet, and soaking the magnet in 5% dilute hydrochloric acid in an ultrasonic cleaning mode, performing ultrasonic cleaning for 30S, and then cleaning the magnet with an alcohol solution, wherein the alcohol concentration is 75%. And taking out the magnet, and carrying out component test on the magnet by using an ICP-OES (inductively coupled plasma-optical emission system) as a test instrument and simultaneously carrying out performance test by using an NIM-15000 permanent magnet measuring instrument as the test instrument.
The control group did not have the S2 diffusion source deposition step, and the rest of the steps were the same.
Table 1 properties of example 1 and control
| Br(kGs) | Hcj(kOe) | SQ(％) | Proportion of weight loss/%) | |
| Examples 1 to 1 | 13.4 | 24.32 | 94.1 | 0.13 |
| Examples 1 to 2 | 13.5 | 25.1 | 96.9 | 0.1 |
| Examples 1 to 3 | 13.53 | 25.19 | 96.9 | 0.09 |
| Examples 1 to 4 | 13.53 | 25.11 | 97.2 | 0.08 |
| Examples 1 to 5 | 13.55 | 24.23 | 97.1 | 0.06 |
| Control group 1-1 | 13.61 | 15.12 | 98.3 | |
| Control group 1-2 | 13.6 | 15.09 | 98.3 | |
| Control groups 1 to 3 | 13.6 | 15.13 | 98.3 | |
| Control groups 1-4 | 13.6 | 15.11 | 98.4 | |
| Control groups 1-5 | 13.59 | 15.13 | 98.3 |
The gold phase diagram after acid cleaning and etching is shown in FIG. 1, wherein the left diagram is FeCl with concentration of 5% 3 5g of solution with 5% HNO 3 The right picture is a gold phase picture made by acid washing and etching a pickling solution mixed by 5g of alcohol solution, and FeCl with the concentration of 5 percent 3 Solution 1g with 5% HNO 3 And (3) carrying out acid-washing etching on the acid-washing solution mixed with 9g of alcohol solution to prepare a gold phase diagram.
FIG. 1 in combination with Table 1 shows that 5% FeCl is used for the acid etch 3 Solution 1g with 5% HNO 3 When the alcohol solution is 9g, the metallographic picture shows that the surface of the main phase is greatly corroded besides the surface of the grain boundary phase, so that the weight of a shell layer formed by diffusion is reduced, the increment of Hcj is lower, and the reduction of Br is higher due to the large corrosion of the surface of the main phase; and the FeCl with the concentration of 5 percent used in acid-washing etching 3 5g of solution with 5% HNO 3 When 5g of the mixed pickling solution is mixed with 5g of the alcohol solution, the degree of corrosion is good, and the specific expression is that the surface of the grain boundary phase is corroded in a large amount and is directly exposed on the surface of the matrix, and the surface of the main phase is corroded less.
While FeCl was used at a concentration of 5% 3 9g of solution with 5% HNO 3 Since 1g of the acid solution in an alcohol solution causes less corrosion of the grain boundary phase and a low diffusion efficiency, the increase of Hcj is insufficient.
According to the magnetic performance results, the reduction amount of Br and the increase amount of Hcj of the examples 1-2, 1-3 and 1-4 are low, and the generation of the anti-shell layer is less, so that the magnetic performance after diffusion can be effectively improved by controlling a certain proportion of the corrosive liquid to corrode the substrate.
Example 2:
s1, a magnet with a matrix of N48M was selected, and a cylindrical matrix of Φ 10mm × 10mm was prepared according to the step S1 of example 1.
Then acid-washing etching treatment is carried out, wherein the acid-washing solution adopted in the acid-washing etching is FeCl with the concentration of 5 percent 3 5g of solution with 5% HNO 3 5g of alcohol solution is mixed, and the acid washing etching time is less than 5 seconds.
S2, depositing a diffusion source on the surface of the magnet after acid cleaning and etching by a multi-arc sputtering method, specifically performing magnetron sputtering physical vapor deposition in a plasma vacuum coating machine, wherein the diffusion source is terbium hydride. The thickness of the terbium hydride film layer is 10mm, and the weight ratio of the terbium hydride film layer to the magnet is 1.2 percent, so that the magnet with the terbium hydride film layer deposited on the surface is obtained.
S3, placing the magnet with the surface deposited with the terbium hydride film layer into a high-temperature high-pressure sintering furnace for diffusion treatment, wherein the diffusion temperature is 860 ℃, the time is 6 hours, and before the diffusion is started, vacuumizing is carried out until the absolute vacuum degree is 1.0 multiplied by 10 -3 Pa, then argon is introduced into the reactor to 1.01X 10 5 Pa, namely diffusion under one atmosphere, and after the diffusion is finished, vacuumizing to 1.0 multiplied by 10 -3 Pa, and performing vacuum air cooling with the cooling rate of 5 ℃/min. Cooling to room temperature, tempering at 445 deg.C for 4.5h, vacuum air cooling at 5 deg.C/min, and cooling to room temperature.
And S4, carrying out surface treatment on the diffused magnet, and then carrying out component test and performance test, wherein the steps are the same as S4 of the embodiment 1.
The control group had no diffusion source deposition step, and the rest of the steps were the same.
The above is the first set of experiments in example 2.
The second set of experiments were prepared in the same manner as the first set of experiments, except that the diffusion temperature was 875℃ × 6h.
