DK158159B - CONTINUOUS YARN OR ROPE, ITS MANUFACTURING AND USE - Google Patents

Description

DK 158159 B

in

The present invention relates to a continuous yarn or rope composed of high strength composite fibers, its manufacture and use.

Bundles of very strong non-metallic fibers and semi-metals such as carbon, boron and silicon carbide in the form of filaments, mats, fabrics and cut strands are known to be useful for reinforcing metals and organic polymeric materials. Objects comprising metals and plastics reinforced with such fibers are widely used to replace heavier components made from conventional materials of somewhat lower strength such as aluminum, steel, titanium, vinyl polymers, nylon species and polyesters for use in aircraft such as aircraft, automobiles, office equipment , sports goods and in many other areas.

A common problem with the use of such fibers, as well as glass fibers, asbestos fibers and other fibers, is an apparent lack of ability to transfer the high strength properties of the fibers to the material to which the fibers must eventually enter and have intimate contact.

20 The problem manifests itself in a variety of ways; if e.g. a length of very strong carbon fiber yarn is longitudinally confined in the center of a rod formed from molten solidified lead, and if you pull in the rod until it breaks, the breaking strength will be less than one would expect from the 25 rules for mixtures, but greater than for a rod made of lead alone, namely because of the mechanical confinement of the fibers. The lack of adequate reinforcement is entirely due to poor transfer of the strength between the carbon fibers and the lead. The same thing happens if a very strong fiber is mixed with an incompatible plastic material. If some types of carbon fibers, boron fibers, silicon carbide fibers and the like in the form of e.g. strings, cut strings, non-woven mats, felt or paper, or in the form of woven fabrics are mixed with organic polymeric materials such as phenolic resins, styrene resins, epoxy resins or polycarbonates, or mixed in molten metals such as 2

DK 158159 B

lead, aluminum or titanium, they simply serve as a filler for these without giving them any reinforcement, and in many cases they even cause the physical properties to deteriorate.

5 After years of research, all these problems have now been widely recognized as arising from the need to ensure the necessary bonding between the high strength fiber type and the so-called matrix material, ie. the metal or plastic type that one seeks to reinforce. It is also known that bonding 10 can be enhanced by careful attention to the surface layers of each macro-microfilament or fibril in the material selected for use. Glass filaments are cleaned or cleaned e.g. in flame and then erased or surface-treated with a plastic-compatible organosilane to provide reinforcements which are uncommonly suitable for plastics.

However, such a technique does not work well with other types of fibrous materials and, for obvious reasons, is not suitable for carbon fibers which will not be communicated to surface texture and which have different boundary layers.

High strength carbon fibers are produced by heating polymeric fibers, e.g. acrylonitrile polymers or copolymers, in two stages, one of which serves to remove volatiles and carbonize the material, and the other serves to convert amorphous carbon to crystalline carbon. During such treatment, it is known that carbon changes from amorphous to single crystal state then cause orientation in fibrils. If the fibers are stretched during graphitization, high strength fibers will form. This is critical for the formation of the boundary layer because, as the crystals grow, very high surface energies are formed, as exemplified by incomplete bonds, edge-to-edge stresses and differences in morphology. It is also known that the new carbon fibrils in this form can absorb 35 oxygen in status nascendi from the air and even absorb organic materials to produce non-carbon surfaces.

DK 158159 B

layers which are firmly and chemically bonded thereto, although some of it may, however, be removed by solvent treatment and that certain gaps or open voids exist in the boundary layers.

Not entirely different from the contaminants on uncleaned and 5 non-surface treated glass filaments, these carbon fiber boundary layers are mainly responsible for failure when attempting to obtain reinforcement with plastics materials and metals.

Numerous unsuccessful attempts have been made to report such filaments, especially carbon filaments, a form which should be singularly suitable for use as reinforcement in metals and plastics. Most have involved the deposition of layers of metal, especially nickel and copper, as thin surface layers on the filaments. Such composite fiber must then be used in a plastic or metal matrix. The metals have been vacuum deposited, deposited electrolytically and deposited electrolytically by this type of known method; but the resulting fibers have not proved suitable.

