CN115448712A - Preparation method of LiZn ferrite ceramic with high density and low ferromagnetic resonance line width - Google Patents
Preparation method of LiZn ferrite ceramic with high density and low ferromagnetic resonance line width Download PDFInfo
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- 229910000859 α-Fe Inorganic materials 0.000 title claims abstract description 52
- 239000000919 ceramic Substances 0.000 title claims abstract description 47
- 229910013391 LizN Inorganic materials 0.000 title claims abstract description 46
- 230000005350 ferromagnetic resonance Effects 0.000 title claims abstract description 27
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- 238000005245 sintering Methods 0.000 claims abstract description 72
- 239000000203 mixture Substances 0.000 claims abstract description 46
- 238000007731 hot pressing Methods 0.000 claims abstract description 40
- 238000000034 method Methods 0.000 claims abstract description 33
- 238000000498 ball milling Methods 0.000 claims abstract description 31
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- 238000000137 annealing Methods 0.000 claims abstract description 12
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- 239000000843 powder Substances 0.000 claims description 18
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 12
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 12
- 238000001816 cooling Methods 0.000 claims description 6
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- 238000003756 stirring Methods 0.000 claims description 6
- 239000000463 material Substances 0.000 abstract description 2
- 239000013078 crystal Substances 0.000 abstract 1
- 230000005415 magnetization Effects 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 7
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 230000005418 spin wave Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000005291 magnetic effect Effects 0.000 description 1
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Abstract
The invention discloses a preparation method of LiZn ferrite ceramic with high density and low ferromagnetic resonance line width, which comprises the following steps: weighing raw materials according to a formula to obtain a mixture A; ball-milling the prepared mixture A by adopting a wet process for one time, uniformly mixing and drying to obtain a mixture B; pre-burning the obtained mixture B and then preserving heat; performing secondary ball milling on the pre-sintered mixture B, and pressing the mixture B into a green body after ball milling; carrying out vacuum hot-pressing sintering on the pressed green body; and annealing the green body after vacuum hot-pressing sintering to obtain the LiZn ferrite ceramic with high compactness and low ferromagnetic resonance line width. The LiZn ferrite ceramic prepared by the invention has obviously increased density and the ferromagnetic resonance line width is reduced by about 20 percent. The hot-pressing sintering increases the material density, makes the crystal grains more uniform, finally obviously reduces the ferromagnetic resonance line width, and provides help for the application of LiZn ferrite ceramics in high-performance microwave electromagnetic devices. The method has the characteristics of simple operation, controllable parameters, high repeatability and the like.
Description
Technical Field
The invention belongs to the technical field of magnetic material preparation, and particularly relates to a preparation method of high-density and low-ferromagnetic resonance line width LiZn ferrite ceramic.
Background
The LiZn ferrite ceramic has the characteristics of low ferromagnetic resonance line width, low coercive force, high squareness ratio, high saturation magnetization, high temperature stability and the like, and is widely applied to high-frequency and high-power microwave ferrite devices. The synthesis of LiZn ferrite ceramic generally adopts a solid-phase sintering method, and the process has the advantages of low cost, mass production, simple and convenient operation and the like. However, the ceramic product fired by the traditional solid-phase sintering method has low density and large low ferromagnetic resonance line width, which causes large magnetic loss, and further influences the application of the ceramic product in high-performance microwave electromagnetic devices.
Disclosure of Invention
An object of the present invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, there is provided a method for preparing a high-density low-ferroresonance line width LiZn ferrite ceramic, comprising the steps of:
step one, weighing raw materials according to a formula to obtain a mixture A;
step two, performing primary ball milling on the mixture A prepared in the step one by adopting a wet process, uniformly mixing, and drying to obtain a mixture B;
step three, pre-burning the mixture B obtained in the step two, and then preserving heat;
step four, performing secondary ball milling on the mixture B subjected to the pre-sintering in the step three, and pressing the mixture B into a green body after ball milling;
step five, carrying out vacuum hot-pressing sintering on the green body pressed in the step four;
and step six, annealing the green body after vacuum hot pressing sintering to obtain the LiZn ferrite ceramic with high compactness and low ferromagnetic resonance line width.
Preferably, the specific method of the first step comprises: respectively weighing 12.5 mol percent of Li 2 CO 3 Powder, 8.3% ZnO powder and 79.16% ZnO powderFe 2 O 3 Powder, pouring the weighed powder into a beaker, and manually stirring for 1h to obtain a mixture A, wherein the mixture A is Li 0.375 Zn 0.25 Fe 2.375 O 4 Ferrite.
