阅读说明：本技术 超高性能烧结钐钴磁体的制备方法 (Preparation method of ultrahigh-performance sintered samarium-cobalt magnet ) 是由 宋奎奎 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种超高性能烧结钐钴磁体的制备方法,包括1)铸锭a的制备；2)铸锭b的制备；3)制粉；4)混粉钝化；5)磁场成型、等静压；6)烧结固溶、时效处理。本发明对铸锭进行高温均匀化热处理,同时在高压惰性气氛及金属皮的双重保护下,减少了铸锭的稀土挥发和氧化,得到的磁体均匀性较好,力学性能好。(The invention discloses a preparation method of an ultrahigh-performance sintered samarium-cobalt magnet, which comprises the following steps of 1) preparing an ingot a; 2) preparing an ingot b; 3) milling; 4) passivating the mixed powder; 5) magnetic field forming and isostatic pressing; 6) sintering, solid solution and aging treatment. According to the invention, the ingot is subjected to high-temperature homogenization heat treatment, and meanwhile, under the double protection of high-pressure inert atmosphere and metal skin, the volatilization and oxidation of rare earth of the ingot are reduced, and the obtained magnet has good uniformity and good mechanical property.)

1. A preparation method of an ultrahigh-performance sintered samarium-cobalt magnet is characterized by comprising the following steps:

1) samarium cobalt alloy raw materials are prepared according to the following weight percentages: sm: 26-29%, Fe: 12-25%, Zr: 2-5%, Cu: 3-8% and the balance of Co;

smelting and casting the prepared samarium-cobalt alloy raw material in an inert atmosphere to obtain an alloy ingot a;

2) wrapping the ingot a with a metal skin, then carrying out heat preservation treatment at 1130-1190 ℃ for 4-10 h under an inert atmosphere with the pressure of 1-5 MPa, and then rapidly air-cooling to room temperature to obtain an ingot b;

3) preparing alloy powder by sequentially carrying out mechanical crushing, intermediate crushing and airflow grinding on the ingot b under the protection of nitrogen;

4) adding a lubricant with the total weight of 0.2-0.5 per mill into the alloy powder, and simultaneously supplementing 1000-5000 ppm of oxygen, and mixing the powder for 0.5-3 hours to obtain alloy magnetic powder;

5) directly weighing the alloy magnetic powder in the air, then carrying out orientation molding in an open press, wherein the magnetic field intensity of the orientation molding is 1.2-2T, and then carrying out cold isostatic pressing, wherein the cold isostatic pressing pressure is 200-300 MPa, so as to prepare a green body;

6) carrying out heat preservation on the green body at 500-800 ℃ for 0.5-2 h for exhausting treatment, carrying out heat preservation at 1160-1190 ℃ for 0.5-2 h for presintering, heating to 1190-1220 ℃ for sintering for 0.5-2 h for densification treatment, then cooling to 1130-1180 ℃ for 2-8 h for solid solution treatment, and rapidly cooling to room temperature by air; and then heating to 600-800 ℃, keeping the temperature for 3-5 h, then heating to 800-900 ℃, keeping the temperature for 5-40 h, then controlling the temperature, cooling to 400 ℃, keeping the temperature for 1-20 h, and air-cooling to the room temperature to obtain the sintered samarium-cobalt magnet.

2. The method of making an ultra-high performance sintered samarium cobalt magnet of claim 1 wherein the samarium cobalt alloy starting material of step 1) is melted and cast under argon.

3. The method of making an ultra-high performance sintered samarium cobalt magnet of claim 1 wherein the ingot a wrapped in step 2) is subjected to a heat-preserving treatment under argon protection.

4. The method of making an ultra-high performance sintered samarium cobalt magnet of claim 1, wherein the samarium cobalt alloy starting material is formulated in weight percent as follows: sm: 26-29%, Fe: 12-25%, Zr: 2-4%, Cu: 5-8% and the balance of Co.

5. The method of making an ultra-high performance sintered samarium cobalt magnet of claim 1 wherein the alloy powder after crushing in step 3) has a particle size of 3 to 6 μm.

6. The method of making an ultra-high performance sintered samarium cobalt magnet of claim 1 wherein the orientation molding magnetic field strength in step 5) is 2.0T and the cold isostatic pressure is 300 MPa.

