PREPARATION METHOD FOR LOW-LINE-WIDTH W-TYPE HEXAGONAL CRYSTAL SYSTEM MICROWAVE FERRITE MATERIAL

Abstract

The present application discloses a preparation method for a low-line-width W-type hexagonal crystal system microwave ferrite material. The preparation method comprises: performing weighing, first ball milling treatment, drying, first sintering treatment, second ball milling treatment, granulation and molding, and second sintering treatment in sequence to obtain a low-line-width W-type hexagonal crystal system microwave ferrite material. According to the preparation method of the present application, a rare earth element Gd is employed to replace some Fe ions, appropriate saturation magnetization, remanence ratio and line width are obtained by using electromagnetic properties of Gd and Fe and compensation points, and the microstructure of the W-type hexagonal crystal system microwave ferrite material is improved by jointly adding appropriate quantities of low-melting-point fluxing agents Bi.sub.2O.sub.3, V.sub.2O.sub.5, SiO.sub.2 and ZnO, so that pores are reduced, the line width is decreased and the remanence ratio is increased. The preparation method has good process stability and good repeatability, and is suitable for mass production.

Claims

1. A preparation method for a low line-width W-type hexagonal microwave ferrite material, comprising the following steps: (1) weighing BaCO.sub.3, Gd.sub.2O.sub.3, Ni.sub.2O, and Fe.sub.2O.sub.3 as raw materials according to calculation based on a chemical formula of BaGd.sub.xNi.sub.2Fe.sub.(16-x)O.sub.27, in which 0.1<x<0.25, and then performing a first ball-milling treatment to obtain a first ball-milled slurry with a particle size X50 of 0.9-1.2 m; (2) sequentially subjecting the first ball-milled slurry to drying and a first sintering treatment which is performed at a temperature of 1200-1280 C. to obtain a mixed powder; (3) mixing the mixed powder and a fluxing agent, and performing a second ball-milling treatment to obtain a second ball-milled slurry with a particle size X50 of 0.8-1.1 m; components and mass contents of the fluxing agent are: 0.01-0.1% of Bi.sub.2O.sub.3, 0.01-0.1% of V.sub.2O.sub.5, 0.01-0.1% of SiO.sub.2, and 0.01-0.1% of ZnO, respectively; and (4) sequentially subjecting the second ball-milled slurry to granulation-molding and a second sintering treatment to obtain the low line-width W-type hexagonal microwave ferrite material; the second sintering treatment comprises: first performing a sintering in air, and then performing a sintering in oxygen at a temperature of 1150-1250 C.; the low line-width W-type hexagonal microwave ferrite material has a line-width of less than 400 Oe.

2. The preparation method according to claim 1, wherein the first ball-milling treatment in step (1) is performed at a rotational speed of 60-80 r/min.

3. The preparation method according to claim 1, wherein the first ball-milling treatment is performed for a period of 20-40 h.

4. The preparation method according to claim 1, wherein in the first ball-milling treatment, a dispersant with a mass fraction of 0.01-0.05% is added.

5. The preparation method according to claim 1, wherein the drying in step (2) is performed at a temperature of 120-150 C.

6. The preparation method according to claim 1, wherein the first sintering treatment in step (2) is performed at a heating rate of 1.0-1.5 C./min.

7. The preparation method according to claim 1, wherein the second ball-milling treatment in step (3) is performed at a rotational speed of 60-80 r/min.

8. The preparation method according to claim 1, wherein in the second ball-milling treatment in step (3), a dispersant with a mass fraction of 0.01-0.05% is added.

9. The preparation method according to claim 1, wherein the slurry before the granulation-molding in step (4) has a solid content of more than or equal to 70%.

10. The preparation method according to claim 1, wherein the sintering in air in step (4) comprises: heating from room temperature to 120 C. at a rate of 1.0 C./min, holding the temperature for 2 h, and then heating to 1000 C. at a rate of 2 C./min.

