阅读说明：本技术 镧铈添加钕铁硼磁体的制备方法 (Preparation method of lanthanum-cerium-added neodymium-iron-boron magnet ) 是由 陈秀雷 彭众杰 董占吉 丁开鸿 于 2021-09-16 设计创作，主要内容包括：本发明公开了一种镧铈添加钕铁硼磁体的制备方法,属于磁体制备领域,按照一定元素比例配料,使用真空甩带炉分别制备R1和R2两种合金。两种合金经过氢处理后,分别磨成粒度不同的两种粉末,将两种粉末按照一定的比例混粉,经过成型和取向,冷等静压、烧结、时效等工序得到磁体。通过本专利提供的方法制备的添加镧或铈后的磁体具有较高的性能。(The invention discloses a preparation method of a lanthanum-cerium-added neodymium-iron-boron magnet, belonging to the field of magnet preparation, wherein the lanthanum-cerium-added neodymium-iron-boron magnet is prepared by proportioning according to a certain element proportion and respectively preparing two alloys of R1 and R2 by using a vacuum melt-spinning furnace. After hydrogen treatment, the two alloys are respectively ground into two kinds of powder with different particle sizes, the two kinds of powder are mixed according to a certain proportion, and the magnet is obtained through the working procedures of forming, orientation, cold isostatic pressing, sintering, aging and the like. The magnet added with lanthanum or cerium prepared by the method provided by the patent has higher performance.)

1. The preparation method of the lanthanum-cerium-added neodymium iron boron magnet is characterized by comprising the following steps of:

step (S1) preparing an R1 alloy and an R2 alloy according to proportion by using a vacuum melt-spinning furnace, wherein the R1 alloy contains La and/or Ce elements, and the R2 alloy does not contain the La and/or Ce elements;

step (S2), the R1 alloy and the R2 alloy are respectively subjected to hydrogen absorption and dehydrogenation process treatment and then respectively milled into powder by using airflow milling, after the powder is milled into powder by the airflow milling, the average particle sizes of the R1 alloy powder and the R2 alloy powder meet the relational expression, and the particle size of the R2 alloy powder/the particle size of the R1 alloy powder is more than or equal to 0.32 and less than or equal to 0.66;

a step (S3) of mixing the two alloy powders;

and (S4) forming and orienting the mixed powder, cold isostatic pressing, sintering and aging to obtain the magnet.

2. The method for preparing lanthanum-cerium-added neodymium-iron-boron magnet according to claim 1, which is characterized in that: the total content of rare earth elements in the composition of the R1 alloy in step (S1) is 29.00 to 31.00 wt.%.

3. The method for preparing lanthanum-cerium-added neodymium-iron-boron magnet according to claim 2, which is characterized in that: in the rare earth elements of the R1 alloy, the content of La and/or Ce is 6.00-20.00 wt.%, and the balance is Nd and/or Pr.

4. The method for preparing lanthanum-cerium-added neodymium-iron-boron magnet according to claim 1, which is characterized in that: in the step (S1), the rare earth element contained in the R2 alloy is Pr and/or Nd, and the content thereof is in the range of 33.10 to 35.00 wt.%.

5. The method for preparing lanthanum-cerium-added neodymium-iron-boron magnet according to claim 1, which is characterized in that: in the step (S2), the average particle size of the R1 alloy powder is in the range of 3.1 to 5.5 μm, and the average particle size of the R2 alloy powder is in the range of 1.0 to 3.6 μm.

6. The method for preparing lanthanum-cerium-added neodymium-iron-boron magnet according to claim 1, which is characterized in that: in the step (S1), the R1 alloy and the R2 alloy include, but are not limited to, B, Co, Cu, Ga, Ti, Al, and Fe elements.

7. The method for preparing lanthanum-cerium-added neodymium-iron-boron magnet according to claim 1, which is characterized in that: in the step (S3), the mixing ratio of the R1 alloy powder and the R2 alloy powder is 1: 1.

Technical Field

The invention relates to the field of magnet preparation, in particular to a preparation method of a lanthanum-cerium-added neodymium iron boron magnet.

