EP2437904A1

EP2437904A1 - Process for producing a metal matrix composite material

Info

Publication number: EP2437904A1
Application number: EP10724291A
Authority: EP
Inventors: Isabell Buresch; Werner Krömmer
Original assignee: Wieland Werke AG
Current assignee: Wieland Werke AG
Priority date: 2009-06-03
Filing date: 2010-05-27
Publication date: 2012-04-11
Also published as: JP2012528934A; DE102009026655B3; RU2536847C2; CN102458719A; WO2010139423A1; KR20120027350A; US20120077017A1; EP2261397A1; RU2011154031A

Abstract

The invention proposes a process for producing a metal matrix composite material (200, 210) composed of a metal matrix (201, 211) having at least one metal component and at least one reinforcing component (202) arranged in the metal matrix (201, 211), in which at least one of the components is sprayed onto a substrate (5) by means of a thermal spraying process, use being made of at least one reinforcing component comprising carbon in the form of nano tubes (202), nano fibers, graphenes, fullerenes, flakes or diamond. Also proposed is a corresponding material, in particular in the form of a coating, and the use of such a material.

Description

Method of making a metal matrix composite

The invention relates to a method for producing a metal matrix composite material having a metal matrix having at least one metal component and at least one reinforcing component arranged in the metal matrix, a corresponding material, in particular in the form of a coating, and the use of such a material.

The trend toward increasing miniaturization, the cost pressures associated with rising material costs, and the increasingly demanding requirements of applications in the electrical and electronic industries, as well as the manufacture of technical bearings, require new materials and coatings.

Metal matrix composites or metal matrix composites (MMC) have outstanding combinations of properties compared to exclusively ceramic or metallic materials. For this reason, there is a great deal of interest in using the MMC, originally developed for the aerospace and defense industries, for a number of applications.

The term MMC often refers exclusively to appropriately reinforced aluminum, in special cases also referred to as reinforced magnesium and copper materials. The metal component of the MMC is as elemental metal or in the form of an alloy. As reinforcement phase or component are usually particles (reinforcing particles) (diameter 0.01-150 microns), short fibers (diameter 1-6 microns, length 50-200 microns), continuous fibers (diameter 5-150 microns) or foams with of open porosity, which are usually made of ceramic material (SiC, Al ₂ O ₃ , B ₄ C, SiO ₂ ) or carbon in the form of fibers or graphite (see also and in the following: "Metal matrix composites: properties, Applications and Editing "by Dr. 0.

Beffort, 6th International IMF Colloquium, 18. / 19. April 2002, Egerkingen, Switzerland).

For the production of bulk MMC materials, essentially three process processes are known from the prior art, namely the stirring of ceramic particles into the molten metal, the melt infiltration and the powder metallurgy. For the production of MMC coatings, the prior art discloses the electrodeposition.

In corresponding stirring often the lack of wettability between molten metal and particles must be overcome and a reaction between the two phases are limited. The volume fraction of the particles is limited for viscosity reasons to a maximum of 30%.

During infiltration, the reinforcing component is processed into a porous preform into which the molten metal is subsequently infiltrated with or without pressure. In this case, fibers and foams with very high amplification volume fractions (up to about 80%) can be used as reinforcement in addition to particles become. A local reinforcement in areas of highest stress is possible. However, corresponding methods are expensive.

The powder metallurgy (PM) of MMC differs from commonly used PM processes only in that instead of a metal powder, a powder mixture of Keramikbzw. Reinforcement component and metal particles is used. The PM is only suitable for fine particles (particle size 0.5-20 μm). In addition, a subsequent formability of the MMC obtained by extruding, forging or rolling must be ensured, whereby the maximum volume content of the reinforcing particles is limited to about 40%.

In the case of the electrodeposition of dispersion layers, there is the problem of levitating the particles finely distributed in the electrolyte and at the same time depositing them with the matrix in order to obtain homogeneous layers. The simultaneous deposition of particles and matrix is in many cases impossible because of their different potentials.

Carbon nanotubes (CNT) have outstanding properties. These include, for example, their mechanical tensile strength of about 40 GPa and their stiffness of 1 TPa (20 or 5 times steel). Both CNTs with conductive and those with semiconducting properties exist. CNTs belong to the family of fullerenes and have a diameter of 1 nm to a few 100 nm. Their walls, like the fullerenes or, like the planes of graphite, consist only of carbon. In particular, a mixture of CNT with other components allows composites and coatings with significantly improved properties.

