DE2235453A1 - WAVE CONDUCTOR COMPONENT AND METHOD FOR MANUFACTURING IT - Google Patents

Description

Applicant:. Stuttgart, July 17th, 1972

Hughes Aircraft Company P2565 S / kg Centinela Avenue and Teale Street

Culver City, Calif., V.St.A.

Waveguide component and process for its manufacture

Waveguide components are currently made from metals with excellent electrical conductivity, such as aluminum, silver, Nickel, copper, magnesium, and metal alloys such as brass, manufactured · In such cases, in where significant temperature fluctuations occur or where smaller temperature differences significantly affect the properties impair the arrangements made up of such waveguide components as a result of dimensional changes, alloys with low thermal expansion are used for such waveguide components. Such an alloy is Invar, which has a small coefficient of thermal expansion

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owns. Invar is essentially an iron-nickel alloy and is commonly used for watch parts and precision instruments.

Invar has a high density (see Table I) and components of complex shapes are assembled from simpler Invar parts that are brazed together. The brazing alloys suitable for the connection of Invar, takes place at elevated temperatures in the range of 65O to 870 ⁰ C instead of in a Yakuumofen. Processing at these high temperatures is limited to components of small size and causes some problems with regard to the throwing and warping of the components and thus the adherence to precise dimensions. As a result, intricate Invar waveguide components become very heavy, difficult to manufacture, and costly.

In contrast, the invention is based on the object of dimensional stability even with large temperature fluctuations To create waveguide components with low thermal expansion, which have a low weight, in a simple Wise to manufacture and do not entail great costs.

This object is achieved according to the invention in that the waveguide component consists essentially of one Composite material made of graphite-impregnated synthetic resin fibers with a modulus of elasticity of more than 1,4,10 kg / cm and high strength in its axial direction in a substantially isotropic synthetic resin matrix, which is provided with a microwave-conductive coating.

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The invention thus provides relatively thin and dimensionally stable waveguide components with low weight, which consist of laminated layers of fibers of high strength ", which are usually referred to as" graphite fibers ¹¹ and have a coefficient of thermal expansion which is negative in the longitudinal direction of the fibers. The fibers laid crosswise are connected to one another by an isotropic, polymeric resin, which can also be reinforced by fibers, and the composite material consisting of fibers and matrix material is then coated with a conductive metal.

Waveguide components manufactured in this way are essentially insensitive to temperature and have a light weight, high strength and rigidity and are without limitation in terms of their size Easily manufactured at a reduced cost. The weight reduction compared to metallic waveguide components is on the order of 6: 1

V / urther details and embodiments of the invention will become apparent from the following description _# of the embodiments shown in the drawing. The features that can be taken from the description and the drawing can be used in other embodiments of the invention individually or collectively in any combination. Show it

Fig. 1 is a cross section through a portion of a Waveguide component according to the invention,

3 (J UU 0 B / 0 7 9 B

FIG. 2 shows a cross-section through a wall section of the waveguide component according to FIG. 1 on an enlarged scale Scale,

3 shows a plan view of a prefabricated connecting flange,

Figure 4- is a side view of a waveguide component according to the invention, which illustrates the laying of the fiber layers,

5 shows the perspective illustration of a device for the production of a section of a waveguide component according to the invention and

6 shows the perspective view of a complete waveguide component.

As can also be seen from FIG. 2, the one shown in FIG Section 10 of a waveguide component has two inner conductive coatings 11 and 12, which are of Layers of crosswise arranged fiber layers 1J, 14 and 15 containing graphite fibers of high strength be worn. The waveguide section has a fastening element, namely a connecting flange 16, at its end.

To produce such a semiconductor component, the first fiber layer 13 is not spiral-shaped around one wound core shown whereupon the fiber layers 14 and 15 are applied in such a way that the in each other fibers running parallel to one another

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ORIGINAL INSPECTED

Cross balanced way, namely in such a way that the thermal expansion in any direction of the laminate plane is negligible and a waveguide component with low V / arms from stretching is created. The fibers of the layer 14 run in the longitudinal direction of the waveguide component and the applied coating 11, while the fiber layer 15 is wound over it in this way is that a 9O ° -O ° -90 ° fiber orientation is created. The total thickness of the composite material formed by the fiber layers is approximately 0.4 to 1.8 mm. It can this arrangement of high strength fibers the alternating, parallel layers as well as a mixture of one such fiber material can be used in a variety of balanced, criss-cross layers until the desired one Thickness is reached.

