A ternary compound magnetic material, its preparation method and application

Abstract

This invention relates to the field of magnetic material preparation technology, and in particular to a ternary compound magnetic material, its preparation method, and its applications. The chemical formula of the ternary compound magnetic material is Pr. 1‑ x Dy x Co5,0

Description

Technical Field

[0001] This invention relates to the field of magnetic material preparation technology, and in particular to a ternary compound magnetic material, its preparation method, and its application. Background Technology

[0002] Rare-earth cobalt-based magnetic materials (RCMs) have been widely used in commercial and scientific fields since their discovery in the late 1960s. The most commonly used RCM alloy is currently the 1:5 type rare-earth cobalt permanent magnet alloy SmCo5. Compared with neodymium iron boron materials, RCMs possess irreplaceable properties at high temperatures. Recent research on RCMs has primarily focused on achieving high coercivity (H0) while maintaining high operating temperatures. c High saturation magnetization (M) s High energy product (BH). For example, (Sm,Pr)Co5 permanent magnet alloys are obtained by replacing part of the Sm in SmCo5 alloy with light rare earth element Pr, with the aim of increasing the maximum energy product of the alloy. Because the theoretical saturation magnetization of PrCo5 is higher than that of SmCo5, the addition of praseodymium reduces the anisotropic field, thus the coercivity of the alloy is lower than that of SmCo5. Another example is MMCo5 permanent magnet alloy ("MM" is an abbreviation for Ce-rich mixed rare earth metals). The use of mixed rare earths is mainly to reduce costs, but the energy product of the alloy decreases with the addition of Ce and it is prone to oxidation. Yet another example is (Sm,HRE)Co5 permanent magnet alloy. This type of alloy uses heavy rare earth elements such as Gd, Ho, and Er (abbreviated as HRE) to replace part of the Sm in SmCo5, with the aim of improving the temperature stability of the magnet. However, increasing the HRE content reduces the magnetism and increases the cost. Another example is R(CoCuFe). 5～7 (R = Sm, Ce) permanent magnet alloys. These alloys are based on RCo5 alloys, with Fe and Cu replacing some of the Co. The maximum energy product is slightly lower, but the coercivity is much lower.

[0003] Based on the investigation of SmCo5 materials, it was discovered that the combination of rare earth elements and transition metals can yield high-performance permanent magnets. Among these, transition metals provide a high Curie temperature (T0). c Rare earth atoms possess high saturation magnetization and a large uniaxial anisotropy, enabling magnets to exhibit significant coercivity. In recent years, other RCo5 compounds have been continuously studied in order to find Sm-free materials. Rare earth permanent magnets, such as PrCo5, are characterized by high saturation magnetization, relatively large uniaxial anisotropy, large theoretical magnetic energy product, and high Curie temperature, such as the Ti of PrCo5. c (950K) higher than Nd2Fe 14 B's T c(571K), it is possible to produce magnets with higher magnetic properties and temperature stability, so it is a potential candidate for high-performance magnets. However, due to the easy formation of impurity phases and other factors during the preparation process, PrCo5 has not been actually applied in production.

[0004] The magnetic properties of the reported PrCo5 binary compounds are generally average and do not show the application value of strong magnetic magnets; in addition, the magnetic properties of the binary compound DyCo5 also show average performance, and the magnetic properties are far inferior to other magnetic materials, and have not attracted people's attention. Therefore, these single binary compounds have not been developed and applied. Summary of the Invention