Vacuum deposition, e.g. of nickel according to U.S. Patent No. 4,132,828 provides something which appears to be a continuous coating, but in fact it is not because the vacuum deposited metal first touches the fibrils through voids in the boundary layer and then grows outward as fungi, where they are joined a distance away from the surface, which can be detected during scanning by electron microscope as nodular nucleation. If the fiber is twisted, such a coating will fall off. The low density of non-crystalline deposition limits its use.

Electroless nickel baths have also been used to plaster such fibers; but here too comes the problem, as the initial nickel coating or other electroless coated metal serves only to inoculate as small spots through holes in the boundary layer, whereby new metal 35 grows outside like mushrooms and joins into something that looks like a continuous coating, but as in this 4

DK 158159 B

cases will fall off when the fiber is twisted. The intermetallic compound is very locally nucleated and this phenomenon also limits the use of the fibers. In the case of both vacuum deposition and electroless deposition, the strength of the metal-to-core bond is always substantially below one-tenth of the metal deposit's own tensile strength as a cohesive material.

Finally, electroplating with nickel and other metals is also known as reported in attempts to provide 10 carbon fibers with a metal layer to make them compatible with metals and plastics, see e.g. U.S. Patent No. 3,622,283. Short lengths of carbon fibers are clamped in a battery terminal immersed in an electrolyte and electroplated with nickel.

However, when the plated fibers are placed in a matrix of 15 tin metal, the fibers do not transfer their own strength to the matrix to the extent to be expected from the rule of blends. When fibers made by such a method bend sharply, a number of cracks appear in the transverse direction on the compression side of the bend, and on the stretch side of the bend 20 the metal breaks apart and shells into flakes. If the metal coating is stripped mechanically and the back is examined under a highly magnifying microscope, there is no duplicate or imprint or at best only an insufficient imprint of the fibril, the imprint being limited to an optical resolution of 40 Angstroms in scanning electron microscope. The latter two observations strongly suggest that the inability to reinforce the tin matrix is due to poor bonding between the carbon and the nickel plating.

In these cases, the bond strength between the metal and the core 30 is not greater than half the tensile strength of not more than 10% of the fibers, and it is substantially below one-tenth of the remaining 90%.

It has now been found that, if one chooses electroplating anyway, but applies an outer voltage of a very high order of magnitude far higher than that which, in the prior art, would have been believed to be achievable,

DK 158159 B

uniform, continuously coherent, thin metal coatings are provided to reinforce fibrils, especially carbon fibrils. The voltage must be high enough to provide sufficient energy to push the metal ions through the boundary layer so that uniform nucleation (nucleation) is provided directly on or together with the fibrils.

The continuous yarn or rope according to the invention is thus characterized in that the majority of the fibers have an electrically conductive core of carbon, boron or silicon carbide and at least one thin, uniformly fixed, electrically conductive layer consisting of at least one electrically precipitated (a) by forming a continuous web of a large number of electrically conductive carbon, boron or silicon carbide core fibers; (b) by continuously submerging at least the majority of the web. consisting of said fibers in a bath capable of electrolytically precipitating at least one metal, and c) by connecting the fibers to the bath by an external voltage of at least 10 volts for dissociating the metal deep within the fibers and for nuclear attachment of the dissociated metal uniformly through any barrier layer on the surface of the fibers, and by maintaining said tension sufficiently 1 long to provide a thin, uniform, firmly adherent, electrically conductive layer of electrolytically deposited metal on said core.

The method of the invention for producing a continuous yarn or rope composed of high strength composite fibers, wherein method a) forms a continuous web of a large number of electrically conductive carbon, boron or silicon carbide core fibers, b) at least the majority of the track, which consists of 6

DK 158159 B

said fibers, being continuously immersed in a bath capable of electrolytically precipitating at least one metal, and c) connecting an external voltage between the fibers and the bath, is characterized by the use of an external voltage of at least 10 volts for dissociating the metal deep within the fibers and for uniformly adhering the dissociated metal uniformly through any barrier layer on the surface of the fibers, maintaining this voltage long enough to provide a thin, uniform, firmly adhered, electrically conductive layer of an electrolytically precipitated metal on said core.

