WO2004033746A2

WO2004033746A2 - Production of coated foamed parts, and parts comprising a ceramic or hard material coating

Info

Publication number: WO2004033746A2
Application number: PCT/EP2003/010909
Authority: WO
Inventors: Matthias Maurer; Erich Lugscheider
Original assignee: Rwth Aachen
Priority date: 2002-10-04
Filing date: 2003-10-02
Publication date: 2004-04-22
Also published as: AU2003271671A1; WO2004033746A3; DE10246454A1; AU2003271671A8

Abstract

Disclosed is a method for producing foamed parts which have a density of 0.1 to 8 g/cm3, are provided with a coating on at least one surface thereof, and are obtained by treating the surface of the optionally molded foamable semifinished product, thermally coating a foamable semifinished product with a metallic and/or inorganic applied coating means, whereupon the semifinished coated product is provided with a profile by thermally foaming said semifinished coated product so as to obtain the desired part. Also disclosed is the production of said foamed parts in a rotating unit.

Description

Manufacture of coated foamed components and components with ceramic or hard material coating

The present invention relates to specially coated foamed components and to a method for producing coated foamed components, as explained in detail below.

A component in the sense of the present invention is understood to mean both conventional components such as blocks, plates, pipes and specially shaped components.

Lightweight components made of cellular structures, foams, sponges or the like are known. However, since such components have a porous surface, it became necessary to improve these components and their properties.

Blocks or plates made of metal foam are produced according to WO 91/01387 or WO 91/03578 by introducing nitrogen or the like gas or by means of a blowing agent into a metal melt; a foam layer forms on this, which is peeled off and then solidifies. In certain applications of such blocks or plates, a cover layer that peels off at about 120 ° C. is adhered to their porous surface, which reduces the usability of such components and increases their production time.

DE 43 21 393 A1 discloses a method which makes it possible to dispense with bonding a metal layer to a metal foam substrate; on this the metal layer is applied by thermal spraying, a high proportion of the spraying material penetrating into the pores of the foam structure. The amount of spray material used - and the amount of the additional weight resulting from it - depends on the pore size, which cannot be determined exactly beforehand, and which is reciprocal to the density of the metal foam substrate. Its weight increases undesirably due to the material of the sprayed-on metal layer with decreasing density - i.e. increasing pore size.

DE 19526 057 C1 proposes to heat the surface of the metal foam, to compress it by pressure and to apply a separate layer to this dense surface by thermal spraying.

Compared to the glued-on or plated-on layers mentioned above, which increase the mechanical strength of the metal foam structure and are only suitable for simple surface structures, the use of thermal coating methods, in particular spraying methods, permits the production of metal foam composites of almost any contour.

From WO 00/3883863 the production of a profile part consisting of metal foam and sheet metal is known, in which the metal sheet is provided with a foamable metal powder, the profiling of the metal composite sheet being carried out by means of high-pressure forming in a die and the foamable metal powder simultaneously or subsequently thermally foamed directly in the die using a blowing agent. This prior art with a metal sheet as a mandatory component already differs generically from the present invention and processing by high pressure forming in a die is technically very complex.

DE 100 52 405 A1 discloses a method for producing a composite structure with a cellular workpiece formed from a metal foam part and at least one cover layer applied to it by thermal spraying, the material for the cover layer being matched to the properties of the workpiece from a cellular structure is thermally sprayed onto the undamaged surface of the workpiece. This method is disadvantageous in that Due to the sequence of processes of this prior art, an insufficient adhesive strength is obtained between the foamed layer and the coating itself, as follows from the exemplary embodiments.

The present invention has for its object to provide a novel manufacturing process for coated foamed components.

This task is solved by a special sequence of process steps and the use of special materials.

The present invention thus relates to a method for producing foamed components with a density of 0.1 to 8 g / cm ³ . preferably 0.3 to 5 g / cm ³ , which have a coating on at least one of their surfaces and which are obtainable by

- a surface treatment of the foamable semifinished product that may be formed,

a thermal coating of a foamable semi-finished product with a metallic and / or inorganic applied coating agent,

- followed by a profile to the component, in which the coated semi-finished product is thermally foamed.