Another very useful arrangement of the high strength fibers in the composite is in use of four layers of parallel fibers that are oriented 0 °, 90 °, 90 ° and 0 ° to each other

to have. For most components, the 0 direction corresponds to the longitudinal axis of the component. This so-called "Balanced" laying is particularly useful because it is stable to manufacture and not to Preparation, still in the application and use throws. Furthermore, it has become essentially isotropic Strength and rigidity properties in the plane of the laminate and one essentially isotropic and very low thermal expansion (see Tables I and H), leaving a solid and rigid base

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for the conductive coating is created when it is properly applied.

Fibers with a low coefficient of thermal expansion are used for the waveguide component according to the invention and a modulus of elasticity of at least 1.4.10 kg / cm is used. Preferably in the Commercially available graphite fibers with a modulus of elasticity of more than 3 »5« 10 kg / cm Application, the layer by layer arranged parallel to one another and connected to one another in the form of a cross-wise laminate and are embedded in a matrix made of an isotropic polymer resin to create the best basic structure for the waveguide component to build. The isotropic polymer can also be a mixture of short fibers of the same fiber material which serves as an additional reinforcement of the matrix.

In the case of the waveguide component according to FIG. 4, the orientation is of the fiber layers with respect to the longitudinal axis of the waveguide 0 °, + 60 ° and -60 °, as shown in Fig. 4 by the Hatching is indicated. That way becomes a Basic structure for the waveguide component in one thickness created from 0.4 to 0.5 mm, this in terms of temperature changes an extreme stability of the dimensions, a low weight and also a bigger one Has rigidity as a known waveguide. When such a body is properly used with a conductive Coating is provided, the waveguide component allows a controlled transmission of microwave energy without

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significant losses. Such waveguide components can also be used as straight waveguide sections in the form of bends, angles, branches, antenna horns, phase shifters, microwave switches, filters, the most diverse elements of planar antenna systems or of feed arrangements, parabolic antennas and the like getting produced. This also includes those waveguide components that are used for focusing high-frequency radiation in the area of the V-band and the millimeter waves are suitable

A waveguide component made of anisotropic substances in the form of the fibers having a preferred direction, which are shown in Fiber direction have a negligibly small coefficient of thermal expansion and their modulus of elasticity is at least 1.4.10 kg / cm, and one im essentially isotropic matrix, which encloses the fibers, as well as with a coating of a conductive Metal on the composite can be made as follows.

Organic graphite fibers made of graphite-impregnated polyacrylonitrile or rayon and the like, are commercially available. This material is sold in the form of yarn or strands, as well as in the form of cables, which contain a large number of continuous single fibers. These fibers are called high modulus fibers and have a modulus of elasticity of 1.4.10

P fi P

kg / cm and more, for example 14.10 kg / cm

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The graphite fiber cable can be pre-impregnated as a continuous single cable material or combined into an endless band of parallel strands with a thermosetting resin material, such as an epoxy, polyphenylene, pyrron or polyimide-forming resin in combination with a hardener, in the prescribed form around a suitable core wound or put in two or more crossed layers and cured. Instead, it is also possible to produce a basic block of individual laminates, which consist of parallel single filaments with a microscopic diameter, which are arranged in a plane and which are embedded in an isotropic matrix, by adding not yet hardened, relatively saturated, cross-wise layers of the pre-impregnated graphite fiber material, for example four Layers or more, are placed on a pressing tool which is coated with a release agent such as ornauba wax or the like. The orientation of the fibers in the stack is preferably chosen so that a ^{0 0} -90 ° -90 ⁰ -0 ° - laminate is formed, so that after curing of the stack under pressure and heat, the coefficient of expansion is neutralized or close to zero. The matrix used is preferably (cycloaliphatic) epoxy resins which are mixed with a hardener which promotes hardening in the heat, such as metaphenylenediamine, for example. In a waveguide component with a crossed composite material, each layer of high-modulus fibers is placed at an angle to the preceding fiber layer. In a preferred embodiment of the invention

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In the waveguide component, the fibers of each layer form an angle with the fibers of the previous layer of 90 °.

