TWI699345B - Method of fabricating modified gyromagnetic embryo and material thereof - Google Patents

Abstract

A method of fabricating a modified gyromagnetic embryo and material thereof is provided. The method of fabricating modified gyromagnetic embryo comprises steps of: providing a gyromagnetic material precursor; performing a calcination step of performing the diamagnetic material precursor at a temperature between 1200 and 1300 °C for 1 to 3 hours; adding alumina to the diamagnetic material precursor after the calcination step to form a mixture, wherein the alumina is between 0.1 and 0.3 parts by weight based on 100 parts by weight of a total weight of the gyromagnetic material precursor; performing a ball milling step on the mixture for 1.5 to 2.5 hours; and performing a molding step on the mixture after the ball milling step to form the gyromagnetic material embryo.

Description

Modified gyromagnetic blank and its material manufacturing method

The invention relates to a manufacturing method involving a gyromagnetic material, in particular to a manufacturing method of a modified gyromagnetic blank and its material.

Gyromagnetic materials are the basic materials for microwave communication components such as phase shifters, circulators, and isolators. The magnetic properties of gyromagnetic materials will directly affect the performance of microwave communication components.

According to the existing manufacturing method of the gyromagnetic material, it is roughly as follows: first, the material is proportioned according to the molecular formula of the gyromagnetic material, and then through mixing, calcining, ball milling, molding, and sintering steps to form a magnet with gyromagnetic properties. Next, according to the shape of the gyromagnetic member required for the phase shifter, circulator, or isolator, the magnet is processed and ground into the gyromagnetic member.

However, the gyromagnetic member manufactured according to the above method still has the limit on the magnetic properties. Therefore, it is necessary to provide a manufacturing method of modified gyromagnetic materials to solve the problems existing in the conventional technology.

One objective of the present invention is to provide a method for manufacturing modified gyromagnetic blanks and materials thereof, which improves the magnetic properties by adding alumina after the calcination step and before the ball milling step.

In order to achieve the above objective, the present invention provides a method for manufacturing a modified gyromagnetic blank, which includes the steps of: providing a gyromagnetic material precursor; and performing a calcination step, wherein the gyromagnetic material precursor is 1200 to 1300 Hold the temperature between ℃ for 1 to 3 hours; add alumina to the gyromagnetic material precursor after the calcination step to form a mixture, wherein a total weight of the gyromagnetic material precursor is 100 parts by weight The alumina is between 0.1 to 0.3 parts by weight; the mixture is subjected to a ball milling step for 1.5 to 2.5 hours; and the mixture after the ball milling step is subjected to a molding step to form a gyromagnetic material blank .

In an embodiment of the present invention, the gyromagnetic material precursor includes at least one of a garnet-based gyromagnetic material and a spinel-based gyromagnetic material.

In an embodiment of the present invention, the garnet-based gyromagnetic material includes iron oxide and yttrium oxide.

In an embodiment of the present invention, the garnet-based gyromagnetic material further includes alumina and manganese oxide, wherein the ratio of alumina, manganese oxide, iron oxide and yttrium oxide is based on a molecular formula of the garnet-based gyromagnetic material Y ₃ (Al _x Mn _y Fe _(5-xy) )O ₁₂ is allocated, where x is greater than 0 and less than or equal to 1, and y is greater than 0 and less than or equal to 1.

In an embodiment of the present invention, the spinel-based gyromagnetic material includes iron oxide and magnesium carbonate.

In an embodiment of the present invention, in the spinel-based gyromagnetic material, the ratio of iron oxide to magnesium carbonate is distributed according to a molecular formula of the spinel-based gyromagnetic material, MgFe ₂ O ₄ .

In an embodiment of the present invention, the spinel-based gyromagnetic material further includes alumina and manganese oxide, wherein the ratio of alumina, manganese oxide, iron oxide and magnesium carbonate is based on a ratio of the garnet-based gyromagnetic material The molecular formula Mg(Al _x Mn _y Fe _(2-xy) )O ₄ is assigned, wherein x is greater than 0 and less than or equal to 0.5, and y is greater than 0 and less than or equal to 0.5.

In an embodiment of the present invention, the forming step is performed by a cold equalizing forming method.

