CA2055660A1 - Process for obtaining a composite material having controlled electromagnetic properties and the material obtained - Google Patents
Process for obtaining a composite material having controlled electromagnetic properties and the material obtainedInfo
- Publication number
- CA2055660A1 CA2055660A1 CA002055660A CA2055660A CA2055660A1 CA 2055660 A1 CA2055660 A1 CA 2055660A1 CA 002055660 A CA002055660 A CA 002055660A CA 2055660 A CA2055660 A CA 2055660A CA 2055660 A1 CA2055660 A1 CA 2055660A1
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- Prior art keywords
- binder
- process according
- fillers
- fibre
- fibres
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/71—Ceramic products containing macroscopic reinforcing agents
- C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
- C04B35/80—Fibres, filaments, whiskers, platelets, or the like
- C04B35/82—Asbestos; Glass; Fused silica
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B18/00—Layered products essentially comprising ceramics, e.g. refractory products
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/71—Ceramic products containing macroscopic reinforcing agents
- C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
- C04B35/80—Fibres, filaments, whiskers, platelets, or the like
- C04B35/83—Carbon fibres in a carbon matrix
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2237/00—Aspects relating to ceramic laminates or to joining of ceramic articles with other articles by heating
- C04B2237/30—Composition of layers of ceramic laminates or of ceramic or metallic articles to be joined by heating, e.g. Si substrates
- C04B2237/32—Ceramic
- C04B2237/34—Oxidic
- C04B2237/341—Silica or silicates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2237/00—Aspects relating to ceramic laminates or to joining of ceramic articles with other articles by heating
- C04B2237/30—Composition of layers of ceramic laminates or of ceramic or metallic articles to be joined by heating, e.g. Si substrates
- C04B2237/32—Ceramic
- C04B2237/34—Oxidic
- C04B2237/343—Alumina or aluminates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2237/00—Aspects relating to ceramic laminates or to joining of ceramic articles with other articles by heating
- C04B2237/30—Composition of layers of ceramic laminates or of ceramic or metallic articles to be joined by heating, e.g. Si substrates
- C04B2237/32—Ceramic
- C04B2237/38—Fiber or whisker reinforced
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2237/00—Aspects relating to ceramic laminates or to joining of ceramic articles with other articles by heating
- C04B2237/30—Composition of layers of ceramic laminates or of ceramic or metallic articles to be joined by heating, e.g. Si substrates
- C04B2237/32—Ceramic
- C04B2237/38—Fiber or whisker reinforced
- C04B2237/385—Carbon or carbon composite
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Composite Materials (AREA)
- Reinforced Plastic Materials (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
- Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
- Woven Fabrics (AREA)
- Glass Compositions (AREA)
- Soft Magnetic Materials (AREA)
- Manufacture Of Alloys Or Alloy Compounds (AREA)
- Superconductors And Manufacturing Methods Therefor (AREA)
- Laminated Bodies (AREA)
Abstract
DESCRIPTIVE ABSTRACT
Process for obtaining a composite material with controlled electro-magnetic properties and the material obtained.
The process for obtaining a composite material having controlled electromagnetic properties and with a fibre reinforcement essentially consists of a) impregnating (10) each fibre with a solution containing pulver-ulent fillers having electromagnetic properties, a solvent and a first binder soluble in the solvent, b) evaporating the solvent from the filled charges, c) weaving (40) the filled fibres obtained in b) to form the rein-forcement and d) rigidifying (50) the reinforcement obtained in c) by a second binder.
Fig. 1 SP 6556.69 LC
Process for obtaining a composite material with controlled electro-magnetic properties and the material obtained.
The process for obtaining a composite material having controlled electromagnetic properties and with a fibre reinforcement essentially consists of a) impregnating (10) each fibre with a solution containing pulver-ulent fillers having electromagnetic properties, a solvent and a first binder soluble in the solvent, b) evaporating the solvent from the filled charges, c) weaving (40) the filled fibres obtained in b) to form the rein-forcement and d) rigidifying (50) the reinforcement obtained in c) by a second binder.
Fig. 1 SP 6556.69 LC
Description
2~5~60 Process for obtaining a composite material naving controlled electro-magnetic properties and the material obtained.
DRSCRIPTION.
The present invention relates to a process for obtaining a composite material having controlled electromagnetic properties, in which the fibres are filled prior to their weaving for cons~ituting the fibrous reinforcement of the sought composite material.
A composite material is constituted by a fibrous reinforcement and a binder ensuring the rigidity of the material. The reinforcement is essentially obtained from very strong textile fibres such as fibres of glass, silica, carbon, silicon carbide, alumina, alumino-silicate, polyamide and other fibres having in combination the elem-ents Si, N and C. The binder can be an organic resin, a metal or a refractory product.
The fibres of the reinforcement can be oriented in two or more direc-tions in space. They can be oriented in a random manner (D risk~, in a manner organized in two directions {2D) or three directions (3D or 3D evo).
These composite material can be used in numerous industrial fields and in particular in the space, aeronautical and nautical fields requiring the production of lightweight mechanical parts.
The invention applies to so-called woYen 2D reinforcements produced on machines known as "looms"~ which have emanated from the textile industry and which have been adapted to the needs of composi~e mate-rials. For example, laminates belong to this category. The fibrescan be woven in 2,3 or more directions in the same plane. The inven-tion more particularly applies to the fibrous reinforcement described in FR-A-2 610 951 and which is referred to as 2.5D.
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-The invention also applies to so-called 3D reinforcements constit-uted by an arrangement of threads in three directions in space giving parts with all shapes (bloc~, cylinder, cone, more complex reinforcement) and also using a weaving method.
S For example, the invention applies to the three-dimensional struc-tures described in FR-A-2 612 950 and FR-A-2 486 0~7.
Contrary to the situation in other fields, the aim is to adapt composite materials to the final applications in a very precise manner. At present, technologies make it possible to inter alia orient the reinforcing fibres in the directions of the stresses to which these materials are exposed and to give them excellent mechanical properties.
