阅读说明：本技术 低温度系数高使用温度烧结钐钴磁体的制备方法 (Preparation method of sintered samarium-cobalt magnet with low temperature coefficient and high use temperature ) 是由 宋奎奎 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种低温度系数高使用温度烧结钐钴磁体的制备方法,包括：1)铸锭a和b的制备；2)粉末的制备；3)粉末的混合；4)磁场成型、等静压；5)烧结固溶、时效处理。本发明将合金铸锭a(高温磁体)和铸锭b(低温度系数磁体)按照合适的比例进行制粉,然后混粉、压制、热处理,制备的烧结钐钴磁体同时具有低温度系数和高使用温度的双重特性。(The invention discloses a preparation method of a sintered samarium cobalt magnet with low temperature coefficient and high use temperature, which comprises the following steps: 1) preparing ingots a and b; 2) preparing powder; 3) mixing the powder; 4) magnetic field forming and isostatic pressing; 5) sintering, solid solution and aging treatment. According to the invention, an alloy ingot a (high-temperature magnet) and an alloy ingot b (low-temperature coefficient magnet) are pulverized according to a proper proportion, then the powders are mixed, pressed and subjected to heat treatment, and the prepared sintered samarium-cobalt magnet has the dual characteristics of low-temperature coefficient and high service temperature.)

1. A preparation method of a sintered samarium-cobalt magnet with low temperature coefficient and high use temperature is characterized by comprising the following steps:

1) the components of the ingot a are Sm: 24-28%, Fe: 5-8%, Zr: 2-5%, Cu: 4-8% and the balance of Co;

the components of the ingot b are Sm: 12-21% and Gd: 5-10%; dy: 2-5%; fe: 10-15%, Zr: 2-5%, Cu: 4-8% and the balance of Co;

burdening according to the components, and then respectively smelting and casting in an inert atmosphere to obtain an ingot a and an ingot b;

2) mechanically crushing, medium crushing and jet milling the ingot a and the ingot b according to the weight ratio of 1: 0.5-1.5 under the protection of nitrogen to obtain alloy powder;

3) adding lubricant with the total weight of 0.1-0.5 per mill into the alloy powder, and mixing for 0.5-3 h to obtain alloy magnetic powder;

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

5) keeping the temperature of the green body at 300-500 ℃ for 0.5-2 h for exhausting treatment, heating to 1200-1220 ℃ for 0.5-2 h for pre-densification treatment, heating to 1220-1240 ℃ for sintering for 1-3 h for further densification treatment, then cooling to 1130-1180 ℃ for 4-8 h for solid solution treatment, and rapidly cooling to room temperature by air; and then heating to 800-900 ℃, keeping the temperature for 10-40 h, then cooling to 400 ℃ by controlling the temperature, keeping the temperature for 1-20 h, and carrying out air cooling to the room temperature to obtain the sintered samarium-cobalt magnet.

2. The method of making a low temperature coefficient high use temperature sintered samarium cobalt magnet of claim 1 in which the samarium cobalt alloy starting material of step 1) is melted and cast under argon shield.

3. The method of making a low temperature coefficient high use temperature sintered samarium cobalt magnet of claim 1 wherein the thickness of both ingot a and ingot b of step 1) is 6 mm.

4. The method of making a low temperature coefficient high use temperature sintered samarium cobalt magnet of claim 1, wherein the alloy powder particle size in step 2) is 3 to 5 μ ι η.

5. The method of making a low temperature coefficient high use temperature sintered samarium cobalt magnet of claim 1 wherein the orientation forming magnetic field strength of step 4) is 2T and the cold isostatic pressure is 300 MPa.

6. A sintered samarium cobalt magnet obtained by the process of any of claims 1 to 5.

Technical Field

The present invention relates to a magnetic material. More specifically, the invention relates to a preparation method of a sintered samarium cobalt magnet with low temperature coefficient and high use temperature.

Background

As a second-generation rare earth permanent magnet material 2:17 type samarium cobalt permanent magnet material, the material is widely applied to the fields of rail transit, satellite communication, aerospace and the like due to excellent high-temperature stability, corrosion resistance and oxidation resistance, and the 2:17 type samarium cobalt permanent magnet material is mainly divided into sintered type samarium cobalt, adhesive type samarium cobalt and hot-pressed type samarium cobalt, wherein the sintered type samarium cobalt is most widely applied.

