CN101200367A - Preparation method of yttrium iron garnet ferrite material - Google Patents

Abstract

The method for preparing yttrium iron garnet ferrite material relates to the field of electronic materials. The invention comprises the following steps: 1) calculating the required raw materials Fe ₂ O ₃ and Y ₂ O according to the chemical formula Y ₃ Fe ₅ O ₁₂ of yttrium iron garnet ₃ ; 2) According to the ratio calculated in step 1), Fe ₂ O ₃ and Y ₂ O ₃ were mixed and ball milled; 3) Drying and crushing; 4) Microwave sintering the dried and crushed powder; 5) granulation; 6) compression molding. The invention has the following advantages: (1) compact structure; (2) excellent magnetic performance; (3) large dielectric constant and small dielectric loss; (4) small magnetoelectric loss.

Description

Preparation method of yttrium iron garnet ferrite material

technical field

The invention relates to the field of electronic materials, in particular to the preparation technology of microwave ferrite materials.

Background technique

Microwave heating is a heating method for heating materials as a whole. It has the characteristics of high efficiency, energy saving, and no pollution. Now it is getting more and more attention. Although microwave sintering technology is still immature and imperfect, it has advantages that conventional technologies cannot match: first, as a time-saving, energy-saving, labor-saving, and pollution-free technology, microwave sintering can meet The requirements of energy and environmental protection; secondly, its activated sintering characteristics are conducive to obtaining excellent microstructures, thereby improving material performance; thirdly, the characteristics of microwave and material coupling determine that microwaves can be used for selective heating. Thus, structural materials with special organization can be prepared, such as gradient functional materials. These advantages make microwave sintering have broad prospects in the field of preparation of high-tech ceramics and metal-ceramic composite materials.

In the prior art, the preparation of yttrium iron garnet gyromagnetic ferrite material is mainly the conventional resistance furnace sintering method, that is, the solid phase reaction sintering method. Drying-granulation-forming-sintering, this method is time-consuming and energy-consuming.

Contents of the invention

The technical problem to be solved by the present invention is to provide a new preparation method of yttrium-iron-garnet ferrite material, the prepared yttrium-iron-garnet gyromagnetic ferrite material can provide better than the yttrium-iron-garnet gyromagnetic ferrite material prepared by the prior art. Ferrite materials have better performance parameters.

The technical solution adopted by the present invention to solve the technical problem is that the preparation method of yttrium iron garnet ferrite material comprises the following steps:

1) Calculate the ratio of the required raw materials Fe ₂ O ₃ and Y ₂ O ₃ according to the chemical formula Y ₃ Fe ₅ O ₁₂ of yttrium iron garnet;

2) According to the ratio calculated in step 1), Fe ₂ O ₃ and Y ₂ O ₃ are mixed and ball milled;

3) drying, crushing;

4) Microwave sintering the dried and pulverized powder,

5) Granulation;

6) Press molding.

In the step 2), steel ball milling is used, and a certain amount of iron-deficiency formula is adopted.

In the step 5), the ball-milled ferrite material is dried and sieved, then 10% of binder is added for granulation, and then pressed.

The raw materials are analytically pure Fe ₂ O ₃ with a purity of 99.99% and analytically pure Y ₂ O ₃ with a purity of 99.99%.

In the step 1), Y ₂ O ₃ is 45.8996 units by weight; and Fe ₂ O ₃ is 51.1004 units in the formula of 3% iron deficiency.

Compared with the yttrium iron garnet ferrite material sintered by conventional methods, the present invention has the following advantages:

(1) Dense structure: Most of the grain size of conventional sintered powder is about 3.0-5.0 μm, while the grain size of microwave sintered powder is between 0.5-1.5 μm. When other raw materials are sintered by microwave, it is also found that the crystal grains of the microwave sintered powder are much smaller than those of conventional sintered powder. Therefore, the microwave sintering process preferentially improved the densification process of the material, but did not promote the grain growth.

(2) Excellent magnetic properties: the saturation magnetization Mc of the sample after microwave sintering is 14.49emu/g, and the value of coercive force Hc is 31.94Oe.

(3) Large dielectric constant and small dielectric loss: This is because the microwave sintering treatment technology improves the microstructure of the material and can obtain better fine-grained microstructure. Microwave sintering samples have fewer pores, which leads to The resulting reduction of the low dielectric constant phase and the increase in density lead to a larger dielectric coefficient of the microwave sintered sample than that of the conventional sintered sample, and a smaller dielectric loss than the conventional sintered sample.

(4) The magnetoelectric loss is small.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

Figure 2 is a schematic diagram of the interior of the microwave sintering furnace. Among them, an infrared temperature measuring hole 1, a quartz crucible with a cover 2, a material to be fired 3, silicon carbide powder 4, a corundum crucible 5, an outer cavity of a microwave oven 6, and a refractory brick 7.

Figure 3 is the microwave sintering curve.

Figure 4 is the XRD pattern of the microwave sintered powder.

Figure 5 is the SEM photo of the microwave sintered powder (900°C, 20min).