Assemblies of yarns or ropes (tows) comprising the thin metal coatings on fibers, woven textiles, yarns and the like of the invention can be knotted and folded without the metal breaking off in flakes. These composite materials can be clearly distinguished from those known in the art because they can bend sharply without the fibrils failing and being lost through a tube of the metal, as can be found by electroless metal deposition or vacuum deposition of composite materials when these bends sharply, which is especially true of nickel, in addition to the fact that the fibers in question are neither exposed to cracking in the transverse direction ("crocodile skin") on the bending side of the bend nor to breaking and peeling in flakes when the elastic limit of metal is exceeded at the bend side of the bend. In other words, the composite fibers of the invention can be clearly distinguished from the prior art materials because (i) they are continuous, (ii) the majority of the composite lizards are uniformly metal coated, and (iii) the bond strength 30 (between metal and core) on the majority of the fibers is at least 10% of the tensile strength of the metal deposit, but is preferably not substantially below approx. In particular, and preferably not substantially less than about 25%. 50%. In the most preferred embodiments, the metal-to-core bond strength will not be substantially below ca. 90% of the metal deposit's own tensile strength. The best properties will be achieved by 7

DK 158159 B

yarns or ropes of the composite fibers in which the metal-to-core bond strength approaches approx. 99% of the tensile strength of the metal is considered as coherent material, and a separate discussion of these will be given later.

Furthermore, articles made by adding the yarns or peat of the present invention to a matrix of molding material are distinctly different from the prior art because they are greatly reinforced. In addition, these objects have other advantages in that they e.g. distributes 10 electrical charges, and if certain harmless metals are used in the coatings, e.g. gold and platinum, they will not be rejected when implanted in the body.

For easier and clearer understanding of the invention, the accompanying drawing, in which FIG. 1 is a cross-sectional view taken across a metal-coated fiber of the invention; FIG. 1a is a longitudinal cross-sectional view taken of a metal fiber according to the invention; FIG. Figures 2 and 2a show cross-sectional views of respective 20 sections of a multinodal core and a cracked core fiber coated with metal according to the invention; 3 shows a longitudinal cross-section of a sharply bent metal-coated fiber according to the invention, while FIG. Fig. 3a shows a cross-sectional view taken longitudinally of a sharply bent metal-coated composite fiber made according to the prior art; 4 shows a partial section of a polymer reinforced with a metal-coated composite fiber made according to the invention, and FIG. 5 shows a view of an apparatus for carrying out the method according to the invention.

All the figures shown in the drawing represent models of the objects described herein.

Continuous high-strength composite fibers or yarns 35 are provided, the majority of the high-strength fibers, the majority of the fibers comprising

DK 158159 B

is a core and at least one thin, uniformly fixed, electrically conductive layer of at least one electrodepositive metal, the bond strength between that layer and the core not being substantially below about 10% of the tensile strength of the metal.

The bond strength of each fiber is at least sufficient to provide such a strength of the fiber that when it bends sharply enough to break the coating on the bending side, because the metal coating's elastic limit is exceeded, the coating on the bending compression side will remain bonded to core and will not crack along the perimeter of the fiber.

As mentioned, the core comprises carbon, boron or silicon carbide, but especially carbon fibrils.

The most preferred yarns or composite fibers 15 will be those in which, when the coating is removed by mechanical means and examined, there will be a reproduction or imprint of the fiber or fibril surface on the inner or inward surface of the removed coating, as examined under scanning electron microscope 20 at an optical resolution of 49 Angstroms or better.

Among the particular features of the present invention may be mentioned that the ropes or yarns of the present invention or the new composite fibers may be knotted or knotted and may for the same reason be included in textiles woven from such yarns, 25 nonwoven sheets, mats and papers laid with such fibers, such fibers can be cut into shorter strands, and such fibers may be uniformly dispersed in a matrix comprising a metal or an organic polymeric material.

