DE1942741A1 - Material or objects made from it - Google Patents

Description

19427A-1

PATiENT ADVOCATE

. DlFL-IMG.

6 Frankiijii a ro Main 70

Sdinecksnhofsir. ^ 7-part. 61 7079 August 20, 1969

Gzy / goe UNION CAIiDIDE CORPORATION

Material or objects made from it.

The invention relates to a material or consisting thereof Objects eius a metallic matrix and embedded in it Carbon fibers.

For the construction of spacecraft, rockets and the like, a material is needed that has special physical properties, for example a low density together with high strength and rigidity within a wide temperature range. As a rule, a material composed of various components is used for this purpose.

Particularly promising for the production of such composite materials are parsers are made of carbon having a high elasticity and a high strength _s, it is known to use such composite materials au.i textiles made of carbon and synthetic resins to produce also made of fibers of carbon and metals, more recently * The carbon fibers have a much lower density than the metal and have a high elasticity and strength, which at temperatures up to

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at least 2000 C are not influenced by this. It should thus, such carbon fibers are expected to be a particularly good one good reinforcing agents for metals are to composite materials with a high elasticity, a high Strength, low density and good properties to produce elevated temperatures »

™ The latter are composed of carbon fibers and metal are usually manufactured in such a way that one who have coated carbon fibers with metal and then in compressing heat, combining them. Break here but the carbon fibers lightly, especially at high pressures, because the carbon fibers are irregular lie on top of each other and cross each other, this creates breaks in these Fibers. Especially with fibers lying across each other *, especially at high pressures. This increases the strength

λ of the composite materials even when using so low pressing pressures, such as 175 kg / cm, weakened

The invention is based on the knowledge that the tensile strength of composite materials of metal and fibers of carbon can be considerably improved if one is involved in the production well-aligned carbon fibers in an untwisted tone? State used. The alignment of the fibers leads to one More even deposition of the metallic coating, the fibers themselves also break less easily than before

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used unaligned fibers. You can therefore use compression pressures of up to 300 kg / cm in the production, oline that a larger proportion of the fibers .bricht-. There are also no particularly high pressures when pressing parallel fibers together, in contrast to the pressures occurring inside when fibers are not aligned. The strength of the material is therefore significantly improved, namely by up to 50 % compared to materials that are made from non-aligned fibers.

The composite material of a metallic matrix and carbon fibers according to the invention contains, among others, twisted ones aligned carbon fibers, all with one are provided with a thin coating of metal and are connected in a mutually parallel position by a metallic matrix.

The invention also relates to a method for producing such Materials. The process is characterized in that the carbon fibers are coated with a metal and they are then in an unswirled state in parallel layers to one another compresses hot. After the material has cooled down, it can be converted into objects of the desired type by methods known per se Shape to be processed.

Fig. 1 shows a yarn made of carbon fibers that are not - lie parallel and have a usual twist.

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Figure 2 shows a single strand of non-twisted yarn made of carbon, in which the fibers are parallel to each other *.

Textiles made of carbon are commercially available and are generally used to in the US Patents No. _s 3 "10 7" 152 and no. 3, methods described Il6,975 prepared. The inventive materials with a high elasticity, a high strength, a low density and a good resistance to high temperatures can be produced using fibers made of carbon, which have a relatively low elasticity and strength. For best results, however, one should use a graphite yarn that has high elasticity and strength. Such a yarn can be made, for example, by converting it into graphite under tension, as described in British Patent No. 1,093,084. Any twist that may be present must of course be eliminated before the fibers are coated with metal according to the invention.

■ For the production of the materials according to the invention, the Carbon fibers are coated with any metal that does not cause the fibers to degrade. To these metals include copper, silver, magnesium, aluminum, titanium, zircon, Hafnium, niobium, tantalum, chromium, molybdenum, rhenium, iron, cobalt, Nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum

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_ Ct _

and the same. These metals can be found on the carbon fibers can be applied by various methods. These processes include electrolytic deposition from one molten salt bath, thermal deposition using a suitable metal halide and spraying. That Electroplating from a molten salt bath is an ideal method of coating carbon fibers with a thin metal layer. This procedure is carried out in the process of the invention as a rule, since this creates a uniform and firmly adhering metallic coating. The carbon fibers, coated in this way with metal, are then connected to one another by being pressed together under heat in a non-oxidizing atmosphere, for example under an inert gas or in a vacuum.

The pressing is usually done at such a high temperature carried out that the metallic coating sinters and under so high a pressure that those coated with the sintered metal Fibers are connected to each other. The pressing pressure also depends on the temperature, with lower temperatures higher pressures are required.

When pressing, unnecessarily harsh conditions should be avoided, since these damage the fibers physically and chemically and

ir

»Lon material can weaken» So ζ , B ₉ at allssu high temperatures the fibers can be connected with each other or with

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react with the metal to form carbides. Too high pressures can break the fibers. One therefore uses As a rule, the lowest possible pressures and temperatures that are sufficient to bring about maximum compression, i.e. practical eliminate all pores.