7. The method of making an ultra-high performance sintered samarium cobalt magnet of claim 1, wherein after densification in step 6), first cooling to 1150-1180 ℃ for 1-3 hours of high temperature solution treatment, and finally cooling to 1130-1150 ℃ for 2-6 hours of low temperature solution treatment, and rapidly air cooling to room temperature; and then heating to 800-900 ℃, keeping the temperature for 5-40 h, cooling to 620 ℃ at the speed of 0.6-1 ℃/min, keeping the temperature for 2-5 h, cooling to 400 ℃ at the speed of 0.6-1 ℃/min, keeping the temperature for 1-20 h, and air-cooling to room temperature to obtain the sintered samarium-cobalt magnet.

8. A sintered samarium cobalt magnet obtained by the process of any of claims 1 to 7.

Technical Field

The present invention relates to a magnetic material. More specifically, the invention relates to a method for preparing an ultra-high performance sintered samarium cobalt magnet.

Background

The rare earth permanent magnet material is mainly developed in three stages, namely a first generation 1:5 type samarium cobalt permanent magnet material, a second generation 2:17 type samarium cobalt permanent magnet material and a third generation neodymium-iron-boron permanent magnet material, and the second generation 2:17 type samarium cobalt permanent magnet material has higher magnetic property, low temperature coefficient and pole due to higher magnetic propertyHas strong corrosion resistance and is widely applied to instruments and equipment such as aerospace and ship propulsion systems, but the squareness (knee point coercive force H) of samarium cobalt_k) The magnetic material is a main index for measuring the uniformity of the magnet, the size of the magnetic material directly determines the high-temperature magnetic loss of the material, however, the higher the magnetic energy product of the samarium cobalt is, the lower the squareness of the samarium cobalt is, and how to enable the samarium cobalt magnet to have both high magnetic energy product and high squareness directly determines the development of the samarium cobalt material.

Generally, a large amount of iron element is added into alloy, however, the higher the content of the iron element is, the poorer the squareness of the magnet is, and further the improvement of the magnetic energy product is restricted, so how to improve the squareness of the magnet through the improvement of the process is a problem to be solved urgently.

The phase structure of the samarium cobalt magnet mainly comprises a samarium cobalt 2:17R main phase, a 1:5H cell wall phase and a zirconium-rich sheet phase, the residual magnetism of the samarium cobalt mainly depends on the 2:17R main phase, the coercive force is from pinning of the 1:5H cell wall relative to a domain wall, the 2:17R main phase and the 1:5H phase are from decomposition of a solid solution phase 1:7H phase in the aging process, if the solid solution of the samarium cobalt magnet is not uniform, other impurity phases are contained in the magnet, the performance of the magnet is inevitably deteriorated, most of enterprises adopt the technology for obtaining qualified magnetic performance to infinitely increase the time for sintering and solid solution, however, the technology can cause over-thick blank oxide scale, increase the difficulty of post-processing and simultaneously cause waste of a large amount of materials, so a new high-performance preparation technology is urgently needed to be researched, and the invention with the application publication number of CN 102543340B discloses a preparation method of high-performance samarium cobalt, however, the heat treatment process is long (the ingot, the magnetic powder and the magnet are respectively subjected to heat treatment), which is equivalent to that the samarium cobalt is subjected to twice sintering and solution treatment, so that a large amount of rare earth is volatilized and oxidized, the squareness and the magnetic energy product of the magnet are low, and the maximum potential of the samarium cobalt magnet can be exerted by adopting a proper formula and a proper ingot treatment process.

Disclosure of Invention

An object of the present invention is to solve at least the above problems and to provide at least the advantages described later.

The invention also aims to provide a preparation method of the ultrahigh-performance sintered samarium cobalt magnet, which is used for carrying out high-temperature homogenization heat treatment on the cast ingot, simultaneously reducing the volatilization and oxidation of rare earth of the cast ingot under the double protection of high-pressure inert atmosphere and metal skin, and obtaining the magnet with better uniformity and mechanical property.