In preferred embodiments, the coating metals 30 will be nickel, silver, zinc, copper, lead, arsenic, cadmium, tin, cobalt, gold, indium, iridium, iron, palladium, platinum, tellurium, tungsten or a mixture of any one or more that of the foregoing, without any limitation hereby otherwise, but preferably in crystalline form.

In a preferred embodiment, the plurality of core fibers comprise a rope carbon fiber and the product thereof 9

DK 158159 B

method is a rope of composite fibers that can be knotted in knot without separating the metal layer or parts thereof from the core fibers.

Other preferred features include the steps of weaving or knitting the yarns made by the method of the invention into a textile, applying them to a nonwoven sheet, or cutting them into short lengths.

In addition, other preferred trade includes conducting the process in an electrolytic bath which is recycled in contact with the fibers immediately prior to their immersion in the bath, so as to provide an increased current-carrying capacity to the fibers, and the electrolyte is renewed and supplemented on the fiber surface.

Referring now to FIG. 1 and 1a, 15 are continuous yarns and ropes for use as a core 2 in composite fibers of the invention and available from a variety of commercial sources. Eg. appropriate carbon fiber yarns are available from Hercules Company, Hitco, Great Lakes Carbon Company, AVCO Company and 20 similar sources in the United States and other countries. All are generally prepared by the methods disclosed in U.S. Patent No. 3,677,705. The fibers may be long and continuous or they may be shorter, e.g. with a length from 1-15 cm. As stated above, all such carbon fibers will contain a thin, incomplete or not perfectly perfect boundary layer (though not shown here) of chemically bonded oxygen and of chemically or mechanically bonded other materials such as organic matter.

A metal layer 4 will be of any electrodepositable metal and it will be electrically continuous. Two or even more metal layers can be applied and the metal may be the same or different metals as shown in the exemplary embodiments. In any case, the innermost layer will be so strongly and strongly bonded to the core 35 that, by a sharp bending of the fiber, it will be seen that the metal is clamped together as shown in FIG. 3, the fiber core 10

DK 158159 B

breaks over and the metal breaks on the bending tensile side of the bend when its limit of elasticity is exceeded. This is accomplished without causing the metal to peel off in flakes, which is otherwise the case and constitutes a problem with prior art metal-coated fibers (Fig. 3a). As a further feature, wherein the present invention differs from the prior art, the metal layer of the present invention fills the spaces and "cracks" of the fibers uniformly and completely as illustrated in FIG. 2 and 2a.

The very strong metal-coated fibers of the invention can be assembled by conventional composite article measures as depicted in FIG. 4, wherein a matrix 6 is constituted by a plastic material, e.g. epoxy resin, or a metal, e.g. lead, which matrix is enhanced by the presence of the very strong core-coated metal fibers 2.

The formation of the metal-coated layer by the electrodeposition method of the invention can be accomplished in a variety of ways. Eg. For example, a plurality of core fibers can be immersed in an electrolytic bath, and through appropriate electrical connections, the required high external voltage can be applied. In one method, the voltage of this high magnitude is applied only for a short period of time. Eg. For example, a pulse generator through the electrolyte will send a voltage wave sufficient to push or force the metal ions through the boundary layer and into contact with the carbon or other fiber-forming components that make up the cathode. The short time that elapses under this pulsating voltage will prevent heat from accumulating or accumulating in the fiber and burning it up or burning it out. Since the fibers are so small, e.g. of the order of 5 to 10 microns (µm) in diameter, and because the innermost fibers are usually surrounded by hundreds or even thousands of other fibers, external stresses in massive amounts of the order of 5 times the dissociation value (although only 0.5 to 2.6 volts theoretically 11

DK 158159 B

is necessary for dissociating the electrolyte metal to ions, e.g. where these are of nickel, gold, silver or copper), which depends on the salt specifically used. Using such strong stresses, it has now been found that the ions are uniformly nucleated through the bundle of fibers and migrate to the innermost fibrils and then further through the boundary layer. Preferably, external stresses are applied to e.g. 10 to 50 volts or possibly even more.