As indicated, the fibers in the winding surrounding the core or the laminate layers can be saturated a priori with the isotropic matrix in the form of cable bundles. The matrix of the roll formed from such pre-impregnated graphite fiber material in the desired shape or of the layer material having the desired number of layers can then be cured using heat and pressure. Instead, it is also possible to wind unsaturated fiber strands in the desired shape around a core or in layers to form a composite material with a layer sequence of b ^ö -90 ° -90 ° -0 ^o, 0 ^o -90 ^o -0 ^o -90 ^o , 90 ^o -0 ^o ^ 90 ^o -ö °, 0 ^o -4-5 ^O -45 ^O -0 °, 0 ° -60 ⁰ -60 ° -0 ^Ö etc. to stack each layer or thereafter the To saturate all of the layers with an isotropic binder, which may or may not contain loose high modulus fibers, as indicated in the following example.

' Example Λ

It is made from / 11O to 120 parts of Epoxp-d in the form of a cycloaliphatic liquid and 27 parts / ilätaphenylenediamine a solution prepared as a hardener with which the - ■ fibers are impregnated. A typical lamination '■ process. runs as follows *, - ■; ; ■ .. -: ·· ■ · ■ .-- ■ - ■ · -.

1. It 'is pre-impregnated graphite fiber material, so a flexible, epoxy-impregnated cable in the desired Orientation on one with a release agent

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provided tool is placed until a four-layer laminate with a layer sequence of 0 ° -90 ° -90 ⁰ -O ^{0 is} created · It could also be a layer sequence of 0 ° -4-5 ^o -45 ^o -0 °, 0 ^o -90 ^o -0 ^o -90 ° or the like can be used. This process can be repeated until the desired wall thickness is achieved.

2. An overlay is prepared for curing by using a bleeder cloth, a PVO or polyester membrane and sealing material is applied and finally applied under pressure to to achieve the desired shape.

3 · The laid laminate is then placed in an oven with air circulation. The oven temperature is increased at a rate of 1.6 to 2.2 C / min until a temperature of 180 ^{0 is} reached. Der.Ofen is kept two hours at 180 ⁰ C and then slowly cooled to room temperature while the vacuum is maintained.

4, Then the negative pressure is released and the Part removed from the tool.

5 # This is followed by processing to the final one Dimensions, the preparation of the flanges and other details in the same manner.

6 «The finished waveguide parts are bonded together using an epoxy glue.

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7. The surfaces are coated with a conductive metal ·

The molded body formed from the graphite fibers and the hardened isotropic matrix is a very poor electrical conductor transmitted or * reflected. * Attempts to galvanically coat the shaped body formed from the graphite fibers and the matrix, however, shows that the conductive metal applied had only very poor adhesion. It has been found, however, that a suitable pretreatment of the surface with a sensitizing solution and chemical deposition of a metallic intermediate layer enables electrodeposition of conductor metals such as copper, silver, nickel, gold and the like in the usual manner. The chemically applied metallic intermediate layer can consist of gold or another suitable conductive metal such as silver, copper or the like, followed by electrolessly applied copper or a conductive metal applied in another suitable manner.

The coating of the prepared molded body made of graphite fibers and an isotropic matrix on one or more surfaces with a conductor can be done in the following manner happen:

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Example 2

1. There are 55 g of tin (II) chloride in 100 ml more concentrated HCl, which had been heated to 70 to 75 ° C, dissolved. The solution was then distilled with H2O diluted to 1 liter. This solution is then at Room temperature can be used as a sensitizing solution.