In order to achieve the above objective, the present invention provides a method for manufacturing a modified gyromagnetic material, which includes the steps of: providing a gyromagnetic material blank, wherein the gyromagnetic material blank is passed through the gyromagnetic material as described in any of the above embodiments. A material blank is manufactured by a manufacturing method; a sintering step is performed to hold the gyromagnetic material blank at a sintering temperature of 1350 to 1450°C for 5 to 7 hours to form a gyromagnetic material sintered part; And performing a grinding step on the gyromagnetic material sintered part, so that the gyromagnetic material sintered part forms a modified gyromagnetic material.

In order to make the above and other objectives, features, and advantages of the present invention more obvious and understandable, the following will specifically cite the preferred embodiments of the present invention, together with the accompanying drawings, and describe in detail as follows. Furthermore, the directional terms mentioned in the present invention, such as up, down, top, bottom, front, back, left, right, inside, outside, side, surrounding, center, horizontal, horizontal, vertical, vertical, axial, The radial direction, the uppermost layer or the lowermost layer, etc., are only the direction of reference to the attached drawings. Therefore, the directional terms used are used to describe and understand the present invention, rather than to limit the present invention.

Referring to Figure 1, the manufacturing method 10 of the modified gyromagnetic blank of an embodiment of the present invention mainly includes the following steps 11 to 14: providing a gyromagnetic material precursor (step 11); performing a calcination step, The gyromagnetic material precursor is maintained at a temperature between 1200 and 1300°C for 1 to 3 hours (step 12); alumina is added to the gyromagnetic material precursor after the calcination step to form a mixture, wherein Based on the total weight of the precursor of the gyromagnetic material being 100 parts by weight, the alumina is between 0.1 to 0.3 parts by weight (step 13); the mixture is subjected to a ball milling step for 1.5 to 2.5 hours (step 14) And performing a molding step on the mixture after the ball milling step to form a gyromagnetic material blank (step 15). The present invention will describe the implementation details and principles of the above steps of an embodiment in detail below one by one.

The manufacturing method 10 of a modified gyromagnetic blank according to an embodiment of the present invention first includes step 11: providing a gyromagnetic material precursor. In one embodiment, the gyromagnetic material precursor may include at least one of a garnet-based gyromagnetic material and a spinel-based gyromagnetic material. In one embodiment, the garnet-based gyromagnetic material includes iron oxide (Fe ₂ O ₃ ) and yttrium oxide (Y ₂ O ₃ ). For example, the ratio of the iron oxide to the yttrium oxide can be distributed according to a molecular formula Y ₃ Fe ₅ O _{12 of} the garnet-based gyromagnetic material. In other words, when distributing according to the molecular formula Y ₃ Fe ₅ O ₁₂ , the molar ratio of the iron oxide to the yttrium oxide can be, for example, 5:3 (that is, the molar ratio of the iron oxide to the yttrium oxide is 5/3 ) To avoid using excess iron oxide and yttrium oxide. In one embodiment, due to inevitable errors, losses or other factors that may occur during the manufacturing process, the molar ratio of the iron oxide to the yttrium oxide may have a range value, for example, between 1.5 and 1.8. For example, it is 1.55, 1.6, 1.65, 1.7 or 1.8.

On the other hand, the garnet-based gyromagnetic material contains aluminum oxide and manganese oxide in addition to iron oxide and yttrium oxide. The ratio of aluminum oxide, manganese oxide, iron oxide and yttrium oxide is based on the garnet-based gyromagnetic material. The material has a molecular formula Y ₃ (Al _x Mn _y Fe _(5-xy) )O ₁₂ for distribution, where x is greater than 0 and less than or equal to 1, and y is greater than 0 and less than or equal to 1.

In one embodiment, the spinel-based gyromagnetic material includes iron oxide and magnesium carbonate. For example, the ratio of the iron oxide to the magnesium carbonate (MgCO ₃ ) can be distributed according to a molecular formula of the spinel-based gyromagnetic material MgFe ₂ O ₄ . In other words, when the distribution is performed according to the molecular formula MgFe ₂ O ₄ , the molar ratio of the iron oxide to the magnesium carbonate may be, for example, about 1:1 (that is, the molar ratio of the iron oxide to the magnesium carbonate is 1). Avoid using excess iron oxide and magnesium carbonate. In one embodiment, due to inevitable errors, losses or other factors that may occur during the manufacturing process, the molar ratio of the iron oxide to the magnesium carbonate is, for example, between 0.8 and 1.2, such as 0.85, 0.9 , 0.95, 1.05, 1.1, or 1.15.