The third set of experiments was prepared identically to the first set of experiments except that the diffusion temperature was 890 deg.c for 6h.
The fourth set of experiments was prepared in the same manner as the first set of experiments except that the diffusion temperature was 905 ℃ for 6h.
The fifth set of experiments were prepared in the same manner as the first set of experiments, except that the diffusion temperature was 920 ℃ for 6h.
The sixth set of experiments were prepared in the same manner as the first set of experiments except that the diffusion temperature was 935 deg.c for 6h.
The seventh set of experiments were prepared in the same manner as the first set of experiments, except that the diffusion temperature was 950 ℃ for 6h.
The eighth experiment set is the same as the fourth experiment set in preparation method, except that acid-washing etching is not performed.
The ninth experiment and the fourth experiment are identical in preparation method, and different in that vacuum diffusion is performed without pressure diffusion, and the vacuum diffusion is performed by vacuumizing until the absolute vacuum degree is 1.0X 10 -3 Pa below, and keeping the temperature for 6h at 905 ℃.
TABLE 2 compositional proportions (in wt%) of the magnets of the control group and each of the groups of example 2
| Pr | Nd | Dy | Al | Cu | Co | Ga | Zr | B | Fe | Tb | |
| Control | 22.9 | 7.4 | 0.1 | 0.301 | 0.18 | 0.4 | 0.1 | 0.12 | 0.95 | Balance of | 0 |
| Example 2-1 | 22.71 | 7.35 | 0.1 | 0.3 | 0.18 | 0.4 | 0.1 | 0.12 | 0.93 | Balance of | 0.31 |
| Examples 2 to 2 | 22.72 | 7.34 | 0.1 | 0.301 | 0.18 | 0.4 | 0.1 | 0.13 | 0.94 | Balance of | 0.32 |
| Examples 2 to 3 | 22.7 | 7.33 | 0.1 | 0.299 | 0.18 | 0.4 | 0.1 | 0.12 | 0.93 | Balance of | 0.3 |
| Examples 2 to 4 | 22.7 | 7.34 | 0.1 | 0.298 | 0.18 | 0.39 | 0.1 | 0.12 | 0.95 | Allowance of | 0.33 |
| Examples 2 to 5 | 22.76 | 7.36 | 0.1 | 0.301 | 0.17 | 0.4 | 0.1 | 0.12 | 0.96 | Balance of | 0.34 |
| Examples 2 to 6 | 22.72 | 7.36 | 0.1 | 0.3 | 0.19 | 0.4 | 0.1 | 0.12 | 0.95 | Balance of | 0.34 |
| Examples 2 to 7 | 22.71 | 7.36 | 0.1 | 0.297 | 0.18 | 0.4 | 0.1 | 0.13 | 0.95 | Allowance of | 0.34 |
| Examples 2 to 8 | 22.78 | 7.36 | 0.1 | 0.299 | 0.19 | 0.39 | 0.1 | 0.12 | 0.95 | Balance of | 0.15 |
| Examples 2 to 9 | 22.80 | 7.36 | 0.1 | 0.301 | 0.18 | 0.4 | 0.1 | 0.12 | 0.94 | Balance of | 0.26 |
TABLE 3 comparison of the Performance of the control with that of example 2
| Br(kGs) | Hcj(kOe) | SQ(％) | |
| Example 2-1 | 13.53 | 18.22 | 97.30 |
| Examples 2 to 2 | 13.52 | 19.01 | 96.90 |
| Examples 2 to 3 | 13.52 | 21.38 | 96.90 |
| Examples 2 to 4 | 13.53 | 22.36 | 97.20 |
| Examples 2 to 5 | 13.53 | 21.03 | 97.10 |
| Examples 2 to 6 | 13.52 | 20.16 | 97.20 |
| Examples 2 to 7 | 13.53 | 19.08 | 97.00 |
| Examples 2 to 8 | 13.55 | 18.62 | 98.10 |
| Examples 2 to 9 | 13.54 | 19.39 | 97.80 |
| Control group 2-1 | 13.61 | 15.12 | 98.30 |
| Control group 2-2 | 13.60 | 15.09 | 98.30 |
| Control group 2-3 | 13.60 | 15.13 | 98.30 |
| Control groups 2-4 | 13.60 | 15.11 | 98.40 |
| Control groups 2 to 5 | 13.59 | 15.13 | 98.30 |
| Control groups 2 to 6 | 13.60 | 15.13 | 98.40 |
| Control groups 2 to 7 | 13.59 | 15.10 | 98.30 |
| Control groups 2 to 8 | 13.59 | 15.12 | 98.30 |
| Control groups 2-9 | 13.60 | 15.13 | 98.40 |
The above table leads to the conclusion that:
1. starting from the diffusion temperature of 860 c, hcj increases as the temperature increases, but Hcj instead begins to decrease after the temperature is higher than 905 c.
2. Changing the temperature can change the amount of diffusion of the diffusion source Tb, but the change is small, but although the difference in the amount of diffusion of Tb is not large, the increment of Hcj of the magnet after diffusion changes greatly.
3. It has been found through studies that the diffusion temperature is changed, mainly by the phase precipitated in the grain boundary phase, for example, when Tb is in the grain boundary phase 2 Fe 14 The Hcj can be greatly increased by increasing the precipitation ratio of the B phase, whereas if the precipitation ratio is not high, the Hcj increase amount is not large.