2. To prepare a 1% gold chloride solution 1 g gold chloride dissolved in 100 ml distilled water (temperature 66 + 3 ° C)

3 · Ks becomes a Fehling's solution for copper reduction prepared by adding 170 g Rocheliealz, 50 g sodium hydroxide, 35 S copper sulfate and 30 g sodium carbonate be dissolved in 5OO ml of distilled water. To the Solution are 20 ml of an organic chelating agent or a conventional equivalent wetting agent or Chelating agents such as ethylenediaminetetruacetic acid and their soluble salts or the like, including dihydroxyethylaminoacetic acid, hydroxyethylethylenediamine triacetic acid and their salts or the like added. Then make up to 1 liter with distilled water.

4-, A 38 to 40% formaldehyde solution is produced.

Solutions 3 and 4 are proportioned before use mixed from 2 parts of Fehling's solution to one part of formaldehyde solution at room temperature.

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5. It is made from 225 g of copper sulfate (CuSO ,, · 5Η 0),

ζ 2 χ

56 g (J2 cmr) sulfuric acid and 4 Ma 8 cnr a brightener prepares a copper bath. A suitable brightener is that in U.S. Patent 2,882,209. Other suitable brighteners contain as active substances Thiohydantoin, acetyl-2-hydantoin, propenyl ^ -2-hydantoin, Dimethylsafranine, azodimethylaniline, Janus blue, (Janice blue), green, gray or -black or mixtures of these substances. Distilled water is also required

Using the solutions above, do the following:

1. The surfaces of the molding to be metallized are _{lightly roughened with fine emery paper 9} steel wool or caustic liquids.

2. Then with trichlorethylene, trichlorathane or a similar degreasing agent degreased »

3 · The molded body is then immersed in the Solution 1 immersed.

4. It is then washed with distilled water «,

5. The shaped body is then left for 1 to 2 minutes immersed in solution 2.

6. It is then washed with distilled water.

7 · The shaped body is then dipped into the mixture of solutions 3 and 4, bia Copper spring strike has arisen «The time required is 5 to 10 minutes«

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8. It is then washed with distilled water.

9. Galvanic copper plating with a current density is then carried out in the copper bath for 20 minutes of 4.3 A / dm. This is a copper

layer of about 0.03 nua thickness achieved.

10. It is then washed with tap water and then with distilled water.

The deposited copper layer was subjected to an adhesion test with scotch tape (commercially available adhesive tape). No copper was lifted off the composite material and no copper remained on the adhesive tape be liable. Accordingly, good adhesion of the deposited copper layer was achieved using the method described achieved on the composite.

The following table I illustrates the properties of the used for the waveguide component according to the invention Composite material compared to conventional Y / er materials. The composite material used as a comparison had a thickness of about 0.9 mm and consisted of four layers at 0 °, 90 °, 90 °, 0 ° oriented graphite fibers. The proportion of graphite in the material was about 55% by volume. This composite faced in all directions of the planes of the laminate an unusual behavior with regard to thermal expansion, namely a negligibly small to negative expansion with increasing temperatures.

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Table I.

Material heat expansion density expansion p / cm? coefficient per 10-6g _r a.-1

Tensile strength ο

kp / cm χ ₁₀ ~ 6

Elongation

module

(Stiffness)

Rectified graphite fibers in an epoxy matrix

In the direction of the grain

- 0.07

1.5

5.6

53

Across the
Grain direction + 25.2 1.5 0 ₃ 42 20th Crossed
Graphite fibers +
in epoxy matrix 0.49 ■ 1.5 3 _S 15 10 aluminum
alloy '+ ■ 25.0 2.8 2 * 24 11 Silver + 19.6 10.4 0.56 20th Invar + 1.2 8.1 4.9

Fig. 5 illustrates the manufacture of one half of a waveguide filter with the aid of a pre-impregnated tape made of endless graphite fibers with a stretch or chip

6 2 voltage modulus of preferably 5.5 »10 kg / cm or more, which is impregnated with a conventional mixture of a cycloaliphatic epoxy and a hardener. 90 ^o -90 ^o -0 ° produced which has such a length and width

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have that a side part of a waveguide with mounting flanges 21 and 21 'is generated on the longitudinal edges. It is placed over a core 22 which is adapted to the internal shape of the waveguide. After placing, a vacuum bag molding pressure is applied with the help of a conventional low-pressure laminating tool, which is not shown in detail, in order to cure the fiber body under vacuum (for example at about 1.05 kg / cm ² in an oven at 177 ° C.). The core 22 can also be designed for the production of waveguide components with bends, angles, curves, grooves and other desired deformations in the basic structure for duplication or for adaptation to other molded parts. For example, assembly grooves (not shown) can be present in the mold in order to facilitate the assembly and fastening of diaphragm plates 23 in the waveguide. On the other hand, in other applications in microwave circuitry, the resin impregnated with high modulus graphite can be cast instead of being formed into fibers and provided with a suitable conductive coating.