The 2:17 type sintered samarium cobalt permanent magnet material is mainly divided into three types, namely a high-performance samarium cobalt magnet, a low-temperature coefficient magnet and a high-use temperature magnet. The composition analysis shows that the high-performance magnet contains higher Fe content, the weight percentage is about 13-22%, and the high-performance magnet has higher magnetic energy product at normal temperature but poorer high-temperature performance; the low-temperature coefficient magnet is formed by adding Dy and Gd into a magnet to reduce the temperature coefficient of the magnet, and the temperature coefficient is lower at 0-200 ℃; the high-use-temperature magnet contains high Cu element, Co element and low Fe content, wherein the weight percentage of Fe is about 4-8%, the normal-temperature magnetic energy product is not high due to the low Fe content, the weight percentage of Cu is about 5-8%, the Cu element mainly enters a cell wall, the high Cu content can increase the anisotropy of a main phase and the cell wall phase, and therefore the coercive force of the magnet is increased, the coercive force of the high-temperature magnet is high at normal temperature, the Curie temperature of the magnet can be increased due to the high Co content, the maximum magnetic energy product of the high-temperature magnet is high at 500 ℃, and the comprehensive magnetic performance is good. The magnet has higher normal temperature magnetic performance, does not necessarily represent that the high temperature magnetic performance is also high, if the prepared magnet has higher normal temperature performance and stable performance at high temperature, the use potential of the samarium cobalt material can be exerted to a great extent, and the comprehensive national strength level of China can be promoted to be improved by a large step.

Analysis on the components of samarium cobalt materials shows that a vacancy of 8-13% exists in the Fe content of a high-performance samarium cobalt magnet and a high-use-temperature magnet, and the Fe content of the low-temperature-coefficient samarium cobalt magnet is just in the range, so that how to combine the components of the high-use-temperature magnet and the characteristics of the low-temperature-coefficient magnet to prepare the low-temperature-coefficient high-use-temperature sintered samarium cobalt magnet is a technical problem to be solved urgently.

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 sintered samarium cobalt magnet with low temperature coefficient and high use temperature, which comprises the steps of preparing powder from an alloy ingot a (high-temperature magnet) and an alloy ingot b (low-temperature coefficient magnet) according to a proper proportion, mixing the powder, pressing and carrying out heat treatment, wherein the prepared sintered samarium cobalt magnet has the dual characteristics of low temperature coefficient and high use temperature.

To achieve these objects and other advantages in accordance with the purpose of the invention, there is provided a method of manufacturing a low temperature coefficient high use temperature sintered samarium cobalt magnet, comprising:

1) the components of the ingot a are Sm: 24-28%, Fe: 5-8%, Zr: 2-5%, Cu: 4-8% and the balance of Co;

the components of the ingot b are Sm: 12-21% and Gd: 5-10%; dy: 2-5%; fe: 10-15%, Zr: 2-5%, Cu: 4-8% and the balance of Co;

burdening according to the components, and then respectively smelting and casting in an inert atmosphere to obtain an ingot a and an ingot b;

2) mechanically crushing, medium crushing and jet milling the ingot a and the ingot b according to the weight ratio of 1: 0.5-1.5 under the protection of nitrogen to obtain alloy powder;

3) adding lubricant with the total weight of 0.1-0.5 per mill into the alloy powder, and mixing for 0.5-3 h to obtain alloy magnetic powder;

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

5) keeping the temperature of the green body at 300-500 ℃ for 0.5-2 h for exhausting treatment, heating to 1200-1220 ℃ for 0.5-2 h for pre-densification treatment, heating to 1220-1240 ℃ for sintering for 1-3 h for further densification treatment, then cooling to 1130-1180 ℃ for 4-8 h for solid solution treatment, and rapidly cooling to room temperature by air; and then heating to 800-900 ℃, keeping the temperature for 10-40 h, cooling to 400 ℃ by controlling the temperature, keeping the temperature for 1-20 h, and carrying out 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 thickness of the ingot a and the ingot b in the step 1) is 6 mm.

Preferably, the granularity of the alloy powder in the step 2) is 3-5 μm.

Preferably, the orientation molding magnetic field intensity in the step 4) is 2T, and the cold isostatic pressure is 300 MPa.

The sintered samarium-cobalt magnet obtained by the preparation method.

The invention at least comprises the following beneficial effects:

according to the invention, only two kinds of ingots are needed to be smelted, then the alloy ingot a (high-temperature magnet) and the ingot b (low-temperature coefficient magnet) are pulverized according to a proper proportion, then the powders are mixed, pressed and thermally treated, the magnet with excellent performance can be prepared by regulating and controlling the components and the process, the absolute value of the temperature coefficient of remanence at 25-500 ℃ reaches about 0.03%, the absolute value of the temperature coefficient of coercive force reaches about 0.2%, and the magnetic energy product at 500 ℃ reaches 13 MGOe.