11. The preparation method according to claim 1, wherein the sintering in oxygen in step (4) comprises: introducing oxygen with an oxygen content of more than or equal to 98% by a flow rate of 30-50 L/min, heating to an oxygen-sintering temperature at a rate of 2.5 C./min, holding the temperature for 3-8 h, then cooling to 700 C. at a rate of 2.5 C./min, and stopping the introduction of oxygen and cooling in furnace.

12. The preparation method according to claim 1, comprising the following steps: (1) weighing BaCO.sub.3, Gd.sub.2O.sub.3, Ni.sub.2O, and Fe.sub.2O.sub.3 as raw materials according to calculation based on a chemical formula of BaGd.sub.xNi.sub.2Fe.sub.(16-x)O.sub.27, in which 0.1<x<0.25, and then performing a first ball-milling treatment at a rotational speed of 60-80 r/min for 20-40 h to obtain a first ball-milled slurry with a particle size X50 of 0.9-1.2 m; in the first ball-milling treatment, a dispersant with a mass fraction of 0.01-0.05% is added; (2) sequentially subjecting the first ball-milled slurry to drying which is performed at a temperature of 120-150 C. for 16-20 h, and a first sintering treatment which is performed at a temperature of 1200-1280 C. with a heating rate of 1.0-1.5 C./min to obtain a mixed powder; (3) mixing the mixed powder and a fluxing agent, and performing a second ball-milling treatment at a rotational speed of 60-80 r/min for 15-24 h to obtain a second ball-milled slurry with a particle size X50 of 0.8-1.1 m; components and mass contents of the fluxing agent are: 0.01-0.1% of Bi.sub.2O.sub.3, 0.01-0.1% of V.sub.2O.sub.5, 0.01-0.1% of SiO.sub.2, and 0.01-0.1% of ZnO, respectively; in the second ball-milling treatment, a dispersant with a mass fraction of 0.01-0.05% is added; and (4) sequentially subjecting the second ball-milled slurry to granulation-molding and a second sintering treatment to obtain the low line-width W-type hexagonal microwave ferrite material; the low line-width W-type hexagonal microwave ferrite material has a line-width of less than 400 Oe; the slurry before the granulation-molding has a solid content of more than or equal to 70%; a sample obtained from the granulation-molding has a density of 3.4-3.6 g/cm.sup.3; the second sintering treatment comprises first performing a sintering in air and then performing a sintering in oxygen; the sintering in air comprises: heating from room temperature to 120 C. at a rate of 1.0 C./min, holding the temperature for 2 h, and then heating to 1000 C. at a rate of 2 C./min; the sintering in oxygen comprises: introducing oxygen with an oxygen content of more than or equal to 98% by a flow rate of 30-50 L/min, heating to a sintering temperature of 1150-1250 C. at a rate of 2.5 C./min, holding the temperature for 3-8 h, then cooling to 700 C. at a rate of 2.5 C./min, and stopping the introduction of oxygen and cooling in furnace.

13. The preparation method according to claim 1, wherein the drying in step (2) is performed for a period of 16-20 h.

14. The preparation method according to claim 1, wherein the second ball-milling treatment in step (3) is performed for a period of 15-24 h.

15. The preparation method according to claim 1, wherein a sample obtained from the granulation-molding has a density of 3.4-3.6 g/cm.sup.3.

Description

DETAILED DESCRIPTION

[0049] To better illustrate the present application, examples are listed below in the present application. Those skilled in the art should understand that the examples merely assist in understanding the present application and should not be regarded as a specific limitation to the present application.

[0050] The present application is further explained in detail below. However, the following examples are only brief examples of the present application, and do not represent or limit the protection scope of claims in the present application. The protection scope of the present application is defined by the claims.