Moreover, the diversity of uses of these materials obliges manu-facturers to control other properties such as physicochemical prop-erties (heat resistance, o~idation resistance) and also electro-magnetical properties (antistatic material, electromagnetic shield-ing of comple~ electronic circuits, microwave absorbers).
The invention more particularly applies to obtaining a composite material having a controlled electrical conductivity and/or magnetic ~ 20 permeability.
:~ In these composite materials, the binder can be deposited in the fibrous reinforcement either by the gaseous route, or by the liquid route.
In the case of the gaseous route, the reinforcement is placed in an enclosure at ~i~ed temperature and pressure and is subjec~ to a gaseous ~low, whose molecules decompose in contact with the fib-res, said process being called chemical vapour infiltration (CVI).
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DRSCRIPTION.
The present invention relates to a process for obtaining a composite material having controlled electromagnetic properties, in which the fibres are filled prior to their weaving for cons~ituting the fibrous reinforcement of the sought composite material.
A composite material is constituted by a fibrous reinforcement and a binder ensuring the rigidity of the material. The reinforcement is essentially obtained from very strong textile fibres such as fibres of glass, silica, carbon, silicon carbide, alumina, alumino-silicate, polyamide and other fibres having in combination the elem-ents Si, N and C. The binder can be an organic resin, a metal or a refractory product.
The fibres of the reinforcement can be oriented in two or more direc-tions in space. They can be oriented in a random manner (D risk~, in a manner organized in two directions {2D) or three directions (3D or 3D evo).
These composite material can be used in numerous industrial fields and in particular in the space, aeronautical and nautical fields requiring the production of lightweight mechanical parts.
The invention applies to so-called woYen 2D reinforcements produced on machines known as "looms"~ which have emanated from the textile industry and which have been adapted to the needs of composi~e mate-rials. For example, laminates belong to this category. The fibrescan be woven in 2,3 or more directions in the same plane. The inven-tion more particularly applies to the fibrous reinforcement described in FR-A-2 610 951 and which is referred to as 2.5D.
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-The invention also applies to so-called 3D reinforcements constit-uted by an arrangement of threads in three directions in space giving parts with all shapes (bloc~, cylinder, cone, more complex reinforcement) and also using a weaving method.
S For example, the invention applies to the three-dimensional struc-tures described in FR-A-2 612 950 and FR-A-2 486 0~7.
Contrary to the situation in other fields, the aim is to adapt composite materials to the final applications in a very precise manner. At present, technologies make it possible to inter alia orient the reinforcing fibres in the directions of the stresses to which these materials are exposed and to give them excellent mechanical properties.
Moreover, the diversity of uses of these materials obliges manu-facturers to control other properties such as physicochemical prop-erties (heat resistance, o~idation resistance) and also electro-magnetical properties (antistatic material, electromagnetic shield-ing of comple~ electronic circuits, microwave absorbers).
The invention more particularly applies to obtaining a composite material having a controlled electrical conductivity and/or magnetic ~ 20 permeability.
:~ In these composite materials, the binder can be deposited in the fibrous reinforcement either by the gaseous route, or by the liquid route.
In the case of the gaseous route, the reinforcement is placed in an enclosure at ~i~ed temperature and pressure and is subjec~ to a gaseous ~low, whose molecules decompose in contact with the fib-res, said process being called chemical vapour infiltration (CVI).
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In the liquid route a liquid impregnating agent is made to penetrate the reinforcement which, by a subsequent treatment, is transformed into a composite material ha~ing the requisite mechanical character-istics.
At present two groups of processes for introducing charges or fil-lers into a composite material are known. The first group consists of introducing the fillers into the fibrous s~ructure during the rigidification of the reinforcement by the binder or just prior to said rigidification and the second group consists of the fillers being carried by the fibres prior to the production of the reinforc-ement.
According to the first group, the introduction of the charges can take place by gaseous route infiltration into the reinforcement~
- The principle is the same as that described hereinbefore for putting the binder into place in the reinforcement. Following CVI deposi-tion o the fillers in the fibrous reinforcement, the thus filled reinforcement is densified by the liquid route.
The major disadvantage of this process is that the fillers are only deposited on the preferred chemical sites, which is contrary to the obtaining of a homogeneously filled material. Moreoqer, this process cannot be applied to all types of fibres. Thus, the deposition temperature of the fillers by W I mu~t be below that of the fibre deterioration temperature.
Another procedure for infiltrating fillers into ~he reinforcement consists of impregnating the latter with a liquid resin to which the fillers have been added. This process described e.g. in EP-A-0 307 968 suffers from several disadvantages.
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The quantity of fillers in the resin conditions the viscosity of the impregnating resin. Thus, the more filled or charged with powder the resin, the more it is viscous and the more difficult its ~ !
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introduction into the reinforcement. Moreover, in the case of a large filler grain size, the final material is not homogeneous and has at the surface a high filler level, which tends to decrease on approaching the centre of the part.
The infiltration of the fillers into the reinforcement can also be brought about by a filter press, as described in EP-A- 130 105.
In this case, the reinforce~ent is placed in an enclosure, in which the fillers flow suspended in a solvent. The reinforcement, placed in front of the filter, is traversed by said solution before depos-iting the fillers thereon.
The disadvantage of this procedure is that it is very difficultto control the q~antity of fillers deposited in the reinforcement.
Moreover, the powder grain size is dependent on the size of the cavities between the fibres of the reinforcement and conditions the infiltration quality.
These filler infiltration processes lead to composite materials, whose physicochemical and/or electromagnetic properties do not always correspond to those which are sought.
According to the second gro~p which consists of the fillers being carried by the fibres of the reinforcement prior to the production thereof, reference can be made to that described in FR-A-2 566 324, which teaches the production of a fibre-metal or fibre-mineral prepreg for producing a high performance, composite material object.
The strands of preimpregnated fibres are covered with a sheath permitting the retention of the metallic or mineral powder and can then be woven.
FR-~-2 562 467 describes a flexible composite ma~erial constituted by a thermoplastic sheath con~aining a strand of fibres covered with a thermoplastic powder.