Preferably, wherein the Li 2 CO 3 The purity of the powder is more than 97.00wt%, the purity of the ZnO powder is more than 99.70wt%, and Fe 2 O 3 The purity of the powder was greater than 99.85wt%.
Preferably, the ball milling time in the second step is 5h.
Preferably, the pre-sintering temperature in the third step is 850 ℃, and the heat preservation time is 3 hours.
Preferably, the time of the secondary ball milling in the fourth step is 10 hours, the secondary ball milling is carried out and then dried, polyvinyl alcohol with the concentration of 10% is added for granulation, the volume of the polyvinyl alcohol is 10% of the volume of the mixture B, and the granulated sample is pressed into a green body with the diameter of 40mm and the length of 20 mm.
Preferably, in the fifth step, a specific method of vacuum hot-pressing sintering includes: and putting the green body obtained in the step four into a vacuum hot-pressing sintering furnace, and performing vacuum hot-pressing sintering, wherein the vacuum degree is 0.1-1 Pa, the sintering temperature of the hot-pressing sintering is 950-1020 ℃, the temperature is kept for 2h, and the pressure is 14MPa in the sintering process.
Preferably, in the sixth step, the specific method for green body annealing includes: and placing the green body subjected to vacuum hot pressing sintering in the step five in a muffle furnace, heating the green body from room temperature to 950 ℃ at the heating rate of 5 ℃/min in the air atmosphere, preserving the heat for 4h, and finally cooling along with the furnace.
The invention at least comprises the following beneficial effects: in the process of preparing LiZn ferrite ceramic, the invention uses Li with the mol percentage of 12.5 percent 2 CO 3 8.3% ZnO and 79.16% Fe 2 O 3 The LiZn ferrite ceramic is taken as a raw material, a mode of firstly carrying out vacuum hot pressing and then carrying out annealing is adopted, the density of the LiZn ferrite ceramic subjected to annealing treatment after hot pressing sintering is obviously increased, and the ferromagnetic resonance line width is reduced by about 20%. The hot-pressing sintering increases the density of the material, and simultaneously, the annealing treatment is combined to release the interior of the ceramicAnd the grains are more uniform due to redundant stress, so that the line width of ferromagnetic resonance is obviously reduced, and the application of LiZn ferrite ceramic in high-performance microwave electromagnetic devices is facilitated. The method has the characteristics of simple operation, controllable parameters, high repeatability and the like.
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 an XRD pattern of a sample of LiZn ferrite ceramic after sintering according to examples 1-4;
FIG. 2 is a graph showing the density and saturation magnetization of LiZn ferrite ceramic samples after sintering according to examples 1 to 4;
FIG. 3 shows the ferromagnetic resonance line width and spin wave line width of LiZn ferrite ceramic samples after sintering according to examples 1 to 4;
fig. 4 is a graph showing the comparison of the density and saturation magnetization of the LiZn ferrite ceramics obtained in examples 1 to 4 and comparative examples 1 to 2.
Detailed Description
The present invention is described in further detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.
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.
Example 1
A preparation method of LiZn ferrite ceramic with high density and low ferromagnetic resonance line width comprises the following steps:
step one, weighing raw materials according to a formula to obtain a mixture A: with Li 2 CO 3 (purity of>97.00 wt%), znO (purity)>99.70wt％)、Fe 2 O 3 (purity of>99.85 wt%) as raw material for preparing Li 0.375 Zn 0.25 Fe 2.375 O 4 Ferrite, each 4.62g of Li 2 CO 3 And 6.76g ZnO and 63.21g Fe 2 O 3 Will bePouring the weighed powder into a beaker, and manually stirring for 1h;
step two, ball milling and drying: ball-milling the mixture A obtained in the step one for 5 hours by adopting a wet process, uniformly mixing and drying to obtain a mixture B;
step three, pre-burning: pre-sintering the mixture B obtained in the step two at 850 ℃, and preserving heat for 3 hours;
step four, secondary ball milling, green pressing: performing secondary ball milling on the mixture B subjected to the pre-sintering in the step three for 10 hours, and drying; adding 10% polyvinyl alcohol for granulation, wherein the volume consumption of the polyvinyl alcohol is 10% of the volume of the mixture B, and forming into a green body with the diameter of 40mm and the length of 20 mm;
step five, vacuum hot-pressing sintering: and putting the green body pressed in the step four into a vacuum hot-pressing sintering furnace, and performing vacuum hot-pressing sintering. The vacuum degree is 0.1Pa, the sintering temperature of hot-pressing sintering is 950 ℃, the temperature is kept for 2h, and the pressure is 14MPa in the sintering process.