[0005] To solve the above problems, the present invention provides a ternary compound magnetic material, its preparation method and application. The present invention designs to mix the light rare earth Pr, heavy rare earth Dy and transition element Co together to prepare the ternary Pr 1-x Dy x Co5 compound, and then use the single-roller melt spinning at high speed to obtain a thin strip sample, and the crystal structure always maintains the CaCu5-type rhombohedral phase of 1:5. This method can not only reduce the separation cost of rare earth Pr and Dy, but also significantly improve the magnetic properties of both PrCo5 and DyCo5. The present invention develops a ternary composite magnet (Pr, Dy)Co5. By changing the process conditions, the ternary compound Pr 1-x Dy x Co5 magnetic tape is obtained by melt spinning at a wheel speed of 30 - 35 m / s. Melt quenching can obtain samples with nanometer size. Nanocrystalline materials are one of the key research fields of permanent magnets in the past decade because nanocrystalline magnets can generate very high coercive force.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a ternary compound magnetic material, and the chemical formula of the ternary compound magnetic material is Pr 1-x Dy x Co5, 0 < x < 1, and the ratio of the total number of atoms of Pr and Dy to the number of atoms of Co is 1:5.

[0008] Preferably, the x is 0.2 - 0.8.

[0009] Preferably, the x is 0.4 - 0.6.

[0010] The present invention also provides a preparation method of the ternary compound magnetic material according to the above technical solution, including the following steps:

[0011] 1) Mix the Pr, Dy and Co and then melt them to obtain an alloy;

[0012] 2) The alloy obtained in step 1) is subjected to heat treatment to obtain a heat-treated product;

[0013] 3) Place the heat-treated material obtained in step 1) into an ice-water mixture until it reaches a constant temperature, and then soak it to obtain a ternary compound magnetic material.

[0014] Preferably, the melting conditions in step 1) include repeating the process 4 to 6 times under argon protection and an arc current of 80 to 120 A.

[0015] Preferably, the conditions for the heat treatment in step 2) include: a temperature of 750–800°C and a time of 2 hours to 7 days.

[0016] Preferably, the soaking time in step 3) is 0.5 hours.

[0017] Preferably, the alloy obtained in step 2) is subjected to a strip spinning process followed by heat treatment. The conditions for the strip spinning process include: argon protection and a roller speed of 30-35 m / s.

[0018] This invention also provides the application of the ternary compound magnetic material described in the above technical solution in improving the coercivity of magnetic materials.

[0019] This invention also provides the application of the ternary compound magnetic materials described in the above technical solution in improving the magnetic properties of magnetic materials.

[0020] The beneficial effects of this invention are:

[0021] This invention addresses the problems of weak magnetic properties, long preparation cycles, and high costs associated with existing PrCo5 and DyCo5 binary intermetallic compounds. Compared to single PrCo5 and DyCo5 binary compounds, the mixed addition of light and heavy rare earth elements not only reduces the cost of rare earth separation but also significantly improves the magnetic properties of the synthesized ternary compound (Pr,Dy)Co5. The melt quenching preparation method greatly improves material properties while shortening the preparation time. Both the alloy and thin strip samples can achieve nanoscale grains after appropriate heat treatment. Modifying the process conditions can maximize the improvement of magnetic properties. Furthermore, the cobalt-based compound obtained by adding the heavy rare earth element Dy to PrCo5 exhibits even superior magnetic properties, further reducing costs. This is of great significance for alleviating resource pressure and promoting sustainable resource development. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the embodiments will be briefly described below.

[0023] Figure 1 For Pr 1-x Dyx The hysteresis loop of Co5 (x = 0.0-1.0) alloy at room temperature after annealing at 800℃ for 7 days;

[0024] Figure 2 For Pr 1-x Dy x The changes in coercivity and saturation magnetization of Co5 (x = 0.0-1.0) alloy at room temperature after annealing at 800℃ for 7 days;

[0025] Figure 3 Pr prepared at 30 m / s 1-x Dy x Single-phase XRD pattern of Co5 (x = 0.0-1.0) ribbon after annealing at 750℃ for 4 h;

[0026] Figure 4 Pr prepared at 30 m / s 0.8 Dy 0.2 Morphology of Co5 thin strip annealed at 750℃ for 4 hours;

[0027] Figure 5 Pr prepared at 30 m / s 1-x Dy x The hysteresis loop of Co5 (x = 0.0-1.0) ribbon at room temperature after annealing at 750℃ for 4 hours;