Figure 6 is the B-H hysteresis curves of conventional sintered and microwave sintered materials (sample weight 1 g), where "A" is the conventional sintered sample and "B" is the microwave sintered sample.

Figure 7 is the dielectric loss curves of the conventional sintered and microwave sintered samples, where "A" is the conventional sintered sample and "B" is the microwave sintered sample.

Figure 8 is the magnetoelectric loss curves of the conventional sintered and microwave sintered samples, where "A" is the conventional sintered sample and "B" is the microwave sintered sample.

Detailed ways

The microwave sintered yttrium-iron-garnet ferromagnetic ferrite material proposed by the present invention has its process equipment as shown in Figure 2. The NL75 microwave sintering furnace is used to crystallize the material. The device includes an infrared temperature measuring hole 1 and a quartz crucible 2 with a cover. , material to be fired 3, silicon carbide powder 4, corundum crucible 5, microwave oven outer cavity 6, refractory brick 7.

A microwave sintered yttrium iron garnet microwave ferrite material provided by the present invention is mainly made by the following five steps:

Step 1: Ingredients

Using analytically pure Fe ₂ O ₃ with a purity of 99.99% and analytically pure Y ₂ O ₃ with a purity of 99.99% as raw materials, the required ratio of raw materials was calculated according to the chemical formula (Y ₃ Fe ₅ O ₁₂ ) of pure yttrium iron garnet.

For example: the required yttrium iron garnet ferrite material is about 100g, so the experiment uses 100g to calculate the raw material ratio, and the result is: Y ₂ O ₃ needs 45.8996g; considering the use of steel balls for ball milling, 3% iron deficiency is used The formula of Fe ₂ O ₃ needs 51.1004g to compensate for the iron mixed in the ball mill.

Step 2: Ball Milling

In the experiment, the ball milling time was 10h (hour), and deionized water was used as the dispersant.

Step 3: drying, granulation

The ball-milled ferrite material is dried and sieved, and then 10% of binder is added for granulation. The coarse sieve is 40 mesh, and the fine sieve is 100 mesh.

Step 4: Microwave Sintering

During the microwave sintering process, due to the rapid heating rate and uneven microwave field strength, it is easy to generate a temperature gradient inside the sample, resulting in cracks in the sintered product. Therefore, in the experiment, the device cannot be pressed into shape and then sintered, otherwise the device will crack at the end, which is useless. In the experiment, the prepared powder was subjected to microwave sintering treatment, and then pressed into shape. During the microwave sintering process, put the pulverized material into a quartz crucible with a lid, bury it in silicon carbide powder, then turn on the microwave oven and adjust it to 400W for preheating, and increase the power to 500W after 3 minutes. During this process, the heating rate gradually increases. Slow down, after 10 minutes, increase the power to 600W to the sintering temperature point, then reduce the power by about 20W to keep it warm at the temperature point, then adjust the power to 0, cool down to room temperature and take it out.

Step 5: Granulation, pressing

After the granulation is completed, the material is weighed to press the device, and a part of the sheet-shaped and ring-shaped devices are respectively pressed. The pressure is 50MPa.

It can be seen from Figure 3-8 that microwave sintering has the following advantages compared with conventional sintering: 1) compact structure 2) excellent magnetic properties; 3) large dielectric constant and small dielectric loss; 4) small magnetoelectric loss; 5) saving , energy saving.

Claims (7)

1. method for preparing yttrium iron garnet ferrite material is characterized in that, may further comprise the steps:

1) according to the chemical formula Y of yttrium iron garnet ₃Fe ₅O ₁₂Calculate needed raw material Fe ₂O ₃And Y ₂O ₃Ratio;

2) ratio of calculating according to step 1) is with Fe ₂O ₃And Y ₂O ₃Mix ball milling;

3) oven dry is pulverized;

4) powder after oven dry, the pulverizing is carried out microwave sintering;

5) granulation;

6) compression moulding.

2. method for preparing yttrium iron garnet ferrite material as claimed in claim 1 is characterized in that, described step 2) in, adopt the steel ball ball milling, and take a certain amount of iron deficiency prescription.

3. the described method for preparing yttrium iron garnet ferrite material of claim 1 is characterized in that, in the described step 4), adopts the method for microwave heating to carry out sintering;

4. method for preparing yttrium iron garnet ferrite material as claimed in claim 1 is characterized in that, in the described step 5), the Ferrite Material behind the sintering is added 10% tackiness agent and carries out granulation, compacting then.

5. method for preparing yttrium iron garnet ferrite material as claimed in claim 1 is characterized in that, described step 2) in, adopt deionized water as disperse means in the mechanical milling process.

6. method for preparing yttrium iron garnet ferrite material as claimed in claim 1 is characterized in that, described raw material is that purity is 99.99% analytical pure Fe ₂O ₃With purity be 99.99% analytical pure Y ₂O ₃

7. method for preparing yttrium iron garnet ferrite material as claimed in claim 1 is characterized in that, in the described step 1), and in weight unit, Y ₂O ₃Be 45.8996 units; Adopt the prescription of iron deficiency 3%, Fe ₂O ₃Be 51.1004 units.

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