Step six, annealing: and placing the green body subjected to vacuum sintering in the step five in a muffle furnace, heating the green body from room temperature to 950 ℃ at the heating rate of 5 ℃/min in the air atmosphere, preserving the heat for 4h, and finally cooling the green body along with the furnace to obtain the LiZn ferrite ceramic with high compactness and low ferromagnetic resonance line width.
Example 2
A preparation method of LiZn ferrite ceramic with high density and low ferromagnetic resonance line width comprises the following steps:
step one, weighing raw materials according to a formula to obtain a mixture A: with Li 2 CO 3 (purity of>97.00 wt%), znO (purity)>99.70wt％)、Fe 2 O 3 (purity of>99.85 wt%) as raw material for preparing Li 0.375 Zn 0.25 Fe 2.375 O 4 Ferrite, each 4.62g of Li 2 CO 3 And 6.76g ZnO and 63.21g Fe 2 O 3 Pouring the weighed powder into a beaker, and manually stirring for 1 hour;
step two, ball milling and drying: ball-milling the mixture A obtained in the step one for 5 hours by adopting a wet process, uniformly mixing, and drying to obtain a mixture B;
step three, pre-burning: pre-sintering the mixture B obtained in the step two at 850 ℃, and preserving heat for 3 hours;
step four, secondary ball milling, green pressing: performing secondary ball milling on the mixture B subjected to the pre-sintering in the step three for 10 hours, and drying; adding 10% polyvinyl alcohol for granulation, wherein the volume consumption of the polyvinyl alcohol is 10% of the volume of the mixture B, and forming into a green body with the diameter of 40mm and the length of 20 mm;
step five, vacuum hot-pressing sintering: and putting the green body pressed in the step four into a vacuum hot-pressing sintering furnace, and performing vacuum hot-pressing sintering. The vacuum degree is 0.1Pa, the sintering temperature of hot-pressing sintering is 980 ℃, the temperature is kept for 2h, and the pressure is 14MPa in the sintering process.
Step six, annealing: and placing the green body subjected to vacuum sintering in the step five in a muffle furnace, heating the green body from room temperature to 950 ℃ at the heating rate of 5 ℃/min in the air atmosphere, preserving the heat for 4h, and finally cooling the green body along with the furnace to obtain the LiZn ferrite ceramic with high compactness and low ferromagnetic resonance line width.
Example 3
A preparation method of LiZn ferrite ceramic with high density and low ferromagnetic resonance line width comprises the following steps:
step one, weighing raw materials according to a formula to obtain a mixture A: with Li 2 CO 3 (purity of>97.00 wt%), znO (purity)>99.70wt％)、Fe 2 O 3 (purity of>99.85 wt%) as raw material for preparing Li 0.375 Zn 0.25 Fe 2.375 O 4 Ferrite, each 4.62g of Li 2 CO 3 And 6.76g ZnO and 63.21g Fe 2 O 3 Pouring the weighed powder into a beaker, and manually stirring for 1 hour;
step two, ball milling and drying: ball-milling the mixture A obtained in the step one for 5 hours by adopting a wet process, uniformly mixing and drying;
step three, pre-burning: pre-sintering the mixture A obtained in the step two at 850 ℃, and preserving heat for 3 hours;
step four, secondary ball milling, green pressing: performing secondary ball milling on the mixture B subjected to the pre-sintering in the step three for 10 hours, and drying; adding 10% polyvinyl alcohol for granulation, wherein the volume consumption of the polyvinyl alcohol is 10% of the volume of the mixture B, and forming into a green body with the diameter of 40mm and the length of 20 mm;
step five, vacuum hot-pressing sintering: and putting the green body pressed in the step four into a vacuum hot-pressing sintering furnace, and performing vacuum hot-pressing sintering. The vacuum degree is 0.1Pa, the sintering temperature of hot-pressing sintering is 1000 ℃, the temperature is kept for 2h, and the pressure is 14MPa in the sintering process.