To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a method of manufacturing an ultra-high performance sintered samarium cobalt magnet, comprising:

1) samarium cobalt alloy raw materials are prepared according to the following weight percentages: sm: 26-29%, Fe: 12-25%, Zr: 2-5%, Cu: 3-8% and the balance of Co;

smelting and casting the prepared samarium-cobalt alloy raw material in an inert atmosphere to obtain an alloy ingot a;

2) wrapping the ingot a with a metal skin, then carrying out heat preservation treatment at 1130-1190 ℃ for 4-10 h under an inert atmosphere with the pressure of 1-5 MPa, and then rapidly air-cooling to room temperature to obtain an ingot b;

3) preparing alloy powder from the cast ingot b by mechanical crushing, medium crushing and airflow grinding in sequence under the protection of nitrogen;

4) adding a lubricant with the total weight of 0.2-0.5 per mill into the alloy powder, and simultaneously supplementing 1000-5000 ppm of oxygen, and mixing the powder for 0.5-3 hours to obtain alloy magnetic powder;

5) directly weighing the alloy magnetic powder in the air, then carrying out orientation molding in an open press, wherein the magnetic field intensity of the orientation molding is 1.2-2T, and then carrying out cold isostatic pressing, wherein the cold isostatic pressing pressure is 200-300 MPa, so as to prepare a green body;

6) carrying out heat preservation on the green body at 500-800 ℃ for 0.5-2 h for exhausting treatment, carrying out heat preservation at 1160-1190 ℃ for 0.5-2 h for presintering, heating to 1190-1220 ℃ for sintering for 0.5-2 h for densification treatment, then cooling to 1130-1180 ℃ for 2-8 h for solid solution treatment, and rapidly cooling to room temperature by air; and then heating to 600-800 ℃, keeping the temperature for 3-5 h, then heating to 800-900 ℃, keeping the temperature for 5-40 h, then controlling the temperature, cooling to 400 ℃, keeping the temperature for 1-20 h, and air-cooling to the room temperature to obtain the sintered samarium-cobalt magnet.

Preferably, the samarium cobalt alloy raw material in the step 1) is smelted and cast under the protection of argon.

Preferably, the ingot a wrapped in the step 2) is subjected to heat preservation treatment under the protection of argon.

Preferably, the samarium cobalt alloy raw material is prepared according to the following weight percentage: sm: 26-29%, Fe: 12-25%, Zr: 2-4%, Cu: 5-8% and the balance of Co.

Preferably, the granularity of the alloy powder crushed in the step 3) is 3-6 μm.

Preferably, the orientation molding magnetic field intensity in the step 5) is 2.0T, and the cold isostatic pressure is 300 MPa.

Preferably, after the densification treatment in the step 6), firstly cooling to 1150-1180 ℃ for 1-3 h of high-temperature solid solution treatment, finally cooling to 1130-1150 ℃ for 2-6 h of low-temperature solid solution treatment, and quickly cooling to room temperature by air; and then heating to 800-900 ℃, keeping the temperature for 5-40 h, cooling to 620 ℃ at the speed of 0.6-1 ℃/min, keeping the temperature for 2-5 h, cooling to 400 ℃ at the speed of 0.6-1 ℃/min, keeping the temperature for 1-20 h, and air-cooling to room temperature to obtain the sintered samarium-cobalt magnet.

The sintered samarium cobalt magnet obtained by the preparation method.

The invention at least comprises the following beneficial effects:

the invention adopts the high-pressure high-purity inert atmosphere and the double protection of the metal sheet to carry out homogenization treatment on the cast ingot to prepare a series of sintered samarium-cobalt magnets with very excellent magnetic property, and meanwhile, the magnets have excellent mechanical property, the bending strength is more than 160MPa, the compressive strength is more than 300MPa, and the sintered samarium-cobalt magnets have better economic benefit and are suitable for industrialization.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Detailed Description

The present invention is further described in detail below with reference to examples to enable those skilled in the art to practice the invention with reference to the description.

It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.

It is to be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified.

The preparation method of the ultrahigh-performance sintered samarium-cobalt magnet comprises the following steps:

1) preparation of an ingot a:

samarium cobalt alloy raw materials are prepared according to the following weight percentages: sm: 26-29%, Fe: 12-25%, Zr: 2-5%, Cu: 3-8% and the balance of Co;

preferably Sm: 26-29%, Fe: 12-25%, Zr: 2-4%, Cu: 5-8% and the balance of Co;

smelting and casting the prepared samarium cobalt alloy raw material in an inert atmosphere (comprehensive cost and effect, preferably under the protection of argon, aiming at effectively preventing volatilization of Sm and oxidation of cast ingots), wherein the smelting is carried out in a medium-frequency smelting furnace, and the casting is carried out in a cold water copper mold of a disc to obtain alloy cast ingots a with the thickness of about 6 mm;

