JPS61268759A - Radio absorbing material - Google Patents

Abstract

PURPOSE:To obtain the titled material with absorption characteristics stable to temperature variation, usable in high-frequency zone, by incorporating a polymeric resin with transition metal element-contg. fibrous noncrystalline alloy or either granular or foil-shaped transition metal element (such as iron or nickel)-contg. noncrystalline alloy. CONSTITUTION:The objective material can be obtained by incorporating (A) a polymeric resin 1 with (B) transition metal element (such as iron or nickel)- contg. fibrous noncrystalline alloy 2. For such ratio absorbing material as to be effective for both electric and magnetic field components of electromagnetic wave, at least one kind of granular or foil-shaped noncrystalline alloy 3 containing crystalline transition metal element such as iron or nickel is preferably dispersed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a radio wave absorbing material used for radio wave absorbers and electromagnetic shields.

(Prior Art and its Problems) Materials that have a radio wave absorption effect by dispersing metal bodies of various shapes in a polymer resin have already been developed.

Since radio wave shields are used under various environmental conditions, materials with stable characteristics over a wide temperature range are desired. Conventional radio wave absorbing materials utilize the conductivity of metal bodies, but
In general, the temperature coefficient of conductivity of metals is not small, and there is a drawback that the properties of the absorbent material are unstable when used over a wide temperature range. In absorbent materials that use fibrous metal, the fibers are cut during the mixing process with resin, causing problems in design and development. Designed with size in mind. On the other hand, if a metal body with magnetic properties is used, it becomes possible to create an efficient absorber that uses both electrical loss and magnetic loss.

(Objective of the invention) The present invention is to obtain an absorber that has stable absorption characteristics against temperature changes and can be used in a high frequency band, and an absorber that uses both electrical and magnetic losses. .

(Structure of the Invention) The present invention provides a radio wave absorbing material characterized by blending a fibrous amorphous alloy containing a transition metal element such as iron or nickel into a polymer resin, This radio wave absorbing material is characterized by containing at least one of non-amorphous iron, nickel, or an amorphous alloy containing a transition metal element.

(Explanation regarding configuration) FIG. 1 shows an example of the structure of the absorbent material according to the first invention.

(1) is a polymer resin, and (2) is an amorphous alloy fiber containing transition metal elements such as iron and nickel. The radio wave characteristics of the absorbing material are mostly determined by the function of the metal fibers in (2), and the effect of the polymer resin is small, so any resin can be used.

Figure 2 shows granular non-amorphous iron in polymer resin (1).
This is an absorbent material in which at least one type of amorphous alloy (2) containing nickel or a transition metal element is dispersed.

The temperature change in resistivity of amorphous metals is as small as 1/200 to 1/9000 of that of general metals. Therefore, when fibers of amorphous alloy are dispersed in resin as shown in Figure 1, the characteristics as a radio wave absorbing material determined mainly by the conductivity of the fibers are different from those when ordinary metal fibers are used. In comparison, stable characteristics against temperature changes can be obtained.

Amorphous alloys have greater mechanical strength than ordinary metals,
This is an important factor when used in the form of fibers. Especially Fe
Those containing transition metal elements such as , Co, and Ni have a tensile strength of 200 to 4oo (KII/wIP), which is 5 to 10 oo compared to the value of normal metals of 40 to 50 (assistance/recommendation).
It has twice the value. Because of its high tensile strength, even if thin fibers with a small cross-sectional area are mixed into the resin, the fibers will not be cut during the mixing process. Since thin fibers can be used, even short fibers can effectively act as an antenna in the absorbing material for radio wave absorbers. The shorter the fiber length, the more it can be used as an absorber for high frequency bands, so when amorphous metal fibers are mixed, it is more desirable for designs in high frequency bands than absorbers using ordinary metal fibers.

Next, a radio wave absorbing material that is effective against both the electric field component and the magnetic field component of electromagnetic waves will be described. Conventionally, absorption materials made by mixing granular or foil-shaped metals with resin have been known, focusing on the electrical conductivity of metal objects, but if magnetic loss is included, it is possible to efficiently provide loss to electromagnetic waves. Can be done. Metals having magnetic properties include metals such as iron, nickel, and cobalt, and amorphous alloys containing transition metal elements such as these. However, if it is made into a male shape, it will act as an antenna or the probability of fibers coming into contact with each other will increase, so the effect of electrical conductivity will be too large compared to the magnetic effect. Therefore, it is desirable to use it in the form of granules or foil as shown in FIG. In this case, since the magnetic and electrical effects increase as the amount of metal added increases, the amount used is increased within a range that does not seriously impair the performance of the resin. If the size of the particles and the thickness of the foil are larger than the skin depth, electromagnetic waves will not penetrate and it will simply act as a metal body, so it is important that the foil thickness is below the skin depth at the upper limit frequency of the target frequency band. desirable.

(Effect of the invention) According to the present invention, the temperature change in absorption characteristics is small.

Moreover, an absorbent material that can be designed and manufactured in a high frequency band can be obtained.

In addition, an absorbent material having both electrical conductivity and magnetic effect can be obtained.

[Brief explanation of drawings]

FIGS. 1 and 2 are diagrams showing examples of radio wave absorbing materials according to the present invention. (1) is polymer resin, (2) is amorphous alloy fiber, (3
) is iron or nickel or an amorphous alloy in granular or foil form.

Claims (2)

[Claims] (1) A radio wave absorbing material characterized by blending a fibrous amorphous alloy containing a transition metal element with a polymer resin. (2) A radio wave absorbing material characterized in that a polymer resin is blended with at least one amorphous alloy containing granular or foil-like iron, nickel, or a transition metal element.