On the other hand, the spinel-based gyromagnetic material contains aluminum oxide and manganese oxide in addition to iron oxide and magnesium carbonate, and the ratio of aluminum oxide, manganese oxide, iron oxide and yttrium oxide is based on the garnet-based spinel The magnetic material has a molecular formula Mg(Al _x Mn _y Fe _(2-xy) )O ₄ for distribution, where x is greater than 0 and less than or equal to 0.5, and y is greater than 0 and less than or equal to 0.5.

The manufacturing method 10 of the modified gyromagnetic blank according to an embodiment of the present invention is followed by step 12: a calcination step is performed, and the temperature of the gyromagnetic material precursor is held between 1200 and 1300° C. for 1 to 3 hours. In this step 12, the calcination step is, for example, a heating rate of 4 to 6° C. per minute so that the gyromagnetic material precursor is maintained at a temperature between 1200 and 1300° C. for 1 to 3 hours.

The manufacturing method 10 of the modified gyromagnetic blank according to an embodiment of the present invention is followed by step 13: adding alumina to the gyromagnetic material precursor after the calcination step to form a mixture, wherein the gyromagnetic material precursor A total weight of the substance is 100 parts by weight, and the alumina is between 0.1 and 0.3 parts by weight. In this step 13, alumina is mainly added to compensate or modify the magnetic properties and microwave properties of the modified gyromagnetic blank that is finally formed. The detailed analysis data will be described in the following paragraphs.

The manufacturing method 10 of the modified gyromagnetic blank according to an embodiment of the present invention is followed by step 14: performing a ball milling step on the mixture for 1.5 to 2.5 hours. In this step 14, the ball milling step is, for example, ball milling in a commercially available vibration mill for 2 hours, and ball milling using a zirconia column, so that the gyromagnetic material precursor after the calcination step can be ground to the desired level particle size range (e.g., D ₅₀ is about 2 to 3 microns).

The manufacturing method 10 of the modified gyromagnetic blank according to an embodiment of the present invention finally includes step 15: performing a forming step on the mixture after the ball milling step to form a gyromagnetic material blank. In this step 15, the forming step is, for example, using the "cold isostatic pressing (CIP)" method to press the gyromagnetic material mixture after the ball milling step into the gyromagnetic material without adding any organic binder. Material embryo.

Another embodiment of the present invention provides a manufacturing method 20 of a modified gyromagnetic material, which includes steps 21 to 23: providing a gyromagnetic material blank, wherein the gyromagnetic material blank is passed through any one of the above embodiments. The gyromagnetic material blank is manufactured by the manufacturing method (step 21); a sintering step is performed, and the gyromagnetic material blank is held at a sintering temperature of 1350 to 1450°C for 5 to 7 hours to form a A sintered gyromagnetic material (step 22); and a grinding step is performed on the sintered gyromagnetic material to make the sintered gyromagnetic material form a modified gyromagnetic material (step 23). The present invention will describe the implementation details and principles of the above steps of an embodiment in detail below one by one.

The manufacturing method 20 of a modified gyromagnetic material according to an embodiment of the present invention first includes step 21: providing a gyromagnetic material blank, wherein the gyromagnetic material blank is passed through the gyromagnetic material blank as described in any of the above embodiments Made by the manufacturing method. In this step 21, it is mainly to provide the gyromagnetic material blank made by adding alumina.

The manufacturing method 20 of the modified gyromagnetic material according to an embodiment of the present invention is followed by step 22: performing a sintering step, holding the gyromagnetic material blank at a sintering temperature of 1350 to 1450°C for 5 to 7 hours , To form a sintered piece of gyromagnetic material. In this step 12, for example, through a commercially available atmosphere sintering furnace, the gyromagnetic material blank is densely sintered at a temperature between 1350°C and 1450°C in an atmosphere where all or almost all of oxygen is used. 5 to 7 hours, where the rate of temperature increase is, for example, 3 to 5°C (for example, 4°C) per minute. After the sintering step, the gyromagnetic material sintered part is slowly cooled to room temperature (for example, the cooling rate is 2 to 4° C. per minute).