Example 1

[0051] The example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material, and the preparation method comprises the following steps: [0052] (1) raw materials BaCO.sub.3, Gd.sub.2O.sub.3, Ni.sub.2O, and Fe.sub.2O.sub.3 were weighted out according to calculation based on a chemical formula of BaGd.sub.xNi.sub.2Fe.sub.(16-x)O.sub.27, in which x=0.2; wherein a purity of BaCO.sub.3 was 99.65%, a purity of Gd.sub.2O.sub.3 was 99.5%, a purity of Ni.sub.2O was 99.5%, and a purity of Fe.sub.2O.sub.3 was 99.5%; [0053] (2) the raw materials were put into a ball-mill tank to be mixed by a ball mill according to a weight ratio of the raw materials to deionized water to zirconium oxide balls (large to small) being 1000:1000:(4000:1000), and subjected to a first ball-milling treatment at a rotational speed of 70 r/min for 24 h; in the first ball-milling treatment, a dispersant with a mass fraction of 0.02% was added; a particle size X50 of the slurry after the first ball-milling treatment was 0.9-1.2 m; [0054] (3) the slurry after the first ball-milling treatment was put into an oven and dried at a drying temperature of 140 C. for 18 h; and then the dried powder was sieved with a 60-mesh screen and put into an air-sintering furnace for a first sintering treatment for 5 h, and heated to a first sintering temperature of 1250 C. with a rate of 1.5 C./min to obtain a mixed powder; [0055] (4) the mixed powder was mixed with a fluxing agent and a dispersant having a mass fraction of 0.02%, and then put into a ball-mill tank to be mixed by using a horizontal ball mill according to a weight ratio of materials to deionized water to zirconium oxide balls (large to small) being 1000:1000:(4000:1000), and subjected to a second ball-milling treatment of 70 r/min for 16 h; a particle size X50 of the slurry after the second ball-milling treatment was 0.8-1.1 m; components and mass contents of the fluxing agent were 0.06% of Bi.sub.2O.sub.3, 0.06% of V.sub.2O.sub.5, 0.06% of SiO.sub.2, and 0.06% of ZnO, respectively; [0056] (5) excess water in the slurry after the second ball-milling treatment was filtered off with a filter cloth, so that the solid content of the slurry was more than or equal to 70%; [0057] (6) the processed slurry was subjected to orientation-molding to obtain a sample having a size of Z42*8 and a molding density of 3.4 g/cm.sup.3; and [0058] (7) the sample was subjected to a sintering in air a and then a sintering in oxygen; the sintering in air comprised: the temperature was raised from room temperature to 120 C. at a rate of 1.0 C./min, held for 2 h, and then raised to 1000 C. at a rate of 2 C./min; the sintering in oxygen comprised: oxygen with an oxygen content of 98% was introduced by a flow rate of 40 L/min, the temperature was raised to an sintering temperature of 1180 C. at a rate of 2.5 C./min, held for 6 h, and then reduced to 700 C. at a rate of 2.5 C./min, oxygen was stopped from being introduced and furnace cooling was performed to obtain the low line-width W-type hexagonal microwave ferrite material.

Example 2

[0059] This example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this example is the same as in Example 1 except that x=0.18 in step (1).

Comparative Example 1

[0060] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that x=0 in step (1).

Comparative Example 2

[0061] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that x=0.3 in step (1).

Comparative Example 3

[0062] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that in step (3), the first sintering treatment was performed at a temperature of 1150 C.

Comparative Example 4

[0063] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that in step (3), the first sintering treatment was performed at a temperature of 1300 C.

Comparative Example 5

[0064] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that in step (4), components and mass contents of the fluxing agent were 0.12% of Bi.sub.2O.sub.3, 0.12% of V.sub.2O.sub.5, 0.12% of SiO.sub.2, and 0.06% of ZnO, respectively.

Comparative Example 6

[0065] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that in step (4), the fluxing agent was not added.

Comparative Example 7

[0066] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that in step (4), components and mass contents of the fluxing agent was 0.12% of V.sub.2O.sub.5, 0.12% of SiO.sub.2, and 0.06% of ZnO, respectively.

Comparative Example 8

[0067] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that in step (2), the first ball-milling treatment was performed for a period of h, and the slurry obtained after the first ball-milling treatment had a particle size X50 of m.