[0028] Figure 6 Pr prepared at 30 m / s 1-x Dy x The changes in coercivity and saturation magnetization of Co5 (x=0.0-1.0) thin strips after annealing at 750℃ for 4 hours;

[0029] Figure 7 Untreated Pr prepared at 35 m / s 1-x Dy x The hysteresis loop of Co5 (x = 0.0-1.0) thin strips at room temperature;

[0030] Figure 8 Untreated Pr prepared at 35 m / s 1-x Dy x The graph shows the changes in coercivity and saturation magnetization of Co5 (x = 0.0-1.0) thin strips at room temperature;

[0031] Figure 9 Pr prepared at 35 m / s 1-x Dy x The hysteresis loop of Co5 (x = 0.0-1.0) ribbon at room temperature after annealing at 800℃ for 2 hours;

[0032] Figure 10Pr prepared at 35 m / s 1-x Dy x Variation diagrams of coercivity and saturation magnetization of Pr 1-x Dy x Co5 (x = 0.0 - 1.0) ribbons after annealing at 800 °C for 2 h;

[0033] Figure 11 Pr 1-x Dy x Variation diagrams of coercivity of Pr 1-x Dy x Co5 (x = 0.0 - 1.0) samples under different states, different spinning speeds and different heat treatment conditions. Detailed implementation manners

[0034] The present invention provides a ternary compound magnetic material, and the chemical formula of the ternary compound magnetic material is Pr 1-x Dy x Co5, 0 < x < 1, and the ratio of the total atomic number of Pr and Dy to the atomic number of Co is 1:5. In the present invention, x is preferably 0.2 - 0.8. In the present invention, x is preferably 0.4 - 0.6.

[0035] The present invention also provides a preparation method of the ternary compound magnetic material described in the above technical solution, including the following steps:

[0036] 1) Mix the Pr, Dy and Co and then melt them to obtain an alloy;

[0037] 2) Perform heat treatment on the alloy obtained in step 1) to obtain a heat-treated product;

[0038] 3) Place the heat-treated product obtained in step 1) in an ice-water mixture until it reaches a constant temperature, and then perform soaking treatment to obtain a ternary compound magnetic material.

[0039] In the present invention, the Pr, Dy and Co are mixed and then melted to obtain an alloy. In the present invention, the melting conditions preferably include: repeating 4 - 6 times under argon protection and an arc current of 80 - 120 A.

[0040] In the present invention, the obtained alloy is subjected to heat treatment to obtain a heat-treated product. In the present invention, the heat treatment conditions preferably include: a temperature of 750 - 800 °C and a time of 2 h - 7 d.

[0041] In the present invention, the obtained heat-treated product is placed in an ice-water mixture until it reaches a constant temperature, and then subjected to soaking treatment to obtain a ternary compound magnetic material. In the present invention, the soaking treatment time is preferably 0.5 h.

[0042] ​​​​Preferably, the obtained alloy is subjected to a strip-spinning process followed by heat treatment. The strip-spinning process is preferably carried out under argon protection and a roller speed of 30–35 m / s. Alternatively, the alloy is preferably melted into a liquid state under a cavity pressure of 0.04–0.06 MPa and argon protection before being subjected to the strip-spinning process.

[0043] This invention also provides the application of the ternary compound magnetic material described in the above technical solution in improving the coercivity of magnetic materials.

[0044] This invention also provides the application of the ternary compound magnetic materials described in the above technical solution in improving the magnetic properties of magnetic materials.