Compared to the aforementioned German published patent application 100 52 405, the following advantages in particular result:

1. A very simple sample preparation can be carried out by means of the method according to the invention since the otherwise usual problems of cleaning and surface activation of the foams are eliminated;

2. Compared to the aforementioned method, the method according to the invention gives a significantly higher surface quality without further finishing, since the roughness and surface ripple of the coated semifinished products are substantially less than that of the coated foams and, in contrast to the foam components, they contain no open pores , with which corresponding intermediate treatment steps such as decay or filling can be omitted. 3. Within the scope of the method according to the invention, the layer is metallurgically bonded to the foamed material, that is to say complete wetting and thus a metallurgical bond or quality of soldering. The adhesive strength of the layers produced in this way exceeds that of conventionally manufactured products many times over.

4. According to the prior art, thermally sprayed layers often contain a large number of microcracks and defects due to their production, which can have a disadvantageous effect on the mechanical properties. During the foaming process using the method according to the invention, these micro defects partially heal as a result of the annealing treatment and the mechanical properties of the layers and composites are significantly improved.

5. The coating of the foamable material, which has a higher softening temperature than the foamable material itself, already defines one or two dimensions of the later component, depending on the number of surfaces. The foaming itself only serves to increase the rigidity of the component. This means that simple foam shapes can be used or eliminated entirely.

6. The foamed coated components produced by the method according to the invention have a very high reproducibility, so that simple implementation at an industrial level, for example in the automotive industry or the construction industry, is possible.

7. The melting step used according to the invention as the last method step can also be carried out inductively, whereby series production is also possible and better foam quality is made possible than with conventional heating in ovens. In this context, the foaming, for example the foaming of tubular extrusion profiles coated on the outer surface, can take place inductively, and as a result both the technical steps in production can be significantly reduced, and the foam becomes significantly more homogeneous due to the very short foaming phase a higher quality product can be produced. The integration of induction furnaces in the process chain is easy and in turn leads to full automation for series production.

8. Non-metallic layers, for example ceramics, can also be applied by thermal spraying. Wetting these ceramic layers is also possible by adding reactive elements.

According to a preferred embodiment of the present invention, the surface treatment of the surface to be coated is carried out as a first process step using a mechanical, chemical or physical process. This surface treatment is done in particular by fine grinding, microblasting, conventional blasting, cryogenic blasting, by a liquid nitrogen jet; chemical stripping and / or laser beam treatment. For example, fine grinding with sandpaper, microblasting by blasting with (low) pressure and not too hard blasting material, cryogenic blasting with dry ice, blasting with liquid nitrogen, pickling with chemical solutions and scanning the surface with a laser.

In the case of special combinations of coating and foamable material, it has proven advantageous here that the semi-finished product is preheated before the thermal coating in order to improve the adhesion.

According to a further preferred embodiment of the method according to the invention, the thermal coating is carried out as a second method step by a method which is selected from the group consisting of arc wire spraying methods, flame spraying methods, high-speed flame spraying methods (HVOF),

Plasma spraying, cold gas spraying, vacuum plasma spraying and / or high-performance plasma spraying. An overview of these spray processes can be found, for example, in Römpp Lexikon Chemie, 10th ed., 1998, keyword metal spray process and the literature cited therein in the overview Hipercoat, high-performance coating and decoating technology from the research association DACH and for thermal spraying in "Handbuch der thermal Spritztechnik", E. Lugscheider (editor), DVS-Verlag Düsseldorf, ISBN: 3-87155-186-4.

The mechanical properties of sprayed materials are not identical to the properties of the solid material, since the structure differs significantly: spray layers are anisotropic because they have a lamellar structure due to the manufacturing process. The modulus of elasticity of the layer is maximal in the direction of the layer and minimal perpendicular to it. The very rapid cooling of melted or melted spray particles on the substrate leads to strong internal stresses, which are expressed in - in some cases also translamellar - microcracks. Interlamellar pores result from the cooling shrinkage or from surface roughness, which are not completely filled by the spray particles. The adhesion between individual spray fins can be reduced by residual stresses or oxide layers to such an extent that the fins can slide off under load. Sharp-edged pores and deposits - for example jet residues - can lead to a notch effect and brittle phases (e.g. oxides) further reduce the strength. This is usually below the strength of the intrinsic solid material. The mechanical properties can, however, be significantly improved by suitable processes and process parameters; preheating the substrate reduces the cooling rate and thus the shrinkage stress. The proportion of brittle phases can be restricted by suitable process control, e.g. B. by using an inert gas as atomizing gas instead of compressed air.