Comparative Example 9

[0068] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that in step (4), the second ball-milling treatment was performed for a period of h, and the slurry obtained after the second ball-milling treatment had a particle size X50 of m.

Comparative Example 10

[0069] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that in step (7), the sintering in oxygen was performed at a temperature of 1100 C.

Comparative Example 11

[0070] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this comparative example is the same as in Example 1 except that in step (7), the sintering in oxygen was performed at a temperature of 1280 C.

Comparative Example 12

[0071] This comparative example provides a preparation method for a low line-width W-type hexagonal microwave ferrite material. The preparation method in this example is the same as in Example 1 except that in step (7), the sintering was performed without introducing oxygen, and air cooling was directly performed.

[0072] The W-type hexagonal microwave ferrite materials obtained in the above examples and comparative examples were processed into 2.5 mm balls, and the saturation magnetizations of the balls were measured; [0073] the W-type hexagonal microwave ferrite materials obtained in the above examples and comparative examples were processed into Z38*6 samples, and the remanence ratios of the samples were measured; [0074] the W-type hexagonal microwave ferrite materials obtained in the above examples and comparative examples were processed into 1 mm balls, and the line-widths of the balls were measured; [0075] the densities of the W-type hexagonal crystalline microwave ferrite materials obtained in the above examples and comparative examples were measured by the water displacement method, and the test results are shown in Table 1.

TABLE-US-00001 TABLE 1 Saturation emanence ine-width magnetization ratio H Density 4Ms (Gs) Mr/Ms (Oe) (g/cm.sup.3) Standard 3800 100 >0.9 <400 >5.0 Example 1 3810 0.92 366 5.05 Example 2 3832 0.92 369 5.04 Comparative 3915 0.95 769 4.86 Example 1 Comparative 3812 0.86 699 5.04 Example 2 Comparative 3722 0.91 678 5.04 Example 3 Comparative 3722 0.89 828 4.94 Example 4 Comparative 3722 0.84 918 5.04 Example 5 Comparative 3622 0.86 998 4.86 Example 6 Comparative 3822 0.86 998 4.86 Example 7 Comparative 3722 0.88 698 5.04 Example 8 Comparative 3622 0.82 998 4.86 Example 9 Comparative 3422 0.86 898 4.85 Example 10 Comparative 3822 0.88 798 5.06 Example 11 Comparative 3422 0.9 588 5.06 Example 12 indicates data missing or illegible when filed

[0076] As can be seen from Table 1, the W-type hexagonal microwave ferrite material obtained by the preparation method provided in the present application has a line-width of less than 400 Oe, a saturation magnetization of 3700-3900 Gs, a remanence ratio of more than 0.9, and a density of more than 5.0 g/cm.sup.3, which has the prospect of large-scale popularization and application.

[0077] In a case where Gd is not added to the raw material, or the proportion of Gd is too much, the line-width of the obtained W-type hexagonal microwave ferrite material will be high; in a case where the temperature of the first sintering treatment is low, although other properties are comparable to those of Example 1, the line width will be higher; in a case where the fluxing agent is not added, or the composition and content of each substance in the fluxing agent are not within the range of the present application, the W-type hexagonal microwave ferrite material will have a high line-width and a small remanence ratio; in a case where the particle size of the slurry after the first ball-milling treatment and the particle size of the slurry after the second ball-milling treatment are larger, the W-type hexagonal microwave ferrite material will have a high line-width, a small remanence ratio, and a low density; in a case where the temperature of the sintering in oxygen is not within the range of the present application, the W-type hexagonal microwave ferrite material will have a high line-width and a small remanence ratio.

[0078] In summary, the preparation method for a low line-width W-type hexagonal microwave ferrite material provided in the present application has a stable process and good repeatability, and has a prospect of large-scale popularization and application.

[0079] The applicant declares that the above is only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art should understand that any changes or replacements, which can be easily thought of by a person skilled in the art within the scope of the technology disclosed in the present application, shall fall within the protection scope and disclosure scope of the present application.