[0045] To further illustrate the present invention, the following detailed description is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] A method for preparing a coercivity-enhanced magnetic material comprises the following steps:

[0048] Step (1): Weigh rare earth Pr, Dy and raw material Co according to the atomic ratio of rare earth and Co of 1:5, and prepare Pr by argon arc melting (repeatedly melting with 100A current 4 times). 1-x Dy x Co5 (x = 0.0-1.0) alloy, where x is 0, 0.2, 0.4, 0.6, 0.8 and 1;

[0049] Step (2): The Pr prepared in step (1) 1-x Dy x Co5 (x = 0.0-1.0) alloy was sealed in a vacuum quartz tube, heat-treated in an annealing furnace at 800°C for 7 days, then rapidly cooled to room temperature in an ice-water mixture and soaked for half an hour to obtain Pr. 1-x Dy x Co5 (x = 0.0-1.0) sample.

[0050] To test the hysteresis loop of the sample at room temperature, the magnetic properties of the sample were measured using a vibrating sample magnetometer (VSM). The specific method is as follows:

[0051] A 20mg sample was selected, and an external magnetic field with a maximum value of ±2T was applied to Pr. 1-x Dy x The Co5 (x = 0.0-1.0) sample was placed parallel to the external magnetic field. The test results showed that its magnetic moment had reached saturation under an external magnetic field of ±2T. Figure 1As shown, the coercivity exhibits a trend of first increasing and then decreasing. The coercivity at x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 are 0.085, 0.157, 0.200, 0.196, 0.195, and 0.187 kOe, respectively; it reaches a maximum value of 0.20 kOe at x = 0.4. The saturation magnetization shows a decreasing trend with increasing heavy rare earth Dy content, as shown in the figure. Figure 2 .

[0052] Example 2

[0053] A method for preparing a coercivity-enhanced magnetic material comprises the following steps:

[0054] Step (1): Weigh the raw materials according to the ratio of rare earth to Co atoms of 1:5, and prepare Pr by argon arc melting. 1-x Dy x Co5 (x = 0.0-1.0) alloy, where x is 0, 0.2, 0.4, 0.6, 0.8 and 1;

[0055] Step (2): The Pr prepared in step (1) 1-x Dy x In an induction melting and strip spinning device under argon atmosphere, the molten Co5 (x = 0.0-1.0) alloy is rapidly cooled into a thin strip at a roller speed of 30 m / s.

[0056] Step (3): The thin strip of Pr prepared in step (2) at 30 m / s 1-x Dy x Co5 (x = 0.0-1.0) samples were sealed in a vacuum quartz tube and heat-treated in an annealing furnace at 750°C for 4 hours. After heat treatment, the samples were rapidly cooled to room temperature in an ice-water mixture and then soaked for half an hour to obtain Pr. 1-x Dy x Co5 (x = 0.0-1.0) sample.

[0057] To determine the composition and structure of the sample, X-ray diffraction tests were performed. 1-x Dy x The X-ray results of the Co5 (x = 0.0-1.0) sample are as follows: Figure 3 As shown, the sample exhibits a single-phase crystal structure of the CaCu5 type rhombohedral. To verify that the sample is a single-phase structure, a thin strip sample was selected, etched with metallographic etching solution, wiped clean with alcohol, and observed under a scanning electron microscope (SEM). Pr 0.8 Dy 0.2 The morphology of Co5 thin bands is as follows Figure 4 As shown, the SEM image reveals that the sample contains only one phase. The obtained Pr 1-x Dy xThe magnetic properties of Co5 (x = 0.0-1.0) permanent magnet materials, such as... Figure 5 As shown, the coercivity exhibits a trend of first increasing and then decreasing. The coercivity at x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 are 2.80, 4.55, 3.38, 2.28, 0.53, and 0.11 kOe, respectively; it reaches a maximum value of 4.55 kOe at x = 0.2. The saturation magnetization shows a decreasing trend with increasing heavy rare earth Dy content, as shown in the figure. Figure 6 .

[0058] To demonstrate the effect of belt spinning speed on material properties, Examples 3 and 4 are provided, in which samples with the same composition were prepared and Pr were spun at a speed of 35 m / s. 1-x Dy x Co5 (x = 0.0-1.0) permanent magnet material.