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.

Drawings

FIG. 1 is a flow chart of the preparation method of the present 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 sintered samarium-cobalt magnet with low temperature coefficient and high use temperature comprises the following steps:

1) preparation of ingots a and b:

the components of the ingot a are Sm: 24-28%, Fe: 5-8%, Zr: 2-5%, Cu: 4-8% and the balance of Co;

the components of the ingot b are Sm: 12-21% and Gd: 5-10%; dy: 2-5%; fe: 10-15%, Zr: 2-5%, Cu: 4-8% and the balance of Co;

the preparation method comprises the following steps of proportioning according to components, smelting and casting respectively in a high-purity inert atmosphere (preferably argon), effectively preventing Sm from volatilizing and ingot casting from oxidizing, smelting in a medium-frequency smelting furnace, and casting in a cold-water copper mould to obtain an ingot casting a and an ingot casting b with the thickness of 6 mm;

2) preparation of powder:

mechanically crushing and crushing the ingot a and the ingot b according to the weight ratio of 1: 0.5-1.5 under the protection of high-purity nitrogen, wherein the particle size of the crushed ingot a is about 100-500 mu m, and carrying out jet milling to obtain alloy powder with the particle size of 3-5 mu m;

3) mixing of the powder:

adding a lubricant with the total weight of 0.1-0.5 per mill into the alloy powder, and mixing for 0.5-3 hours to ensure uniform mixing to obtain alloy magnetic powder;

4) magnetic field forming, isostatic pressing:

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

5) sintering solid solution and aging treatment:

keeping the temperature of the green body at 300-500 ℃ for 0.5-2 h for exhausting treatment, heating to 1200-1220 ℃ for 0.5-2 h for pre-densification treatment, heating to 1220-1240 ℃ at the heating rate of 1 ℃/min for sintering for 1-3 h for further densification treatment, then cooling to 1130-1180 ℃ for 4-8 h for solid solution treatment, and quickly cooling to room temperature by air; and then heating to 800-900 ℃, keeping the temperature for 10-40 h, cooling to 440 ℃ at the speed of 0.7-1 ℃/min, keeping the temperature for 1-20 h, and air-cooling to room temperature to obtain the sintered samarium-cobalt magnet.

< example 1>

The preparation method of the sintered samarium-cobalt magnet with low temperature coefficient and high use temperature comprises the following steps:

1) the cast ingot a comprises the following components in percentage by weight: sm: 26.5%, Fe: 7.7%, Zr: 2.4%, Cu: 7.2 percent and the balance of Co;

the components of the ingot b are as follows: sm: 14.6%, Gd: 8.3 percent; dy: 3.6 percent; fe: 13.8%, Zr: 2.5%, Cu: 6.8 percent and the balance of Co;

preparing materials according to the components, then respectively smelting and casting 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 of a disc, so as to obtain an ingot a and an ingot b with the thickness of 6 mm;

2) mechanically crushing and crushing the ingot a and the ingot b according to the weight ratio of 1:0.93 under the protection of high-purity nitrogen, wherein the crushed particle size is 300 mu m, then putting the crushed powder into an airflow mill together for further crushing, and obtaining alloy powder with the particle size of 3.35 mu m after crushing;

3) adding a lubricant with the total weight of 0.35 per mill into the alloy powder, and mixing for 2 hours to obtain alloy magnetic powder in order to ensure uniform mixing;

4) weighing the alloy magnetic powder, then performing orientation molding in an open press, wherein the orientation molding magnetic field intensity is 2T, and then performing cold isostatic pressing, wherein the cold isostatic pressing pressure is 300MPa, so as to prepare a green body;

5) carrying out exhaust treatment on the green body by keeping the temperature of 385 ℃ for 2h, heating to 1203 ℃ for 1h for pre-densification treatment, heating to 1229 ℃ at the heating rate of 1 ℃/min for sintering for 1h for further densification treatment, then cooling to 1175 ℃ for 6h for solution treatment, and rapidly cooling to room temperature by air; and then heating to 830 ℃, keeping the temperature for 10 hours, cooling to 440 ℃ at the speed of 0.75 ℃/min, keeping the temperature for 10 hours, and cooling to room temperature by air to obtain the sintered samarium-cobalt magnet.

