KR920007820B1 - Magnetic materials - Google Patents

Abstract

Theis magnetic material is formed by sintering a mixture of iron compound, bivalent metallic compound and 1-90 wt.% inorganic material containing silicate. The inorganic material containing silicate is obtained from crushed industrial waste and at least more than one iron compound is selected from iron oxide, ionic magnetite, mill-scale or iron hydroxide, which is obtained by acid cleaning waste water. And a mixture of electric furnace dust, bivalent metallic compound and inorganic material containing silicate are sintered to produce the magnetic material for high frequency and high magnetic loss.

Description

High Frequency High Loss Magnetic Materials

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to high frequency high loss magnetic materials used for electromagnetic wave absorbers, heating elements and heat storage elements, and more particularly to magnetic materials in which iron compounds, divalent metal compounds, and siliceous-containing inorganic materials are mixed.

Ferrite, which is a magnetic material, generally increases its magnetic loss in microwave frequency metabolism and converts electromagnetic energy into thermal energy, leading to electrical energy loss. There is much room for improvement in electromagnetic wave absorption performance, and microwaves, which are widely used around the world, can cook various foods quickly, but they do not tan the surface of foods such as fish or meat. There was a flaw that led to the loss of feeling.

Therefore, in order to improve the above drawbacks, there was an additional heating wire inside the microwave oven, but it was not economical because it requires extra energy.

In recent years, there has been an attempt to yellow the surface layer of food or to develop a heat storage body by making a heating element made mainly of ferrite, a magnetic material having high frequency loss characteristics, into a special shape container.

That is, Japanese Patent Application Publication No. 55-20614 proposes a heating element that absorbs electromagnetic wave energy by ceramic material represented by Li ₂ O (1-y) Al ₂ O ₃ yFe ₂ O ₃ ㆍ XSiO ₂ . The thermal shock resistance was excellent, but when used inside the microwave oven, the temperature spread in 4 minutes was only 250 degrees Celsius.

In addition, Japanese Patent Application Publication No. 55-137183 discloses that a magnetic material having a high frequency loss property generates a magnetic semiconductor and emits heat by irradiating high frequency, but the surface temperature of the magnetic semiconductor is irradiated with electromagnetic waves for 1 minute. As a result, only 220 degrees Celsius, the above-mentioned things can be quickly cooked the food of the microwave oven, but the surface layer of the food does not reach the heating temperature sufficient for tanning.

The present inventors have diligently studied the current electromagnetic wave absorber, heating element, heat storage element, etc. The high-frequency lossless magnetic material used here is selected by using the highest purity of the main component compounds as high as possible to increase the super-permeability and minimize the magnetic loss. If the magnetic material is used for a core, for example (the core has a lower magnetic loss, the performance is better), but the magnetic material having the lower magnetic loss has better performance. It is proved to be because it is used for heat storage bodies.

In addition, the high frequency loss magnetic material known to date is called the high frequency high loss material because its magnetic loss is larger than that of a general insulating material. However, the higher the magnetic loss, the higher the magnetic loss is. This smallness also proved inadequate.

The present invention is to provide a high frequency high loss magnetic material having good electromagnetic wave absorption capacity and high heat generation temperature in a short time in view of the fact that the loss is increased when the silica and the magnetic material is mixed with the above facts.

Another object of the present invention is to provide a magnetic material having high thermal shock strength and good heat storage performance.

The present invention is characterized by mixing and firing an iron compound, a divalent metal compound and a siliceous-containing inorganic material in order to achieve the above object.

The present invention considers the principle of improving the electromagnetic wave absorbing ability of the magnetic material and the electromagnetic radiation absorbing ability by multiple radiation, and increases the electromagnetic wave absorbing capacity by forming a multi-radiation structure by the silicic acid-containing inorganic material which is electromagnetic wave permeability and at the same time strengthening the strength. In addition, it is possible to obtain a high frequency high loss magnetic material having a short heat generation time and a high heat resistance and impact strength, due to the improvement of the electromagnetic wave absorption ability.

Examples of the iron compound used in the present invention include iron oxide, iron powder, magnetite, mill scale, pickling waste liquid (iron hydroxide), dust in an electric furnace, and the like. As the divalent metal, manganese, nickel, copper, zinc, magnesium, cobalt barium, Compounds such as strontium or oxide mixtures thereof may be used. Examples of the siliceous-containing inorganic materials include sand, silica sand, kaolin, clay, bentonite, chamotte, zircon, eu cryptite, cordierite, steatite, murite and waste pottery. Industrial waste grinding is used. In addition, the iron compounds, divalent metals, and siliceous-containing inorganic materials used in the present invention may be used alone or in combination of two or more thereof. In addition, the inorganic material of the present invention may be mixed with an inorganic or organic binder to form an arbitrary shape such as a plate, rod, spherical body, or the like, and a conductive loss material such as carbon may be added.