4. Temperature has less effect on the amount of diffusion from the diffusion source, but is still a non-negligible effect.
5. The electron microscope images of the fourth group and the eighth group are respectively shown in fig. 2 and fig. 3, and the comparison of the components, the electron microscope images and the performances of the two groups shows that the grain boundary phase ratio is far lower than that of the matrix subjected to pickling etching after the matrix is not subjected to pickling etching diffusion, so that the diffusion rate of the matrix is far lower than that of the matrix subjected to pickling etching without pickling etching, the Tb content diffused in the magnet is also lower, the coercive force promotion amount is not high, and the diffusion effect is not good.
6. By comparing the fourth group with the ninth group, it was found that Hcj was not increased by the pressurizing step by 4.26KOe, which is much smaller than 7.25KOe by the pressurizing step.
Example 3:
s1, selecting a magnet with a matrix of N48M, wherein the specific composition is R 1 R 2 M 1 M 2 A 1 T 1 ，R 1 Pr + Nd, contents of 22.80wt% and 7.48wt%, respectively, R 2 Dy is 0.1wt%, M 1 Al and Cu in an amount of 0.3wt% and 0.18wt%, respectively, and M 2 Is Co, ga or Zr, the contents are respectively 0.4wt%, 0.1wt% and 0.14wt%, A 1 B, content 0.95wt%, prevents the high Ga low B phenomenon from occurring, and reduces diffusion effect. The balance being T 1 And is Fe. The matrix is prepared by conventional powder metallurgy process, and is generally processed into a cylindrical matrix of phi 10mm to 10mm by smelting, crushing, press molding, sintering and linear cutting, and pickling etching is carried out by using a pickling solution which is FeCl with the concentration of 5% 3 5g of solution with 5% HNO 3 5g of alcohol solution is mixed to obtain the alcohol.
S2, depositing a diffusion source on the surface of the magnet after acid cleaning and etching by a multi-arc sputtering method, specifically performing magnetron sputtering physical vapor deposition in a plasma vacuum coating machine, wherein the diffusion source is terbium hydride. The thickness of the terbium hydride film layer is 10mm, and the weight ratio of the terbium hydride film layer to the magnet is 1.2 percent, so that the magnet with the terbium hydride film layer deposited on the surface is obtained.
S3, placing the magnet with the surface deposited with the terbium hydride film layer into a high-temperature high-pressure sintering furnace for diffusion treatment, wherein the diffusion temperature is 905 ℃, the time is 6 hours, and before the diffusion starts, vacuumizing to the absolute vacuum degree of 1.0 multiplied by 10 -3 Pa, then argon is introduced into the reactor to 1.01X 10 5 Pa, namely diffusion under one atmosphere, and after the diffusion is finished, vacuumizing to 1.0 multiplied by 10 -3 Pa, and performing vacuum air cooling with the cooling rate of 5 ℃/min. Cooling to room temperature, tempering at 445 deg.C for 4.5h, vacuum air cooling at 5 deg.C/min, and cooling to room temperature.
And S4, carrying out surface treatment on the diffused magnet, and then carrying out component test and performance test, wherein the steps are the same as S4 of the embodiment 1.
The control group had no diffusion source deposition step, and the rest of the steps were the same.
The above is the first set of experiments of example 3:
the second set of experiments were prepared in the same manner as the first set of experiments except that the diffusion temperature was 905 ℃ for 4.5h.
The third set of experiments were prepared in the same manner as the first set of experiments except that the diffusion temperature was 905 ℃ for 7.5h.
The fourth set of experiments was prepared in the same manner as the first set of experiments except that the diffusion temperature was 905 ℃ for 9h.
The fifth set of experiments was prepared in the same manner as the first set of experiments except that the diffusion temperature was 905 ℃ for 12h.
The sixth set of experiments were prepared in the same manner as the first set of experiments, except that the diffusion temperature was 905 ℃ for 18h.
The seventh set of experiments were prepared in the same manner as the first set of experiments except that the diffusion temperature was 905 ℃ for 24h.