Step six, annealing: and placing the green body sintered in the step five in vacuum in a muffle furnace, heating the green body from room temperature to 950 ℃ at the heating rate of 5 ℃/min in the air atmosphere, preserving the heat for 4h, and finally cooling along with the furnace to obtain the LiZn ferrite ceramic with high compactness and low ferromagnetic resonance line width.
Example 4
A preparation method of LiZn ferrite ceramic with high density and low ferromagnetic resonance line width comprises the following steps,
step one, weighing raw materials according to a formula to obtain a mixture A: with Li 2 CO 3 (purity of>97.00 wt%), znO (purity)>99.70wt％)、Fe 2 O 3 (purity of>99.85 wt%) as raw material for preparing Li 0.375 Zn 0.25 Fe 2.375 O 4 Ferrite, each 4.62g of Li 2 CO 3 And 6.76g ZnO and 63.21g Fe 2 O 3 Pouring the weighed powder into a beaker, and manually stirring for 1 hour;
step two, ball milling and drying: ball-milling the mixture A obtained in the step one for 5 hours by adopting a wet process, uniformly mixing and drying;
step three, pre-burning: pre-sintering the mixture A obtained in the step two at 850 ℃, and preserving heat for 3 hours;
step four, secondary ball milling, green pressing: performing secondary ball milling on the mixture B subjected to the pre-sintering in the step three for 10 hours, and drying; adding 10% polyvinyl alcohol for granulation, wherein the volume consumption of the polyvinyl alcohol is 10% of the volume of the mixture B, and forming into a green body with the diameter of 40mm and the length of 20 mm;
step five, vacuum hot-pressing sintering: and putting the green body pressed in the step four into a vacuum hot-pressing sintering furnace, and performing vacuum hot-pressing sintering. The vacuum degree is 0.1Pa, the sintering temperature of hot-pressing sintering is 1020 ℃, the temperature is kept for 2h, and the pressure is 14MPa in the sintering process.
Step six, annealing: and placing the green body sintered in the step five in vacuum in a muffle furnace, heating the green body from room temperature to 950 ℃ at the heating rate of 5 ℃/min in the air atmosphere, preserving the heat for 4h, and finally cooling along with the furnace to obtain the LiZn ferrite ceramic with high compactness and low ferromagnetic resonance line width.
Comparative example 1
The comparative example provides a method for preparing high-density low-ferromagnetic resonance line width LiZn ferrite ceramic, in which the hot press sintering temperature in the fifth step becomes 1050 ℃, which is the same as the operation in examples 1 to 4.
Comparative example 2
The hot-pressing sintering temperature of the preparation method of the high-density low-ferromagnetic resonance line width LiZn ferrite ceramic provided by the comparative example in the fifth step is 1150 ℃, and the operation is the same as that of the examples 1-4.
The XRD pattern, density rho and saturation magnetization 4 pi Ms, ferromagnetic resonance line width Delta H and spin wave line width Delta H of the LiZn ferrite ceramics with high density and low ferromagnetic resonance line width prepared in examples 1 to 4 are respectively measured k Fig. 1, fig. 2 and fig. 3 are obtained, respectively, wherein the vacuum hot-pressing sintering temperatures adopted in the fifth step of examples 1 to 4 are different, and the vacuum hot-pressing sintering temperatures corresponding to the fifth step of examples 4 are 950 ℃, 980 ℃, 1000 ℃ and 1020 ℃. As can be seen from fig. 1, 2 and 3, the LiZn ferrite ceramic bodies prepared in examples 1 to 4 all had very high density under a pressure of 14MPa during the vacuum hot press sintering, and the LiZn ferromagnetic resonance line width Δ H and magnetization 4 π Ms, which were prepared at a vacuum hot press sintering temperature of 980 ℃, were the lowest. Meanwhile, the density ρ and the saturation magnetization 4 π Ms of the LiZn ferrite ceramic prepared in comparative example 1 were 4.36g/cm, respectively 3 4423Gauss, comparative example 2, the LiZn ferrite ceramic obtained had a density ρ and a saturation magnetization 4 π Ms of 4.81g/cm, respectively 3 4910Gauss, and the density ρ and saturation magnetization 4 π Ms of the high-density, low-ferromagnetic resonance line width LiZn ferrite ceramic obtained in examples 1-4 are plotted to obtain FIG. 4, and the result is that the surface is made after vacuum hot-pressing sinteringAlthough the density ρ of the obtained LiZn ferrite ceramic is higher than that of the LiZn ferrite ceramic with the saturation magnetization of 4 π Ms at 1020 ℃, the results are inferior to those of the LiZn ferrite ceramic with high compactness and low ferromagnetic resonance line width prepared in example 2.
