WO2005047208A2

WO2005047208A2 - Fibre used as a component of a composite material, composite material and method for the production of said type of fibre

Info

Publication number: WO2005047208A2
Application number: PCT/EP2004/011942
Authority: WO
Inventors: Volker Gallatz; Meinhardt Hirsch
Original assignee: Volker Gallatz; Meinhardt Hirsch
Priority date: 2003-11-06
Filing date: 2004-10-22
Publication date: 2005-05-26
Also published as: WO2005047208A3; DE10352709A1

Abstract

The invention relates to a fibre which is used as a component of a composite material. The fibre contains at least one part non-ferrous metallic, amorphic or ceramic material, in particular, at least one part ceramic material which is resistant to high temperatures. The shape of said fibre is different from the shape of a cylinder. The invention also relates to said type of composite material and a method for the production thereof.

Description

Volker Gallatz Horber Strasse 8, 72186 Receiving

Fiber for use as a component of a composite material and such a composite material and a manufacturing method for such a fiber

The invention relates to a fiber for use as a component of a composite material as well as such a composite material and a manufacturing method for such a fiber.

Numerous applications for so-called composite materials and in particular fiber composite materials are known from the prior art. For example, molded plastic parts with improved performance properties are produced by using a polymer plastic such as polyamide or epoxy resin with a fiber insert. Glass fibers or carbon fibers are customarily used as fibers, the fibers being produced by simply cutting off a continuous fiber and consequently having a cylindrical shape, in particular a circular cylindrical shape. According to the prior art, particularly good properties can be achieved by using relatively long fibers with a fiber length of several cm to several meters. In some cases, fiber fabrics are also used. Despite the improvements achieved through the use of fiber storage, the manufacturing and use properties of the known fiber composite materials are not optimal for some applications. In addition, the area of application is limited by the maximum processing and, above all, operating temperature, which is generally predetermined by the polymer plastic.

The object of the invention is therefore to provide a fiber for use as a component of a composite material and such a composite material which overcome the disadvantages of the prior art. In addition, an associated manufacturing process for the fiber according to the invention is to be provided.

This object is achieved by the fiber defined in claim 1 and by the composite material defined in the subordinate claim; the associated manufacturing process for the fiber is determined in the corresponding subordinate process claim. Particular embodiments of the invention are defined in the subclaims.

According to the invention, the fiber has at least a portion of a non-ferrous metal, amorphous or ceramic material. According to the invention is also a fiber which has at least a portion of a metal with a melting point of more than 2000 ° C, in particular more than 2500 ° C, and preferably more than 3000 ° C, for example osmium or rhenium, and their alloys. The fiber can also consist entirely of such metals or their alloys. The fiber can also consist entirely of a ceramic material or consist of an all-ceramic or a ceramic material having a ceramic component, including sintered Fibers, or have only a ceramic portion, for example a ceramic coating of a fiber core made of plastic, metal, glass or the like. Portions of an amorphous material such as glass or suitable metal oxide polymers can also be used. The combination of ceramic and metal oxides is particularly advantageous. The fiber materials according to the invention enable high tensile, compressive and / or flexural strengths to be achieved with high temperature resistance and / or high chemical resistance, in particular oxidation resistance. Combinations of ceramic and amorphous materials for the fiber are also possible. The at least one further component of the fiber which is present in addition to the ceramic or amorphous component which is resistant to high temperatures can, but does not have to, be resistant to high temperatures.

A ceramic component of the fiber is preferably in particular a ceramic material which is resistant to high temperatures and which ensures high chemical resistance both when the molded body is manufactured and when the molded body is used later. For example, aluminum oxide, aluminum nitride, boron nitride or silicon carbide are suitable as fiber materials.

The fibers can be formed at least in sections as hollow bodies, in particular have a hollow shape overall, or can be solid.

The fibers have a shape that deviates from the cylindrical or rod shape. A cylinder is to be understood as a geometric body in which two parallel, flat and congruent base areas are connected to one another by a jacket with a straight longitudinal axis. Form the base area can be arbitrary, in particular circular, elliptical, regular or irregular triangular or polygonal, with or without rounded edges, sickle-shaped or ring-shaped to form a hollow fiber.