TABLE 4 compositional proportions (in wt%) of the magnet of each of the control and example 3 groups
| Pr | Nd | Dy | Al | Cu | Co | Ga | Zr | B | Fe | Tb | |
| Example 3-1 | 22.69 | 7.38 | 0.1 | 0.3 | 0.18 | 0.39 | 0.1 | 0.12 | 0.95 | Balance of | 0.33 |
| Example 3-2 | 22.69 | 7.39 | 0.1 | 0.3 | 0.18 | 0.4 | 0.1 | 0.13 | 0.93 | Balance of | 0.28 |
| Examples 3 to 3 | 22.69 | 7.39 | 0.1 | 0.3 | 0.18 | 0.39 | 0.1 | 0.13 | 0.93 | Balance of | 0.43 |
| Examples 3 to 4 | 22.69 | 7.39 | 0.1 | 0.3 | 0.18 | 0.4 | 0.1 | 0.14 | 0.95 | Balance of | 0.53 |
| Examples 3 to 5 | 22.69 | 7.38 | 0.1 | 0.3 | 0.18 | 0.4 | 0.1 | 0.12 | 0.94 | Balance of | 0.6 |
| Examples 3 to 6 | 22.68 | 7.38 | 0.1 | 0.3 | 0.18 | 0.39 | 0.1 | 0.14 | 0.95 | Allowance of | 0.65 |
| Examples 3 to 7 | 22.67 | 7.39 | 0.1 | 0.3 | 0.18 | 0.39 | 0.1 | 0.12 | 0.94 | Balance of | 0.73 |
| Control | 22.8 | 7.48 | 0.1 | 0.3 | 0.18 | 0.4 | 0.1 | 0.14 | 0.95 | Balance of | 0 |
TABLE 5 Performance of examples and control
| Br(kGs) | Hcj(kOe) | SQ(％) | Br(kGs) | Hcj(kOe) | SQ(％) | ||
| Example 3-1 | 13.87 | 22.19 | 97.01 | Control group 3-1 | 14.01 | 14.89 | 98.5 |
| Examples 3 to 2 | 13.89 | 19.9 | 97.03 | Control group 3-2 | 14.01 | 14.93 | 98.5 |
| Examples 3 to 3 | 13.87 | 23.38 | 96.98 | Control group 3-3 | 14 | 14.92 | 98.39 |
| Examples 3 to 4 | 13.87 | 23.6 | 96.95 | Control group 3-4 | 13.99 | 14.9 | 98.42 |
| Examples 3 to 5 | 13.83 | 23.79 | 97.1 | Control groups 3-5 | 13.99 | 14.89 | 98.48 |
| Examples 3 to 6 | 13.8 | 23.94 | 97.01 | Control group 3-6 | 14 | 14.9 | 98.43 |
| Examples 3 to 7 | 13.72 | 24.04 | 97 | Control groups 3 to 7 | 14 | 14.92 | 98.46 |
The conclusion is drawn from tables 4, 5:
1. the diffusion amount of the diffusion source can be increased by increasing the diffusion time, but after the diffusion time is longer than 12h, the increment of Hcj is not obvious, and the Br reduction is obvious.
2. The research shows that the diffusion source diffuses along the grain boundary and enters the main phase to diffuse due to the fact that the diffusion time is long (after the time is longer than 12 h), so that the structure of the main phase is damaged, br is greatly reduced, the Hcj lifting amount is not obvious, and the like.
Example 4:
s1, selecting a magnet with a matrix of N48M, wherein the specific composition is R 1 R 2 M 1 M 2 A 1 T 1 ，R 1 Pr + Nd, 22.90wt% and 6.90wt% respectively, R 2 Dy is 0.1wt%, M 1 Al and Cu in an amount of 0.3wt% and 0.18wt%, respectively, and M 2 Is Co, ga or Zr, the content is 0.4wt%, 0.1wt% and 0.12wt%, respectively, A 1 B, content 0.95wt%, prevents the high Ga low B phenomenon from occurring, and reduces diffusion effect. The balance being T 1 And is Fe. The matrix is prepared by conventional powder metallurgy process, and is generally processed into a cylindrical matrix of phi 10mm to 10mm by smelting, crushing, press molding, sintering and linear cutting, and pickling etching is carried out by using a pickling solution which is FeCl with the concentration of 5% 3 5g of solution with 5% HNO 3 5g of alcohol solution is mixed to obtain.
S2, depositing a diffusion source on the surface of the magnet after acid cleaning and etching by a multi-arc sputtering method, specifically performing magnetron sputtering physical vapor deposition in a plasma vacuum coating machine, wherein the diffusion source is terbium hydride. The thickness of the terbium hydride film layer is 10mm, and the weight ratio of the terbium hydride film layer to the magnet is 1.2 percent, so that the magnet with the terbium hydride film layer deposited on the surface is obtained.
S3, placing the magnet with the surface deposited with the terbium hydride film layer into a high-temperature high-pressure sintering furnace for diffusion treatment, wherein the diffusion temperature is 905 ℃, the time is 9 hours, and before the diffusion starts, vacuumizing to the absolute vacuum degree of 1.0 multiplied by 10 -3 Pa, then argon is introduced into the reactor to 1.01X 10 5 Pa, namely diffusion under one atmosphere, and after the diffusion is finished, vacuumizing to 1.0 multiplied by 10 -3 Pa, and performing vacuum air cooling with the cooling rate of 5 ℃/min. Cooling to room temperature, tempering at 445 deg.C for 4.5h, vacuum air cooling at 5 deg.C/min, and cooling to room temperature.
And S4, carrying out surface treatment on the diffused magnet, and then carrying out component test and performance test, wherein the steps are the same as S4 of the embodiment 1.
The control group had no diffusion source coating step, and the rest of the steps were the same.
The above is the first set of experiments in example 4:
the second set of experiments were prepared in the same manner as the first set of experiments, except that the terbium hydride film layer was 14mm thick and 1.5% by weight.
The third set of experiments was prepared in the same manner as the first set of experiments, except that the thickness of the terbium hydride film layer was 18mm and the weight ratio was 2.16%.
The fourth set of experiments was prepared in the same manner as the first set of experiments except that the terbium hydride film layer was 22mm thick and 2.5% by weight.
The fifth set of experiments was prepared in the same manner as the first set of experiments except that the terbium hydride film layer was 26mm thick and 3.16% by weight.
The sixth set of experiments was prepared in the same manner as the first set of experiments except that the terbium hydride film layer was 30mm thick and 3.6% by weight.
The seventh set of experiments was prepared in the same manner as the first set of experiments except that the terbium hydride film layer was 34mm thick and 4.1% by weight.