2) preparation of an ingot b:

wrapping the ingot a with a metal skin, then carrying out heat preservation treatment at the temperature of 1130-1190 ℃ for 4-10 h under the inert atmosphere with the pressure of 1-5 MPa (the comprehensive cost and effect are preferably carried out under the protection of argon with the purity of 99.999%), and then rapidly air-cooling to the room temperature to obtain an ingot b with the thickness of about 6 mm;

the thickness of the metal sheet is 0.05-6 mm, and the material is preferably high temperature (1200 ℃) resistant metal alloy, stainless steel, iron sheet, etc. Adopt high-purity argon gas to protect, the purpose is the volatilization of tombarthite and the ingot casting oxidation under the effectual protection high temperature state, adopts highly compressed purpose to improve the speed of ingot casting homogenization, reduces the time of solid solution and reduces the temperature of solid solution, can cause the superficial layer oxidation of ingot casting if pressure is low excessively to cause the performance deterioration of magnet, if pressure is too high can have safe hidden danger, argon gas non-cyclic utilization moreover can cause the waste of resource.

3) Milling:

sequentially carrying out mechanical crushing, medium crushing and airflow grinding on the cast ingot b under the protection of nitrogen to prepare alloy powder with the average particle size of 3-6 microns;

4) mixed powder passivation:

adding a lubricant with the total weight of 0.2-0.5 per mill into the alloy powder, and simultaneously supplementing 1000-5000 ppm of oxygen, wherein in order to ensure uniform mixing, the powder mixing time is 0.5-3 h, so as to prepare alloy magnetic powder;

the proper oxygen is supplemented in the powder mixing process, so that the magnet can be fully combined with the oxygen, and therefore, a uniformly distributed rare earth-rich phase (Sm) is formed in the magnet in the subsequent sintering process₂O₃) The rich-rare earth phase can absorb a large amount of energy in a mechanical experiment, and the stress concentration of the material is reduced, so that the mechanical property of the material is improved, and the sintered samarium-cobalt magnet with better mechanical property is obtained.

5) Magnetic field forming, isostatic pressing:

the in-process of mixing powder adopts the oxygenating technique to carry out effective passivation to alloy powder for alloy powder after the mixture can directly weigh the material in the air, and in opening the press in the orientation shaping, had both avoided the dangerous phenomenon of powder contact oxygen spontaneous combustion like this, and convenient operation is swift simultaneously, then carries out cold isostatic pressing again, prepares out the unburned bricks, specifically does: directly weighing the alloy magnetic powder in the air, then carrying out orientation molding in an open press, wherein the magnetic field intensity of the orientation molding is 1.2-2T, and then carrying out cold isostatic pressing, wherein the cold isostatic pressing pressure is 200-300 MPa, so as to prepare a green body;

6) sintering solid solution and aging treatment:

carrying out exhaust treatment on the green body at 500-800 ℃ for 0.5-2 h, carrying out presintering at 1160-1190 ℃ for 0.5-2 h, heating to 1190-1220 ℃, sintering for 0.5-2 h for densification, then carrying out solid solution treatment in two steps, firstly cooling to 1150-1180 ℃ for 1-3 h for solid solution treatment, then cooling to 1130-1150 ℃ for 2-6 h for solid solution treatment, and rapidly cooling to room temperature by air; and heating to 600-800 ℃, keeping the temperature for 3-5 h, then heating to 800-900 ℃, keeping the temperature for 5-40 h, then controlling the temperature, cooling to 400 ℃, keeping the temperature for 1-20 h, and air-cooling to room temperature to obtain the sintered samarium-cobalt magnet.

The oxygen content of the prepared sintered samarium-cobalt magnet is 1000-5000 ppm, the bending strength is more than 160MPa, and the compressive strength is more than 300 MPa.