Although, as described above, pulsating voltages are suitable for small scale operations, e.g. however, for metallizing pieces of woven fabrics and small lengths of carbon fiber yarns or ropes, it is preferred to practice the method continuously on a moving fiber rope. In order to overcome the problem of fiber burnout due to the high stresses, it is preferred to cool them sufficiently outside the bath, as this can be accomplished by separating the fibers and pouring water on them; however, it is preferable to operate by means of an apparatus such as schematically shown in FIG. 5. Here, an electrolytic bath solution 8 is kept in a tank 10. In addition, anode curve 12 and idle rollers 14 are placed near the bottom of the tank 10. Two electrical contact rollers 16 are located above the tank. A rope 24 is pulled by means of a feed roller 25 26 (the drive of which is not shown here) over the first contact roller 16 and down into the bath further under the idle rollers 14 and up again by the bath over the second contact roller 16 on to roll 28. For illustration. It may be mentioned that the length of the submerged rope will be approx. Optionally, but 30 strongly preferred, a further simple circuit comprising a pump 18, a conduit 20 and a feeding head 22 for transporting bath solution is included. This allows to recycle the plating solution at a fairly high flow rate, e.g. 5 to 8 liters per per minute and pump it out over the contact rollers 16. As the bath solution is discharged immediately over the rollers with the occurring sections of the bladder 24, 12

DK 158159 B

especially the part of the bladder leaving the solution is completely bathed and cooled. Otherwise, by the high current flowing to the bladder, one could find that in some cases the heat generated by I could destroy the fibers 5 before they reach or before leaving the bath surface if such cooling were not avoided. . In addition, by allowing the electrolyte to flow, anisotropy is overcome. Of course, more than one plating bath can be used in series and the fibers can be rinsed free of electrolyte solution, treated with other conventional materials and dried, cut and woven into fabrics, however, all of this is done by conventional methods.

The following examples serve to further illustrate the invention by reviewing certain preferred embodiments.

Example 1 In a continuous electroplating system, a bath having the following composition is provided: 20

Ingredient Quantity

Nickel sulphate (NiSO 4 * 6H 2 O) 300 g / liter nickel chloride (NiCl 2 6 H 2 O) 90-150 g / liter boric acid (H3B03) 37.5-60 g / liter wetting agent (WA-129, State Chemical) 2% by volume of detergent ( Starlite 915, State

Chemical) 2% by volume The bath is heated to 60-71 ° C and has a pH of 2.8-4.2.

Anode baskets are filled with electrolytic nickel pellets, and have 4 ropes (fiber bundles) with 12,000 strands of carbon fiber with a diameter of 7 microns (μιη) continuously drawn through the bath while applying an external voltage of 30 volts to a current. which is set to give a total of 10 amperes-minutes per minute. 1000 strings. At the same time, the electrolytic solution is recycled through a circuit to contact the incoming and outgoing parts of the rope. The rope is then continuously passed through an identical bath at a rope 13

DK 158159 B

1.52 m / minute with a current of 180 amps in each bath. The end product is a rope of high strength composite fibers according to the invention comprising a 7 μη fiber core and approx. 50% by weight, based on the entire composite fiber, 5 of crystalline electrodeposited nickel, which adheres very strongly to the core.

If a fiber length is sharply bent and then examined, no cracking appears along the circumference of the metal coating in the bending side of the bend. The rope can be twisted and tied in knot without causing the coating to peel off or fall off as powder. If a section of the coating is mechanically stripped from the fibrils, a perfect reverse image or imprint will appear on the back.

Example 2

If the procedure of Example 1 is repeated, replacing the two baths with the following compositions in series and using silver in the anode curves, silver coated graphite fibers of the invention will be obtained.