Background

The addition of the high-abundance light rare earth elements is an important means for reducing the material cost of the neodymium-iron-boron magnet. However, the high-abundance rare earth elements such as lanthanum and cerium have lower magnetic performance parameters, and the magnetic performance is obviously reduced after the rare earth elements are added. Nd (neodymium)₂Fe₁₄J of B_s(magnetic polarization strength) 1.61T, H_A(magnetocrystalline anisotropy field) 73 kOe; pr (Pr) of₂Fe₁₄J of B_sIs 1.56T, H_AIs 75 kOe; and La₂Fe₁₄J of B_sIs 1.38T, H_AIs 20 kOe; ce₂Fe₁₄J of B_sIs 1.17T, H_AWas 26 kOe. In order to reduce the influence of elements such as lanthanum and cerium on the magnetic performance of the rare earth magnetic material as much as possible, in recent years, the magnet is optimized by adopting a multi-main-phase process, surface layer grain boundary diffusion, intercrystalline addition and other modes in the industry. Chinese patent with publication number CN102800454A and named as low-cost double-main-phase Ce permanent magnet alloy and preparation method thereof, by forming two different H types of Nd-Fe-B and (Ce, Re) -Fe-B_AThe main phase of the magnetic material can obtain higher magnetic performance. However, the H of the (Ce, Re) -Fe-B main phase in this process_AThe reduction is excessive, limiting the improvement of magnetic performance. The method for adding the coercive force of a neodymium-hydride cerium-iron-boron sintered magnet is disclosed as CN106710768A and is characterized in that NdH is added on the basis of a double-main-phase process_XThe powder mode forms a hard magnetic layer of Nd on the outer layer of the Nd-Ce-Fe-B to improve the magnetocrystalline anisotropy field, and the mode effectively improves the coercive force. However, this method requires three kinds of powders to be prepared and then mixed, and the process is complicated. And the problem of dehydrogenation needs to be considered in the sintering process of the added NdHx powder, so that the process difficulty is increased. The method for preparing the low-cost sintered neodymium iron boron by doping lanthanum and cerium with the authorization notice number CN102842400B can prevent excessive lanthanum and cerium from entering a main phase of the neodymium iron boron by adding lanthanum and cerium powder treated by a special process to replace a neodymium-rich phase of the neodymium iron boron, thereby achieving the effect of improving the product performance and reducing the cost. However, lanthanum and cerium are the most active rare earth elements, and lanthanum and cerium powder is very easy to oxidize and nitrify, so that the addition effect is influenced. The manufacturing process of the lanthanum-cerium powder is difficult, and the process control cost is high.

Disclosure of Invention

The purpose of the invention is as follows: in order to overcome the defects in the prior art, the invention provides a preparation method of a lanthanum-cerium-added neodymium iron boron magnet, which aims to solve the problem of over-low performance of the magnet caused by adding light rare earth lanthanum or cerium.

The technical scheme is as follows: in order to achieve the purpose, the preparation method of the lanthanum-cerium-added neodymium iron boron magnet comprises the following steps:

step (S1) preparing an R1 alloy and an R2 alloy according to proportion by using a vacuum melt-spinning furnace, wherein the R1 alloy contains La and/or Ce elements, and the R2 alloy does not contain the La and/or Ce elements;

step (S2), the R1 alloy and the R2 alloy are respectively subjected to hydrogen absorption and dehydrogenation processes and then respectively milled into powder by using airflow, after the powder is milled into powder by the airflow, the average particle sizes of the R1 alloy powder and the R2 alloy powder meet the relational expression, and the particle size of the R2 alloy powder/the particle size of the R1 alloy powder is less than or equal to 0.66;

a step (S3) of mixing the two alloy powders;

the powder mixed in the step (S4) is formed into a magnet through the processes of molding, orientation, cold isostatic pressing, sintering, aging and the like.

Preferably, the total content of rare earth elements in the composition of the R1 alloy in the step (S1) is 29.00 to 31.00 wt.%.

Further, in the rare earth elements of the R1 alloy, the content of La and/or Ce is 6.00-20.00 wt.%, and the balance is Nd and/or Pr.

Preferably, in the step (S1), the rare earth element contained in the R2 alloy is Pr and/or Nd, and the content thereof is in the range of 33.10 to 35.00 wt.%.

Preferably, in the step (S2), the average particle size of the R1 alloy powder is in the range of 3.1 to 5.5 μm, and the average particle size of the R2 alloy powder is in the range of 1.0 to 3.6 μm.