Table 6 example 4 properties after diffusion and Tb content
The above results can be obtained:
1. according to the Tb ratio after diffusion and the Hcj increase, as the diffusion source ratio increases, the difference in internal and external concentrations of the magnet increases, the Tb content after diffusion increases, and Hcj increases.
2. With the increase of the thickness of the Tb diffusion film, br is greatly reduced, and after the thickness of the film is more than 26mm, the increment of Hcj is not high, but the reduction of Br is higher, and the maximum reduction of Br can reach 0.34KGs. According to analysis, when the proportion of the diffusion source is high, a large amount of diffusion sources enter the main phase after entering the grain boundary phase, the main phase structure is damaged, and the situations that the Br reduction amount is increased and the Hcj increment is not high are caused.
Example 5:
s1, selecting a magnet with a matrix of N48M, wherein the specific composition is R 1 R 2 M 1 M 2 A 1 T 1 ，R 1 Pr + Nd, 22.90wt% and 6.90wt% respectively, R 2 Dy is 0.1wt%, M 1 Al and Cu in an amount of 0.3wt% and 0.18wt%, respectively, and M 2 Is Co, ga or Zr, the contents are respectively 0.4wt%, 0.1wt% and 0.12wt%, A 1 As B, the content is 0.95wt%The phenomenon of high Ga and low B is prevented, and the diffusion effect is reduced. The balance being T 1 And is Fe. The matrix is prepared by conventional powder metallurgy process, and is generally processed into a cylindrical matrix of phi 10mm to 10mm by smelting, crushing, press molding, sintering and linear cutting, and pickling etching is carried out by using a pickling solution which is FeCl with the concentration of 5% 3 5g of solution with 5% HNO 3 5g of alcohol solution is mixed to obtain the alcohol.
S2, depositing a diffusion source on the surface of the magnet after acid cleaning and etching by a multi-arc sputtering method, specifically performing magnetron sputtering physical vapor deposition in a plasma vacuum coating machine, wherein the diffusion source is terbium hydride. The thickness of the terbium hydride film layer is 22mm, and the weight ratio of the terbium hydride film layer to the magnet is 2.5 percent, so that the magnet with the terbium hydride film layer deposited on the surface is obtained.
S3, placing the magnet with the surface deposited with the terbium hydride film layer into a high-temperature high-pressure sintering furnace for diffusion treatment, wherein the diffusion temperature is 860 ℃, 890 ℃, 920 ℃, 960 ℃ and 980 ℃ (one group at every 30 ℃), the diffusion treatment time is 9 hours, and before the diffusion starts, vacuumizing is carried out until the absolute vacuum degree is 1.0 multiplied by 10 -3 Pa, then argon is introduced to 1.01X 10 5 Pa, i.e. diffusion under one atmosphere, after the diffusion is finished, vacuumizing to 1.0 × 10 -3 Pa, and performing vacuum air cooling with the cooling rate of 5 ℃/min. Cooling to room temperature, tempering at 445 deg.C for 4.5h, vacuum air cooling at 5 deg.C/min, and cooling to room temperature.
And S4, carrying out surface treatment on the diffused magnet, and then carrying out component test and performance test, wherein the steps are the same as S4 of the embodiment 1.
The control had no diffusion source coating step, and the rest of the procedure was the same.
The above is the first set of experiments of example 5:
the second set of experiments was prepared in the same way as the first set of experiments, except that the pressure was 1.0Mpa.
The third set of experiments was prepared in the same manner as the first set of experiments except that the pressure was 2.0MPa. The fourth set of experiments was prepared in the same manner as the first set of experiments except that the pressure was 3.0MPa.
The fifth set of experiments was prepared in the same manner as the first set of experiments except that the pressure was 4.0MPa.
The sixth set of experiments was prepared in the same manner as the first set of experiments except that the pressure was 5.0MPa.
The seventh set of experiments was prepared in the same manner as the first set of experiments except that the pressure was 6.0MPa.
The eighth set of experiments was prepared in the same manner as the first set of experiments except that the pressure was 10Mpa.
The ninth set of experiments were performed in the same manner as the first set of experiments, except that the pressure was 5.8MPa.
TABLE 7 magnet Properties of control and example 5 groups
In Table 7, 5-m-n, m represents the experiment of the group, m =1 to 9 corresponding to pressures of 0.1MPa, 1MPa,2MPa, 3MPa, 4MPa, 5MPa, 6MPa, 10MPa and 5.8MPa, respectively; n represents the diffusion temperature in the set of experiments, n = 1-5, representing temperatures of 860 deg.C, 890 deg.C, 920 deg.C, 960 deg.C, 980 deg.C, respectively.
From the above results, it can be concluded that:
1. the optimal increment of the Hcj is more than 11KOe when the pressure is between 1MPa and 5.8MPa, the optimal increment of the Hcj does not reach 11KOe when the pressure is lower than 1MPa or higher than 5.8MPa, and the optimal increment of the Hcj is lower when the pressure is higher than 1MPa and 5.8MPa.
2. The temperature is changed, the air pressure intensity during diffusion is changed, the diffusion effect of the magnet can be improved, and the diffusion source can be diffused inwards due to the pressure and does not enter the main phase.