20

Ingredient First bath Second bath Silver cyanide 0.75-2.25 g / liter 52.5-82.5 g / liter

Potassium cyanide 90-150 g / liter 90 g / liter Potassium hydroxide --- 7.5-15 g / liter

The first bath is operated at room temperature and a voltage of 12-36 volts, and the second bath is operated at room temperature and 6-18 volts.

30

Example 3

The process of Example 2 can be modified by using as the feed material in fibrous form the nickel-plated graphite fibers produced according to Example 1, and the tension in the first bath is lowered to approx. 18 volts. High strength composite fibers are provided in accordance with the present invention, wherein a silver coating surrounds a nickel coating on a graphite fiber core.

14

DK 158159 B

Example 4

The procedure of Example 1 can be modified by using, instead of the nickel bath, a bath composition as follows, using zinc in the anode curves, and then zinc-coated graphite fibers of the invention will be obtained:

Component Amount

Zinc sulphate 60 g / liter 10 Ammonium alum 22.5-45 g / liter

Potassium hydroxide 120 g / liter

Potassium cyanide 22.5 g / liter

The bath is run at 38 ° C and an external voltage 15 of 18 volts is applied.

Example 5

The method of Example 1 can be modified by using, instead of the nickel bath, a bath of the following composition, using copper in the anode curves, and copper-coated graphite fibers of the invention will then be obtained:

Ingredient Quantity 25 Copper cyanide 26.2 g / liter

Sodium cyanide 34.5 g / liter

Sodium carbonate 30.0 g / liter

Sodium hydroxide 3.75 g / liter

Rochelle salt 45.0 g / liter 30

The bath is kept at a temperature of 60 ° C and an external voltage of 18 volts is applied. Copper plated fibers should be washed with sodium dichromate solution immediately after plating to prevent tarnishing. If the procedure of Example 35 is repeated, using the copper bath in this example instead of the silver bath, high strength composite fibers of the invention will be obtained, wherein a copper coating surrounds a nickel coating on a graphite fiber core.

15

DK 158159 B

Example 6

The method of Example 1 can be modified by using instead of the nickel bath two baths of the following composition, using standard 80% copper / 20% 5 zinc as anodes to give brass coated graphite fibers of the invention:

Ingredient Quantity 10 Copper cyanide 30.0 g / liter

Zinc cyanide 9.4 g / liter

Sodium cyanide 56.0 g / liter

Sodium carbonate 30.0 g / liter 15 Both baths are kept at an operating temperature of 43 to 49 ° C. Since one third of the brass metal is applied to stain in the first bath at a voltage of 24 volts and two thirds are applied in the second bath at a voltage of 15 volts, the baths are supplied proportionally with current. After two rinses with 20 water, the brass plated fibers are washed with a solution of sodium dichromate to prevent tarnishing and then rinsed twice with water.

Example 7 The procedure of Example 1 can be modified by using, instead of the nickel bath, a bath of the following composition, using solid lead bars in the anode curves, thereby providing lead-coated graphite fibers of the invention: Component Amount

Lead fluoroborate, Pb (BF4) 2,105 g / Pb / liter

Fluoroboric acid, HBF4 97 g / liter 35 Optionally, approx. 2 g / liter / 3-naphthol and gel thaw. The pH is below 1, the bath is operated at a temperature of 27 ° C and an external voltage of 12 volts is applied. If the coating thickness exceeds 0.5 microns, there is an inclined 16

DK 158159 B

similarity that the lead bridges the individual filaments.

Example 8 5 In the general procedure described in Example 1, and using a conventional gold bath instead of the nickel electroplating bath and applying sufficient external tension, high strength composite fibers comprising a gold coating on a graphite core are obtained.

10

Example 9

Silicon carbide filaments and boron filaments are coated with nickel by cathodic contact with a nickel plating bath of Example 1, and an external voltage of approx. 30 volts.

Example 10

A composite material is prepared by cutting the composite fibers of Example 1 to short lengths of 20 to 25 mm, mixing them thoroughly with thermoplastic nylon (polyamide) in an extruder, and cutting the extrudate into mold pellets according to conventional methods. These pellets are used in injection molding to make 10 cm x 20 cm x 3 mm sheets. The plates are reinforced with the composite fibers. Due to the metal content, the plates will also not build up electrostatic charge, but can on the contrary act as electrical shielding in assemblies within the electronics.