Preferably, in the step (S1), the R1 alloy and the R2 alloy include, but are not limited to, B, Co, Cu, Ga, Ti, Al, and Fe elements.

Preferably, in the step (S3), the mixing ratio of the R1 alloy powder and the R2 alloy powder is 1: 1.

The preparation method of the lanthanum-cerium-added neodymium-iron-boron magnet at least has the following technical effects: the R2 alloy powder without lanthanum and cerium has higher total rare earth content to form more praseodymium and neodymium-rich phases, and meanwhile, the alloy powder can be better coated on the periphery of large lanthanum and cerium-containing particles because the average particle size of the alloy powder is smaller; the praseodymium-neodymium-rich phase introduced by coating the small particles can be diffused to the periphery of the lanthanum-cerium-containing large particles in the sintering and aging processes, and a hard magnetic layer is formed on the outer side of the large particles, so that the magnetic property of the main phase containing lanthanum and cerium is improved, and the magnetic property deterioration caused by adding lanthanum and cerium is weakened; the grain diameter ratio of the two kinds of alloy powder is limited by the scheme, so that a better coating effect can be obtained, the rare earth content of the two kinds of alloy powder is limited, a proper rare earth concentration gradient can be generated, and the rich praseodymium and neodymium phase can fully coat the outer side of the lanthanum-containing cerium particles.

Drawings

Fig. 1 is a structural mechanism diagram of a lanthanum-cerium-added neodymium-iron-boron magnet.

Detailed Description

The principles and features of the present invention are described below in conjunction with fig. 1, which is provided by way of example only to illustrate the present invention and not to limit the scope of the present invention.

Example 1

Step (S1) batching in proportion, and preparing R1 alloy and R2 alloy using a vacuum melt-spun furnace. Wherein, the types and contents (mass percent) of each element in the R1 alloy are as follows: 23.00% of Nd, 6.00% of Ce, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance of Fe and inevitable impurities; the R2 alloy comprises the following elements in percentage by mass: 35.00% of Pr, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance Fe and inevitable impurities. The R1 alloy and the R2 alloy were respectively formed into thin strip alloy pieces by using a vacuum strip casting furnace.

Step (S2) is to grind the R1 alloy into powder with average grain size of 5.5 μm and grind the R2 alloy into powder with average grain size of 3.6 μm after conventional hydrogen absorption and dehydrogenation processes.

The step (S3) mixes the R1 alloy powder and the R2 alloy powder, wherein the weight ratio of the R1 alloy powder and the R2 alloy powder is 50.0%.

And (S4) uniformly mixing, then carrying out processes of molding, orientation, cold isostatic pressing and the like, then sintering for 5 hours at 1030 ℃, cooling to room temperature, then heating to 850 ℃, preserving heat for 3 hours, cooling to room temperature, then heating to 500 ℃, and preserving heat for 3 hours. And (5) carrying out magnetic property test on the obtained sample.

Example 2

Step (S1) batching in proportion, and preparing R1 alloy and R2 alloy using a vacuum melt-spun furnace. Wherein, the types and contents (mass percent) of each element in the R1 alloy are as follows: 8.8% of Nd, 2.2% of Pr, 10% of Ce, 10.00% of La, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance of Fe and inevitable impurities; the R2 alloy comprises the following elements in percentage by mass: 26.5% of Nd, 6.6% of Pr, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance Fe and inevitable impurities, and the R1 alloy and the R2 alloy were respectively formed into thin strip alloy pieces using a vacuum strip furnace.

Step (S2) is to grind the R1 alloy into powder with average grain size of 3.1 μm and grind the R2 alloy into powder with average grain size of 1.0 μm after conventional hydrogen absorption and dehydrogenation process treatment.

The step (S3) mixes the R1 alloy powder and the R2 alloy powder, wherein the weight ratio of the R1 alloy powder and the R2 alloy powder is 50.0%.

And (S4) uniformly mixing, then carrying out processes of molding, orientation, cold isostatic pressing and the like, then sintering for 5 hours at 1030 ℃, cooling to room temperature, then heating to 850 ℃, preserving heat for 3 hours, cooling to room temperature, then heating to 500 ℃, and preserving heat for 3 hours. And (5) carrying out magnetic property test on the obtained sample.