In general, with high-energy spraying processes - for example the high-speed flame spraying process (HVOF) - better particle clinging of the sprayed particles to the substrate and very low layer porosity due to higher particle speeds, so that properties similar to those of forged materials can be achieved.

The densities of the foam structure and the top layer as well as their elasticity modules are essential for the production of a composite optimized for specific stiffness. When optimizing for specific strength, it is important to prevent various failure mechanisms; this includes exceeding the flow limit of the top layer when the relative foam density _is too high (pschaum / psoii _d ) Buckling of the cover layer when the relative foam density is too low - insufficient support effect - and failure of the foam under the shear load if the ratio of the cover layer thickness to the component length is too large. If the adhesion of the cover layer to the foam is too low, delamination occurs as a result of the shear stress, ie the cover layer is detached due to crack propagation in the boundary layer and the component fails.

According to a further preferred embodiment of the present invention, the method is characterized in that compressed air or an inert gas, in particular nitrogen, argon or helium, is used as the process gas for the thermal coating.

It has proven useful here that the pressure of the propellant gas in the thermal coating is set between 1 to 30 bar, preferably 2 to 10 bar.

According to a further preferred embodiment of the present invention, the method is characterized in that the foamable semi-finished product contains a metallic, ceramic and / or inorganic material and an effective amount of at least one blowing agent. The effective amount of blowing agent is always chosen so that the foamable mass can be expanded to up to 1500% of its volume, preferably to 300 to 1000%, in particular to 400 to 800%, by its decomposition.

According to a further preferred embodiment of the present invention, the method is characterized in that the metallic, ceramic and / or inorganic material is selected from the group consisting of aluminum, aluminum-based alloy, zinc or a zinc-based alloy, copper or a copper-based alloy, iron or an iron-based alloy, nickel or a nickel-based alloy, cobalt or a cobalt-based alloy, to which hard materials may have been added.

According to a further preferred embodiment of the present invention, the method is characterized in that the blowing agent is selected from metal hydrides the main and subgroup metals whose decomposition point is below or close to the softening point of the semi-finished product. Titanium dihydride or magnesium dihydride is mentioned as an example of this.

According to a further preferred embodiment of the present invention, the method is characterized in that the thermally applied

Coating agent is selected from the group consisting of aluminum or an aluminum-based alloy, zinc or a zinc-based alloy, iron or an iron-based alloy, copper or a copper-based alloy, made of nickel or a nickel Base alloy, made of cobalt or a cobalt-base alloy, made of a hard material or a hard material mixture, made of a metallic hard material, a hard material-metal mixture and / or ceramic materials.

Hard materials in the sense of the present invention are understood to mean carbides of tungsten, tital and tantalum and their mixed crystals as well as hard materials from the group of the borides and nitrides. We refer to Ulimann, Encyclopedia of Technical Chemistry, 4th ed. Vol. 19, 1 keyword powder metallurgy, 563 ff, 572 ff.

According to a further preferred embodiment of the present invention, the method is characterized in that the thermal foaming is carried out continuously or discontinuously by heat sources or by means of electromagnetic radiation, preferably by means of ovens, induction ovens or lasers.

According to a further preferred embodiment of the present invention, the method is characterized in that the thermal foaming and / or heating of the coated semi-finished product takes place at temperatures between 200 ° C. to 2000 ° C., preferably 500 ° C. to 1500 ° C.

According to a further preferred embodiment of the present invention, the method is characterized in that the thermal foaming takes place at normal pressure or a pressure of up to 4 bar.