[0059] Example 3

[0060] The preparation method of a coercivity-enhanced magnetic material is not described. It is the same as that in Example 2, except that the spinning speed used in step (3) is 35 m / s, the spinning is rapidly cooled into a thin strip, and no other heat treatment is performed.

[0061] Pr was measured 1-x Dy x The magnetic properties of Co5 (x = 0.0-1.0) permanent magnet materials, such as... Figure 7 As shown, the coercivity exhibits a trend of first increasing and then decreasing. The coercivity at x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 are 3.46, 4.43, 4.03, 3.10, 0.72, and 0.26 kOe, respectively; it reaches a maximum value of 4.43 kOe at x = 0.2. The saturation magnetization shows a decreasing trend with increasing heavy rare earth Dy content, as shown in the figure. Figure 8 .

[0062] Example 4

[0063] The preparation method of a coercivity-enhanced magnetic material is not described, but is the same as in Example 2, except that the strip-spinning speed used in step (3) is 35 m / s, and the resulting strip-shaped Pr... 1-x Dy x Co5 (x = 0.0-1.0) samples were sealed in a vacuum quartz tube and heat-treated in an annealing furnace at 800℃ for 2 hours. Afterward, they were rapidly cooled to room temperature in an ice-water mixture and soaked for half an hour to obtain Pr. 1-x Dy x Co5 (x = 0.0-1.0) material.

[0064] Pr was measured 1-x Dy xThe magnetic properties of Co5 (x = 0.0-1.0) permanent magnet materials, such as... Figure 9 As shown, the coercivity exhibits a trend of first increasing and then decreasing. The coercivity at x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 are 4.19, 11.27, 6.11, 3.21, 0.54, and 0.26 kOe, respectively; it reaches a maximum of 11.27 kOe at x = 0.2. The saturation magnetization shows a decreasing trend with increasing heavy rare earth Dy content, as shown in the figure. Figure 10 .

[0065] A comparison of Examples 2, 3, and 4 demonstrates that the hub speed during belt spinning has a significant impact on the permanent magnetic properties of the material. When the roller speed is 35 m / s and after certain heat treatment, the coercivity of the material is 11.27 kOe, which is currently the highest among Pr materials. 1-x Dy x The highest coercivity was obtained with Co5 (x = 0.0-1.0) material. Currently, the optimal roller speed for this material is 35 m / s, and it has been found that samples prepared at higher belt speeds exhibit higher coercivity. 1-x Dy x Comparison of coercivity of Co5 (x = 0.0-1.0) thin strip samples under different states, different spinning speeds, and different heat treatment conditions, such as... Figure 11 As can be seen from the figure, after adding Dy to the PrCo5 binary compound to form a ternary compound, the coercivity is significantly enhanced with the increase of the amount of x added. This is very useful for developing and improving the coercivity and magnetic properties of magnetic materials, and its application will be comprehensively improved.

[0066] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. Application of ternary compound magnetic materials in improving the coercivity of magnetic materials; The chemical formula of the ternary compound magnetic material is Pr. 0.8 Dy 0.2 The ratio of the total number of atoms of Co5, Pr and Dy to the number of atoms of Co is 1:5; The preparation method of the ternary compound magnetic material includes the following steps: 1) The Pr, Dy and Co are mixed and smelted to obtain an alloy; 2) The alloy obtained in step 1) is subjected to heat treatment to obtain a heat-treated product; 3) Place the heat-treated material obtained in step 1) in an ice-water mixture until it reaches a constant temperature, and then soak it to obtain a ternary compound magnetic material; The conditions for melting in step 1) include: repeating the process 4 times under argon protection and an arc current of 100A; The conditions for heat treatment in step 2) include: a temperature of 800℃ and a time of 2 hours; The soaking time in step 3) is 0.5 hours; The alloy obtained in step 2) is subjected to a strip spinning process followed by heat treatment. The conditions for the strip spinning process include: argon protection and a roller speed of 35 m / s.

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