The production of the waveguide component is then carried out by drilling and other machining to the desired Dimensions and there is a number of conventional diaphragm plates 23 made of a conventional graphite composite material inside the U-shaped channel with the help of conventional hardening epoxy adhesives or the like. attached. This structure or its inner channel can then be provided with a conductive coating either before or after attachment the prefabricated end plates 24, which the

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view the prefabricated connection f! 16 comparable are. As an alternative metallic coating, the Shipley plating process or other suitable Metallization solutions for plastics are used to make the critical combination of graphite fibers to be coated in a resin matrix as described.

As shown in Fig. 6, the mirror image fiber bodies 20 and 20 'of Fig. 5 are connected by means of a number of bolts 25 or other suitable connecting means and the entire assembly is chemically treated and metallized in the manner described above. Such a filter was compared with a similar filter made from Invar. The weight reduction achieved was 1ι6 in relation to Invar · In addition, the switch-on attenuation and the frequency shift with temperature changes were measured · The filter was tuned to 4.16 GHz. The Switch-on was 0.29 db at mb · This value is low compared to typical values of Invar filters between ₉ O 25 and 0.30 dB · the temperature characteristic of the filter was measured with an automatic analyzer Fetzwerk · The Filter behavior was ^{observed between -18 0} G and 60 ⁰ O »The results result from the following list?

Filter AF / 50 ⁰ O

GFRP with isolator -0.65 MHz

GFRP without isolator -0.36 MHz

Invar +1.03

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The negative coefficient of thermal expansion of the graphite composite material results from the following tests, in which the coefficient of thermal expansion of a number of Tnfein was measured, which consisted of a composite material of graphite fibers with an elongation module of 3 »5 · 10 kg / cm and an ic © tropical epoxy resin . The panels were cut from a number of prepared laminates and measured from 25 to -193 C, and between 25 and +116 ⁰ C.

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Table II

summer, Length 1 and fiber orientation of the sample

Expansion or contraction at maximum temperature 5

Expansion length or Difference drawing Al _-3 , at lowest 10 temperature 5

Temperature difference Δ Τ degrees

Thermal expansion coefficient in 10 ~ 6 degrees

Remarks

-1

Table 18 1 = 3.925 rectified

Plate 20

112 ° C: -0.41 -198 ° C: +0.38 0.79

co co ο co

Panel 46 ι = 4.14 cm 000

112 ° G: -0.36 -198 ° G: +0.74 1.10

112 ⁰ G: +0.38 -198 ° C: -O.25 0.63

118 ° C: -0 ₅ 36

Plate 47 1 = 4.11 cm 90 ° -0 ° -0 -90

Table 48 0 ° -90O-0 °

Plate 49

1-4.74 cm 120 ° C: -0.25

0 ° -90o-90 ° -Q °

Plate 55 I _n = 4.05 ° 909

-198 ° G: -1 _? 22 1 ₉ 60

l: +0.25 0.61

-198 ° C: + O ₉ 2O 0 _s 45

-198 ° C: -0.25 0.00

310

310

310

316

316 318

316

0.64

0.85

1 ₉ 23

0.41 0.32

0.00

Negative expansion

Negative expansion

Positive expansion "»

Positive expansion

Negative expansion

Negative expansion ¹ J, pressure plate 7 kg / cm ²

Negative results.

elongation pi

Vacuum bag p co 0.98 kg / cm

As can be seen from the table, the thermal expansion of composites with high modulus graphite fibers is at unidirectional fibers negative and negative to substantially in the case of strands laid in different directions negative and slightly positive, depending on the orientation of the fiber layers.