It is known to mix CNT with conventional plastic to improve its mechanical and electrical properties. Metal-based CNT composites, such as those described in DE 10 2007 001 412 A1, comprise a metal matrix, such as Fe, Al, Ni, Cu or alloys thereof, and carbon nanotubes as a reinforcing component in the matrix. Due to the large density differences between metals and CNT and the resulting strong demixing tendencies as well as the lack of wettability of the CNT with metal, a melt metallurgical application for the production of corresponding metal-CNT composite materials is problematic. DE 10 2007 001 412 A1 therefore proposes depositing a galvanically applied composite coating on a substrate by using a plating solution which contains metal cations of a metallic matrix to be deposited and carbon nanotubes. The composite coating then comprises the metallic matrix and carbon nanotubes disposed in the matrix, thereby improving the mechanical and tribological properties of the coating. However, galvanic application is difficult or impossible to achieve in many areas.

The invention has for its object to provide a method for producing a metal matrix composite material, in particular with CNT as a reinforcing component, which allows to distribute the components used in a technically simple manner as evenly as possible, wherein In particular, the reinforcing components should be as unchanged as possible in their physicochemical properties and contained in the metal matrix composite material to the highest possible percentage.

This object is achieved by a method for producing a metal matrix composite material and by such a metal matrix composite material, as such as a workpiece or as a coating of a workpiece or as a material for producing a

Workpiece can be used, with the features of the independent claims. Preferred embodiments are given in the respective dependent claims.

The invention includes the technical teaching, to

Producing a metal matrix composite material) for electrical components, electrical components or heat sinks with a metal matrix having at least one metal component and at least one reinforcing component arranged in the metal matrix to spray at least one of the components onto a substrate by a thermal spraying method, wherein at least one reinforcing component comprises carbon in the form of nanotubes, nanofibers, graphenes, fullerenes, flakes or diamond is used.

Composite particles such as single and multi-walled CNT (Single Walled / Multi Walled CNT, abbreviated SW / MW-CNT) with a length of 0.2 to 1000 μm, preferably of 0.5 to 500 μm and a bundle size of 5 to 1200 nm, preferably from 40 to 900 nm, have proven to be particularly advantageous. SW-CNT or MW-CNT cold gas spray particles may also be previously used to improve their properties chemical processes with metals such as Cu or Ni sheathed or coated. A further advantageous variant involves mixing and drying the metal powder with a CNT dispersion / suspension so that the metal powder particles are coated with the CNT. The proportion of SW-CNT or MW-CNT in the carrier gas or in the powder stream, for example, ranges from 0.1 to 30%, preferably from 0.2 to 10%.

With the aid of one of the spraying methods mentioned, it is possible to incorporate single-walled and multi-walled CNTs in a metal matrix. According to the Applicant's investigations, an MMC coating or corresponding MMC strip with at least 0.3% SW or MW CNT produced in this way exhibits exceptional wear behavior with coefficients of friction and contact resistance values which are far below the previously known values of comparable metal layers. With particular advantage can be used as reinforcing component carbon in the form of nanotubes, fullerenes, graphenes, flakes, nanofibers, diamond or diamond-like

Structures are used. Composite particles such as single wall and multiwalled CNT (single walled / multi walled CNT, abbreviated SW / MW CNT) having a length of 0.2 to 1000 μm, preferably 0.5 to 500 μm and a bundle size of 5 to 1200 nm, preferably from 40 to 900 nm, have proven to be particularly advantageous. In order to improve their properties, SW-CNT or MW-CNT cold spraying particles can also be previously coated or coated with metals such as Cu or Ni by means of chemical processes. Another advantageous variant involves mixing and drying the metal powder with a CNT dispersion / suspension so that the metal powder particles are coated with the CNT. The share of SW-CNT or MW CNT in the carrier gas or in the powder stream, for example, ranges from 0.1 to 30%, preferably from 0.2 to 10%.

With the aid of one of the spraying methods mentioned, it is possible to incorporate single-walled and multi-walled CNTs in a metal matrix. According to the Applicant's investigations, an MMC coating or corresponding MMC strip with at least 0.3% SW or MW CNT produced in this way exhibits exceptional wear behavior with coefficients of friction and contact resistance values which are far below the previously known values of comparable metal layers.