According to a further preferred embodiment of the present invention, the method is characterized in that the softening temperature of the Coating agent or the coating is always chosen so that it is more than 50 ° C, preferably 100 ° C, in particular 200 ° C above the softening temperature of the foamable semi-finished product. This has the advantage that the coating itself can serve as a built-in component shape in one dimension, but also in two dimensions, due to its higher softening temperature compared to the foamable semi-finished product. For example, from profiled sheets that have been profiled in a half-shell shape and contain the coating on their lower outer surface, corresponding hemispheres with a defined volume can be obtained without problems by targeted foaming.

A further preferred embodiment of the present invention relates to a method of the aforementioned type, which is characterized in that the coating is further treated mechanically, thermally, chemically, thermochemically or by means of electromagnetic radiation and / or provided with polymeric coatings. In particular, this includes cutting, radiating, rubbing, grinding, polishing processing of the layer, the application of further layer systems by physical, chemical or thermochemical processes as well as the structuring of the surface by means of lasers or electron beams and the application of decorative or protective coatings.

According to a further preferred embodiment, the thermal coating and / or profiling takes place in a rotating unit. This can be used as a profile to be foamed, a reusable foam mold and / or a coated semi-finished foam product.

The rotation creates centrifugal forces that push the liquid metal outwards and there lead to an increased mass accumulation (thicker foam skin). At the same time, the foam bubbles are compressed by the forces (finer pore structure), this effect is stronger on the outside (graded pore structure). The pore size can be adjusted by a suitable choice of the rotation speed. Pore diameters of less than or equal to 5 mm, but particularly less than or equal to 3 mm, in particular less than or equal to 1 mm, have been found to be particularly favorable for the component properties. Furthermore, shrinkage and unevenness on the outer surface of the component are prevented by these forces and the material flow: very dimensionally stable foam bodies with clearly increased surface quality. The unfavorable foam drainage is prevented by the centrifugal forces and the rotation, the mass is distributed very evenly: homogeneous foams with significantly reduced imbalance.

The reusable foam molds generally have the shape of the later components or further processable semi-finished profiles.

This rotating unit is generally operated at a rotational speed which results from the following formula:

General: 'ideal ~ CO / 7Sr. ^• p

With:

Rotation frequency f [U / min] - in example: approx. 180 U / min

Specific density of the alloy to be foamed (before foaming!): P [g / cm ³ ] in

Example: Al base leg. p = approx.2.7 g / cm ³

Component radius (outside) r in [m], in example: approx. 0.044 m

Favorable: 40 -

Especially: 50 ^• I ≤ f ≤ 75 ^• pr pr

In particular: 60 ^•

According to a preferred embodiment of the present invention, the temperature range between the melting temperature of the foamable alloy and the melting temperature of the layer is set as follows: According to a further preferred embodiment of the present invention, the

Melting temperature of the layer chosen so that it is more than 400 ° C above the

Melting temperature of the foamable semi-finished product; Example: foamable semi-finished product made of AI-based alloy with steel layer: the affordable one

Interval of the foaming temperature is between approx. 600 ° C and 1000 ° C, particularly favorable 700 ° C - 900 ° C; Example: foamable semi-finished product made of magnesium-lithium alloy with aluminum

Alloy layer: foaming at temperatures of approx. 200 ° C - 600 ° C; Example: foamable semi-finished product made of steel-based alloy with molybdenum layer: from approx.

1200 ° C - 2000 ° C, particularly cheap 1400 ° C-1800 ° C.

According to a further preferred embodiment, the rotating unit contains 0 to 35% by weight, preferably 5 to 25% by weight, of functional particles or inorganic fibers, based on the finished component, the functional particles or inorganic fibers having a density which differs from that of the metal foam , especially a higher density or a lower density.

Functional particles in the sense of the present invention are understood to mean both particles, for example made of the aforementioned hard materials, and inorganic fibers.

For the purposes of the present invention, inorganic fibers are understood to be glassy fibers, carbon fibers, polycrystalline inorganic fibers or metal fibers. We refer to Ullmann, 4th edition, volume 11, 1976, keyword inorganic fibers on p. 359 - 390.