The magnetic performance of the prepared sintered samarium cobalt magnet is as follows: remanence of B at 25 DEG C_r9.3kGs magnetic product (BH)_max20.45 MGOe, intrinsic coercivity H_cj32.14 kOe; remanence B at 500 deg.C_r7.67kGs magnetic product (BH)_max13.15MGOe, intrinsic coercivity H_cj8.33kOe, wherein the temperature coefficient of remanence is-0.037% and the temperature coefficient of coercivity is-0.156%.

< example 2>

The preparation method of the sintered samarium-cobalt magnet with low temperature coefficient and high use temperature comprises the following steps:

1) the cast ingot a comprises the following components in percentage by weight: sm: 25.3%, Fe: 6.8%, Zr: 3.1%, Cu: 6.9 percent and the balance of Co;

the components of the ingot b are as follows: sm: 13.7%, Gd: 7.8 percent; dy: 4.7 percent; fe: 12.8%, Zr: 2.3%, Cu: 6.8 percent and the balance of Co;

preparing materials according to the components, then respectively smelting and casting 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 of a disc, so as to obtain an ingot a and an ingot b with the thickness of 6 mm;

2) mechanically crushing and crushing the ingot a and the ingot b according to the weight ratio of 1:0.71 under the protection of high-purity nitrogen, wherein the crushed particle size is 360 mu m, then putting the crushed powder into an airflow mill together for further crushing, and obtaining alloy powder with the particle size of 3.8 mu m after crushing;

3) adding a lubricant with the total weight of 0.24 per mill into the alloy powder, and mixing for 2.5 hours to obtain alloy magnetic powder in order to ensure uniform mixing;

4) weighing the alloy magnetic powder, then performing orientation molding in an open press, wherein the orientation molding magnetic field intensity is 1.8T, then performing cold isostatic pressing, and the cold isostatic pressing pressure is 260MPa, thus preparing a green body;

5) the green body is subjected to heat preservation at 415 ℃ for 2h for exhaust treatment, heated to 1205 ℃ and subjected to heat preservation for 1h for pre-densification treatment, heated to 1232 ℃ at the heating rate of 1 ℃/min for sintering for 1h for further densification treatment, then cooled to 1185 ℃ for 4h for solid solution treatment, and rapidly air-cooled to room temperature; and then heating to 860 ℃, preserving heat for 10 hours, cooling to 440 ℃ at the speed of 0.8 ℃/min, preserving heat for 6 hours, and cooling to room temperature by air to obtain the sintered samarium-cobalt magnet.

The magnetic performance of the prepared sintered samarium cobalt magnet is as follows: remanence of B at 25 DEG C_r9.35kGs magnetic product (BH)_max21.75 MGOe, intrinsic coercivity H_cj37.14 kOe; remanence B at 500 deg.C_r7.63kGs magnetic product (BH)_max12.75 MGOe, intrinsic coercivity H_cj8.56kOe, wherein the temperature coefficient of remanence is-0.038% and the temperature coefficient of coercivity is-0.162%.

< example 3>

The preparation method of the sintered samarium-cobalt magnet with low temperature coefficient and high use temperature comprises the following steps:

1) the cast ingot a comprises the following components in percentage by weight: sm: 25.6%, Fe: 7.1%, Zr: 2.7%, Cu: 7.6 percent, and the balance of Co;

the components of the ingot b are as follows: sm: 13.7%, Gd: 8.5 percent; dy: 4.4 percent; fe: 13.1%, Zr: 2.5%, Cu: 6.2 percent and the balance of Co;

preparing materials according to the components, then respectively smelting and casting in a high-purity argon 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 of a disc to obtain an ingot a and an ingot b with the thickness of 6 mm;

2) mechanically crushing and crushing the ingot a and the ingot b according to the weight ratio of 1:1.13 under the protection of high-purity nitrogen, wherein the crushed particle size is 260 mu m, then putting the crushed powder into an airflow mill together for further crushing, and obtaining alloy powder with the particle size of 4.5 mu m after crushing;

3) adding a lubricant with the total weight of 0.44 per mill into the alloy powder, and mixing for 3 hours to obtain alloy magnetic powder in order to ensure uniform mixing;

4) weighing the alloy magnetic powder, then performing orientation molding in an open press, wherein the orientation molding magnetic field intensity is 1.5T, then performing cold isostatic pressing, and the cold isostatic pressing pressure is 240MPa, thus preparing a green body;

5) keeping the temperature of the green body at 445 ℃ for 2h for exhausting treatment, heating to 1201 ℃ for 1h for pre-densification treatment, heating to 1231 ℃ at the heating rate of 1 ℃/min for sintering for 1h for further densification treatment, then cooling to 1180 ℃ for 4h for solid solution treatment, and quickly cooling to room temperature by air; and then heating to 820 ℃, keeping the temperature for 12h, cooling to 440 ℃ at the speed of 0.88 ℃/min, keeping the temperature for 10h, and cooling to room temperature by air to obtain the sintered samarium-cobalt magnet.