The required pressing temperature depends on the type of each metal used, while the required pressure depends on the temperature used. When using Nickel are pressing temperatures of about 700 to about 1300 C ge

suitable. You can press at a pressure of over 35 kg / cm, preferably at a pressure of over 100 kg / cm. To avoid breaking the fibers during pressing, it is preferable not to use pressures above 300 kg / cm.

The hot pressing is continued until the fibers are effectively bonded together and maximum compaction is achieved. This time depends on the temperature and the pressure. If, for example, nickel-coated fibers are pressed together at a temperature of 100 ° C. under a pressure of 250 kg / cm, it takes about 3/4 hours to remove practically all of the porosity »At a temperature of 1050 ° C and a pressure of 210 kg / cm, about 1 hour is required. B «i a temperature of 9P0 C and a pressure of 2fjO kg / cm is also S i tunde erfordorlieh *

example

A yarn consisting of 2 graphite strands was used, which had 720 threads per strand. The threads had a young

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Modulus of 3,500,000 kg / cm and an average tensile strength of 19,000 lcg / cra. The yarn was split into both strands and each strand was wound on a separate spool. The bobbins could rotate independently in two directions: rotating in one direction eliminated the twist of the yarn. When rotating in the other direction, the untwisted yarn could be removed. After the two strands of graphite yarn had been separated, the bobbins were brought into position and rotated in two directions in order to untwist the yarn and continuously withdraw the untwisted yarn. The untwisted, ribbon-like yarn was fed from these bobbins at a speed of 3 »8 cm / min. Through a 38 cm long tube furnace which was heated to about 850.degree. The polyvinyl alcohol size was removed. The yarn was then passed between two copper rollers placed about 5 cm in front of a plating bath. The copper rollers were connected to a power source. The yarn was then passed through the plating bath where nickel was deposited onto the fibers from a nickel anode. The residence time of the yarn in the bath was 10 minutes. The aqueous electroplating solution contained 200 g of NiSO per liter. .6H ₀ O, 50 g NiCl ₀ .61H ₀ O and 30 g H_B.0_. The temperature of the plating solution was maintained at about 52 ° C. The amperage was between about 400 and about 1500 mA * after the

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Passing through the electroplating solution was made the yarn washed with hot waaser, dried at 200 ° C. and taken up on bobbins. A metallographic examination of the so nickel plated yarn indicated that all of the individual fibers had a nickel coating of 1 to 3 microns thick. Then cut these nickel-coated fibers were brought into lengths of about 2.5 cm, the sections placed parallel to one another in a compression mold made of graphite and pressed hot in a vacuum of about

20 microns of mercury for 1 hour. From the aligned Fully condensed patterns were created from sections of yarn about 3j.2 χ 1.6 χ 25.4 mm. Each swatch contained approximately 120 such sections of yarn.

The procedure has been carried out at various pressures, temperatures and Repeated amounts of fiber in the metal. The tensile strengths of the so The materials obtained are contained in Table I and there compared to the tensile strengths of materials made from twisted yarn.

Table I ~

Compression temperature fiber concentration tensile strength

tration in twisted, non-twisted metal. Yarn yarn

liO kg / cm ² 1050 ° C 33 % by volume 5250 kg / cm ² 7950 kg / cm ² 250 kg / cm ² 90O ⁰ C k5 ^: % by volume 4550 kg / cm ² 65ΟΟ kg / cm ²

The materials produced in this way can be used very well as construction material for aircraft that travel at speeds below

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ter the speed of sound and above the speed of sound should fly, for spacecraft and various propulsion systems.

It is clear that the materials according to the invention and
Objects made therefrom can be changed in terms of their dimensions, shape, stresses and the like. So you can also produce objects in which the metal-coated fibers made of carbon are wound or
are stacked parallel to each other ". One can, for example
Winding such fibers on a core and hot pressing, whereby
a coiled material is created, but you can use the fibers
also arrange them parallel to one another and press them together to obtain panels of different dimensions and shapes. If the material is to be more isotropic, laminates can also be produced in which the metal-coated fibers within each layer are parallel to one another, while the individual layers are in Can be arranged at angles to each other.
The term "carbon ¹¹ " as used above includes both non-graphitic and graphitic carbon.

Claims (1)

. - 10 - Claims 1.Material or objects made of it made of a metallic matrix and carbon fibers embedded in it, characterized in that the fibers are arranged parallel to one another. it 2 »Material or objects consisting of it according to claim i, thereby g e Ic e η η ζ e i c h η e t that the metallic matrix consists of nickel. 3 · Material or objects consisting of it according to claim 1 or 2, d a d u r c h g e k e η η ze i c h η et that the carbon fibers have high elasticity (Young's modulus) and have high tensile strength, 4, material or consisting thereof articles according to any one of claims 1 to 3 »dadurchg Ic θ e η η ζ ei c h ~ et η that the fibers are made of carbon graphite. 5a method for the production of a material or objects consisting of it according to one of the claims 1 to ^ ₁ thereby ge could ie h. η © t ₍ that one overlooks the faaeni made of carbon with e.iiiöm metal uiid then in an ungu © tlrailtöm state hot in parallel layers.