Fibers made of: metal, metal alloys, particularly favorable ferritic steel fibers (high magnetic permeability, strongly favors inductive coupling), ceramic fibers (SiC, glass fibers, boron fibers), carbon fibers. Typical fiber lengths are: short fibers made of glass fibers (e.g.: 0.1-2 mm length and diameter 10-30 μm, especially 15 μm) or long fibers made of glass fibers (e.g.: 30-80 mm, especially 25 mm.) Or endless steel fibers Example: diameter 0.1 mm. If functional particles or fibers are introduced into the rotation unit, which have a higher density than the metal foam, then these are thrown outwards during the rotation, thus forming the surface of the foam. Alternatively, lighter particles or fibers can be left in the foam volume. This creates a foam with a functional surface (wear protection, corrosion protection, other function) or a fiber or particle-reinforced foam with significantly increased strength. However, fiber orientation is unfavorable due to foaming. The process can be influenced favorably by the rotation and the properties can be controlled.

If profiles are foamed, the wetting and connection in the interface is influenced very favorably by the rotation.

The present invention is further based on the object of providing novel coated foamed components.

This object is achieved by means of special foamed components made of metallic materials which have a coating of special thickness made of a hard material, a hard material mixture, a metallic hard material, a hard material-metal mixture or a ceramic material and thus have improved mechanical properties.

The invention relates to a component, in particular obtainable according to any of the prescribed process steps, which has a coating of up to 2 cm, preferably 10 μm to 3000 μm, of a hard material, a hard material mixture, a metallic hard material, a hard material on at least one of its surfaces. Metal mixture or of a ceramic material and wherein the foamed component in addition from a metallic material, in particular aluminum, aluminum-based alloy, zinc, zinc-based alloy, copper, copper-based alloy, iron, iron Base alloy, nickel, nickel base alloy, cobalt and / or a cobalt base alloy. According to a preferred embodiment, the component according to the invention is characterized in that it has an adhesive strength between the inner layer and the coating of 50 to 1000 MPa, preferably 50 to 300 MPa according to DIN EN 582.

According to a further preferred alternative embodiment, the component according to the invention is characterized in that it has a ceramic coating and the foamed component also consists of a metallic material, an adhesive strength between the inner layer and the coating of 50 to 300 MPa, preferably 60-300 MPa according to DIN EN 582.

According to a further preferred alternative embodiment, the component according to the invention is characterized in that it has a hard material coating and the foamed component also consists of a metallic material, an adhesive strength between the inner layer and the coating of 50 to 1000 MPa, preferably 50 to 300 MPa according to DIN EN 582.

Finally, the present invention relates to the use of the components described above, which have been produced by the methods described above, for industrial series production, preferably in the automotive industry or construction industry.

The present invention will now be explained in more detail with reference to figures.

Show it

1 shows a micro section through a coated foamed component produced according to the invention in accordance with Example 1,

2 shows a micro section through a coated component produced according to DE 100 52 405 A1 (comparative example).

3 shows a cross section through a component produced according to the invention according to Example 1 (left) and according to Example 2 (right). In Fig. 1 it can be seen that the foamed material A with the coating B has formed a metallurgical bond in the border area D, which results from the spots / interaction of the two zones. Furthermore, a significantly lower roughness / waviness can be seen here between zone A and zone B compared to FIG. 2.

In contrast, in FIG. 2, between the foamed material A and the primer layer C, which has to be added to the coating B in order to promote adhesion, there are no approaches for a metallurgical bond between the layer A and the layer C in the sense of a toothing, but rather a high one can be seen Roughness between zone A and zone C.

In FIG. 3 it can be seen that a component that is foamed without rotation has a consistently porous structure (left), whereas a component that is foamed during rotation (right) has a more or less hollow core in the center surrounded by a fine-pored foam in the area towards the edge ,

The present invention is now explained in more detail by means of production examples.

example 1

A powder-metallurgical AISi7 alloy was turned into a foamable tubular semi-finished product with a surface roughness of R _a <5 μm, R _z <10 μm, R _max <15 by adding approx. 1% by weight titanium hydride powder, mixing and uniaxial pressing and subsequent extrusion μm manufactured. This foamable semi-finished product was lightly roughened on its outer surface by corundum blasting with F22 corundum in an industrially customary sandblasting cabin, then dedusted and degreased with alcohol for thermal spraying.