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 in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.
Claims (8)
1. A preparation method of LiZn ferrite ceramic with high density and low ferromagnetic resonance line width is characterized by comprising the following steps:
step one, weighing raw materials according to a formula to obtain a mixture A;
step two, ball-milling the mixture A prepared in the step one by adopting a wet process, uniformly mixing and drying to obtain a mixture B;
step three, pre-burning the mixture B obtained in the step two, and then preserving heat;
step four, performing secondary ball milling on the mixture B subjected to the pre-sintering in the step three, and pressing the mixture B into a green body after ball milling;
step five, carrying out vacuum hot-pressing sintering on the green body pressed in the step four;
and step six, annealing the green body after vacuum hot pressing sintering to obtain the LiZn ferrite ceramic with high compactness and low ferromagnetic resonance line width.
2. The preparation method of the high-density low-ferromagnetic resonance line width LiZn ferrite ceramic according to claim 1, wherein the specific method in the first step comprises the following steps: respectively weighing MobaiFraction of 12.5% Li 2 CO 3 Powder, 8.3% ZnO powder, and 79.16% Fe 2 O 3 Powder, pouring the weighed powder into a beaker, and manually stirring for 1h to obtain a mixture A, wherein the mixture A is Li 0.375 Zn 0.25 Fe 2.375 O 4 A ferrite.
3. The method of claim 2, wherein the Li is selected from the group consisting of Li, zn, fe, zn, and Li 2 CO 3 The purity of the powder is more than 97.00wt%, the purity of the ZnO powder is more than 99.70wt%, and Fe 2 O 3 The purity of the powder was greater than 99.85wt%.
4. The method for preparing high-density low-ferromagnetic resonance line width LiZn ferrite ceramic according to claim 1, wherein the ball milling time in the second step is 5h.
5. The preparation method of the high-density low-ferromagnetic resonance line width LiZn ferrite ceramic according to claim 1, wherein the pre-sintering temperature in the third step is 850 ℃ and the holding time is 3h.
6. The method for preparing high-density low-ferromagnetic resonance line width LiZn ferrite ceramic according to claim 1, wherein the time of the secondary ball milling in the fourth step is 10h, the secondary ball milling is followed by drying, polyvinyl alcohol with the concentration of 10% is added for granulation, the volume usage of the polyvinyl alcohol is 10% of the volume of the mixture B, and the granulated sample is pressed into a green body with the diameter of 40mm and the length of 20 mm.
7. The method for preparing high-density low-ferromagnetic resonance line width LiZn ferrite ceramic according to claim 1, wherein in the fifth step, the specific method of vacuum hot-pressing sintering comprises: and putting the green body obtained in the step four into a vacuum hot-pressing sintering furnace, and performing vacuum hot-pressing sintering, wherein the vacuum degree is 0.1-1 Pa, the sintering temperature of the hot-pressing sintering is 950-1020 ℃, the temperature is kept for 2 hours, and the pressure is 14MPa in the sintering process.
8. The method for preparing high-compactness LiZn ferrite ceramic with a low ferromagnetic resonance line width according to claim 1, wherein in the sixth step, the specific method for green body annealing comprises the following steps: and placing the green body subjected to vacuum hot pressing sintering in the step five in a muffle furnace, heating the green body from room temperature to 950 ℃ at the heating rate of 5 ℃/min in the air atmosphere, preserving the heat for 4h, and finally cooling along with the furnace.
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| CN116854459A (en) * | 2023-05-19 | 2023-10-10 | 江苏阜宁海天金宁三环电子有限公司 | High-frequency high-impedance lean iron-manganese-zinc ferrite and preparation method thereof |
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| CN114956800A (en) * | 2022-05-23 | 2022-08-30 | 西南应用磁学研究所(中国电子科技集团公司第九研究所) | High-performance microwave polycrystalline ferrite material |
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| CN114956800A (en) * | 2022-05-23 | 2022-08-30 | 西南应用磁学研究所(中国电子科技集团公司第九研究所) | High-performance microwave polycrystalline ferrite material |
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| CN116854459A (en) * | 2023-05-19 | 2023-10-10 | 江苏阜宁海天金宁三环电子有限公司 | High-frequency high-impedance lean iron-manganese-zinc ferrite and preparation method thereof |
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