The final step 23 of the manufacturing method 20 of the modified gyromagnetic material according to an embodiment of the present invention is to perform a grinding step on the sintered gyromagnetic material to make the sintered gyromagnetic material form a modified gyromagnetic material. In this step 13, the modified gyromagnetic material may have a predetermined shape, for example, including a spherical shape, a rod shape, a wafer shape, a square shape, a plate shape or a cylindrical shape. In an embodiment, the selection of the predetermined shape can be selected according to the gyromagnetic member required in the final product. For example, when the final product is a phase shifter, the predetermined shape is, for example, a square shape or a plate shape; or when the final product is a circulator, the predetermined shape is, for example, a wafer shape or a cylindrical shape. In another embodiment, the selection of the predetermined shape can be selected according to the desired shape of the magnetic test sample. For example, when measuring the dielectric constant ( □ ), the predetermined shape is, for example, cylindrical, with a diameter ranging from 1.2 to 1.3 mm and a length of about 10 mm; when measuring the ferromagnetic resonance linewidth (∆H), the The predetermined shape is, for example, a ball type.

What I want to mention here is that the manufacturing method 20 of the modified gyromagnetic material in the embodiment of the present invention mainly uses the gyromagnetic material blank with alumina as the initial material, and the modified gyromagnetic material is made through specific parameters and specific steps. Magnetic materials, so that the modified gyromagnetic material has excellent magnetic properties and microwave properties when used as various microwave-related parts. The detailed analysis and comparison will be described in detail later.

Several examples and comparative examples will be cited below to prove that the modified gyromagnetic material produced by the method 20 of the modified gyromagnetic material according to an embodiment of the present invention has excellent magnetic properties and uses the modified gyromagnetic material. Microwave communication components made of magnetic materials also have better performance.

Example 1

First, the ratio of iron oxide and yttrium oxide is distributed according to the molecular formula Y ₃ Fe ₅ O ₁₂ , where the molar ratio of the iron oxide to the yttrium oxide is approximately 5:3, and the finished iron oxide and yttrium oxide are mixed ( Adding additives as appropriate), and grinding with zirconia beads to obtain a gyromagnetic material precursor. Afterwards, the gyromagnetic material precursor is subjected to a calcination step, and the temperature is maintained between 1200 and 1300° C. for 1 to 3 hours, and the heating rate is 5° C. per minute. Then, based on a total weight of 100 parts by weight of the gyromagnetic material precursor, 0.1 parts by weight of alumina was added to the gyromagnetic material precursor to form a mixture. The mixture was ball milled with a zirconia column in a vibrating mill for 2 hours, and pressed into a gyromagnetic material blank by a cold equalizing molding method.

Then, the gyromagnetic material blank is subjected to a sintering step, mainly through a commercially available atmosphere sintering furnace, so that the gyromagnetic material blank is exposed to an atmosphere of all or almost all oxygen at a temperature of 1350°C to 1450°C. Dense sintering at a temperature between ℃ for 5 to 7 hours to form a sintered gyromagnetic material. Afterwards, a grinding step is performed on the gyromagnetic material sintered part to make the gyromagnetic material sintered part form a modified gyromagnetic material. In this embodiment, based on the purpose of testing the magnetic properties and/or based on the gyromagnetic member conforming to the final product, multiple samples with different predetermined shapes can be produced.

Examples 2 to 4 and Comparative Examples 1 to 4

The manufacturing methods of Examples 2 to 4 and Comparative Examples 1 to 4 are substantially similar to those of Example 1. However, the differences generally include: the molecular formula of the gyromagnetic material precursor is different (that is, the material of the gyromagnetic material precursor is different, in which x and y of Example 3 and Comparative Example 3 are both about 1; Example 4 and Comparative Example 4 X and y are both about 0.5), and whether to perform the step of adding alumina addition amount. For detailed parameter differences, please refer to Table 1 below.