3. This experiment from examples 5-2-1 to 5-6-1, it was found that there is a relationship between the increase in Hcj and the pressure temperature, which is approximately equal to
Increment of Hcj = (T-860)/30 + (P +4 MPa)/MPa + K,1 formula;
increment of Hcj =22.4- { (T-860)/30 + (P +4 MPa)/MPa + K },2 formula, and when the increment of Hcj calculated by 1 formula is greater than 11.5KOe, the calculation is performed by 2 formula
Wherein T is temperature, P is pressure intensity, K is a numerical value which changes along with the pressure, the constant is 2.2 when the pressure is 1-5 MPa, and the K is greatly reduced when the pressure is higher than 5MPa or lower than 1 MPa.
The results of the embodiment of the invention show that the difference between the actual increment of Hcj and the increment obtained by the formula is within 0.25 KOe.
Example 6:
s1, selecting different-grade matrixes, preparing the matrixes by a conventional powder metallurgy process, generally smelting, crushing, press-forming, sintering and wire-cutting the matrixes to obtain cylindrical matrixes phi 10mm/10mm, and performing acid-washing etching treatment by using FeCl with the acid-washing solution of which the concentration is 5% 3 5g of solution with 5% HNO 3 5g of alcohol solution is mixed to obtain the alcohol.
S2, depositing a diffusion source on the surface of the magnet after acid cleaning and etching by a multi-arc sputtering method, specifically performing magnetron sputtering physical vapor deposition in a plasma vacuum coating machine, wherein the diffusion source is terbium hydride. The thickness of the terbium hydride film layer is 10mm, and the weight ratio of the terbium hydride film layer to the magnet is 1.2 percent, so that the magnet with the terbium hydride film layer deposited on the surface is obtained.
S3, placing the magnet with the surface deposited with the terbium hydride film layer into a high-temperature high-pressure sintering furnace for diffusion treatment, wherein the diffusion temperature is 890 ℃, the time is 9 hours, and before the diffusion is started, vacuumizing is carried out until the absolute vacuum degree is 1.0 multiplied by 10 -3 Pa, then filling argon to 5MPa, after the diffusion is finished, vacuumizing to 1.0 multiplied by 10 -3 Pa, and performing vacuum air cooling with the cooling rate of 5 ℃/min. Cooling to room temperature, tempering at 445 deg.C for 4.5h, vacuum air cooling at 5 deg.C/min, and cooling to room temperature.
And S4, carrying out surface treatment on the diffused magnet, and then carrying out component test and performance test, wherein the steps are the same as S4 of the embodiment 1.
The control had no diffusion source coating step, and the rest of the procedure was the same.
TABLE 8 base Components of different designations
| Nd | Pr | Dy | B | Fe | Ho | Al | Co | Cu | Ga | Gd | Tb | Zr | |
| N38M | 22.86 | 5.51 | 0.62 | 0.99 | Balance of | 0.55 | 0.69 | 0.85 | 0.21 | 0.12 | 0.33 | 0.09 | 0.05 |
| N35SH | 20.45 | 5.48 | 2.40 | 0.99 | Allowance of | 0.97 | 0.24 | 1.51 | 0.19 | 0.25 | 0.13 | 0.25 | 0.13 |
| N40UH | 20.20 | 6.02 | 4.15 | 0.96 | Allowance of | 0.28 | 1.54 | 0.15 | 0.33 | 0.06 | 0.11 | ||
| 42SH | 22.65 | 7.11 | 1.43 | 0.93 | Allowance of | 0.41 | 0.5 | 0.348 | 0.242 | ||||
| N50H | 21.54 | 6.71 | 0.94 | Balance of | 0.12 | 1.40 | 0.14 | 0.30 | 1.15 | 0.11 | |||
| N42UH | 22.46 | 7.10 | 0.56 | 0.96 | Balance of | 0.44 | 1.72 | 0.14 | 0.17 | 0.70 | 0.21 | 0.11 | |
| N38SH | 22.32 | 7.31 | 1.05 | 0.94 | Balance of | 1.49 | 0.45 | 0.79 | 0.15 | 0.20 | 0.14 | ||
| N45M | 21.97 | 7.15 | 0.93 | Balance of | 0.49 | 0.20 | 0.38 | 0.27 |
TABLE 9 Performance of control and examples
From the above results, it can be concluded that:
magnets of other brands are suitable for the above formula:
increment of Hcj = (T-860)/30 + (P +4 MPa)/MPa + K,1 formula;
increment of Hcj =22.4- { (T-860)/30 + (P +4 MPa)/MPa + K },2 formula, and when the increment of Hcj calculated by 1 formula is greater than 11.5KOe, the calculation is performed by 2 formula
Wherein T is temperature, P is pressure intensity, K is a numerical value changing with the pressure, the constant is 2.2 when the pressure is 1-5 MPa, and K is greatly reduced when the pressure is higher than 5MPa or lower than 1MPa
In this example, the theoretical increment of Hcj is 14.2KOe, which is calculated according to equation 1, and is greater than 11.5KOe, so that the theoretical increment of Hcj is calculated to be 10.2 by using equation 2 instead, and the difference is within 0.16KOe compared with the actual increment of Hcj.
According to multiple experiments, when the pressure is 1-5 MPa, the diffusion temperature is 860-980 ℃, the diffusion time is 8-12 h, and the thickness of the heavy rare earth element diffusion layer is 10-25 mu m, the theoretical increment of Hcj is calculated by adopting the formula, and the experimental result shows that the difference value between the actual increment of Hcj and the increment obtained by the formula is basically within 0.25 KOe.