< example 1>

The preparation method of the ultrahigh-performance sintered samarium-cobalt magnet comprises the following steps:

1) preparation of an ingot a:

samarium cobalt alloy raw materials are prepared according to the following weight percentages: 28.3 percent of Sm, 20.5 percent of Fe, 2.5 percent of Zr, 5.5 percent of Cu and the balance of Co;

smelting and casting the prepared samarium cobalt alloy raw material in a high-purity helium atmosphere, wherein the smelting is carried out in a medium-frequency smelting furnace, and the casting is carried out in a cold water copper cooling mold to obtain an alloy ingot a with the thickness of about 6 mm;

2) preparation of an ingot b:

wrapping the cast ingot a with an iron sheet with the thickness of 2mm, then carrying out heat preservation treatment at 1135 ℃ for 6h under a high-purity helium atmosphere (the purity is 99.999%) with the pressure of 3.5MPa, and then rapidly cooling to room temperature by air to obtain a cast ingot b with the thickness of about 6 mm;

3) milling:

sequentially carrying out mechanical crushing, medium crushing and airflow grinding on the cast ingot b under the protection of nitrogen to prepare alloy powder with the average particle size of 3.45 microns;

4) mixed powder passivation:

adding a lubricant with the total weight of 0.35 per mill into the alloy powder, and simultaneously supplementing 2000ppm of oxygen, wherein in order to ensure uniform mixing, the powder mixing time is 2.5 hours, so as to prepare alloy magnetic powder;

5) magnetic field forming, isostatic pressing:

directly weighing the alloy magnetic powder after powder mixing in air, then carrying out orientation molding in an open press, wherein the orientation molding magnetic field intensity is 1.8T, then carrying out cold isostatic pressing, and the cold isostatic pressing pressure is 290MPa to prepare a green body;

6) sintering solid solution and aging treatment:

keeping the temperature of the green body at 780 ℃ for 1h for degassing treatment, keeping the temperature at 1170 ℃ for 0.5h for presintering, heating to 1200 ℃ for sintering for 1.5h for densification treatment, then carrying out solution treatment in two steps, firstly cooling to 1170 ℃ for 2h for solution treatment, then cooling to 1135 ℃ for 6h for solution treatment, and rapidly cooling to room temperature by air; and heating to 680 ℃, preserving heat for 4h, then heating to 830 ℃, preserving heat for 24h, then cooling to 635 ℃ at the speed of 0.65 ℃/min, preserving heat for 5h, then cooling to 400 ℃ at the speed of 0.8 ℃/min, preserving heat for 10h, and air-cooling to room temperature to obtain the sintered samarium-cobalt magnet.

The oxygen content of the prepared sintered samarium cobalt magnet was 2200 ppm. Bending strength is 165MPa, and compressive strength is more than 320 MPa.

< example 2>

The preparation method of the ultrahigh-performance sintered samarium-cobalt magnet comprises the following steps:

1) preparation of an ingot a:

samarium cobalt alloy raw materials are prepared according to the following weight percentages: 27.6 percent of Sm, 17 percent of Fe, 2.7 percent of Zr, 5.9 percent of Cu and the balance of Co;

smelting and casting the prepared samarium cobalt alloy raw material in a high-purity helium atmosphere, wherein the smelting is carried out in a medium-frequency smelting furnace, and the casting is carried out in a cold water copper cooling mold to obtain an alloy ingot a with the thickness of about 6 mm;

2) preparation of an ingot b:

wrapping the cast ingot a with alloy stainless steel with the thickness of 1mm, then carrying out heat preservation treatment at 1148 ℃ for 5h under the atmosphere of high-purity helium with the pressure of 3MPa (the purity is 99.999%), and then rapidly cooling to room temperature by air to obtain a cast ingot b with the thickness of about 6 mm;

3) milling:

sequentially carrying out mechanical crushing, medium crushing and airflow grinding on the cast ingot b under the protection of nitrogen to prepare alloy powder with the average particle size of 3.85 microns;

4) mixed powder passivation:

adding a lubricant with the total weight of 0.26 per mill into the alloy powder, and simultaneously supplementing 3000ppm of oxygen, wherein in order to ensure uniform mixing, the powder mixing time is 2 hours, so as to prepare alloy magnetic powder;

5) magnetic field forming, isostatic pressing:

directly weighing the alloy magnetic powder after powder mixing in air, then carrying out orientation molding in an open press, wherein the orientation molding magnetic field intensity is 1.6T, then carrying out cold isostatic pressing, and the cold isostatic pressing pressure is 260MPa, thus preparing a green body;