Table I Molecular formula Alumina addition (parts by weight) 4π M _s (G) B _r (G) H _c (O _e ) (∆ H ) (O _e ) SQR Example 1 Y ₃ Fe ₅ O ₁₂ 0.1 576 500 0.90 33 0.87 Comparative example 1 Y ₃ Fe ₅ O ₁₂ Not added 587 503 0.88 38 0.85 Example 2 MgFe ₂ O ₄ 0.3 1138 1002 1.32 180 0.88 Comparative example 2 MgFe ₂ O ₄ Not added 1162 980 1.27 186 0.84 Example 3 Y ₃ (Al _x Mn _y Fe _(5-xy) )O ₁₂ 0.25 700 608 0.87 25 0.87 Comparative example 3 Y ₃ (Al _x Mn _y Fe _(5-xy) )O ₁₂ Not added 720 610 0.85 29 0.84 Example 4 Mg(Al _x Mn _y Fe _(2-xy) )O ₄ 0.15 1280 1137 1.02 92 0.89 Comparative example 4 Mg(Al _x Mn _y Fe _(2-xy) )O ₄ Not added 1350 1148 1.15 106 0.85

Next, first, the magnetic properties of Examples 1 to 4 and Comparative Examples 1 to 4 were analyzed. Magnetic properties include: saturation magnetization (4π M _s ), residual magnetization (B _r ), coercive force (H _c ), ferromagnetic resonance linewidth (∆ H ), and squareness ratio (SQR), where Saturation magnetization, residual magnetization, coercivity and angular ratio can be measured by a commercially available magnetic property analyzer (Japan; Yokogawa company; model SK-130 BH tracer analyzer). The ferromagnetic resonance line width is measured according to the "IEC60556" measurement method developed by the International Electrotechnical Commission.

For gyromagnetic materials, it is generally desirable to have low coercivity, low ferromagnetic resonance linewidth and high angle ratio. It can be seen from the above measurement results that, compared with Comparative Examples 1 to 4, Examples 1 to 4 all have a low ferromagnetic resonance line width and a high angle ratio. As for the coercivity, although Examples 1 to 3 are slightly larger than Comparative Examples 1 to 3, they are still within the commercially acceptable range, and Example 4 is significantly smaller than Comparative Example 4. In summary, Examples 1 to 4 mainly add specific proportions of alumina to make them have better magnetic properties.

In addition, it should be mentioned that the alumina added after the calcination step in the embodiment of the present invention has a different mechanism from the alumina used when providing the gyromagnetic material precursor. Specifically, the alumina used in providing the gyromagnetic material precursor (for example, Examples 3 and 4 and Comparative Examples 3 and 4) will form a crystal phase structure through a calcination step. The alumina added after the calcination step is used as an additional additive and provides additional effects (such as increasing the magnetic properties or improving the microwave properties of the subsequent analysis. Therefore, the two mechanisms of action are different.

On the other hand, the modified gyromagnetic materials of Examples 1 to 4 and the gyromagnetic materials of Comparative Examples 1 to 4 were used as gyromagnetic members in phase shifters and circulators, and measured with a commercially available network analyzer Microwave properties, detailed analysis results, please refer to Table 2 below.

Table II Communication components S ₁₁ (dB) S ₂₁ (dB) S ₁₂ (dB) S ₂₂ (dB) Example 1 Phase shifter -20.8 0.92 -19.9 -20.3 Circulator -21.3 0.93 -19.8 -20.1 Comparative example 1 Phase shifter -16.8 1.05 -17.3 -17.2 Circulator -18.5 1.07 -19.1 -19.3 Example 2 Phase shifter -18.1 0.96 -18.5 -19.0 Circulator -19.5 0.94 -19.4 -20.2 Comparative example 2 Phase shifter -15.3 1.15 -15.8 -16.1 Circulator -16.0 1.13 -16.3 -17.1 Example 3 Phase shifter -22.6 0.88 -20.5 -21.8 Circulator -23.0 0.90 -20.3 -21.7 Comparative example 3 Phase shifter -17.7 0.99 -18.0 -18.3 Circulator -19.1 1.02 -19.3 -19.8 Example 4 Phase shifter -18.9 0.93 -19.4 -19.7 Circulator -20.4 0.91 -20.2 -21.1 Comparative example 4 Phase shifter -16.4 1.02 -17.1 -18.0 Circulator -17.2 0.98 -17.8 -18.9

Generally speaking, when evaluating the pros and cons of microwave components, the evaluation is conducted through S parameters, which include S ₁₁ , S ₂₁ , S ₁₂ and S ₂₂ parameters. For the parameters of S ₁₁ , S ₁₂ and S ₂₂ , the lower the value, the better the performance of the microwave component; for the parameter of S ₂₁ , the closer the value is to 0, the better the performance of the microwave component. It can be seen from Table 2 above that, based on the same molecular formula of the gyromagnetic material and the same microwave element as a comparison standard, Examples 1 to 4 have better microwave element performance than Comparative Examples 1 to 4.