To summarize: this experiment can accurately obtain the numerical value of Hcj increment through changing temperature and pressure, to the production experiment, can carry out the precomputation through the diffusion formula, sets for technology, obtains required magnet performance rapidly, has reduced loaded down with trivial details experimental step, all has the significance to production, research and development.
Claims (10)
1. A diffusion method for improving the performance of a sintered NdFeB magnet, characterized in that the method comprises the steps of:
(1) Carrying out acid washing and etching on the sintered NdFeB magnet matrix by using a pickling solution, wherein the pickling solution is prepared by mixing a ferric chloride aqueous solution and a nitric acid alcohol solution, and FeCl is contained in the pickling solution 3 1.5-3.5 percent of nitric acid and 1.5-3.5 percent of nitric acid to obtain an acid-washed etched magnet, and then depositing a heavy rare earth element diffusion layer on the surface of the acid-washed etched magnet;
(2) Performing diffusion treatment on the magnet with the heavy rare earth element diffusion layer deposited on the surface: the diffusion temperature is 800-1000 ℃, the heat preservation time is 0.5-48 h, argon is introduced until the pressure is 1-10 MPa, and tempering treatment is carried out after cooling to prepare the high-performance sintered NdFeB magnet after diffusion.
2. The method according to claim 1, wherein in the step (1), the weight loss ratio of the acid-washed and etched magnet is 0.06% to 0.13%.
3. The method according to claim 1, wherein in the step (1), the heavy rare earth element diffusion layer has a thickness of 10 to 30 μm in a weight ratio of 1.2 to 3.4% of the weight of the magnet.
4. The method according to claim 1, wherein in the step (1), the sintered NdFeB magnet matrix is a magnet matrix having a rare earth content of 30.5wt% or less.
5. The method according to claim 1, wherein in the step (1), the heavy rare earth element diffusion source is a pure heavy rare earth element metal, a heavy rare earth element hydride, a fluoride or an oxide, or an alloy of a heavy rare earth element with other metal elements, and the heavy rare earth element is at least one of Dy, tb or Ho.
6. The method of claim 1, wherein in the step (2), the diffusion temperature is 860 to 980 ℃ and the holding time is 6 to 12 hours.
7. The method according to claim 1, wherein in the step (2), the pressure is 1MPa to 5.8MPa.
8. The method according to claim 1, wherein in the step (2), after the diffusion heat preservation is finished, the vacuum air cooling is performed at a cooling rate of 3-8 ℃/min.
9. A diffused, high-performance sintered NdFeB magnet produced by the method according to any one of claims 1 to 8, wherein the mass fraction of the diffusion source entering the magnet is 0.28 to 0.83%, and the Hcj increment is in the range of 3 to 11.5KOe.
10. The magnet of claim 9, wherein the theoretical value of Hcj delta is calculated by the formula:
the diffusion pressure is within 1-5 Mpa, and the Hcj increment formula is as follows:
increment of Hcj = (T-860)/30 + (P +4 MPa)/MPa + K,1 formula;
hcj increment =22.4- { (T-860)/30 + (P +4 MPa)/MPa + K },2, when Hcj increment calculated by formula 1 is greater than 11.5KOe, calculated by formula 2; wherein T is temperature, P is pressure intensity, K is a numerical value changing along with the pressure, and the constant is 2.2 when the pressure is 1-5 MPa.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211626912.0A CN115863040A (en) | 2022-12-16 | 2022-12-16 | Diffusion method for improving performance of sintered NdFeB magnet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211626912.0A CN115863040A (en) | 2022-12-16 | 2022-12-16 | Diffusion method for improving performance of sintered NdFeB magnet |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115863040A true CN115863040A (en) | 2023-03-28 |
Family
ID=85673826
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211626912.0A Pending CN115863040A (en) | 2022-12-16 | 2022-12-16 | Diffusion method for improving performance of sintered NdFeB magnet |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115863040A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN119274957A (en) * | 2024-10-26 | 2025-01-07 | 瑞金麦戈科技(北京)有限公司 | High-efficiency preparation method of NdFeB magnets based on grain boundary diffusion |
| CN119943556A (en) * | 2023-11-02 | 2025-05-06 | 浙江东阳东磁稀土有限公司 | Diffusion method of high-Ga low-B magnets, NdFeB magnets |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010075856A2 (en) * | 2009-01-02 | 2010-07-08 | Ries, Ernst | Method for cooling the troposphere |
| CN110534331A (en) * | 2019-09-23 | 2019-12-03 | 广西科技大学 | A kind of preparation method of high energy product, high-coercive force Sintered NdFeB magnet |
| CN112420305A (en) * | 2020-11-10 | 2021-02-26 | 四川大学 | Grain boundary diffusion method for improving magnetic property of rare earth permanent magnetic material |
| CN112927921A (en) * | 2021-03-18 | 2021-06-08 | 昆明理工大学 | Method for preparing high-coercivity sintered neodymium-iron-boron magnet through crystal boundary diffusion |