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~r The disadvantage of these methods based on the fibres carrying fillers is that the protect~ve sheath around the thread increases the apparent cross-section thereof. This sheath must be eliminated by a subsequent treatment, which makes the production o composite materials somewhat more difficult. Moreover, this leads to an excessive porosity of the materials obtained and to a non-optimum fibre filling, which is prejudicial to a good mechanical behaYiour.
The principle of inserting fillers on a fibre is also known in the case of wound composite materials, i.e. produced by filamentary winding onto a mandrel. This method consists of impregnating the basic thread with a solution containing fillers, a liquid resin serYing as the binder and a solvent.
The special feature of this impregnation is that it is necessary to deposit on the fibre the entire resin (binder) quantity necessary for the final material during this stage.
Following the deposition of the solution on the basic thread, the latter traverses a spinneret or die making it possible to retain a clearly defined solution quantity and then flows into an oven in order to transform the resin from the liquid state to the gelled state and eliminate the solvent. The thread obtained is called a prepreg or filled prepreg and is sticky on contact wi~h the hand.
This thread cannot be woven. The sticky thread is then deposited ; on a mandrel by winding in successive layers.
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The finished part is obtained after placing in an oven with a view to rigidifying or hardening the resin by polymerization. This ; final operation ca~ be followed by pyrolysis transforming the resin into carbon. It is clear that the composite material obtained under these conditions with layer-type fibre winding is consequently subject to a delamination risk.
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The invention relates to a process for obtaining a composite mate-rial having controlled electromagnetic properties in which the fibres are previously charged or filled making it possible to obviate the disadvantages referred to hereinbefore. It makes it possible to increase the homogeneity of the com?osi~e material, increase the weavability of the fibres facilitating the production of the reinforcement, as well as an excellent control of the elect-romagnetic and/or physicochemical properties of the material obtai-ned.
More specifically, the inYention relates to a process for obtaining a composite material having controlled electromagnetic properties and with a fibre reinforcement, essentially comprising:
a) - impregnating each fibre with a solution containing pulverulent fillers having electromagnetic properties, a solvent and a first binder soluble in the solvent, b) - evaporating the solvent from the filled fibres, c) ~ weaving the filled fibres obtained in b) in order to form the reinforcement and d) - rigidifying the reinforcement obtained in c) by a second binder.
The term fillers having electromagne~ic properties is understood to mean fillers ha~ing magnetic, conducting or semiconducting prop-erties.
The process according to the invention makes it possible to give the reinforcement of ~he composite material special properties without modifying the basic mechanical characteristics of the mater-ial. In particular, it makes it possible to place electromagnetic fillers in a very thick material in a perfectly homogeneous manner, SP 6555.59 LC
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both in the core of the material and on the surface, no matter - what the shape i.e. complex or simple of the fibrous reinforcement.
As a function of the envisaged application of the filled composite material, it is possible to use fillers having magnetic properties such as iron, ferrite, nickel or cobalt powder, filler~ having electricity conducting properties such as platinum, silver, copper, nickel or carbon powder, or fillers having semiconducting properties such as silicon, germaniu~ or silicon carbide properties.
The fillers are in the form of a powder or a mixture of powders having a grain size of approximately 1 micrometre or a submicronic grain size. The fibres of the reinforcement are in particular those described hereinbefore.
The process of the invention more particularly makes it possible to ob$ain a woven, rigidified reinforcemen~ in which ~he electrical conduction is controlled in a ~ery precise manner. Thus, starting with a basic fibre behaving electrically like a dielectric (or insulant), it is possible ~o introduce conductive charges or fillers onto it in a very precise quantity in order to make the final ma~er-ial assume a state intermedia~e between a conducti~e and a non-conductive material.
This very considerable con~rol of the electrical conductivity makesit possible to envisage a varia~ion thereof as a func~ion of the material thickness. Thus, independently of the homogeneitY of the material, it is possible by means of the present invention to produce a material having a controlled conductivity, which is dependent on the thickness.
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The reinforcement is then constituted by layers of superimposed threads or fibres having different filler levels between the indi-vidual layers and/or fillers having different conductivities.
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Thus, it is possible to produce a conductivity gradient in the thickness of the material and e.g. produce a ma~eri~l, whose condu-- ctivity decreases progressively from its centre to its surface.
Thus, the invention is more particularly applied to fibres which do not conduct electricity, such as glass, silica, alumina, silicon carbide, aluminosilicate or polyamide fibres. In addition, the invention more particularly applies ~o a dielectric ri8idification binder.
The solution containing the fillers, the solvents and the first binder is ~laced in and on each fibre forming a smooth, sliding sheath around the sa~e and serving in part as a size. This makes it possible to significalltly reduce the friction coefficient of ~he fibre with the ~urrounding elements and thus improve its weav-ability.
However, no matter whether the prepreg, which may or may not be - filled, used for the filamentary winding is not weavable as a result of the stickiness due to the gelled state of the resin during the elimination of the solvent.
The fibre generally used in composite materials is constituted by parallel fibrils. The cross-section of each of them does not, according to the prior art, give the flbre a maximum composite filling level. Moreover, by using the process according to the invention, it i~ possible to fill the cavities between the fibrils by fillers and thus significantly increase the material filling level without changin8 the cross-section of the fibre.
Following the weaving of the fibres, it is necessary to rigidify the reinforce~ent by a binder. In the case of thermostructural composites of the ceramic-vitroceramic, ceramic-ceramic and carbon-ceramic type, said rlgidification stage can be long and costly.
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In addition, by depositing the fillers on the fibre before weaving the reinforcement, there is a reduction in the densification time and therefore in the production costs of the composite material parts. This densification time reduction is considerable in the case of densification by CVI, the time gain being 20 to 60%.
Thus, the reinforcement according to the invention, prior to densi-fication, has a larger quantity of products than a reinforcement without a filler. Therefore, in order to terminate densification, less rigidification binder has to be deposited.
This time gain is due to a reduction in the porosity of the fibrous structure and more particularly a modification of the architecture of the gaps between the fibres. The fillers deposited on the fibres create bridges, which aid the grafting of the matrix.