Example 3

Step (S1) batching in proportion, and preparing R1 alloy and R2 alloy using a vacuum melt-spun furnace. Wherein, the types and contents (mass percent) of each element in the R1 alloy are as follows: 18% of Pr, 12% of La, 0.95% of B, 1% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance Fe and inevitable impurities; the R2 alloy comprises the following elements in percentage by mass: 34% of Nd, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance Fe and inevitable impurities. The R1 alloy and the R2 alloy were respectively formed into thin strip alloy pieces by using a vacuum strip casting furnace.

Step (S2) is to grind the R1 alloy into powder with average grain size of 4.0 μm and grind the R2 alloy into powder with average grain size of 2.0 μm after conventional hydrogen absorption and dehydrogenation processes.

The step (S3) mixes the R1 alloy powder and the R2 alloy powder, wherein the weight ratio of the R1 alloy powder and the R2 alloy powder is 50.0%.

And (S4) uniformly mixing, then carrying out processes of molding, orientation, cold isostatic pressing and the like, then sintering for 5 hours at 1030 ℃, cooling to room temperature, then heating to 850 ℃, preserving heat for 3 hours, cooling to room temperature, then heating to 500 ℃, and preserving heat for 3 hours. And (5) carrying out magnetic property test on the obtained sample.

The rare earth element contents in the R1 alloy and the R2 alloy in examples 1 to 3 are shown in table 1, and the particle sizes of the R1 alloy powder and the R2 alloy powder and the magnetic properties of the resulting magnets in examples 1 to 3 are shown in table 2.

Rare earth element content of alloy in example of Table 1

Table 2: example alloy powder particle size and magnetic Properties

Comparative example 1

Step (S1) batching in proportion, and preparing R1 alloy and R2 alloy using a vacuum melt-spun furnace. Wherein, the types and contents (mass percent) of each element in the R1 alloy are as follows: 23.00% of Nd, 6.00% of Ce, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance of Fe and inevitable impurities; the R2 alloy comprises the following elements in percentage by mass: 35.00% of Pr, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance Fe and inevitable impurities. The R1 alloy and the R2 alloy were respectively formed into thin strip alloy pieces by using a vacuum strip casting furnace.

Step (S2) is to grind the R1 alloy into powder with average grain size of 3.6 μm and grind the R2 alloy into powder with average grain size of 3.6 μm after conventional hydrogen absorption and dehydrogenation process treatment.

The step (S3) mixes the R1 alloy powder and the R2 alloy powder, wherein the weight ratio of the R1 alloy powder and the R2 alloy powder is 50.0%.

And (S4) uniformly mixing, then carrying out processes of molding, orientation, cold isostatic pressing and the like, then sintering for 5 hours at 1030 ℃, cooling to room temperature, then heating to 850 ℃, preserving heat for 3 hours, cooling to room temperature, then heating to 500 ℃, and preserving heat for 3 hours. And (5) carrying out magnetic property test on the obtained sample.

Comparative example 2

The R1 alloy and the R2 alloy are prepared by proportioning and using a vacuum melt-spun furnace. Wherein, the types and contents (mass percent) of each element in the R1 alloy are as follows: 26.00% of Nd, 6.00% of Ce, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance of Fe and inevitable impurities; the R2 alloy comprises the following elements in percentage by mass: 32.00% of Pr, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance of Fe and inevitable impurities. The R1 alloy and the R2 alloy were respectively formed into thin strip alloy pieces by using a vacuum strip casting furnace.

Step (S2) is to grind the R1 alloy into powder with average grain size of 5.5 μm and grind the R2 alloy into powder with average grain size of 3.6 μm after conventional hydrogen absorption and dehydrogenation processes.

The step (S3) mixes the R1 alloy powder and the R2 alloy powder, wherein the weight ratio of the R1 alloy powder and the R2 alloy powder is 50.0%.

And (S4) uniformly mixing, then carrying out processes of molding, orientation, cold isostatic pressing and the like, then sintering for 5 hours at 1030 ℃, cooling to room temperature, then heating to 850 ℃, preserving heat for 3 hours, cooling to room temperature, then heating to 500 ℃, and preserving heat for 3 hours. And (5) carrying out magnetic property test on the obtained sample.