In this regard, in some cases it may be desirable to use chopped fibers with an elongation modulus in the Of the order of 3 »5 · 1Ο kg / cm or more to be used, which are randomly distributed in an isotropic synthetic resin from which molded components are formed which are provided with a chemically or electrolytically applied, firmly adhering conductive coating in order to in this way to manufacture waveguide components at low cost that replace those cast from metal Components occur in the manufacture of waveguide components with high accuracy and complicated shapes can.

As described, Fig. 6 illustrates a waveguide component, which consists of one of high-modulus fibers and one Epoxy resin matrix consisting of low-pressure laminate The channel-shaped fiber body 20 and its counterpart 20 ' are, as discussed above, formed in one piece with mounting flanges 21 and 21 '. Before the parts come together are adapted and connected to each other, conventional end plates 24, the connecting flanges 16, attached to the ends of the fiber bodies 20 and 20 '. In addition, the usual aperture

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- c. I -

panels 2J made of prefabricated graphite fiber Composite material inserted and fixed in fiber bodies 20 and 20 ". The machined surfaces of the diaphragm plate are machined with an accuracy of 25 y ^ -m. The attachment of the end plates 24 and the diaphragm plates 23 takes place on the fiber bodies with the aid of a number of spacers made of aluminum (not shown) using a conventional one Epoxy resin adhesive. The waveguide sections are connected to one another by screw bolts 25 »Then ■ the waveguide component is made through subsequent processing steps, i.e. milling, drilling and thread cutting can include, brought into the intended shape. The attachment of threaded holes can, for example serve to insert tuning screws, not shown. After all mechanical work is completed the waveguide component is chemically treated and silvered, as described above. The chemical treatment and the application of the conductive coating can be carried out on the entire structure or only on such sections. which must have a permanent conductive coating.

For the composite material of anisotropic high-modulus fibers and matrix materials as a conductive coated base body for waveguide components impregnated fibers are preferably graphite having a negligible or negative coefficient of thermal expansion _s used have a flexural modulus (flexual modulus) of more than 2.1 »10 kg / cm *, Such fibers gives θβ as with

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Graphite-impregnated synthetic fibers made of polyacrylonitrile, nylon, polyimide and the like. As well as mixtures of such fibers and optionally bound by an isotropic matrix into which reinforcing particles of high-modulus fibers may or may not be mixed. With a conductive coating, these base bodies form new waveguide components that have a high degree of dimensional stability, are more rigid and yet are lower in weight than previously known waveguide components. Typical epoxy plastics for the production of such composite materials for waveguide components are listed in the following table:

Bisphenol A.

NOVOLAG

Multifunctional parts
Pereassigaic acid

(cycloaliphatic)

Table III

resin
(Trade name)

THE 351
EPON 828 ERL 2774 DER 661 (fixed)

EPON 1001 (fixed) DEN 438 EPON 154-EPN 1138

EPON 1031 EON 1273 ERL 4617 CY 178 GY 179

Harder

(stoichiometric amounts)

Metaphenylenediamine

Methylenedianiline BF, - monoethylamine

NADIL methyl anhydride, hexahydrophthalic anhydride

Benzyldimethylamine Diaminediphenylsulphene

Then the currently available high modulus fibers and synthetic fiber cables are listed:

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Table Iv 5.0 Modulus of elasticity E in 10 kg / cm union
Carbides
Thornel '
755 1.0 2.0 3.5 Union Carbide
Thome 1 505
Rayon yarn Celanese
75 Hitco Hitron Hitco Kitron
HMG 15 HLiG 25 ■ Thornel 400.
Hi Ten.Str. Courtaulds Courtaulds
AS HMS
, E = 1.75 ■ E - 3.5 Courtaulds
Polyacrylic HTS
nitril cable E »2.2 Bristol
Hyfil
E - 1.9 Morganite Morganite
Modmor II Modmor I
E = 2.5 E- 3.8

Waveguide components from the conductively coated composite of graphite fibers and an epoxy matrix retain their strength and stability at temperatures up to 180 ⁰ C. When a greater thermal stability of the matrix is desired when using fibers having a critical value of elasticity of at least 1,4.10 kg / cm "of the flexural modulus can be used as a matrix for the high-modulus