| CN114141522A (en) * | 2021-11-18 | 2022-03-04 | 安徽大地熊新材料股份有限公司 | Method for improving coercive force of sintered neodymium-iron-boron magnet and application |
| CN114464444A (en) * | 2022-01-25 | 2022-05-10 | 浙江英洛华磁业有限公司 | Grain boundary diffusion method for improving diffusion performance of R-T-B magnet |
| CN115172034A (en) * | 2022-06-28 | 2022-10-11 | 山西师范大学 | Step-by-step grain boundary diffusion process for high-performance sintered neodymium-iron-boron magnet |
-
2022
- 2022-12-16 CN CN202211626912.0A patent/CN115863040A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010075856A2 (en) * | 2009-01-02 | 2010-07-08 | Ries, Ernst | Method for cooling the troposphere |
| CN110534331A (en) * | 2019-09-23 | 2019-12-03 | 广西科技大学 | A kind of preparation method of high energy product, high-coercive force Sintered NdFeB magnet |
| CN112420305A (en) * | 2020-11-10 | 2021-02-26 | 四川大学 | Grain boundary diffusion method for improving magnetic property of rare earth permanent magnetic material |
| CN112927921A (en) * | 2021-03-18 | 2021-06-08 | 昆明理工大学 | Method for preparing high-coercivity sintered neodymium-iron-boron magnet through crystal boundary diffusion |
| CN114141522A (en) * | 2021-11-18 | 2022-03-04 | 安徽大地熊新材料股份有限公司 | Method for improving coercive force of sintered neodymium-iron-boron magnet and application |
| CN114464444A (en) * | 2022-01-25 | 2022-05-10 | 浙江英洛华磁业有限公司 | Grain boundary diffusion method for improving diffusion performance of R-T-B magnet |
| CN115172034A (en) * | 2022-06-28 | 2022-10-11 | 山西师范大学 | Step-by-step grain boundary diffusion process for high-performance sintered neodymium-iron-boron magnet |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN119943556A (en) * | 2023-11-02 | 2025-05-06 | 浙江东阳东磁稀土有限公司 | Diffusion method of high-Ga low-B magnets, NdFeB magnets |
| CN119274957A (en) * | 2024-10-26 | 2025-01-07 | 瑞金麦戈科技(北京)有限公司 | High-efficiency preparation method of NdFeB magnets based on grain boundary diffusion |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5477282B2 (en) | R-T-B system sintered magnet and manufacturing method thereof | |
| US8420160B2 (en) | Method for producing sintered NdFeB magnet | |
| EP3438997B1 (en) | Method for grain boundary diffusion of r-fe-b rare earth sintered magnets, hre diffusion source and preparation method therefor | |
| EP3182423B1 (en) | Neodymium iron boron magnet and preparation method thereof | |
| CN105185497B (en) | A kind of preparation method of permanent-magnet material | |
| CN109616310B (en) | High-coercivity sintered neodymium-iron-boron permanent magnet material and manufacturing method thereof | |
| EP3121823B1 (en) | Method for preparing grain boundary diffused rare earth permanent magnetic material by vapor deposition using composite target | |
| JP5831451B2 (en) | Method for producing RTB-based sintered magnet | |
| JP6385551B1 (en) | Method for enhancing coercive force of Nd-Fe-B magnetic material | |
| WO2007102391A1 (en) | R-Fe-B RARE EARTH SINTERED MAGNET AND METHOD FOR PRODUCING SAME | |
| CN115863040A (en) | Diffusion method for improving performance of sintered NdFeB magnet | |
| US9805850B2 (en) | NdFeB permanent magnet and method for producing the same | |
| WO2008075709A1 (en) | Permanent magnet and method for producing permanent magnet | |
| WO2017107247A1 (en) | Method for improving magnetic properties of sintered neodymium-iron-boron thin-sheet magnet | |
| CN112670073A (en) | Sintered neodymium iron boron grain boundary diffusion tool and grain boundary diffusion method | |
| JPWO2010013774A1 (en) | Corrosion-resistant magnet and manufacturing method thereof | |
| CN109576546B (en) | Preparation method of high-strength and high-toughness non-magnetic Ti (C, N) -based metal ceramic | |
| CN108922709A (en) | Anti- demagnetization functionally gradient permanent-magnet material of one kind and preparation method thereof | |
| CN103219146A (en) | Method for enhancing magnet performance through reducing-dispersing method | |
| WO2015051756A1 (en) | Surface treatment method and preparation method of a sintered ndfeb magnet | |
| JP2005150503A (en) | Manufacturing method of sintered magnet | |
| CN110033940A (en) | A kind of rare-earth iron-boron permanent-magnet material and preparation method thereof containing Al and Cu | |
| Kong et al. | Effect of surface etching on the magnetic properties and grain-boundary Dy-diffusion in DyH2-dip-coated sintered Nd-Fe-B magnets | |
| CN114141522B (en) | Method for improving coercivity of sintered NdFeB magnet and application | |
| CN114717469A (en) | Diffusion source for R-Fe-B series rare earth permanent magnetic material, preparation method thereof and application of diffusion source in grain boundary diffusion method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| CB03 | Change of inventor or designer information | ||
| CB03 | Change of inventor or designer information |
Inventor after: Zhu Xiaohang Inventor after: Wu Langjing Inventor after: Wang Rongjie Inventor after: Zhang Zhaoneng Inventor after: Shen Xiaojie Inventor after: He Xiangjun Inventor before: Zhu Xiaohang Inventor before: Wu Langjing Inventor before: Wang Rongjie Inventor before: Zhang Zhaoneng Inventor before: Shen Xiaojie Inventor before: He Xiangjun |