The binder of the solution can be a liquid organic resin or a mix-ture of liquid organic resins polymerizable by ionizing radiation or thermally. They can be thermosetting or thermoplastic. These resins can be silicone, phenolic, epoxy, metha(acrylic), vinyl and similar resins and in more general terms resins having ethylene unsaturation.
When the binder of the solution containing the fillers is a therm-ally polymerizable resin, it is necessary to evaporate the solvent from the solution at a temperature below the gel point of the binder in the solvent (the gel point of a binder in solution e~ceeds that of the binder alone). It is also preferable to use as the solvent, solven~s having a low vapour tension and a low boiling point.
Said solvent generally has a boiling point at the most equal to 100C and a vapour tension exceeding 92 kPa at 20C.
For e~ample, it is possible to use a lower alcoho~ such as ethanol, n-propanol, isopropanol, n-butanol or lower halogenated alkanes SP 6556.69 LC
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such as dichloromethane, chloroform, dichloroethane or acetone, methyl ethyl ketone, ethyl acetate and tetrahydrofuran.
As a function of the envisaged application, the binder of the solu-tion containing the fillers and the rigidification binder of the fibrous reinforcement can be of the same type, i.e. of the same composition, or of a different type, provided that they are chemi-cally compatible.
The rigidification binder can be an oxide (borosilicate or alumino-silicate) glass, a vitroceramic (lithium aluminosilicate) a refrac-tory product (a dielectric ceramic, more particular]y silica, alum-ina, boron nitride or silicon nitride) or a dielectric organic resin. The resin is more particularly one of those referred to hereinbefore.
Moreover, the fillers can be of the same or different types compared with that of the fibres. They can also be of the same or different type to that of the binder used for the rigidification.
In order to only retain a precise solution quantity, there is advan-tageously a calibration or sizing stage. This stage consists of making the fibre covered with the solution containing the fillers ; 20 pass through a spinneret. The fibre impregnation level is below 5% and in particular approximately 3~.
In case of need, it is possible to carry out a complementary heat treatment following the evaporation of the solvent with a view to stabilizing the state of the binder and ensure the maintenance of the fillers on thç fibre. The stabilization temperature must be between the gel point of the binder and the polymerization temp-erature of said binder in order to permit good weavability.
The invention is described in greater detail hereinafter relative SP 6556.69 LC
' to non-limitative examples and with reference to the attached draw-ings, wherein show:
Fig. 1 diagrammatically the different stages of the process accord-in8 to the invention.
Fig. 2 the fibre filling stage according to the invention.
Fig. 3 a composite material having an electrical conductivity grad-ient according to the invention.
With reference to figs. 1 and 2, the first stage 10 of the process according to the invention consists of depositing conductive, semi-conducting or magnetic pulverulent fillers on each dielectric fibre12 for forming the composite material reinforcement. For this purpose impregnation takes place of each fibre 12 with a solution 14 containing pulverulent fillers, a polymerizable liquid organic binder and an organic solvent at a boiling point below 100C and a vapour tension above 92 kPa at 20C. This impregnation takes place by the transfer to the fibre 12 of the solution 14 contained in a tank 15.
By weight, the solution contains 5 to 13% fillers, 9 to 17% binder and 78 to 86% solvent. The powder has a grain size equal to or ~ 20 below 1 micrometre.
; After depositing the solution on the fibre, the la~ter passes thro-ugh a spinner~t 18 enabling it to only retain an impregnation level of approximately 3%. This calibration stage i9 symbolized at 20 in fig. 1.
After evapora~ing ~he solvent in an oven 24 ~fig. 2) at at the most 100C, a fibre i9 obtained which is constituted by its original material, the binder and the filler~. This i9 referred to as a SP 5556.69 LC
2~55~0 filled fibre. A heat treatment at the gel point of the binder makes it possible to stabilize the latter and maintain the fillers on the fibre. This s~age is symbolized at 30 in fig. 1. ~le fibre can be a glass, silica, aramide, silicon carbide or alumina fibre.
This is followed by a weaYing 40 according to a known process of the filled fibres in order to form a reinforcement of filled fibres of type 2D, 2.5D or 3D, as described hereinbefore.
This is followed by a rigidification or densification 50 using the liquid or gaseous route of the woven reinforcement, according to the prior art, using a dielectric binder. By the liquid route, the filled fibrous reinforcement is impregnated in ~acuo e.g. by a dielectric resin, which is polymerized and then crosslinked hot. These stages are performed seYeral times (generally 5).
In the case of the gaseous route the densification can be carried out in the manner described in FR-A-2 611 198 and FR-A-2 643 898.
The final stage consists of machining 60 the part obtained.
~ E~am~le 1: Impregnation of the so-called "filled" thread in order - to obtain a controlled conducti~ity composite material.
Carbon fillers are introduced onto silica fibres 12 by impregnating each of them with the aid of a solution 14 containing carbon fillers in th form of a submicronic grain si~e powder, the quantity of fillers contained in the solution being proportional to the desired conductivity and is chosen in the range 15 to 35 g, 240g of iso-propanol and 29g of phenolic resin.
The basic thread is unwound from its reel 16 and impregnated in the impregnation tank 15 containing ~he solution 14. After impre-gnating the fibre 12 in the solution, it passes through a sizing or calibrating spinnere~ or die 18 enabling it to retain a clearly SP 6556.69 LC
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defined solution quantity.
The impregnation level is appro~imately 3%, which makes it possible to obtain a material having a controlled electrical conductivity.
In addition, this level is equivalent to that of a size.
The so-called filled thread is wound onto a support 22 after passing through the oven 24 in order to eliminate the solvent~ The oven temperature is appro~imately 100C.
The thread then undergoes thermal stabilization at 95 + 5C in order to block the evolution of the phenolic resin and avoid any risk of dilution of the mixture during subsequent treatments.
:, This is followed by a weaving according to a 3D configuration and the structure is then rigidified by a phenolic resin. This rigid-ification consists of an impregnation of the structure by resin followed by polymerization at 180C. The material is optionally machined. I~ has a homogeneous filler distribution and therefore a perfectly controlled electrical conduc~iYity.
~` Example 2: Producing a laminate.
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In order to create an electrical conductivity gradient in the thick-ness of a composite material, a reinforcement is produced in the manner shown in figo 3 and which is constituted by a stack 1 of fabrics 2,3,4,5 and 6 differing from one another by their filler level. ~ach fabric is produced according to the 2D reinforcement weaving process and uses a glass fibre sized according to the proc-ess described in Example 1. These different fabrics are stacked and impregnated with the epoxy resin which is hardened, thus forming a laminate.
Thu9, the final reinforcement has a thickness-variable conduction, SP 6556~6 9 LC
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which is controlled as from the starting of the production process and not as in the case when the fillers are deposited following the production of the reinforcement.
It is in particular possible to use five different fibre types having a different carbon filler level and gradually varying from 0.5 to 2.5% by volume. This corresponds to a conductivity respect-ively varying from 2 to 20 ohms lm 1. It is then possible to form a laminate 1, whose conductivity e.8. decreases from the upper fabric 2 to the lower fabric 6.
E~amPle 3 This example differs from Example 1 by the use of a solution cont-aining a polymerizable epoxy resin and methyl ethyl ketone in place of the phenolic resin and ~he isopropanol.
Exam~e 4 This example differs from Example 2 by the use of a phenolic resin in place of the epo~y resin.
~P 6556.6~ LC
At present two groups of processes for introducing charges or fil-lers into a composite material are known. The first group consists of introducing the fillers into the fibrous s~ructure during the rigidification of the reinforcement by the binder or just prior to said rigidification and the second group consists of the fillers being carried by the fibres prior to the production of the reinforc-ement.
According to the first group, the introduction of the charges can take place by gaseous route infiltration into the reinforcement~
- The principle is the same as that described hereinbefore for putting the binder into place in the reinforcement. Following CVI deposi-tion o the fillers in the fibrous reinforcement, the thus filled reinforcement is densified by the liquid route.
The major disadvantage of this process is that the fillers are only deposited on the preferred chemical sites, which is contrary to the obtaining of a homogeneously filled material. Moreoqer, this process cannot be applied to all types of fibres. Thus, the deposition temperature of the fillers by W I mu~t be below that of the fibre deterioration temperature.
Another procedure for infiltrating fillers into ~he reinforcement consists of impregnating the latter with a liquid resin to which the fillers have been added. This process described e.g. in EP-A-0 307 968 suffers from several disadvantages.
:
The quantity of fillers in the resin conditions the viscosity of the impregnating resin. Thus, the more filled or charged with powder the resin, the more it is viscous and the more difficult its ~ !
~ SP 6556.69 LC
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introduction into the reinforcement. Moreover, in the case of a large filler grain size, the final material is not homogeneous and has at the surface a high filler level, which tends to decrease on approaching the centre of the part.
The infiltration of the fillers into the reinforcement can also be brought about by a filter press, as described in EP-A- 130 105.
In this case, the reinforce~ent is placed in an enclosure, in which the fillers flow suspended in a solvent. The reinforcement, placed in front of the filter, is traversed by said solution before depos-iting the fillers thereon.
The disadvantage of this procedure is that it is very difficultto control the q~antity of fillers deposited in the reinforcement.
Moreover, the powder grain size is dependent on the size of the cavities between the fibres of the reinforcement and conditions the infiltration quality.
These filler infiltration processes lead to composite materials, whose physicochemical and/or electromagnetic properties do not always correspond to those which are sought.
According to the second gro~p which consists of the fillers being carried by the fibres of the reinforcement prior to the production thereof, reference can be made to that described in FR-A-2 566 324, which teaches the production of a fibre-metal or fibre-mineral prepreg for producing a high performance, composite material object.
The strands of preimpregnated fibres are covered with a sheath permitting the retention of the metallic or mineral powder and can then be woven.
FR-~-2 562 467 describes a flexible composite ma~erial constituted by a thermoplastic sheath con~aining a strand of fibres covered with a thermoplastic powder.
SP 6556.69 LC
~r The disadvantage of these methods based on the fibres carrying fillers is that the protect~ve sheath around the thread increases the apparent cross-section thereof. This sheath must be eliminated by a subsequent treatment, which makes the production o composite materials somewhat more difficult. Moreover, this leads to an excessive porosity of the materials obtained and to a non-optimum fibre filling, which is prejudicial to a good mechanical behaYiour.
The principle of inserting fillers on a fibre is also known in the case of wound composite materials, i.e. produced by filamentary winding onto a mandrel. This method consists of impregnating the basic thread with a solution containing fillers, a liquid resin serYing as the binder and a solvent.
The special feature of this impregnation is that it is necessary to deposit on the fibre the entire resin (binder) quantity necessary for the final material during this stage.
Following the deposition of the solution on the basic thread, the latter traverses a spinneret or die making it possible to retain a clearly defined solution quantity and then flows into an oven in order to transform the resin from the liquid state to the gelled state and eliminate the solvent. The thread obtained is called a prepreg or filled prepreg and is sticky on contact wi~h the hand.
This thread cannot be woven. The sticky thread is then deposited ; on a mandrel by winding in successive layers.
;
The finished part is obtained after placing in an oven with a view to rigidifying or hardening the resin by polymerization. This ; final operation ca~ be followed by pyrolysis transforming the resin into carbon. It is clear that the composite material obtained under these conditions with layer-type fibre winding is consequently subject to a delamination risk.
SP 6556.69 LC
~5~6~
The invention relates to a process for obtaining a composite mate-rial having controlled electromagnetic properties in which the fibres are previously charged or filled making it possible to obviate the disadvantages referred to hereinbefore. It makes it possible to increase the homogeneity of the com?osi~e material, increase the weavability of the fibres facilitating the production of the reinforcement, as well as an excellent control of the elect-romagnetic and/or physicochemical properties of the material obtai-ned.
More specifically, the inYention relates to a process for obtaining a composite material having controlled electromagnetic properties and with a fibre reinforcement, essentially comprising:
a) - impregnating each fibre with a solution containing pulverulent fillers having electromagnetic properties, a solvent and a first binder soluble in the solvent, b) - evaporating the solvent from the filled fibres, c) ~ weaving the filled fibres obtained in b) in order to form the reinforcement and d) - rigidifying the reinforcement obtained in c) by a second binder.
The term fillers having electromagne~ic properties is understood to mean fillers ha~ing magnetic, conducting or semiconducting prop-erties.
The process according to the invention makes it possible to give the reinforcement of ~he composite material special properties without modifying the basic mechanical characteristics of the mater-ial. In particular, it makes it possible to place electromagnetic fillers in a very thick material in a perfectly homogeneous manner, SP 6555.59 LC
2~6~
both in the core of the material and on the surface, no matter - what the shape i.e. complex or simple of the fibrous reinforcement.
As a function of the envisaged application of the filled composite material, it is possible to use fillers having magnetic properties such as iron, ferrite, nickel or cobalt powder, filler~ having electricity conducting properties such as platinum, silver, copper, nickel or carbon powder, or fillers having semiconducting properties such as silicon, germaniu~ or silicon carbide properties.
The fillers are in the form of a powder or a mixture of powders having a grain size of approximately 1 micrometre or a submicronic grain size. The fibres of the reinforcement are in particular those described hereinbefore.
The process of the invention more particularly makes it possible to ob$ain a woven, rigidified reinforcemen~ in which ~he electrical conduction is controlled in a ~ery precise manner. Thus, starting with a basic fibre behaving electrically like a dielectric (or insulant), it is possible ~o introduce conductive charges or fillers onto it in a very precise quantity in order to make the final ma~er-ial assume a state intermedia~e between a conducti~e and a non-conductive material.
This very considerable con~rol of the electrical conductivity makesit possible to envisage a varia~ion thereof as a func~ion of the material thickness. Thus, independently of the homogeneitY of the material, it is possible by means of the present invention to produce a material having a controlled conductivity, which is dependent on the thickness.
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The reinforcement is then constituted by layers of superimposed threads or fibres having different filler levels between the indi-vidual layers and/or fillers having different conductivities.
SP 6556.69 LC
2 ~
Thus, it is possible to produce a conductivity gradient in the thickness of the material and e.g. produce a ma~eri~l, whose condu-- ctivity decreases progressively from its centre to its surface.
Thus, the invention is more particularly applied to fibres which do not conduct electricity, such as glass, silica, alumina, silicon carbide, aluminosilicate or polyamide fibres. In addition, the invention more particularly applies ~o a dielectric ri8idification binder.
The solution containing the fillers, the solvents and the first binder is ~laced in and on each fibre forming a smooth, sliding sheath around the sa~e and serving in part as a size. This makes it possible to significalltly reduce the friction coefficient of ~he fibre with the ~urrounding elements and thus improve its weav-ability.
However, no matter whether the prepreg, which may or may not be - filled, used for the filamentary winding is not weavable as a result of the stickiness due to the gelled state of the resin during the elimination of the solvent.
The fibre generally used in composite materials is constituted by parallel fibrils. The cross-section of each of them does not, according to the prior art, give the flbre a maximum composite filling level. Moreover, by using the process according to the invention, it i~ possible to fill the cavities between the fibrils by fillers and thus significantly increase the material filling level without changin8 the cross-section of the fibre.
Following the weaving of the fibres, it is necessary to rigidify the reinforce~ent by a binder. In the case of thermostructural composites of the ceramic-vitroceramic, ceramic-ceramic and carbon-ceramic type, said rlgidification stage can be long and costly.
SP 6556.69 LC
2~6~
In addition, by depositing the fillers on the fibre before weaving the reinforcement, there is a reduction in the densification time and therefore in the production costs of the composite material parts. This densification time reduction is considerable in the case of densification by CVI, the time gain being 20 to 60%.
Thus, the reinforcement according to the invention, prior to densi-fication, has a larger quantity of products than a reinforcement without a filler. Therefore, in order to terminate densification, less rigidification binder has to be deposited.
This time gain is due to a reduction in the porosity of the fibrous structure and more particularly a modification of the architecture of the gaps between the fibres. The fillers deposited on the fibres create bridges, which aid the grafting of the matrix.
The binder of the solution can be a liquid organic resin or a mix-ture of liquid organic resins polymerizable by ionizing radiation or thermally. They can be thermosetting or thermoplastic. These resins can be silicone, phenolic, epoxy, metha(acrylic), vinyl and similar resins and in more general terms resins having ethylene unsaturation.
When the binder of the solution containing the fillers is a therm-ally polymerizable resin, it is necessary to evaporate the solvent from the solution at a temperature below the gel point of the binder in the solvent (the gel point of a binder in solution e~ceeds that of the binder alone). It is also preferable to use as the solvent, solven~s having a low vapour tension and a low boiling point.
Said solvent generally has a boiling point at the most equal to 100C and a vapour tension exceeding 92 kPa at 20C.
For e~ample, it is possible to use a lower alcoho~ such as ethanol, n-propanol, isopropanol, n-butanol or lower halogenated alkanes SP 6556.69 LC
2~1~5B6 ~
such as dichloromethane, chloroform, dichloroethane or acetone, methyl ethyl ketone, ethyl acetate and tetrahydrofuran.
As a function of the envisaged application, the binder of the solu-tion containing the fillers and the rigidification binder of the fibrous reinforcement can be of the same type, i.e. of the same composition, or of a different type, provided that they are chemi-cally compatible.
The rigidification binder can be an oxide (borosilicate or alumino-silicate) glass, a vitroceramic (lithium aluminosilicate) a refrac-tory product (a dielectric ceramic, more particular]y silica, alum-ina, boron nitride or silicon nitride) or a dielectric organic resin. The resin is more particularly one of those referred to hereinbefore.
Moreover, the fillers can be of the same or different types compared with that of the fibres. They can also be of the same or different type to that of the binder used for the rigidification.
In order to only retain a precise solution quantity, there is advan-tageously a calibration or sizing stage. This stage consists of making the fibre covered with the solution containing the fillers ; 20 pass through a spinneret. The fibre impregnation level is below 5% and in particular approximately 3~.
In case of need, it is possible to carry out a complementary heat treatment following the evaporation of the solvent with a view to stabilizing the state of the binder and ensure the maintenance of the fillers on thç fibre. The stabilization temperature must be between the gel point of the binder and the polymerization temp-erature of said binder in order to permit good weavability.
The invention is described in greater detail hereinafter relative SP 6556.69 LC
' to non-limitative examples and with reference to the attached draw-ings, wherein show:
Fig. 1 diagrammatically the different stages of the process accord-in8 to the invention.
Fig. 2 the fibre filling stage according to the invention.
Fig. 3 a composite material having an electrical conductivity grad-ient according to the invention.
With reference to figs. 1 and 2, the first stage 10 of the process according to the invention consists of depositing conductive, semi-conducting or magnetic pulverulent fillers on each dielectric fibre12 for forming the composite material reinforcement. For this purpose impregnation takes place of each fibre 12 with a solution 14 containing pulverulent fillers, a polymerizable liquid organic binder and an organic solvent at a boiling point below 100C and a vapour tension above 92 kPa at 20C. This impregnation takes place by the transfer to the fibre 12 of the solution 14 contained in a tank 15.
By weight, the solution contains 5 to 13% fillers, 9 to 17% binder and 78 to 86% solvent. The powder has a grain size equal to or ~ 20 below 1 micrometre.
; After depositing the solution on the fibre, the la~ter passes thro-ugh a spinner~t 18 enabling it to only retain an impregnation level of approximately 3%. This calibration stage i9 symbolized at 20 in fig. 1.
After evapora~ing ~he solvent in an oven 24 ~fig. 2) at at the most 100C, a fibre i9 obtained which is constituted by its original material, the binder and the filler~. This i9 referred to as a SP 5556.69 LC
2~55~0 filled fibre. A heat treatment at the gel point of the binder makes it possible to stabilize the latter and maintain the fillers on the fibre. This s~age is symbolized at 30 in fig. 1. ~le fibre can be a glass, silica, aramide, silicon carbide or alumina fibre.
This is followed by a weaYing 40 according to a known process of the filled fibres in order to form a reinforcement of filled fibres of type 2D, 2.5D or 3D, as described hereinbefore.
This is followed by a rigidification or densification 50 using the liquid or gaseous route of the woven reinforcement, according to the prior art, using a dielectric binder. By the liquid route, the filled fibrous reinforcement is impregnated in ~acuo e.g. by a dielectric resin, which is polymerized and then crosslinked hot. These stages are performed seYeral times (generally 5).
In the case of the gaseous route the densification can be carried out in the manner described in FR-A-2 611 198 and FR-A-2 643 898.
The final stage consists of machining 60 the part obtained.
~ E~am~le 1: Impregnation of the so-called "filled" thread in order - to obtain a controlled conducti~ity composite material.
Carbon fillers are introduced onto silica fibres 12 by impregnating each of them with the aid of a solution 14 containing carbon fillers in th form of a submicronic grain si~e powder, the quantity of fillers contained in the solution being proportional to the desired conductivity and is chosen in the range 15 to 35 g, 240g of iso-propanol and 29g of phenolic resin.
The basic thread is unwound from its reel 16 and impregnated in the impregnation tank 15 containing ~he solution 14. After impre-gnating the fibre 12 in the solution, it passes through a sizing or calibrating spinnere~ or die 18 enabling it to retain a clearly SP 6556.69 LC
2~6~
defined solution quantity.
The impregnation level is appro~imately 3%, which makes it possible to obtain a material having a controlled electrical conductivity.
In addition, this level is equivalent to that of a size.
The so-called filled thread is wound onto a support 22 after passing through the oven 24 in order to eliminate the solvent~ The oven temperature is appro~imately 100C.
The thread then undergoes thermal stabilization at 95 + 5C in order to block the evolution of the phenolic resin and avoid any risk of dilution of the mixture during subsequent treatments.
:, This is followed by a weaving according to a 3D configuration and the structure is then rigidified by a phenolic resin. This rigid-ification consists of an impregnation of the structure by resin followed by polymerization at 180C. The material is optionally machined. I~ has a homogeneous filler distribution and therefore a perfectly controlled electrical conduc~iYity.
~` Example 2: Producing a laminate.
. ~
In order to create an electrical conductivity gradient in the thick-ness of a composite material, a reinforcement is produced in the manner shown in figo 3 and which is constituted by a stack 1 of fabrics 2,3,4,5 and 6 differing from one another by their filler level. ~ach fabric is produced according to the 2D reinforcement weaving process and uses a glass fibre sized according to the proc-ess described in Example 1. These different fabrics are stacked and impregnated with the epoxy resin which is hardened, thus forming a laminate.
Thu9, the final reinforcement has a thickness-variable conduction, SP 6556~6 9 LC
.
which is controlled as from the starting of the production process and not as in the case when the fillers are deposited following the production of the reinforcement.
It is in particular possible to use five different fibre types having a different carbon filler level and gradually varying from 0.5 to 2.5% by volume. This corresponds to a conductivity respect-ively varying from 2 to 20 ohms lm 1. It is then possible to form a laminate 1, whose conductivity e.8. decreases from the upper fabric 2 to the lower fabric 6.
E~amPle 3 This example differs from Example 1 by the use of a solution cont-aining a polymerizable epoxy resin and methyl ethyl ketone in place of the phenolic resin and ~he isopropanol.
Exam~e 4 This example differs from Example 2 by the use of a phenolic resin in place of the epo~y resin.
~P 6556.6~ LC
Claims (15)
1. Process for obtaining a composite material having controlled electromagnetic properties and with a fibre reinforcement, essentially comprising.
a) - impregnating (10) each fibre (12) with a solution (14) containing pulverulent fillers having electromagnetic proper-ties, a solvent and a first binder soluble in the solvent, b) - evaporating (24) the solvent from the filled fibres, c) - weaving (40) the filled fibres obtained in b) to form the reinforcement and d) - rigidifying (50) the reinforcement obtained in c) by a second binder.
a) - impregnating (10) each fibre (12) with a solution (14) containing pulverulent fillers having electromagnetic proper-ties, a solvent and a first binder soluble in the solvent, b) - evaporating (24) the solvent from the filled fibres, c) - weaving (40) the filled fibres obtained in b) to form the reinforcement and d) - rigidifying (50) the reinforcement obtained in c) by a second binder.
2. Process according to claim 1, characterized in that the fibres do not conduct electricity.
3. Process according to claim 1, characterized in that the fillers conduct electricity.
4. Process according to claim 1, characterized in that the second binder is dielectric.
5. Process according to claim 1, characterized in that there is a calibration (20) of the deposited solution quantity bet-ween stages a) and b).
6. Process according to claim 5, characterized in that calibration is carried out by passing each filled fibre (12) into a spinn-eret (18).
SP 6556.69 LC
SP 6556.69 LC
7. Process according to claim 1, characterized in that the fibre impregnation level is approximately 3%.
8. Process according to claim 1, characterized in that a heat treatment (30) is performed between stages b) and c) in order to stabilize the first binder deposited on each fibre.
9. Process according to claim 1, characterized in that the first binder is a polymerizable organic resin.
10. Process according to claim 9, characterized in that the solvent has an evaporation temperature below the gel point of the first binder in solution.
11. Process according to claim 8, characterized in that the heat treatment is performed at a temperature between the gel point of the first binder and the polymerization temperature.
12. Process according to claim 1, characterized in that the fillers and the first binder are of the same type.
13. Process according to claim 1, characterized in that the fibres are of silica, the fillers of carbon and the first and second binders are polymerizable organic resins.
14. Composite material having controlled electromagnetic proper-ties obtained by the process of claim 1, characterized in that the fillers are electricity conducting and it has an electrical conductivity gradient (fig. 3).
15. Material according to claim 14, characterized in that the fibres and first and second binders are dielectric.
SP 6556.69 LC
SP 6556.69 LC
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9014574 | 1990-11-22 | ||
| FR9014574A FR2669623B1 (en) | 1990-11-22 | 1990-11-22 | PROCESS FOR OBTAINING A COMPOSITE MATERIAL FROM PRE-LOADED FIBERS AND MATERIAL THUS OBTAINED. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2055660A1 true CA2055660A1 (en) | 1992-05-23 |
Family
ID=9402469
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002055660A Abandoned CA2055660A1 (en) | 1990-11-22 | 1991-11-15 | Process for obtaining a composite material having controlled electromagnetic properties and the material obtained |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0487417B1 (en) |
| JP (1) | JPH04300366A (en) |
| AT (1) | ATE148877T1 (en) |
| CA (1) | CA2055660A1 (en) |
| DE (1) | DE69124668T2 (en) |
| DK (1) | DK0487417T3 (en) |
| ES (1) | ES2100221T3 (en) |
| FR (1) | FR2669623B1 (en) |
| GR (1) | GR3023223T3 (en) |
| IE (1) | IE913883A1 (en) |
| NO (1) | NO914575L (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2724131C2 (en) * | 1977-05-27 | 1982-06-09 | C. Conradty Nürnberg GmbH & Co KG, 8505 Röthenbach | Plate-shaped carbon body and method for its manufacture |
| FR2544661A1 (en) * | 1983-04-19 | 1984-10-26 | Europ Propulsion | COMPOSITE MATERIALS CONSISTING OF A RESIN CARBON COKE MATRIX, REINFORCED BY REFRACTORY FIBERS COATED WITH PYROLYTIC CARBON, AND PROCESS FOR OBTAINING THEM |
| JPS6121973A (en) * | 1984-07-10 | 1986-01-30 | 住友電気工業株式会社 | Manufacture of carbon fiber reinforced carbon material |
| US4975261A (en) * | 1987-09-22 | 1990-12-04 | Petoca Ltd. | Process for producing high strength carbon-carbon composite |
-
1990
- 1990-11-22 FR FR9014574A patent/FR2669623B1/en not_active Expired - Fee Related
-
1991
- 1991-11-07 IE IE388391A patent/IE913883A1/en not_active Application Discontinuation
- 1991-11-15 CA CA002055660A patent/CA2055660A1/en not_active Abandoned
- 1991-11-20 ES ES91403132T patent/ES2100221T3/en not_active Expired - Lifetime
- 1991-11-20 DK DK91403132.3T patent/DK0487417T3/en active
- 1991-11-20 AT AT91403132T patent/ATE148877T1/en active
- 1991-11-20 DE DE69124668T patent/DE69124668T2/en not_active Expired - Fee Related
- 1991-11-20 EP EP91403132A patent/EP0487417B1/en not_active Expired - Lifetime
- 1991-11-22 NO NO91914575A patent/NO914575L/en unknown
- 1991-11-22 JP JP3307839A patent/JPH04300366A/en active Pending
-
1997
- 1997-04-22 GR GR970400884T patent/GR3023223T3/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| EP0487417B1 (en) | 1997-02-12 |
| DE69124668D1 (en) | 1997-03-27 |
| ATE148877T1 (en) | 1997-02-15 |
| NO914575L (en) | 1992-05-25 |
| EP0487417A1 (en) | 1992-05-27 |
| FR2669623A1 (en) | 1992-05-29 |
| GR3023223T3 (en) | 1997-07-30 |
| NO914575D0 (en) | 1991-11-22 |
| JPH04300366A (en) | 1992-10-23 |
| DK0487417T3 (en) | 1997-07-28 |
| DE69124668T2 (en) | 1997-08-07 |
| FR2669623B1 (en) | 1993-12-17 |
| ES2100221T3 (en) | 1997-06-16 |
| IE913883A1 (en) | 1992-06-03 |
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