The magnetic performance of the prepared sintered samarium cobalt magnet is as follows: remanence of B at 25 DEG C_r9.11kGs magnetic product (BH)_max20.14 MGOe, intrinsic coercivity H_cj26.18 kOe; remanence B at 500 deg.C_r7.88kGs magnetic product (BH)_max13.35 MGOe, intrinsic coercivity H_cj7.13kOe, wherein the temperature coefficient of remanence is-0.028%, and the temperature coefficient of coercivity is-0.153%.

< example 4>

The preparation method of the sintered samarium-cobalt magnet with low temperature coefficient and high use temperature comprises the following steps:

1) the cast ingot a comprises the following components in percentage by weight: sm: 24.6%, Fe: 5.6%, Zr: 2.2%, Cu: 6.2 percent and the balance of Co;

the components of the ingot b are as follows: sm: 12.4%, Gd: 9.6 percent; dy: 4.8 percent; fe: 12.4%, Zr: 2.5%, Cu: 6.2 percent and the balance of Co;

preparing materials according to the components, then respectively smelting and casting in a high-purity argon 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 of a disc to obtain an ingot a and an ingot b with the thickness of 6 mm;

2) mechanically crushing and crushing the ingot a and the ingot b according to the weight ratio of 1:1.46 under the protection of high-purity nitrogen, wherein the crushed particle size is 380 mu m, then putting the crushed powder into an airflow mill together for further crushing, and obtaining alloy powder with the particle size of 3.8 mu m after crushing;

3) adding a lubricant with the total weight of 0.37 per mill into the alloy powder, and mixing for 2.5 hours to obtain alloy magnetic powder in order to ensure uniform mixing;

4) weighing the alloy magnetic powder, then performing orientation molding in an open press, wherein the orientation molding magnetic field intensity is 1.25T, and then performing cold isostatic pressing, wherein the cold isostatic pressing pressure is 220MPa, so as to prepare a green body;

5) carrying out exhaust treatment on the green body by keeping the temperature of the green body at 485 ℃ for 1.5h, heating to 1205 ℃ and keeping the temperature for 1h for pre-densification, heating to 1230 ℃ at the heating rate of 1 ℃/min for sintering for 1h for further densification, then cooling to 1195 ℃ for 5h for solid solution treatment, and rapidly cooling to room temperature by air; and then heating to 850 ℃, keeping the temperature for 15h, cooling to 440 ℃ at the speed of 0.95 ℃/min, keeping the temperature for 10h, and cooling to room temperature by air to obtain the sintered samarium-cobalt magnet.

The magnetic performance of the prepared sintered samarium cobalt magnet is as follows: remanence of B at 25 DEG C_r9.04kGs magnetic product (BH)_max19.33 MGOe, intrinsic coercivity H_cj25.18 kOe; remanence B at 500 deg.C_r7.78kGs magnetic product (BH)_max12.78 MGOe, intrinsic coercivity H_cj6.74kOe, wherein the temperature coefficient of remanence is-0.029% and the temperature coefficient of coercivity is-0.154%.

< comparative example 1>

As in example 1, ingot a and ingot b were each subjected directly to crushing, molding and heat treatment.

< comparative example 2>

As in example 2, ingot a and ingot b were each subjected directly to crushing, molding and heat treatment.

< comparative example 3>

As in example 3, ingot a and ingot b were each subjected directly to crushing, molding and heat treatment.

< comparative example 4>

As in example 4, ingot a and ingot b were each subjected directly to crushing, molding and heat treatment.

To verify the present invention convenientlyThe preparation method of sintered samarium cobalt magnet samarium cobalt with low temperature coefficient and high use temperature in Ming patent respectively lists the performance indexes of examples 1-4 and comparative examples 1-4 in the following table 1. It can be seen that the present invention provides a method of making a sintered samarium cobalt magnet having a low temperature coefficient and a high use temperature that has the dual characteristics of both a low temperature coefficient and a high use temperature (e.g., the magnet made in example 1 has both a high energy product (BH) at high temperature)_maxAbout 13.15MGOe and ingot a magnetic energy product (BH)_maxAbout 13.345MGOe, which in turn has a low temperature coefficient of remanence-0.037% and a temperature coefficient of coercivity-0.156% and-0.034%, -0.156% of ingot b).

TABLE 1

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 thus not to be 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.