6) sintering solid solution and aging treatment:

the green body is subjected to heat preservation for 1h at 760 ℃ for exhaust treatment, is subjected to heat preservation for 1h at 1175 ℃ for presintering, is heated to 1204 ℃ for sintering for 1.5h for densification treatment, and then is subjected to solution treatment in two steps, namely, the green body is firstly cooled to 1180 ℃ for 2h for solution treatment, is then cooled to 1140 ℃ for 5h for solution treatment, and is quickly air-cooled to room temperature; and heating to 660 ℃, keeping the temperature for 5h, heating to 845 ℃, keeping the temperature for 18h, cooling to 635 ℃ at the speed of 0.78 ℃/min, keeping the temperature for 4h, cooling to 400 ℃ at the speed of 0.8 ℃/min, keeping the temperature for 10h, and cooling to room temperature by air to obtain the sintered samarium-cobalt magnet.

The oxygen content of the prepared sintered samarium cobalt magnet was 2700 ppm. Bending strength 175MPa, and compression strength more than 360 MPa.

< example 3>

The preparation method of the ultrahigh-performance sintered samarium-cobalt magnet comprises the following steps:

1) preparation of an ingot a:

samarium cobalt alloy raw materials are prepared according to the following weight percentages: 26.5 percent of Sm, 15 percent of Fe, 3.2 percent of Zr, 6.3 percent of Cu and the balance of Co;

smelting and casting the prepared samarium cobalt alloy raw material in a high-purity helium atmosphere, wherein the smelting is carried out in a medium-frequency smelting furnace, and the casting is carried out in a cold water copper cooling mold to obtain an alloy ingot a with the thickness of about 6 mm;

2) preparation of an ingot b:

wrapping the cast ingot a with an alloy low-carbon steel sheet with the thickness of 3mm, then carrying out heat preservation treatment at 1155 ℃ for 4 hours under a high-purity argon atmosphere with the pressure of 2MPa (the purity is 99.999%), and then quickly cooling to room temperature to obtain a cast ingot b with the thickness of about 6 mm;

3) milling:

sequentially carrying out mechanical crushing, medium crushing and airflow grinding on the cast ingot b under the protection of nitrogen to prepare alloy powder with the average particle size of 4.55 mu m;

4) mixed powder passivation:

adding a lubricant with the total weight of 0.4 per mill into the alloy powder, and simultaneously supplementing 4000ppm of oxygen, wherein in order to ensure uniform mixing, the powder mixing time is 3 hours, so as to prepare alloy magnetic powder;

5) magnetic field forming, isostatic pressing:

directly weighing the alloy magnetic powder after powder mixing in the air, then carrying out orientation molding in an open press, wherein the orientation molding magnetic field intensity is 1.5T, then carrying out cold isostatic pressing, and the cold isostatic pressing pressure is 240MPa to prepare a green body;

6) sintering solid solution and aging treatment:

carrying out heat preservation on the green body at 720 ℃ for 1h for exhausting treatment, carrying out heat preservation at 1185 ℃ for 1.5h for presintering, heating to 1208 ℃ for sintering for 1h for densification treatment, then carrying out solid solution treatment in two steps, firstly cooling to 1185 ℃ for 2h for solid solution treatment, then cooling to 1143 ℃ for 4h for solid solution treatment, and rapidly cooling to room temperature by air; and heating to 700 ℃, keeping the temperature for 4h, heating to 865 ℃, keeping the temperature for 18h, cooling to 620 ℃ at the speed of 0.88 ℃/min, keeping the temperature for 2.5h, cooling to 400 ℃ at the speed of 0.75 ℃/min, keeping the temperature for 4h, and cooling to room temperature by air to obtain the sintered samarium-cobalt magnet.

The oxygen content of the prepared sintered samarium cobalt magnet was 3400 ppm. Bending strength is 180MPa, and compressive strength is more than 420 MPa.