According to the invention, both sectionally thickened and / or thinned fibers are possible, as are fibers which have a shape deviating from the cylindrical rod shape, in particular curved, curved, twisted, spiral, wavy, circular, elliptical, triangular or polygonal or the like. The fibers can essentially have a two-dimensional dimension or even a three-dimensional dimension. Combinations of differently shaped fibers are also possible, right up to the formation of two- or three-dimensional structures which are formed from one or more fibers of different or matching fiber shape, the individual fibers being able to be regularly or irregularly linked, hooked, intertwined or the like.

Preferably, at least a first section of the fiber, in particular an end section, has a cross-sectional contour that is different in size and / or shape and / or orientation than a further section of the fiber. Both fiber ends are preferably essentially identical, in particular symmetrical to a central section of the fiber. The formation of such a section ensures a positive connection of the fiber with the matrix surrounding the fiber. Such a positive connection can transmit significantly greater forces than the usual frictional connection between fiber and matrix, in particular compared to the known fibers with a smooth surface, and therefore leads to a higher resilience of the molded articles produced. The section with a different cross-sectional contour, in particular the end section, can have a star shape, pyramid shape, polygon shape, spherical shape, disk shape, ellipsoid shape, hook shape, bone shape, hedgehog shape, eyelet shape or combinations of these shapes. Further fiber shapes or shapes of the sections with a different cross-sectional shape are herringbone shape and leaf rib shape, in particular shapes in which at least one fiber needle branches off from a central fiber at an acute angle, preferably several fiber needles branch off one behind the other in the longitudinal direction. The fiber needles can all lie in one plane, so that the fiber is essentially a two-dimensional body, or project in different spatial directions from the central fiber, so that the fiber is a three-dimensional body.

It is also advantageous that when using the fibers according to the invention, mechanical strengths that are equally good can be achieved in all spatial directions when a molded body is produced from the composite material, i.e. the invention can ensure an isotropy of the mechanical properties of the molded articles produced.

In addition, the fiber can also have grooves or annular notches at regular or irregular intervals, which are spaced apart or connected to one another in the longitudinal or circumferential direction of the fiber. Such grooves or annular notches preferably run transversely to the longitudinal extent of the fiber, in order thereby to improve the form-locking of the fiber with the surrounding matrix.

In a special embodiment of the invention, the fiber has an end section with an irregular geometric shape. Through the Irregularity, for example, creates a highly form-fitting, large-surface connection surface between the fiber and the surrounding matrix. The irregular shape of the end section is preferably formed during the manufacture of the fiber, in particular by laser separation of the fiber from a continuous fiber. The absorption of the laser radiation leads to very rapid local heating and thus to a melting or blasting off of the fiber from the continuous fiber. The very rapid heating and the subsequent rapid cooling result, for example, in end sections with tines and tips oriented on all sides, which ensure particularly good interlocking with the surrounding matrix.

In a special embodiment of the invention, the fibers have a longitudinal extension between 0.01 and 30 mm, in particular between 0.05 and 5 mm, and preferably between 0.1 and 2 mm. According to the invention, the thickness or the diameter of the fibers is less than 50% of the fiber length, in particular less than 20%, and for many applications, in particular for fiber lengths of less than 5 mm, about 10%. These relatively short fibers allow the molded articles to be produced to have a large degree of freedom, while at the same time making the molded articles highly mechanically resilient. The following fiber dimensions length / thickness are particularly advantageous for different applications: 0.01 mm / 0.001 mm, 0.1 mm / 0.01 mm or 30 mm / 0.1 mm.

In a special embodiment, the fiber is curved and, as a result, the fiber length is greater than the longitudinal extent of the curved fiber. As a result, with fibers that are relatively short in terms of their longitudinal extension, there is nevertheless a large surface area of the fibers and thus a high connection effect between the fibers and the surrounding matrix. The invention also relates to a composite material which, as a further component, in addition to the fiber, has a basic matrix in which the fibers are embedded. A composite material is to be understood as a material made from different materials that are firmly bonded to one another.

The basic matrix can have, for example, a powder, in particular a ceramic powder, a metallic powder or a powder mixture of different materials, or a preceramic polymer. Alternatively or additionally, the basic matrix can also have a material in liquid form, in particular a molten metal or metal alloy. Other possible materials for the basic matrix are, for example, plastics, metal oxide polymers and flexible ceramics.

The combination of fibers according to the invention with a basic matrix leads to high-strength, high-temperature-resistant molded articles with great freedom of form at the same time. The base matrix can at least partially have a preceramic polymer, which can also be referred to as a ceramic adhesive, since it bonds the fibers added to form the shaped body during curing, and which preferably has a very low viscosity in the uncured state. As a result, the composite material can be processed, for example, by spraying. In addition to the ceramic polymer and the fibers, the base matrix preferably also has a ceramic powder.

The composite material is preferably used to produce a shaped body from a liquid or free-flowing solid phase into a transferred compact solid phase, for example by cooling a liquid metal, hardening a hardenable mass, sintering, including self-expanding sintering (Seif Heating Sintering or Self-Propagating High-Temperature Synthesis), explosion sintering and hydroth mixes sintering, injection molding, crosslinking, or microwave sintering.

After curing, the base matrix is, for example, dimensionally stable at temperatures above 800 ° C., in particular above 1200 ° C., and preferably above 1600 ° C. The basic matrix can be equipped in such a way that a ceramic which, for example, contains aluminum oxide, aluminum nitride or silicon carbide forms after hardening. The ceramic part in the hardened basic matrix is usually dependent on the hardening temperature. After curing, the basic matrix preferably has a ceramic proportion of more than 50%, in particular more than 65%, and preferably more than 75%.

It is precisely the combination of a preceramic polymer with ceramic fibers with a longitudinal extension of less than 10 mm, in particular less than 5 mm, and preferably less than 2 mm, which enables the production of moldings with great freedom of shape and at the same time high mechanical strength and high temperature resistance.

After curing, the base matrix preferably has a density between 1 and 8 g / cm ³ , in particular between 1.5 and 6 g / cm ³ , and preferably between 2 and 4 g cm ³ . The porosity of the moldings produced can be adjusted in a wide range up to helium tightness. The volume fraction of the basic matrix is at least 50%, preferably more than 65%, based on the total volume of the curable composition. The remaining constituent of the curable composition is essentially formed by the fibers and / or further ceramic constituents, in particular in powder form.

Through the use of relatively short fibers, which have a shape deviating from a straight cylindrical shape, in particular with thickened or thinned fiber sections and / or curved fiber shape, mechanical properties of the molded bodies produced can be achieved, while at the same time simplifying production, as previously only possible with long fibers without having to accept the disadvantages in this regard. The short fibers are preferably arranged irregularly and without a preferred orientation in the shaped body, so that improved mechanical properties and increased strength of the shaped body result in all spatial directions.

The invention also relates to a method for producing a fiber according to the invention, the fibers being separated from an endless fiber by radiation absorption, in particular by absorption of laser radiation. For this purpose, for example, a pulsed laser can be used, the pulse frequency and the feed speed of the continuous fiber are matched to the desired fiber length. As an alternative to this, a continuous wave laser can also be used, the laser beam of which can be deflected by a mirror and can, for example, sweep over a plurality of continuous fibers in succession in order to separate one fiber there. Further possible manufacturing methods according to the invention are the vapor deposition of moldings or fibers, which consist of relatively low-melting materials, with ceramics, metals and / or high-melting metal alloys.

Further advantages, features and details of the invention emerge from the subclaims and the following description, in which several exemplary embodiments are described in detail with reference to the drawings. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination.

Figures 1 to 16 show possible embodiments of the fiber according to the invention.

The fibers according to the invention shown in FIGS. 1 to 8 have an essentially homogeneous cross-sectional area along the fiber length, in particular no thickening or thinning at the fiber ends. For all these fibers, the fiber length is greater than the length of the fiber.

Fig. 1 shows a fiber with a wavy shape in the side view shown. The waveform can also be sinusoidal, in particular the shape of the waves, their amplitude and period length can be adapted to the application. In a plan view, not shown, this fiber appears straight.

Fig. 2 shows a fiber with a triangular shape in the side view shown. The triangular shape can also be sawtooth-shaped, in particular, the angle enclosed by the triangular legs and / or the leg length can be adapted to the application. This fiber also appears straight in a plan view, not shown.

FIG. 3 shows a spiral fiber with a cylindrical outer surface, while FIG. 4 shows a spiral fiber with a conical outer surface.

FIG. 5 shows a clasp-like, not closed elliptical fiber, FIG. 6 shows a corresponding, but essentially circular fiber, FIG. 7 shows a corresponding, but essentially triangular fiber, and FIG. 8 shows a corresponding, but essentially square fiber.

The fibers according to the invention shown in FIGS. 9 to 16 have thickenings at their end sections, preferably symmetrically to a central section of the fiber.

FIG. 9 shows a fiber which at its ends has sections with an irregular geometric shape and numerous peaks of different orientation and longitudinal extension, which are formed by brief, strong energy input. The left end of the fiber in the illustration is essentially regular, in particular uniform, with regard to the spatial distribution of the tips and their length. The right end of the fiber in the illustration, however, is irregular. Deviating from the illustration in FIG. 9, the fiber can also be designed regularly or irregularly at both ends. Fig. 10 shows a fiber with truncated pyramid shaped end portions. The left end of the fiber in the illustration has a flat end face. The right end of the fiber in the illustration, on the other hand, has an end face that is not flat, but in particular pyramid-shaped; in addition, the end section merges smoothly into the middle section of the fiber.

Fig. 1 1 shows a fiber with polygon-shaped or prismatic end sections.

Figure 12 shows a fiber with spherical end portions.

13 shows a fiber with disk-shaped or even perforated disk-shaped end sections.

FIG. 14 shows a fiber with herringbone-like or leaf-rib-like branches both in the middle section and in the end section.

15 shows a cranked fiber with a V-shaped central section.

16 shows a fiber with spherical thickenings at regular intervals along the longitudinal extent, wherein the diameter of the end-side spherical thickenings can be smaller, equal to or larger than the diameter of the spherical thickenings in the middle section.

The basic shape of the fibers according to the invention can be circular, triangular, quadrangular and in particular square, elliptical or the like in cross section. A polygonal or different basic shape of the fiber is also possible, which is torsion-like is twisted and thereby the orientation of the cross-sectional contour changes continuously along the length of the fiber.

Claims

Patent claims

1. fiber for use as a component of a composite material, the fiber having at least a portion of a non-ferrous metal, amorphous or ceramic material, in particular at least a portion of a high-temperature-resistant ceramic material, and wherein the fiber has a shape deviating from the cylindrical shape.

2. Fiber according to claim 1, characterized in that at least a first section of the fiber, in particular an end section of the fiber, has a different cross-sectional contour with respect to size and / or shape and / or orientation compared to a further section of the fiber.

3. Fiber according to claim 1 or 2, characterized in that the fiber has an end portion with an irregular geometric shape, in particular that the irregular geometric shape of the end portion in the manufacture of the fiber is formed by cutting from a continuous fiber, preferably by laser cutting from the continuous fiber ,

4. Fiber according to one of claims 1 to 3, characterized in that the longitudinal extension of the fiber is between 0.01 mm and 30 mm, in particular between 0.05 mm and 5 mm, and preferably between 0.1 mm and 2 mm.

5. Fiber according to one of claims 1 to 4, characterized in that the fiber is curved and thereby the fiber length is greater than the longitudinal extent of the curved fiber.

6. A method for producing a fiber according to any one of claims 1 to 5, characterized in that the fibers are separated from an endless fiber by radiation absorption, in particular by absorption of laser radiation.

7. Composite material comprising a basic matrix and fibers, the fiber having at least a portion made of a non-ferrous metallic, amorphous or ceramic material, in particular having at least a portion made of a high-temperature-resistant ceramic material, and wherein the fiber has a shape deviating from the cylindrical shape.

8. Composite material according to claim 7, characterized in that at least a first section of the fibers, in particular an end section of the fibers, has a different cross-sectional contour with respect to size and / or shape and / or orientation compared to a further section of the fibers.

9. Composite material according to claim 7 or 8, characterized in that the basic matrix can be hardened by cooling, heating, crosslinking or sintering.

10. Composite material according to one of claims 7 to 9, characterized in that the basic matrix forms a ceramic during curing.

1 1. Composite material according to one of claims 7 to 10, characterized in that the basic matrix after curing has a ceramic content of more than 50%, in particular more than 65%, and preferably has more than 75%.

12. Composite material according to one of claims 7 to 1 1, characterized in that the basic matrix is dimensionally stable after curing at temperatures above 800 ° C, in particular above 1200 ° C, and preferably above 1600 ° C.

13. Composite material according to one of claims 7 to 12, characterized in that the basic matrix after curing has a density between 1 and 8 g / cm ³ , in particular between 1, 5 and 6 g / cm ³ , and preferably between 2 and 4 g / cm ³ .

14. Composite material according to one of claims 7 to 13, characterized in that the basic matrix is low-viscosity before curing at room temperature, in particular has a viscosity of less than 300 cps, preferably a viscosity between 100 and 200 cps.

15. Composite material according to one of claims 7 to 14, characterized in that the proportion by weight of the base matrix is at least 50%, based on the total weight of the curable composition, in particular more than 65%, and preferably more than 75%.