Comparative example 3

Step (S1) batching in proportion, and preparing R1 alloy and R2 alloy using a vacuum melt-spun furnace. Wherein, the types and contents (mass percent) of each element in the R1 alloy are as follows: 7.2% of Nd, 1.8% of Pr, 11% of Ce, 11.00% of La, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance of Fe and inevitable impurities; the R2 alloy comprises the following elements in percentage by mass: 26.5% of Nd, 6.6% of Pr, 0.95% of B (boron), 1.00% of Co, 0.60% of Al, 0.15% of Cu, 0.40% of Ga, 0.15% of Ti, and the balance of Fe and inevitable impurities. The R1 alloy and the R2 alloy were respectively formed into thin strip alloy pieces by using a vacuum strip casting furnace.

Step (S2) is to grind the R1 alloy into powder with average grain size of 3.1 μm and grind the R2 alloy into powder with average grain size of 1 μm after conventional hydrogen absorption and dehydrogenation process treatment.

The step (S3) mixes the R1 alloy powder and the R2 alloy powder, wherein the weight ratio of the R1 alloy powder and the R2 alloy powder is 50.0%.

And (S4) uniformly mixing, then carrying out processes of molding, orientation, cold isostatic pressing and the like, then sintering for 5 hours at 1030 ℃, cooling to room temperature, then heating to 850 ℃, preserving heat for 3 hours, cooling to room temperature, then heating to 500 ℃, and preserving heat for 3 hours. And (5) carrying out magnetic property test on the obtained sample.

The rare earth element contents in the alloys of comparative examples 1 to 3 are shown in Table 3, and the particle sizes of the alloy powders and the magnetic properties of the obtained magnets of comparative examples 1 to 3 are shown in Table 4.

TABLE 3 content of rare earth element in comparative example alloy

TABLE 4 comparative example alloy powder particle size and magnetic Properties

From the above, it can be seen that when the final cerium content of the magnet in example 1 is 3.00 wt.% by the method of the present invention, Br is 12.45kGs, Hcj is 19.35 kOe; the magnet of example 2 had a final lanthanum cerium content of 10.00 wt.% with Br of 12.05kGs and Hcj of 16.13 kOe; the magnet of example 3 had a final lanthanum content of 6.00 wt.% Br of 12.43kGs and Hcj of 17.05 kOe; therefore, better magnetic performance can be obtained under the limited conditions of the invention.

Example 1 was the same in composition as comparative example 1, except that the milled powder sizes of alloy R1 and alloy R2 in example 1 were 5.5 μm and 3.6 μm, respectively, and the two alloy powders had appropriate particle size differences, which resulted in a better clad structure, and the magnetic properties of the final magnet were Br12.45kGs, Hcj19.35kOe. Whereas the average particle sizes of the R1 alloy powder and the R2 alloy powder in comparative example 1 were both 3.6 μm, the coercive force of the final magnet was not as high as that of example 1, although the average particle size of the R1 alloy powder was finer relative to that of the R1 alloy powder in comparative example 1. This is because in comparative example 1, the R1 alloy powder and the R2 alloy powder have no particle size difference, and it is difficult to form a structure in which the praseodymium-neodymium rich phase is sufficiently coated, and further, it is difficult to form an effective hard magnetic layer at the periphery of the main phase particle containing lanthanum and cerium by element diffusion during sintering and heat treatment. In comparative example 2, compared with example 1, the particle sizes of the R1 and R2 alloy powders are consistent, and the total amount of rare earth and the content of cerium after mixing are also consistent. However, the total amount of rare earth in the R2 alloy in the comparative example 2 is lower, namely 32.00 wt.%, so that the praseodymium-neodymium-rich phase in the R2 powder is less. Even though the cladding structure is formed by the grain size difference of the R1 powder and the R2 powder, there is not enough praseodymium-neodymium rich phase wrapping the outside of the lanthanum-containing cerium particles, it is difficult to form enough hard magnetic layer during sintering aging, and finally Br is 12.34kGs, Hcj is 18.27kOe, which is lower than the magnetic performance of example 1. The magnetic performance of the comparative example 3 is poor mainly because the magnetic parameters of the magnet are reduced due to the excessively high addition amount of lanthanum and cerium, and meanwhile, the excessively high addition amount of lanthanum and cerium is easy to generate impurity phases, so that the macroscopic magnetic performance is low.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.