According to the above-mentioned embodiments and comparative examples, it can be seen that the modified gyromagnetic material produced by the method of manufacturing the modified gyromagnetic material of the embodiment of the present invention does have better magnetic properties, and the modified gyromagnetic material is used Microwave components made of materials can have better microwave properties.

Although the present invention has been disclosed in the preferred embodiments, it is not intended to limit the present invention. Anyone familiar with the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be subject to the scope of the attached patent application.

10: method 11~15: steps 20: Method 21~23: Steps

Figure 1 is a schematic flow diagram of a manufacturing method of a modified gyromagnetic blank according to an embodiment of the present invention. Figure 2 is a schematic flow diagram of a manufacturing method of a modified gyromagnetic material according to an embodiment of the present invention.

10: method

11~15: steps

Claims (10)

A method for manufacturing modified gyromagnetic blanks, which comprises the steps: Provide a gyromagnetic material precursor; Performing a calcination step, holding the gyromagnetic material precursor at a temperature between 1200 and 1300°C for 1 to 3 hours; Alumina is added to the gyromagnetic material precursor after the calcination step to form a mixture, wherein based on a total weight of the gyromagnetic material precursor being 100 parts by weight, the alumina is between 0.1 to 0.3 parts by weight between; Perform a ball milling step on the mixture for 1.5 to 2.5 hours; and A forming step is performed on the mixture after the ball milling step to form a gyromagnetic material blank. According to the manufacturing method of the modified gyromagnetic blank according to the first item of the scope of patent application, the gyromagnetic material precursor includes at least one of a garnet-based gyromagnetic material and a spinel-based gyromagnetic material. The manufacturing method of the modified gyromagnetic blank as described in item 2 of the scope of patent application, wherein the garnet-based gyromagnetic material includes iron oxide and yttrium oxide. The manufacturing method of the modified gyromagnetic blank as described in item 3 of the scope of patent application, wherein in the garnet-based gyromagnetic material, the ratio of iron oxide to yttrium oxide is based on a molecular formula of the garnet-based gyromagnetic material Y ₃ Fe ₅ O ₁₂ is allocated. As described in item 3 of the scope of patent application, the manufacturing method of the modified gyromagnetic blank, wherein the garnet-based gyromagnetic material further comprises alumina and manganese oxide, wherein the ratio of alumina, manganese oxide, iron oxide and yttrium oxide It is distributed according to a molecular formula Y ₃ (Al _x Mn _y Fe _(5-xy) )O _{12 of} the garnet-based gyromagnetic material, where x is greater than 0 and less than or equal to 1, and y is greater than 0 and less than or equal to 1. The manufacturing method of the modified gyromagnetic blank according to the second item of the scope of patent application, wherein the spinel-based gyromagnetic material includes iron oxide and magnesium carbonate. The manufacturing method of the modified gyromagnetic blank as described in item 6 of the scope of patent application, wherein in the spinel-based gyromagnetic material, the ratio of iron oxide to magnesium carbonate is based on the spinel-based gyromagnetic material One molecular formula MgFe ₂ O ₄ is distributed. The manufacturing method of the modified gyromagnetic blank as described in item 6 of the scope of patent application, wherein the spinel-based gyromagnetic material further comprises aluminum oxide and manganese oxide, wherein aluminum oxide, manganese oxide, iron oxide and magnesium carbonate The proportion is distributed according to a molecular formula Mg(Al _x Mn _y Fe _(2-xy) )O _{4 of} the garnet-based gyromagnetic material, where x is greater than 0 and less than or equal to 0.5, and y is greater than 0 and less than or equal to 0.5. According to the manufacturing method of the modified gyromagnetic blank as described in item 1 of the scope of patent application, the forming step is carried out by a cold equalizing forming method. A manufacturing method of modified gyromagnetic material, which comprises the steps: A gyromagnetic material blank is provided, wherein the gyromagnetic material blank is made by the manufacturing method of the gyromagnetic material blank as described in any one of items 1 to 9 in the scope of patent application; Performing a sintering step, holding the gyromagnetic material blank at a sintering temperature of 1350 to 1450°C for 5 to 7 hours to form a gyromagnetic material sintered part; and A grinding step is performed on the gyromagnetic material sintered piece to make the gyromagnetic material sintered piece form a modified gyromagnetic material.

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