By means of appropriate spraying methods, metal powders which were previously mixed, for example, with carbon components such as CNT or also ceramic reinforcing components can be used. The proportion of metallic particles in the carrier gas can be, for example, in a range of 0.1 to 50%.

Spray processes, such as flame, plasma, and cold gas spraying are known from the prior art for the production of coatings. In flame spraying, a powder, lacing, rod or wire-shaped coating material is heated in a fuel gas flame and injected with the supply of additional carrier gas, for example compressed air, at high speed onto a base material. During plasma spraying, a plasma powder is injected, which is melted by the high plasma temperature. The plasma stream entrains the powder particles and throws them onto the workpiece to be coated. In cold gas spraying, as described, for example, in EP 0 484 533 B1, the spray particles are accelerated to high speeds in a comparatively cold carrier gas. The temperature of the carrier gas is a few hundred ⁰ C and is below the melting temperature of the lowest-melting component sprayed. The coating is formed with the impact of the particles on the high kinetic energy metal tape or component, the particles which do not melt in the cold carrier gas forming a dense and adherent layer upon impact. The plastic deformation and the resulting local heat release thereby ensure a very good cohesion and adhesion of the sprayed layer on the workpiece. Owing to the relatively low temperatures and the possibility of using argon or other inert gases as the carrier gas, oxidation and / or phase conversions of the coating material during cold gas spraying can be avoided. The spray particles are added as a powder, usually with a particle size of 1 to 100 microns. The high kinetic energy get the

Spray particles in the relaxation of the carrier gas in a Laval nozzle.

In the present invention, at least one of the components is preferably sprayed by cold gas spraying, flame spraying, in particular high-speed flame spraying (HVOF), and / or plasma spraying. It is also contemplated, especially in cold gas spraying, to use a carrier gas whose temperature is at room temperature or even below, whereby a thermal load of the sprayed components, in particular the

Reinforcement components, can be safely avoided. The temperature can be down to, for example, 10% below the Melting temperature of the lowest-melting component range. The carrier gas should simultaneously create an inert or even reducing atmosphere in order to prevent oxidation of the powder particles and thus not adversely affect the later layer or material properties such as electrical conductivity, among other things. In particular, a combination of two spraying methods can also be used. A use of two spray nozzles with a mixture of the corresponding components at the coating site is also possible.

As a result of the measures mentioned, significantly improved properties of the coatings and materials produced thereby can be achieved. The corresponding

Products have an increased wear resistance, a better sliding behavior and a higher

Friction corrosion resistance, wherein the friction coefficient can be reduced to about one-tenth of the value of the respective pure metal. Furthermore, the

Conductivity and hardness of the materials increased.

The invention provides a particularly flexible and cost-effective method, since, for example, in the production of printed conductors, lead frames and lead frames by the proposed spraying no prefabrication steps such as rolling, punching or annealing are required.

The substrate used in the process according to the invention may be a film or a substrate which is not wettable by the powder jet, which makes it possible to apply sprayed metal matrix composite materials from the substrate separate. In this way, a component or a pure material, for example in the form of a strip, can be obtained, which can then be further processed in a suitable manner.

However, tape materials and components such as electromechanical components, heatsinks, bearings, and bushings may also be adhesively coated which have improved properties through the metal matrix composite. For the purposes of this invention, a metal strip or an electromechanical component is preferably used as the workpiece, which preferably consists of ceramic, titanium, copper, aluminum and / or iron and alloys thereof. Semifinished products or 3D structures such as Molded Interconnection Devices (MID) can also be used for coating.

According to a particularly preferred embodiment, the method includes at least one surface processing step. Here, for example, on a metal strip or component made of a metallic material, an activation, a Haftungsvermittlungs- and / or a Diffusiorisperrschicht are applied to the then the MMC are sprayed. If no adhesive coating is desired, but should, as shown above, a pure metal matrix composite material can be obtained instead of a

Adhesive layer also be applied a non-stick coating.

Corresponding MMC tapes or coatings can also be used subsequently for smoothing the surface of an additional treatment such as leveling or a reflow / heat treatment. be subjected to treatment. For forming, for example, a soft annealing step, for example at about 0.4 times the melting temperature of the matrix metal, can also be carried out subsequently. For compacting the material and / or for reducing the porosity at the surface, the material can be re-rolled, for example with a degree of deformation of 0.1 to 10%.

In corresponding methods, advantageously at least one metal component and / or at least one

Reinforcement component provided in particle form.

Through an appropriate selection of structure, orientation,

The size and shape of the particles as well as their quantity can be the

Material properties of matrix materials are positively influenced. If appropriate, the formation of whisker crystals can also be promoted or prevented by suitable boundary conditions.

In a particularly advantageous manner, a first component can also be mixed with at least one further component before spraying. Gentle mixing, for example of cold spray particles, may be accomplished by coating the particles with a dispersion or suspension containing the reinforcing particles, followed by drying. Depending on the hardness of the particles, mixing in a ball mill or in an attritor consisting of at least two different components under protective gas can cause the particle shape to be destroyed and thus the flow behavior of the powder to be adversely affected.

In such a method, in the context of an advantageous embodiment, at least one organic and / or at least one ceramic reinforcing component can be used. This can be present in the sprayed mixture or can also be injected or co-injected.

An advantageous method involves using at least one reinforcing component selected from the group consisting of tungsten, tungsten carbide, tungsten carbide cobalt, cobalt, boron, boron carbide, invar, kovar, niobium, molybdenum, chromium, nickel, titanium nitride, alumina, copper oxide, silver oxide , Silicon nitride, silicon carbide, silicon oxide, zirconium tungstate and zirconium oxide.

In this case, it is also possible to use a reinforcing component together with at least one further reinforcing component and / or to mix or mix it accordingly. Through the use of known ceramic components whose advantageous properties, in addition to those of other reinforcing components, can be exploited. By using boron, cobalt, tungsten, niobium, molybdenum and its alloys and Invar or Kovar, the thermal expansion coefficient of the composite can be positively influenced.

Advantageously, a metal matrix composite or a coating with a

Metal matrix can be used which comprises at least one metal and / or an alloy of a metal selected from the group of tin, copper, silver, gold, nickel, zinc, platinum, palladium, iron, titanium and aluminum. As a result, for example, a particularly advantageous wear resistance, corrosion resistance and / or a specific electrical or thermal conductivity and an adapted coefficient of expansion can be provided.

A metal matrix composite material produced by the method according to the invention with a metal matrix having at least one metal component and at least one reinforcing component arranged in the metal matrix is likewise provided by the invention.

A metal matrix composite material which has a proportion of from 0.1 to 20%, preferably from 0.1 to 5%, preferably from 0.2 to 5%, of carbon nanotubes is regarded as being particularly advantageous. The abovementioned proportions have proven to be particularly advantageous in practice, as mentioned above.

A corresponding metal matrix composite material with advantageous properties has, for example, a residual porosity of 0.2 to 20% with respect to the

Reinforcement component and / or from 0.2 to 10% with respect to the metal component. MMC with such residual porosities can be used with advantage when a particularly good abrasion resistance, such as in bearings or sliding surfaces, or a high electrical conductivity, such as in tracks, is required.

The metal matrix composite according to the invention is particularly suitable for a coating for a workpiece. The coating can be used, for example, on bearings and sliding elements, heat sinks, connectors, punched grids and strip conductors, in particular as heating elements usable conductor tracks are applied. Such MMC coatings can be made of, for example, Sn, Cu, Ag, Au, Ni, Zn, Pt, Pd, Fe, Ti, W and / or Al and their alloys such as solders, in particular with a content of SW-CNT or MW. CNT from 0.1 to 20%, preferably from 0.2 to 5%.

In particular, it may be a coated tape for use in electromechanical components such as connectors, springs, e.g. for relays, switching contacts, to act conductor tracks in punched grids and heating elements or heat sinks and elements. The metal strip preferably has a thickness of 0.01 to 5 mm, particularly preferably 0.06 to 3.5 mm. For the production of strips consisting only of the metal matrix composite material, as mentioned, the components may for example be sprayed onto a non-wettable substrate such as films made of PEEK, polyimide or Teflon. Correspondingly produced stamped grids, tracks, heating elements and strips may comprise Cu, Al, Ni and Fe and alloys thereof.

Printed circuit traces comprising at least one metal matrix composite material as prepared above may be printed locally on a printed circuit board, molded interconnection devices (MID), e.g. LSDS or other thermoplastics in particular stencils, sprayed or provided in the form of a sheet-like coating, which is later processed, for example by suitable photolithography process.

An MMC tape or trace may advantageously be made of Cu, Ag, Al, Ni and / or Sn and their alloys a proportion of SW-CNT or MW-CNT from 0.1 to 20%, preferably from 0.1 to 5%.

With regard to further features and advantages, reference is expressly made to the statements relating to the production method according to the invention.

A metal matrix composite material produced according to the method of the invention is particularly suitable for use in the production of workpieces, in particular of electro-mechanical ones

Components. Such a use may either include making the workpiece completely out of the metal matrix composite or coating it with such material.

characters

The invention and its advantages as well as further embodiments of the invention are explained in more detail below with reference to the embodiments illustrated in the figures. In detail shows:

Figure 1 is a schematic representation of a device for

Cold gas spraying, which for carrying out a method according to a particularly preferred

Embodiment of the invention is suitable, and

Figure 2 Microscopic micrographs of the microstructure and scanning electron micrographs of the surfaces of metal matrix composites prepared by methods according to particularly preferred embodiments of the present invention. A device for cold gas spraying suitable for carrying out the method according to a particularly preferred embodiment of the invention is shown in FIG. The device has a vacuum chamber 4 in which, for example, a substrate 5 to be coated can be placed in front of the nozzle of a cold gas spray gun 3. It should be understood, however, that such a spraying process could also be carried out at atmospheric pressure, for which a vacuum chamber is not required. The

Placement of the workpiece 5 in front of the cold gas spray gun 3 takes place, for example, by means of a holder, not shown in Figure 1 for reasons of clarity. Preferably, the substrate 5 is movable, i. displaceable and rotatably arranged, so that a coating can take place at a plurality of positions, in particular band-shaped or flat. Alternatively or additionally, the cold gas spray gun 3 may be movably arranged.

For carrying out the coating of the substrate 5, the vacuum chamber 4 is evacuated and generated by means of the cold gas spray gun 3, a gas jet, are fed into the particles for coating the workpiece 5.

In this case, the main gas flow, for example a helium-nitrogen mixture with about 40% by volume of helium, passes via the gas supply line 1 into the vacuum chamber 4. The spray particles, for example a metal powder with admixed CNT, pass through the auxiliary gas flow

Feed line 2 in the vacuum chamber 4, in which a pressure of about 40 mbar prevails, and there in the cold gas spray gun 3. The supply lines 1, 2 are for this purpose in the vacuum chamber. 4 in which both the cold gas spray gun ^' 3 and the substrate 5 is located. It can also be provided to supply a plurality of components to be sprayed via a plurality of auxiliary gas streams. The entire cold gas spraying process thus takes place in the vacuum chamber 4. The particles are accelerated so much by the cold gas jet that adhesion of the particles on the surface of the workpiece 5 to be coated is achieved by converting the kinetic energy of the particles into thermal energy. The particles can additionally be heated up to the maximum temperature indicated above.

The carrier gas, which passes during the cold gas spraying together with the spray particles from the spray gun 3 and carries the spray particles to the workpiece 5, passes after the injection process in the vacuum chamber 4. The spent carrier gas is removed via the gas line 6 from the vacuum chamber 4 by means of the vacuum pump 8. Between the vacuum chamber 4 and the vacuum pump 8, for example, a particle filter 7 is connected, which removes free spray particles from the spent carrier gas in order to prevent the spray particles from damaging the pump 8.

FIGS. 2A to 2C of FIG. 2 show results of tests in which metal powders with the addition of reinforcing components were injected in each case.

The figures show images of cuts and scanning electron micrographs of the surface of the layers obtained thereby. In the course of the experiments, commercially available Cu, SnAg ₃ and Sn powders were used together with suitable MW-CNT from the manufacturer Ahwahnee

(P / N ATI-BMWCNT-002). FIG. 2A shows the microstructure of a layer 200 obtained by spraying pure copper with 1.5% MW-CNT with a copper matrix 201 and CNT 202 discontinuously distributed therein in a 1000-fold magnification. Furthermore, in the coating 200 so-called oxide skins 203 formed on the Cu grains by a not completely avoidable oxidation of the Cu powder during the mixing process with the MWCNT can be seen. The layers were injected at a nozzle exit temperature of 600 ⁰ C and a pressure of 38 bar under N ₂ -GaS. The density of the layer is 99.5%, its thickness is 280 μm, the layer hardness is 1200 N / mm ² . Due to the good friction behavior, this layer is suitable as a running surface of bearings and bushes. After detachment of the 280 micron thick layer of the carrier material is a tape, which can be used as a conductor in stamped or electromechanical components use.

Figure 2B shows the surface of a layer 210 obtained by spraying pure Sn with 2.1% MW-CNT with a

Tin matrix and herein discontinuously distributed CNT in 300x magnification. FIG. 2C shows a detailed view of FIG. 2B at a magnification of 10,000 times. The layer 210 has spherical Sn bodies 213 with CNTs 202 distributed therebetween. The density of the layer is 99.4%. It has a hardness of 368 N / mm ² and a coefficient of friction of 0.5 in the wear test. When spraying this layer under N ₂ -GaS with a pressure of 32 bar and a nozzle exit temperature of 350 ⁰ C, a layer thickness of 5 microns was achieved. By variation of the

Die exit temperature, the travel speed and the pressure, the layer thickness, the layer hardness and in combination with the CNT content of the powder Friction coefficient significantly changed (reduced). Such produced layers can be optimized by a post-treatment such as leveling or remelting (reflow treatment) in their surface structure specifically targeted to the particular application. Partially or completely applied to Cu alloy strips, these layers can be used to reduce plugging and drawing forces in electromechanical components such as connectors, or after appropriate leveling and reflow steps to improve the

Wear behavior in plain bearings and bushes are used.

Claims

claims

Method for producing a metal matrix composite material (200, 210) for electrical components, electrical components or heat sinks having a metal matrix (201, 211) comprising at least one metal component and at least one reinforcement component (202) arranged in the metal matrix (201, 211) , characterized in that at least one of the components is sprayed onto a substrate (5) by a thermal spray method, and that at least one reinforcing component of carbon in the form of nanotubes (202), nanofibers, graphenes, fullerenes, flakes or diamond is used.

2. The method according to claim 1, characterized in that is used as spraying cold gas spraying, flame spraying and / or plasma spraying.

3. The method according to claim 1 or 2, characterized in that as substrate (5) a film or a substrate with non-wettable surface or a workpiece to be coated, a semifinished product and / or a 3D structure is used.

4. The method according to any one of the preceding claims, characterized in that at least one surface of the substrate (5) and / or the metal matrix composite material (200, 210) is processed.

5. The method according to any one of the preceding claims, characterized in that at least one metal component and / or at least one reinforcing component (202) is provided in particulate form.

6. The method according to any one of the preceding claims, characterized in that a first component is mixed before spraying with at least one further component.

7. The method according to any one of the preceding claims, characterized in that at least one organic and / or at least one ceramic reinforcing component (202) is used.

8. The method according to any one of the preceding claims, characterized in that at least one further reinforcing component is used, which consists of the group of tungsten, tungsten carbide, tungsten carbide-cobalt, cobalt, copper oxide, silver oxide, titanium nitride, chromium, nickel, boron, boron carbide, Invar , Kovar, niobium, molybdenum, alumina, silicon nitride, silicon carbide, silica, zirconium tungstate and zirconia.

9. The method according to any one of the preceding claims, characterized in that a metal matrix component is used which comprises at least one metal and / or an alloy of a metal selected from the group of tin, copper, silver, gold, nickel, zinc, platinum, Palladium, iron, titanium and aluminum is selected.

10. A metal matrix composite material (200, 210) having a metal matrix (201, 211) comprising at least one metal component and at least one reinforcement component (202) arranged in the metal matrix (201, 211), wherein the metal matrix composite material (200, 210) a method according to any one of the preceding claims is made.

11. Metal matrix composite material (200, 210) in particular according to claim 10, which has a proportion of 0.1 to 20%, preferably 0.1 to 5%, preferably 0.2 to 5% carbon nanotubes (202) as a reinforcing component.

A metal matrix composite (200, 210) according to claim 10 or 11, having a residual porosity of 0.2 to 20% with respect to the reinforcing component and / or from 0.2 to 10% with respect to the metal component.

Use of a metal matrix composite according to any one of claims 10 to 12 for the manufacture of a workpiece, wherein the workpiece is coated by the metal matrix composite and / or formed from the metal matrix composite.