METHOD FOR PREPARING HIGH-PERFORMANCE COMPOSITE FERRITE FOR SELF-BIASED CIRCULATOR

Abstract

A magnetic material and method prepares high-performance composite ferrite for a self-biased circulator. The preparation method includes: (1) preparing BaM ferrite initial powder and NiCuZnSn ferrite initial powder, respectively; (2) mixing the BaM ferrite initial powder, the NiCuZnSn ferrite initial powder and deionized water uniformly in proportion, performing ball milling in a high-energy ball mill, and then obtaining mixed powder after primary pre-sintering, secondary pre-sintering and secondary ball milling; and (3) obtaining the high-performance composite ferrite for the self-biased circulator by a low-temperature magnetic field orientation forming technology and magnetic field heat treatment. According to the present invention, the saturated magnetization intensity is enhanced better by compounding the BaM ferrite powder and the NiCuZnSn ferrite powder and through a high-energy ball milling technology, the low-temperature magnetic field orientation forming technology and the magnetic field heat treatment technology, thereby improving the microstructure and the magnetic characteristic of bi-phase composite ferrite.

Claims

1. A method for preparing high-performance composite ferrite for a self-biased circulator, comprising: (1) preparing BaM ferrite initial powder: taking BaCO.sub.3, La.sub.2O.sub.3 and Fe.sub.2O.sub.3 as raw materials, and weighing and mixing the materials according to the proportion of 5-15 mol % of BaCO3, 2-12 mol % of La.sub.2O.sub.3 and 73-93 mol % of Fe.sub.2O.sub.3 to obtain the BaM ferrite initial powder; (2) preparing NiCuZnSn ferrite initial powder: taking NiO, ZnO, CuO, SnO.sub.2, Co.sub.2O.sub.3 and Fe.sub.2O.sub.3 as raw materials, and weighing and mixing the materials according to the proportion of 20-40 mol % of NiO, 5-30 mol % of ZnO, 2-10 mol % of CuO, 1-5 mol % of SnO2, 4-10 mol % of Co.sub.2O.sub.3 and 40-68 mol % of Fe.sub.2O.sub.3 to obtain the NiCuZnSn ferrite initial powder; (3) uniformly mixing the BaM ferrite initial powder obtained in step (1), the NiCuZnSn ferrite initial powder obtained in step (2) and deionized water according to a mass ratio of 1: (0.1-1): (3-5) to obtain mixed powder slurry, and then uniformly mixing the mixed powder slurry in a high-energy ball mill, wherein the high-energy ball-milling time is 1-3 hours; (4) drying ball-milled powder obtained in step (3), sieving, and then performing primary pre-sintering and secondary pre-sintering on the powder to obtain mixed powder, wherein in the primary pre-sintering, the sintering temperature is 1050-1350 C., the heating rate is 1-3 C./min and the heat preservation time is 2-7 hours, and in the secondary pre-sintering, the sintering temperature is 800-1000 C., the heating rate is 1-3 C./min and the heat preservation time is 1-4 hours; (5) uniformly mixing the mixed powder obtained in step (4) and deionized water according to a mass ratio of 1: (3-5), and performing secondary high-energy ball milling to obtain powder slurry, wherein the high-energy ball-milling time is 0.5-1.5 hours; (6) preparing a green compact from the powder slurry obtained in step (5) by a low-temperature magnetic field orientation forming technology, wherein in the low-temperature magnetic field orientation forming technology, the temperature is 50-150 C., the pressure is 40- 150 MPa, and the magnetic field intensity is 2-4 T; and (7) performing magnetic field heat treatment on the green compact obtained in step (6) to finally obtain the high-performance composite ferrite for the self-biased circulator.

2. The method for preparing high-performance composite ferrite for a self-biased circulator according to claim 1, wherein in the magnetic field heat treatment described in step (7), the magnetic field intensity is 1-2 T, the heat treatment temperature is 800-1100 C., the heating rate is 1-3 C./min, the heat preservation time is 2-6 hours, and then emergency cooling is performed to room temperature.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The present invention is further described in detail below with reference to embodiments, but the present invention is not limited to the following embodiments.