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fibers, polyphenylene resins, polyimide adhesives, and other materials can be used. In some In some cases, prefabricated high-modulus fiber structures can also be produced with a conventional binder, even if such prefabrication is less preferred. For example, when manufacturing

certain waveguide components in connection with high-

6 2

modular fibers of 2.1.10 and more kg / cm laminating resins such as polyester, phenolic, melamine resins and the like. Used will. In likewise less preferred arrangements, natural or synthetic can also be used Resin fibers with a more critical elastic flexural

6 2

modulus of at least 2.8.10 kg / cm in a mixed fiber ratio with a binder is provided and in plate form or in the desired construction form, as explained with reference to FIGS. 5 and 6 is and the antenna components and designed differently

Waveguide components may include, molded and placed in the

described manner is provided with a conductive coating.

As indicated, a high modulus fiber laminate is preferred. However, some waveguide components can be included Using randomly oriented short pieces of fiber and mixtures of fibers are produced that an elastic modulus of more than 2.1.10 kg / cm and preferably an elastic modulus of the order of magnitude from 2.8.10 to 5 »2.10 and more kg / cra and mixed in in the form of short fibers, bits or ends. After pouring, these too are grounded

8/0796

Components again in the manner described V / else on one or more surfaces with a conductive coating provided Be ·

It can be seen that the two critical demands that are met on aerospace equipment such as waveguide components. namely dimensional stability and high strength, from the composite materials embedded in a matrix Graphite fibers are met. The fiber material is

6 2 characterized by a high modulus of more than 1 _s 4 ", 10 kg / cm and preferably of the order of 3 * 5 * 10 kg / cm while the resin used as a matrix is preferably selected from such resins ₉ the operating temperatures between - 160 ⁰ G and -5-18O ⁰ O ver

■ = 6 wear and which do not gas at a pressure of 10 Torr and at temperatures of 120 ⁰ _{G and more 0} Furthermore, the plastics should have good adhesion and good bond strength against sheer forces occurring in the laminate, so that the laminate external forces and withstand thermal stresses Furthermore, a modified and economical way of producing waveguide components using high-modulus fibers or thin foils or plates made therefrom is that a metallic © lining, such as a metal foil insert, is used in a combined metal-plastic laminate production in order to reduce the total weight of a waveguide component »If the molded component has long, closed and winding channels

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possess the Beschichtlang the inner surface can take place in that an adhesive is filled and then poured out again, which may then be de-energized provided, such as by direct chemical induction, with a conductive layer, for example with silver. Furthermore, one-piece waveguide components can be produced by using a core made of an alloy that melts at low temperatures, such as Cerrobend or Cerrotrue, or a soluble material, on which the fiber structure is then placed or the composite material of fibers and conductor and matrix described is applied will. After the pad has been shaped, the entire assembly can be placed in an oven to cure. Thereafter, the molded part can be separated from the mold. Before or after cutting, the component can be processed and brought to the desired dimensions. If the component has not previously been provided with a conductive coating , the molded part can be pretreated to apply a microwave-conductive layer .

It goes without saying that the invention is not restricted to the exemplary embodiments shown, but that deviations therefrom are possible without departing from the scope of the invention as defined by the following claims.

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Claims (4)

Claims 2. Waveguide according to claim 1 _S, characterized in that the composite material contains graphite-polyacrylonitrile fibers. 3. Waveguide component according to claim 1 or 2, characterized characterized in that the synthetic resin matrix consists of an epoxy resin. 4. Waveguide component according to one of the preceding claims, characterized in that the coating consists of a thin layer of a metal with high electrical conductivity, 5 · Waveguide component according to one of the preceding. Claims, characterized in that between the composite material and the microwave-conductive coating an intermediate layer of one well-adhering metal is arranged. 8/0795 6. Method for producing a waveguide component according to one of the preceding claims, characterized »that after a molded body has been produced from the composite material thereof the surface to be provided with the coating is chemically sensitized and then applied to the sensitized Surface a thin conductive metal layer is deposited. W il 9 Π ü B / Π 7 ίί !: