CN103714928A - Ferro-cerium-based rapid quenching permanent magnet powder and preparation method of ferro-cerium-based rapid quenching permanent magnet powder - Google Patents

Abstract

The invention relates to a cerium-iron-based quick-quenching permanent magnet powder and its preparation technology. The alloy composition chemical formula of the cerium-iron-based quick-quenching permanent magnet powder is: [Ce _100-x , Re _x ] _a Fe _100-abc B _b TM _c , wherein , x is the mass percentage of the total amount of rare earth, a, b and c respectively represent the mass percentage of the corresponding element, 0≤x≤50%, 27.5%≤a≤32%; 0.8%≤b≤1.5%; 0.5%≤c ≤5%; Re is one or more of Nd, Pr, Dy, Tb elements, TM is one or more of Ga, Co, Cu, Nb, Al elements; the present invention adopts water-cooled electromagnetic roller (copper Alloy roller or molybdenum roller) can prepare two kinds of magnetic powders, cerium-iron-based permanent magnet powder and Ce-free Re'-Fe-B. Using the above two magnetic powders, cerium with double hard magnetic main phase or multiple hard magnetic main phase can be prepared. Iron-based hot-pressed magnets. The invention fills the blank of medium and low-grade magnetic powder in the current market, and the product has high cost performance and is suitable for engineering production.

Description

A kind of cerium-iron-based quick-quenching permanent magnet powder and preparation method thereof

technical field

The invention belongs to the technical field of rare earth permanent magnet materials, and in particular relates to a cerium-iron-based quick-quenching permanent magnet powder and a preparation method thereof.

Background technique

The quick-quenching permanent magnet powder is the core material of the hot-pressed/thermo-rheological permanent magnet, which determines the performance of the magnet. The hot-pressed/thermo-rheological process has the characteristics of simplicity, low temperature, short time, and near-net forming, especially in the radiation orientation and It is unique in the preparation of multi-pole oriented magnetic rings and nano-two-phase composite magnets. The metal neodymium Nd in the current hot-pressed/thermo-rheological NdFeB magnets accounts for more than 90% of the cost of raw materials. With the increasing production of rare earth permanent magnets in the world in recent years, the use of a large amount of metal neodymium makes the application of rare earth elements extremely unbalanced. The new hot-pressed cerium-iron-based quick-quenching permanent magnet powder and its preparation technology of the present invention are to realize the balanced application of rare earth elements. The major breakthrough has great practical significance.

Among natural rare earth resources, besides Nd, there is abundant and cheap metal cerium Ce. However, because the magnetic moment Js and anisotropy field H _A of Ce ₂ Fe ₁₄ B are much lower than that of Nd ₂ Fe ₁₄ B, the products prepared by traditional preparation methods cannot meet the performance requirements of users. In the prior art, the Chinese patent application CN101694797A discloses that the Ce content does not exceed 40wt% of the total amount of rare earths, the production is quick-setting tape, and the final permanent magnet material product is mainly magnetic powder for bonded magnets. In CN102220538A, the main phase (Re ₂ Fe ₁₄ B) alloy does not contain La and Ce; in the auxiliary phase alloy (also known as liquid phase alloy or rare earth-rich phase alloy), the maximum value of Ce accounting for the total weight of the auxiliary phase alloy is 30wt%, and the maximum value of La accounting for the total weight of the auxiliary phase alloy is 25wt%. In the embodiment, the main phase alloy and the auxiliary phase alloy are mixed at the highest ratio of 88:12, and the total amount of Ce and La in the final magnet does not exceed that of the magnet. 12wt% of the total amount of medium rare earths, and the above-mentioned prior art is aimed at so-called low weight loss magnets (the weight loss is as high as 2mg/cm ² ). In CN102360657A, the total amount of rare earth accounts for 35wt% of the total weight of "N35 lanthanum cerium magnet", while La-Ce only accounts for 20wt% of the total amount, and the examples of this application do not provide the ratio of La and Ce to the total amount of rare earth respectively. Percentage, obviously, the proportion of La and Ce is different, and the magnetic properties of the final magnet are also different. It is impossible to appear the only result given in the embodiment, Be=12kOe, Hcj=12.6kOe, (BH)max=34.2MGOe.

In short, the above-mentioned patent applications/patents involve rare earth permanent magnet materials of Ce element, whose Ce content is less than (or equal to) 40% of the total amount of rare earth, and the preparation of permanent magnet quick-setting tape is mostly used to manufacture isotropic bonded magnetic powder . Quick-setting sheet (belt) and quick-quenching sheet (belt) are two different concepts. The roll speed (surface line speed) when preparing quick-quenching sheet (belt) is in the range of 15-50m/s, and the quick-quenching sheet (belt) is amorphous. Ribbon or microcrystalline structure, usually can only be prepared as isotropic magnetic powder, used to make bonded magnets or single main phase hot-pressed magnets. The quick-setting belt is a kind of crystalline cast sheet (belt). The roll speed (surface linear speed) when preparing the quick-setting belt is in the range of 1 to 7m. Axial fine grain composition, mainly used to prepare sintered magnets. In the prior art, there has been no report on the use of high Ce in cerium-iron-based quick-quenching permanent magnet powder.

Contents of the invention

The object of the present invention is to provide a kind of cerium-iron-based quick-quenching permanent magnet powder and preparation method thereof, and this quick-quenching permanent magnet powder can be used for preparing cerium-iron-based hot-pressed/thermo-rheological magnet; or with a certain amount of Re'-Fe-B( Re' is a rare earth element that does not include Ce) and the magnetic powder is mixed in proportion to prepare a new dual (hard magnetic) main phase cerium-iron-based hot-pressed magnet and a conventional Ce-containing NdFeB hot-pressed magnet.

The purpose of the present invention is achieved through the following technical solutions:

A cerium-iron-based quick-quenching permanent magnet powder, the alloy composition chemical formula of the quick-quenching permanent magnet powder is: [Ce _100-x , Re _x ] _a Fe _100-abc B _b TM _c , wherein, x is the mass of Re in the total amount of rare earth Percentage, a, b and c respectively represent the mass percentage of the corresponding element, 0≤x≤50%, 27.5%≤a≤32%; 0.8%≤b≤1.5%; 0.5%≤c≤5%; Re is Nd, One or more of Pr, Dy, Tb elements, TM is one or more of Ga, Co, Cu, Nb, Al elements; wherein, the Ce content in the quick quenching permanent magnet powder is greater than the total amount of rare earth 50%, when Re is Nd, the Nd content is less than or equal to 50% of the total rare earth.

The described iron-based quick-quenching permanent magnet powder is prepared by the following method:

First, the electromagnetic roller of the rapid quenching process is used to prepare the cerium-iron-based rapid quenching permanent tape. The microstructure of the rapid quenching tape is microcrystalline, amorphous or equiaxed, and there will be no columnar crystals in the rapid setting tape prepared by the rapid setting process. ;

The obtained cerium-iron-based quick-quenching permanent magnetic tape is used to prepare two kinds of magnetic powders: cerium-iron-based permanent magnet powder and Ce-free Re'-Fe-B. By mixing the above two magnetic powders, a double hard magnetic main phase or multi-phase hard magnetic powder can be prepared. Cerium-iron-based hot-pressed magnets with hard magnetic main phase.

The preparation method of described iron-based quick-quenching permanent magnet powder,

First, an electromagnetic roller is used to prepare a cerium-iron-based quick-quenching permanent magnetic tape, and the obtained cerium-iron-based quick-quenching permanent magnetic tape is used to prepare a cerium-iron-based permanent magnetic powder and a Ce-free Re'-Fe-B magnetic powder. Using the above two magnetic powders, the A cerium-iron-based hot-pressed magnet with double hard magnetic main phases or multiple hard magnetic main phases is prepared, which specifically includes the following steps:

Step 1: Dosing according to the following composition chemical formula of mass percentage: [Ce _100-x , Re _x ] _a Fe _100-abc B _b TM _c , wherein x is the mass percentage of Re in the total amount of rare earth, a, b and c are respectively Indicates the mass percentage of the corresponding element, 0≤x≤50%, 27.5%≤a≤32%; 0.8%≤b≤1.5%; 0.5%≤c≤5%; Re is Nd, Pr, Dy, Tb elements One or more, TM is one or more of Ga, Co, Cu, Nb, Al elements;

Step 2: Put the prepared raw materials into the quick quenching equipment, then smelt at low temperature under the protection of Ar gas and conduct electromagnetic stirring refining. According to the roll speed and alloy composition, adjust the frequency of the water-cooled electromagnetic roll to zero or between 2000Hz and 9000Hz. Then cast on the surface layer 4 of a water-cooled electromagnetic roller with an electromagnetic frequency set at a linear speed of 15 to 45 m/s to obtain a quenched sheet or a quenched belt 3 with an average thickness of 0.01 to 0.06 mm;

Step 3: crushing the quenched sheet or the quenched belt 3 to obtain the quenched sheet or the quenched belt with a particle size ranging from 0.056 to 0.28 mm.

In the step 2: first put the raw material into the material loading device 1 of the medium frequency induction smelting equipment, use the heating coil 2 to preheat when the vacuum degree reaches 10 ^-2 Pa or more, and wait until the vacuum degree reaches 10 ^{-2 Pa} again Stop vacuuming and fill high-purity Ar after Pa is above, so that the Ar pressure in the furnace reaches -0.04~-0.08MPa and then smelt; after all the raw materials are melted, electromagnetic stirring is used for refining, and then molten steel is poured.

In step 3, according to the different requirements for the quenching sheet or the quenching belt 3, agitation mill or sand mill is used to make powder to obtain magnetic powder that meets the requirements, and prepare the precursor magnetic powder of the magnet.

In order to obtain magnetic powder with uniform particle size, vibrating sieves with different meshes from 45 mesh to 260 mesh are selected, and the magnetic powder is poured into the vibrating sieve for screening, and the magnetic powder with the required particle size is obtained through classification and screening.

The roll surface layer 4 is a copper alloy roll surface or a molybdenum roll surface.

The quick-quenched magnetic powder for the novel hot-pressed cerium-iron-based permanent magnet of the present invention has a crystal structure of Nd ₂ Fe ₁₄ B, but its Ce content is greater than or equal to 50% of the total amount of rare earths, and the content of Nd is less than or equal to 50% of the total amount of rare earths. 50%. By mixing this Ce-Fe-based quick-quenching magnetic powder with a certain amount of NdFeB magnetic powder, after hot pressing/thermo-rheological process, not only conventional NdFeB hot-pressed magnets containing Ce can be prepared, but also new-type NdFeB magnets can be prepared. Cerium-iron-based hot-pressed magnets with double hard magnetic phases or multiple hard magnetic phases.

The beneficial effects of the present invention are:

Compared with the prior art, the present invention has the following advantages:

1. The first is the quick-quenching sheet (tape) and anisotropic magnetic powder with high cerium content, and its cerium content is generally greater than or equal to 50% of the total amount of rare earth; ) smelting temperature and time are significantly reduced, which can save production time and energy consumption;

2. The oxidation resistance of cerium-iron-based quick-quenching sheet (belt) and anisotropic magnetic powder is obviously better than that of metal cerium, which solves the problem of easy oxidation of metal cerium when it is simply stored;

3. The present invention adopts a newly designed water-cooled electromagnetic roller (copper alloy roller surface or molybdenum alloy roller surface), and the prepared quick-quenching zone is basically microcrystalline, amorphous or equiaxed crystal structure, and there will be no quick-setting process Coarse columnar crystals in the prepared quick-setting zone.

4. The present invention is not a simple problem of replacing Nd with Ce. Because the cerium content is generally greater than or equal to 50% of the total amount of rare earths, the product is a novel CeFeB permanent magnet quick-quenching sheet (band) or magnetic powder, which not only can be prepared containing Ce's conventional NdFeB hot-pressed magnets can also prepare new-type cerium-iron-based hot-pressed magnets with double hard magnetic phases or multiple hard magnetic phases. This invention fills the gap of medium and low-grade magnetic powder in the current market. The product is cost-effective and suitable for engineering production.

reference sign

1 loading device

2 heating coils

3 quick-quenching sheet or quick-quenching belt

4 roll surface layers (copper alloy roll surface or molybdenum roll surface)

5 field coils (out)

6 magnetic field coils (in)

Description of drawings

Fig. 1 is a schematic diagram of the rapid quenching process of the present invention.

Fig. 2 is the hysteresis loop of the magnetic powder whose composition is (Ce ₉₀ Nd ₁₀ ) ₃₀ Fe _bal Co ₄ Ga _0.4 B _0.92 according to the present invention.

Fig. 3 is the hysteresis loop of the magnetic powder whose composition is (Ce ₇₀ Nd ₃₀ ) ₃₀ Fe _bal Co _3.9 Ga _0.4 Cu _0.1 B _0.92 according to the present invention.

Fig. 4 is the hysteresis loop of the magnetic powder whose composition is (Ce ₅₀ Nd ₅₀ ) ₃₀ Fe _bal Co _3.9 Ga _0.4 Al _0.1 B _0.92 according to the present invention.

Fig. 5 is the hysteresis loop of the magnetic powder whose composition is (Ce ₅₅ Nd ₄₂ ) ₃₀ Fe _bal Co _3.9 Ga _0.4 B _0.92 according to the present invention.

Fig. 6 is the hysteresis loop of the magnetic powder whose composition is (Ce ₅₀ Nd ₄₇ D _y1 Pr ₁ Tb ₁ ) ₃₂ Fe _bal Co _4.2 Ga _0.8 B _1.5 according to the present invention.

Fig. 7 is the hysteresis loop of the magnetic powder whose composition is (Ce ₇₄ Nd ₂₅ D _y1 ) _27,5 Fe _bal Ga _0.5 B _0.8 according to the present invention.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Using low temperature melting and rapid quenching process to prepare magnetic powder on copper alloy roll or molybdenum roll (as shown in Figure 1), the process steps are as follows:

Step 1: According to the chemical formula of the composition in mass percentage: [Ce _100-x , Re _x ] _a Fe _100-abc B _b TM _c to prepare raw materials (as shown in Table 1), wherein Re is Nd, Pr, Dy, Tb elements One or more of them, TM is one or more of Ga, Co, Cu, Nb, Al elements.

Table 1 Alloy composition chemical formula of different embodiments

nominal component Example 1 (Ce ₉₀ Nd ₁₀ ) ₃₀ Fe _bal Co ₄ Ga _0.4 B _0.92 Example 2 (Ce ₇₀ Nd ₃₀ ) ₃₀ Fe _bal Co _3.9 Ga _0.4 Cu _0.1 B _0.92 Example 3 (Ce ₅₀ Nd ₅₀ ) ₃₀ Fe _bal Co _3.9 Ga _0.4 Al _0.1 B _0.92 Example 4 (Ce ₅₅ Nd ₄₅ ) ₃₀ Fe _bal Co _3.9 Ga _0.4 B _0.92 Example 5 (Ce ₅₀ Nd ₄₇ D _y1 Pr ₁ Tb ₁ ) ₃₂ Fe _bal Co _4.2 Ga _0.8 B _1.5 Example 6 (Ce ₇₄ Nd ₂₅ D _y1 ) _27,5 Fe _bal Ga _0.5 B _0.8

Step 2: The prepared raw materials are smelted separately: as shown in Figure 1, first put the raw materials into the loading device 1 of the medium-frequency induction melting equipment, and use the heating coil 2 to feed the pre-heating when the vacuum degree reaches 10 ^-2 Pa or higher. After the vacuum degree reaches 10 ^-2 Pa again, stop vacuuming and fill high-purity Ar to make the Ar pressure in the furnace reach -0.04～-0.08MPa before melting; Refining with electromagnetic stirring, and then pouring molten steel onto the surface layer 4 of the roll with a line speed of 15-45m/s and an electromagnetic frequency set, to produce a quenched sheet 3 (strip) with an average thickness of 0.01-0.06mm.

The smelting equipment winds a conductive winding that matches its power on the outside of the iron core. This current-carrying coil is magnetic like a magnet, and it is also called an electromagnet. The electromagnet has many advantages: whether the magnetism of the electromagnet can be controlled by on and off current; the magnitude of the magnetism can be controlled by the strength of the current or the number of turns of the coil; the magnitude of the magnetism can also be controlled by changing the resistance to control the magnitude of the current ; its magnetic poles can be controlled by changing the direction of the current, and so on. That is: the strength of magnetism can be changed, the presence or absence of magnetism can be controlled, the direction of magnetic poles can be changed, and magnetism can disappear due to the disappearance of current.

Step 3: According to the different requirements for the quenching sheet 3 (tape), the precursor magnetic powder is prepared by stirring and grinding or hydrogen crushing to obtain the quenching sheet (tape) with a particle size range of 0.056-0.28 mm.

Step 4: In order to obtain magnetic powder with uniform particle size, select a vibrating sieve with different meshes (45 mesh to 260 mesh), pour the magnetic powder into the vibrating sieve for screening, and obtain the magnetic powder with the required particle size through classification and screening.

The specific process parameters of different embodiments are shown in Table 2.

Table 2 Alloy Preparation Process Parameters of Different Examples

Note: The thickness and average particle size of the quenched sheet are related to the speed of the roller and winnowing wheel. When the speed of the roller and winnowing wheel is higher, the thickness and particle size will be smaller.

The magnetic properties of the magnetic powder were measured by the Versalab multifunctional vibrating sample magnetometer, see Table 3 and accompanying drawings 2, 3, 4, 5, 6, and 7.

The magnetic property parameter of table 3 different embodiment alloys

B _r /kGs H _cj /kOe Example 1 5.765 3.508 Example 2 5.474 9.793 Example 3 5.305 12.500 Example 4 5.891 11.367 Example 5 6.313 11.459 Example 6 3.180 1.405

Claims (7)

1. a cerium iron-base quick-quenching permanent magnetism powder, is characterized in that, the alloying component chemical formula of fast quenching permanent magnetism powder is: [Ce _100-x, Re _x] _afe _100-a-b-cb _btM _c, wherein, x is the mass percent of Re in total amount of rare earth, a, and b and c represent respectively the mass percent of corresponding element, 0≤x≤50%, 27.5%≤a≤32%; 0.8%≤b≤1.5%; 0.5%≤c≤5%; Re is Nd, Pr, and Dy, one or more in Tb element, TM is Ga, Co, Cu, Nb, one or more in Al element; Wherein, the Ce content in this fast quenching permanent magnetism powder is greater than 50% of total amount of rare earth, and when Re is Nd, Nd content is less than or equal to 50% of total amount of rare earth.

2. iron-base quick-quenching permanent magnetism powder as claimed in claim 1, is characterized in that, by the following method preparation:

First adopt the electromagnetism roller of rapid quenching technique to prepare cerium iron-base quick-quenching permanent magnetism band, the microstructure of rapid tempering belt is crystallite, amorphous or equiax crystal, and there will not be the column crystal in quick setting belt prepared by strip casting;

With the cerium iron-base quick-quenching permanent magnetism band obtaining, prepare cerium iron-base permanent-magnet powder and do not contain two kinds of magnetics of Re '-Fe-B of Ce, utilizing above-mentioned two kinds of magnetics to mix, can prepare the ferrocerium base hot-pressed magnets of two Hard Magnetic principal phases or many Hard Magnetics principal phase.

3. a preparation method for iron-base quick-quenching permanent magnetism powder as claimed in claim 1, is characterized in that,

First adopt electromagnetism roller to prepare cerium iron-base quick-quenching permanent magnetism band, with the cerium iron-base quick-quenching permanent magnetism band obtaining, prepare cerium iron-base permanent-magnet powder and do not contain Re '-Fe-B magnetic of Ce, utilize above-mentioned two kinds of magnetics, the ferrocerium base hot-pressed magnets that can prepare two Hard Magnetic principal phases or many Hard Magnetics principal phase, specifically comprises the steps:

Step 1: the composition chemical formula according to following mass percent is prepared burden: [Ce _100-x, Re _x] _afe _100-a-b-cb _btM _c, wherein x is the mass percent of Re in total amount of rare earth, a, and b and c represent respectively the mass percent of corresponding element, 0≤x≤50%, 27.5%≤a≤32%; 0.8%≤b≤1.5%; 0.5%≤c≤5%; Re is Nd, Pr, and Dy, one or more in Tb element, TM is Ga, Co, Cu, Nb, one or more in Al element;

Step 2: the raw material preparing packs in fast quenching equipment, then low smelting heat and carry out electromagnetic agitation refining under Ar gas protection, according to roller speed and alloying component, the frequency of adjusting water-cooled electromagnetic roller is between zero or 2000Hz～9000Hz, then being cast in linear velocity is that 15～45m/s has arranged on the water-cooled electromagnetic roller roller superficial layer (4) of electromagnetic frequency, and making average thickness is fast quenching sheet or the rapid tempering belt (3) of 0.01～0.06mm;

Step 3: fast quenching sheet or rapid tempering belt (3) are carried out to fragmentation, obtain particle size range at fast quenching sheet or the rapid tempering belt of 0.056～0.28mm.

4. preparation method as claimed in claim 3, is characterized in that, in described step 2: first raw material are put into the material containing device (1) of the equipment of Medium frequency induction melting, reached 10 in vacuum degree ^-2when Pa is above, use heater coil (2) to feed electric preheating, treat that vacuum degree reaches 10 again ^-2after Pa is above, stop vacuumizing and being filled with high-purity Ar, make in stove after Ar air pressure reaches-0.04～-0.08MPa to carry out melting; Until raw material, all after fusing, impose electromagnetic agitation refining, carry out subsequently molten steel cast.

5. preparation method as claimed in claim 3, is characterized in that, in step 3, according to the different demands to fast quenching sheet or rapid tempering belt (3), adopts stirring mill or sand milling to carry out powder process, is met the magnetic of requirement, prepares forerunner's magnetic of magnet.

6. preparation method as claimed in claim 5, is characterized in that, in order to obtain the magnetic of uniform particle diameter, selects respectively the vibrating screen of 45 order～260 order different meshes, and magnetic is poured in vibrating screen and looked over so as to check, and by category filter, obtains the magnetic of required particle diameter.

7. preparation method as claimed in claim 3, is characterized in that, described roller superficial layer (4) is copper alloy roll surface or molybdenum roll surface.

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