Hereinafter, the present invention will be described based on Examples.

Example 1

60 g of commercially available deferred oxide powder, 20 g of natural manganese dioxide, and commercially available from Dairy Industry Co., Ltd. in 60 g of various types of iron oxide or iron hydroxide powders obtained by treating pickling wastewater generated in steel mills or plating plants by arbitrary methods. 80 g of the elite powder was uniformly mixed and small-component chains were circulated for 4 hours at around 1300 degrees Celsius. 10 g of chlorinated polyethylene was added to 50 g of the powder, and the mixture was heated and kneaded to form a plate having a thickness of 3 mm. As a result, the maximum reflection attenuation characteristic was -25㏈.

Example 2

In Example 1, the plate thickness was 2.3 mm, and the radio wave absorption ability was measured by standing wave measurement at 9.4-㎓.

Example 3

25 g of clay was added to 50 g of the powder obtained in Example 1, kneaded with water, molded into a thickness of 5 mm and a diameter of 50 mm, and sintered at 1300 degrees C for 3 hours to obtain a disk-shaped test piece having a thickness of 4.7 mm and a diameter of 47 mm. The specimens were operated in a commercial 600-watt microwave oven and after 100 seconds the specimens were red and reached 980 degrees Celsius and became an excellent electromagnetic heating element without insulation damage.

[Example 4]

50 g of electric furnace dust (atomic absorption method and wet method, chemical composition analyzed in the steelmaking plant is shown below), 10 g of MgO and mold discarded in the precision casting process (mainly composed of zircon sand and chamotte) 40 g of the pulverized powder was added, mixed homogeneously, molded into a diameter of 50 mm and a thickness of 5 mm, and then calcined and sintered at 1350 degrees for 4 hours to obtain a disk-shaped test piece having a thickness of 4.2 mm and a diameter of 48 mm. As a result of the test, it reached 970 degrees Celsius after 110 seconds and there was no damage such as cracks.

TABLE 1

Example 5

A homogeneous mixture of 40 g of cordierite powder as in Example 1 was uniformly mixed with 50 g of Mn-Zn ferrite powder into a groove of a refractory brick having a groove having a diameter of 50 mm and a depth of 5 mm, homogeneously compressed and compacted. The same test as in Example 3 or 4 resulted in 95 degrees Celsius after 3 minutes and no longer elevated.

As can be seen from the above examples, the magnetic material of the present invention, in which an appropriate amount of a silicic acid-containing inorganic material is mixed with an iron compound and a divalent metal, which are commonly used in the production of ferrite, is reacted at a high temperature, and thus the electromagnetic wave absorbing ability is significantly improved. It became. Although the theoretical explanation for such a result has not been clarified yet, considering the results of Example 5, the slight absorption of electromagnetic waves due to resonance is already known, but the magnetic material of the present invention is siliceous in the firing or sintering process. Reaction occurs between the containing inorganic material and various metal compounds, partly to form ferrite, and partly to form a new compound layer, which causes multiple radiation phenomenon to increase magnetic loss, and high electromagnetic wave absorption ability with high electromagnetic wave absorption ability It is considered to be a magnetic material. In addition, the larger particles in the siliceous-containing inorganic material are thought to improve the thermal shock resistance by buffering the thermal expansion and contraction with some pores in the sintered body.

In the present invention, the adjustment of the electromagnetic wave absorption capacity, the exothermic temperature, etc. is changed by design by increasing or decreasing the amount of the ferrous compound divalent metal compound and the siliceous-containing inorganic material.

As described above, the present invention can obtain a high frequency high loss magnetic material having a very high electromagnetic wave absorbing capacity by mixing and firing an iron compound and a divalent metal compound with a siliceous-containing inorganic material. And the heat storage body can also be easily produced and has the effect of obtaining a material having high heat shock strength.

Claims (7)

High frequency, high loss magnetic material made by mixing and firing iron compound, divalent metal compound and siliceous inorganic material. The high frequency high loss magnetic material of claim 1, wherein the iron compound and the divalent metal compound are metal hydroxides. The high frequency high loss magnetic material according to claim 1 or 2, wherein the siliceous-containing inorganic material is an industrial waste pulverized product. The high frequency high loss magnetic material according to claim 1, wherein the siliceous-containing inorganic material is 1 to 90% by weight. The high frequency high loss magnetic material according to claim 1 or 2, wherein the iron compound is iron oxide or iron hydroxide obtained by pickling wastewater. The high frequency high loss magnetic material of claim 1, wherein the iron compound is at least one trillion selected from iron oxide, iron magnetite, mill scale, and iron hydroxide. High-frequency, high-loss magnetic material made by mixing and firing electric dust, divalent metal compound and siliceous inorganic material.