Embodiment 1

[0018] (1) Preparation of BaM ferrite initial powder: BaCO.sub.3, La.sub.2O.sub.3 and Fe.sub.2O.sub.3 were taken as raw materials, and the materials were weighed and mixed according to the proportion of 5 mol % of BaCO.sub.3, 10 mol % of La and 85 mol % of Fe to obtain the BaM ferrite initial powder. [0019] (2) Preparation of NiCuZnSn ferrite initial powder: NiO, ZnO, CuO, SnO2, Co2O3 and Fe.sub.2O.sub.3 were taken as raw materials, and the materials were weighed and mixed according to the proportion of 20 mol % of NiO, 5 mol % of ZnO, 2 mol % of CuO, 1 mol % of SnO.sub.2, 4 mol % of Co.sub.2O.sub.3 and 68 mol % of Fe.sub.2O.sub.3 to obtain the NiCuZnSn ferrite initial powder. [0020] (3) The BaM ferrite initial powder obtained in step (1), the NiCuZnSn ferrite initial powder obtained in step (2) and deionized water were uniformly mixed according to a mass ratio of 1:0.3:3 to obtain mixed powder slurry, and then the mixed powder slurry was mixed uniformly in a high-energy ball mill, where the high-energy ball-milling time is 1 h. [0021] (4) The ball-milled powder obtained in step (3) was dried and sieved, and then primary pre-sintering and secondary pre-sintering were performed on the powder to obtain mixed powder, where in the primary pre-sintering, the sintering temperature is 1050 C., the heating rate is 1 C./min and the heat preservation time is 6 h, and in the secondary pre-sintering, the sintering temperature is 1000 C., the heating rate is 3 C./min and the heat preservation time is 1 h. [0022] (5) The mixed powder obtained in step (4) and deionized water were mixed uniformly according to a mass ratio of 1:3, and secondary high-energy ball milling was performed to obtain powder slurry, where the high-energy ball-milling time is 0.5 h. [0023] (6) A green compact was prepared from the powder slurry obtained in step (5) by a low-temperature magnetic field orientation forming technology, where in the low-temperature magnetic field orientation forming technology, the temperature is 50 C., the pressure is 150 MPa, and the magnetic field intensity is 2 T. [0024] (7) Magnetic field heat treatment was performed on the green compact obtained in step (6) under the conditions of the magnetic field intensity being 1 T, the heat treatment temperature being 1000 C., the heating temperature being 3 C./min and the heat preservation time being 6 h, and then emergency cooling was performed to room temperature to finally obtain the composite ferrite.

[0025] After the composite ferrite prepared by the present invention is tested by a magnetic performance and vector network analyzer, the saturated magnetization intensity 4M.sub.s is 4850 Gs, the remanence ratio M.sub.r/M.sub.s is 0.89, the coercive force H.sub.c is 4010 Oe, the ferromagnetic resonance linewidth H is 368 Oe, and the anisotropy field H.sub.a is 14.10 kOe.

Embodiment 2

[0026] (1) Preparation of BaM ferrite initial powder: BaCO.sub.3, La.sub.2O.sub.3 and Fe.sub.2O.sub.3 were taken as raw materials, and the materials were weighed and mixed according to the proportion of 10 mol % of BaCO.sub.3, 8 mol % of La.sub.2O.sub.3 and 82 mol % of Fe.sub.2O.sub.3 to obtain the BaM ferrite initial powder. [0027] (2) Preparation of NiCuZnSn ferrite initial powder: NiO, ZnO, CuO, SnO.sub.2, Co.sub.2O.sub.3 and Fe.sub.2O.sub.3 were taken as raw materials, and the materials were weighed and mixed according to the proportion of 30 mol % of NiO, 15 mol % of ZnO, 5 mol % of CuO, 3 mol % of SnO.sub.2, 7 mol % of C.sub.2O.sub.3 and 40 mol % of Fe.sub.2O.sub.3 to obtain the NiCuZnSn ferrite initial powder. [0028] (3) The BaM ferrite initial powder obtained in step (1), the NiCuZnSn ferrite initial powder obtained in step (2) and deionized water were uniformly mixed according to a mass ratio of 1:0.5:4 to obtain mixed powder slurry, and then the mixed powder slurry was mixed uniformly in a high-energy ball mill, where the high-energy ball-milling time is 2 h. [0029] (4) The ball-milled powder obtained in step (3) was dried and sieved, and then primary pre-sintering and secondary pre-sintering were performed on the powder to obtain mixed powder, where in the primary pre-sintering, the sintering temperature is 1150 C., the heating rate is 2 C./min and the heat preservation time is 4 h, and in the secondary pre-sintering, the sintering temperature is 900 C., the heating rate is 2 C./min and the heat preservation time is 2 h. [0030] (5) The mixed powder obtained in step (4) and deionized water were mixed uniformly according to a mass ratio of 1:4, and secondary high-energy ball milling was performed to obtain powder slurry, where the high-energy ball-milling time is 1 h. [0031] (6) A green compact was prepared from the powder slurry obtained in step (5) by a low-temperature magnetic field orientation forming technology, where in the low-temperature magnetic field orientation forming technology, the temperature is 100 C., the pressure is 100 MPa, and the magnetic field intensity is 3 T. [0032] (7) Magnetic field heat treatment was performed on the green compact obtained in step (6) under the conditions of the magnetic field intensity being 1.5 T, the heat treatment temperature being 900 C., the heating temperature being 2 C./min and the heat preservation time being 4 h, and then emergency cooling was performed to room temperature to finally obtain the composite ferrite.