< example 4>

The preparation method of the ultrahigh-performance sintered samarium-cobalt magnet comprises the following steps:

1) preparation of an ingot a:

samarium cobalt alloy raw materials are prepared according to the following weight percentages: 26.2 percent of Sm, 13 percent of Fe, 2.7 percent of Zr, 6.3 percent of Cu and the balance of Co;

smelting and casting the prepared samarium cobalt alloy raw material in a high-purity helium atmosphere, wherein the smelting is carried out in a medium-frequency smelting furnace, and the casting is carried out in a cold water copper cooling mold to obtain an alloy ingot a with the thickness of about 6 mm;

2) preparation of an ingot b:

wrapping the cast ingot a with an iron sheet with the thickness of 1.5mm, then carrying out heat preservation treatment at 1170 ℃ for 4h under a high-purity argon atmosphere with the pressure of 2MPa (the purity is 99.999%), and then quickly cooling to room temperature to obtain an cast ingot b with the thickness of about 6 mm;

3) milling:

sequentially carrying out mechanical crushing, medium crushing and airflow grinding on the cast ingot b under the protection of nitrogen to prepare alloy powder with the average particle size of 5.35 mu m;

4) mixed powder passivation:

adding a lubricant with the total weight of 0.45 per mill into the alloy powder, and simultaneously supplementing 5000ppm of oxygen, wherein in order to ensure uniform mixing, the powder mixing time is 3 hours, so as to prepare alloy magnetic powder;

5) magnetic field forming, isostatic pressing:

directly weighing the alloy magnetic powder after powder mixing in air, then carrying out orientation molding in an open press, wherein the orientation molding magnetic field intensity is 1.4T, then carrying out cold isostatic pressing, and the cold isostatic pressing pressure is 240MPa to prepare a green body;

6) sintering solid solution and aging treatment:

carrying out heat preservation on the green body at 780 ℃ for 1h for exhausting treatment, carrying out heat preservation at 1185 ℃ for 1.5h for presintering, heating to 1213 ℃ for sintering for 2h for densification treatment, then cooling to 1150 ℃ for 3h for solid solution treatment, and rapidly cooling to room temperature by air; and heating to 885 ℃, preserving heat for 10h, cooling to 400 ℃, preserving heat for 1h, and cooling to room temperature by air to obtain the sintered samarium-cobalt magnet.

The oxygen content of the prepared sintered samarium cobalt magnet was 4100 ppm. Bending strength is 180MPa, and compressive strength is more than 440 MPa.

< comparative example 1>

A method for producing an ultra-high performance sintered samarium cobalt magnet, similar to example 1, except that step 2) was not included, namely, the method was carried out without carrying out the homogenization treatment, and the crushing, molding and heat treatment were carried out directly.

< comparative example 2>

The method for producing an ultra-high performance sintered samarium cobalt magnet, as in example 2, was different in that step 2) was not included, that is, the pulverization, molding and heat treatment were carried out without the homogenization treatment.

< comparative example 3>

A method for producing an ultra-high performance sintered samarium cobalt magnet, similar to example 3, except that step 2) was not included, namely, the method was carried out without carrying out the homogenization treatment, and the crushing, molding and heat treatment were carried out directly.

< comparative example 4>

A method for producing an ultra-high performance sintered samarium cobalt magnet, which was the same as in example 4 except that the step 2) was not included, namely, the pulverization, molding and heat treatment were carried out without carrying out the homogenization treatment.

In order to verify the preparation method of the ultrahigh-performance sintered samarium cobalt in the patent of the invention, the performance indexes of examples 1 to 4 and comparative examples 1 to 4 are respectively listed in the following table 1. The preparation method of the ultrahigh-performance sintered samarium cobalt magnet (high magnetic energy product and high knee point coercive force) can be seen, the samarium cobalt cast ingot is subjected to homogenization treatment under the double protection of high-pressure argon and a metal sheet, and the magnetic performance of the magnet is obviously improved.

TABLE 1

	Br(kGs)	Hcj(kOe)	(BH)max(MGOe)	Hk(kOe)
					Example 1	11.74	>25	32.95	19.31
Example 2	11.30	>25	30.2	20.83
					Example 3	10.73	>25	27.11	20.35
Example 4	10.43	>25	24.21	20.45
					Comparative example 1	11.67	>25	31.72	9.83
Comparative example 2	11.27	>25	29.48	11.14
					Comparative example 3	10.70	>25	26.29	12.22
Comparative example 4	10.41	>25	23.35	12.68

The number of apparatuses and the scale of the process described herein are intended to simplify the description of the present invention. Applications, modifications and variations of the present invention will be apparent to those skilled in the art.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable to various fields of endeavor for which the invention may be embodied with additional modifications as would be readily apparent to those skilled in the art, and the invention is therefore not limited to the details given herein and to the examples shown and described without departing from the generic concept as defined by the claims and their equivalents.