Example 11

Bundles of nickel plated graphite fibers with a length of approx. 2.5 cm made by the method of Example 1 are mixed in a 1: 9 ratio with uncoated graphite fibers and placed in a woven mat in an amount of 34 g / m2. The mat 35 has a metal content of approx. 5% by weight nickel and can be impregnated with thermosetting resin varnishes and consolidated

DK 158159 B

17 under heat and pressure for high strength reinforced laminates and excellent ability to distribute electrical charges.

Example 12 5 Long nickel-coated graphite yarns made by the general method of Example 1 are pulverized at high speed with molten lead in an apparatus from which a rod of 3 mm diameter in solidified form emerges, through whose center the nickel-coated graphite fibers extend.

The lead is alloyed to the nickel without complete dissolution against the nickel, and the nickel is still firmly bonded to the graphite glasses. This results in a transfer of the physical strength of the graphite fibers through the nickel plating and the nickel-lead intermediate layer to the lead matrix. A section of the rod pull-15 is tested in an apparatus to measure its breaking strength. Compared to a lead rod of the same diameter, this lead rod reinforced with nickel-coated graphite fibers according to the invention is found to have a much higher breaking strength.

For further details of the prior art, reference is made to the aforementioned publications. It will further be understood that many variations of the subject of the invention may be made by those skilled in the art in light of the foregoing review and the detailed description. Eg. aluminum can be deposited from ethereal solutions. Metals, e.g. tungsten, 25 can be deposited from molten saline solutions, e.g. sodium tungstate. The rope may be treated to remove metal from certain sections thereof, thereby providing segmented structures which e.g. has utility as electrical resistors.

30 f

Claims (6)

Continuous yarn or rope consisting of high-strength composite fibers, characterized in that the majority of the fibers have an electrically conductive core of 5 carbon, boron or silicon carbide and at least one thin, uniform, firmly adhered electrically conductive layer consisting of at least one electrically precipitated metal, on said core, wherein the yarn or rope is made a) by forming a continuous web of a large number of electrically conductive carbon, boron or silicon carbide core fibers, b) by continuously immersing it in the at least the majority of the web consisting of said fibers in a bath capable of electrolytically precipitating at least one metal, 15 and c) by connecting the fibers to the bath of an external voltage of at least 10 volts for dissociating the metal deep within the fibers and for nuclear adhesion of the dissociated metal uniformly through any barrier layer on the surface of the fibers, and by maintaining said tension. long enough to provide a thin, uniform, firmly adhered, electrically conductive layer of an electrolytically precipitated metal on said core. A method of producing a continuous high-strength composite yarn or rope composed of high-strength composite fibers, wherein method a) forms a continuous web of a plurality of electrically conductive carbon, boron, or silicon carbide core fibers; at least the majority of the web consisting of said fibers is continuously immersed in a bath capable of electrolytically precipitating at least one metal, and (c) an external tension between the fibers and the bath, characterized in that it is used. an outer voltage of at least 10 volts for dissociating the metal deep within the fibers and for nuclear adherence of the dissociated metal uniformly through any barrier layer on the surface of the fibers, maintaining this voltage long enough to provide a thin, uniform, permanently adherent, electrically conductive layer of an electrolytic precipitated metal on said core. Use of a yarn or rope made according to claim 2 for providing a piece of clothing or a three-dimensional product by weaving or knitting. Use of a yarn or peat made according to claim 2 for providing a nonwoven sheet or a three-dimensional product. Use according to claim 3 or 4, characterized in that it comprises a step by which the yarn or rope is cut into shorter pieces. Use according to any one of claims 3-5, characterized in that it comprises a step by which a metal or organic polymeric material is brought into close contact with at least a reinforcing amount of said yarn, rope, clothing, sheets or cut fibers. to provide an enhanced composite product.