[0033] After the composite ferrite prepared by the present invention is tested by a magnetic performance and vector network analyzer, the saturated magnetization intensity 4Ms is 4910 Gs, the remanence ratio M.sub.r/M.sub.s is 0.90, the coercive force H.sub.c is 4100 Oe, the ferromagnetic resonance linewidth H is 350 Oe, and the anisotropy field H.sub.a is 13.93 kOe.

Embodiment 3

[0034] (1) Preparation of BaM ferrite initial powder: BaCO.sub.3, La.sub.2O.sub.3 and Fe.sub.2O.sub.3 were taken as raw materials, and the materials were weighed and mixed according to the proportion of 15 mol % of BaCO.sub.3, 5 mol % of La.sub.2O.sub.3 and 80 mol % of Fe.sub.2O.sub.3 to obtain the BaM ferrite initial powder. [0035] (2) Preparation of NiCuZnSn ferrite initial powder: NiO, ZnO, CuO, SnO.sub.2, Co.sub.2O.sub.3 and Fe.sub.2O.sub.3 were taken as raw materials, and the materials were weighed and mixed according to the proportion of 40 mol % of NiO, 25 mol % of ZnO, 8 mol % of CuO, 5 mol % of SnO.sub.2, 9 mol % of Co.sub.2O.sub.3 and 13 mol % of Fe.sub.2O.sub.3 to obtain the NiCuZnSn ferrite initial powder. [0036] (3) The BaM ferrite initial powder obtained in step (1), the NiCuZnSn ferrite initial powder obtained in step (2) and deionized water were uniformly mixed according to a mass ratio of 1:1:5 to obtain mixed powder slurry, and then the mixed powder slurry was mixed uniformly in a high-energy ball mill, where the high-energy ball-milling time is 3 h. [0037] (4) The ball-milled powder obtained in step (3) was dried and sieved, and then primary pre-sintering and secondary pre-sintering were performed on the powder to obtain mixed powder, where in the primary pre-sintering, the sintering temperature is 1350 C., the heating rate is 3 C./min and the heat preservation time is 2 h, and in the secondary pre-sintering, the sintering temperature is 800 C., the heating rate is 1 C./min and the heat preservation time is 4 h. [0038] (5) The mixed powder obtained in step (4) and deionized water were mixed uniformly according to a mass ratio of 1:5, and secondary high-energy ball milling was performed to obtain powder slurry, where the high-energy ball-milling time is 1.5 h. [0039] (6) A green compact was prepared from the powder slurry obtained in step (5) by a low-temperature magnetic field orientation forming technology where in the low-temperature magnetic field orientation forming technology, the temperature is 150 C., the pressure is 60 MPa, and the magnetic field intensity is 4 T. [0040] (7) Magnetic field heat treatment was performed on the green compact obtained in step (6) under the conditions of the magnetic field intensity being 2 T, the heat treatment temperature being 800 C., the heating temperature being 1 C./min and the heat preservation time being 2 h, and then emergency cooling was performed to room temperature to finally obtain the composite ferrite.

[0041] After the composite ferrite prepared by the present invention is tested by a magnetic performance and vector network analyzer, the saturated magnetization intensity 4M.sub.s is 4978 Gs, the remanence ratio M.sub.r/M.sub.s is 0.91, the coercive force H.sub.c is 4250 Oe, the ferromagnetic resonance linewidth H is 340 Oe, and the anisotropy field H.sub.a is 13.55 kOe.