The surface treated in this way was then treated with a commercial arc spraying system (type G30 push / pull, OSU Maschinenbau GmbH) using a thermal coating agent in the form of a filled wire based on 65 % By weight of iron, 29% by weight of chromium and other hard material proportions coated as a spray material 0.2 to 2 mm thick.

After cooling, the foamable coated semi-finished product was foamed in an oven at about 700 ° C.

Comparison:

For comparison, an initially foamed and then coated component was produced from the materials of the example produced according to the invention. A micro section of this is shown in FIG. 2.

Example 2:

Substrate: A 50 cm long, extruded tube (outside diameter: 87 mm, wall thickness: 4 mm), consisting of powder metallurgically produced foamable aluminum of the alloy AIMg1SiO, 6 with approx. 1% by weight TiH ₂ as blowing agent was coated by means of an arc spraying process.

For this purpose, the substrate was first lightly blasted with corundum and thus cleaned and roughened. Parameters: F24 corundum, jet pressure 3 bar.

The coating parameters were as follows:

Atomizing gas compressed air: p = about 3.5 bar, spraying distance: about 10 cm. Coated with the TAFA 9000 system. Layer thickness: approx. 750 μm).

Layer material: 46Cr13 steel (contains approx.0.46% by weight carbon and 13% by weight chromium). This alloy is ferritic (magnetizable) which facilitates inductive heating.

Foaming: Inductive with a 100 kW medium-frequency system and a single or multi-turn toroidal coil (inside diameter approx. 92 mm) - an alternative is one Flat coil possible, which partially surrounds the component on one side. Control over the surface temperature (measured with a pyrometer). The surface temperature was set to approx. 700-750 ° C (for Al foam) and held for approx. 3 - 15 seconds. Rotation speed was v = 0.85 m / s (corresponds to approx. 180 rpm with this component diameter).

The foaming can take place continuously (coil is moved over component) or everywhere at the same time (very long coil, encompasses the entire component). In the example, the foaming was carried out with a single-wind induction coil, which was slowly passed over the component. A cross section of the component is shown in Fig. 3, with a hollow core and fine-pored foam in the area to the edge.

Claims

claims:

1. Process for the production of foamed components with a density of 0.1 to 8 g / cm ³ , preferably 0.3 to 5 g / cm ³ , which have a coating on at least one of their surfaces and which can be obtained by a surface treatment of the possibly shaped foamable

Semi-finished product, a thermal coating of a foamable semi-finished product with a metallic and / or inorganic applied

Coating agent, followed by profiling to the component, in which the coated

Semi-finished product is thermally foamed.

2. The method according to claim 1, characterized in that the surface treatment of the surface to be coated is carried out via a mechanical, chemical or physical method.

3. The method according to claim 2, characterized in that the surface treatment via fine grinding, micro blasting, conventional blasting, cryogenic blasting, through a liquid nitrogen jet; chemical stripping and / or laser beam treatment is carried out.

4. The method according to any one of claims 1 to 3, characterized in that the semi-finished product is preheated before the thermal coating to improve the adhesion.

5. The method according to claim 1 or 4, characterized in that the thermal coating is carried out by a method which is selected from the group consisting of arc wire spraying process, flame spraying process, high-speed flame spraying process (HVOF), plasma spraying process, cold gas spraying, vacuum plasma spraying process and / or high-performance plasma spraying process.

6. The method according to any one of claims 1 and 5, characterized in that a compressed air or inert gas, in particular nitrogen, argon or helium, is used as the process gas for the thermal coating.

7. The method according to any one of claims 5 and 6, characterized in that the pressure of the propellant gas during the thermal coating is set between 1 to 30 bar, preferably 2 to 10 bar.

8. The method according to claim 1, characterized in that the foamable semi-finished product is a metallic, ceramic and / or inorganic material which contains an effective amount of at least one blowing agent.

9. The method according to claim 1, characterized in that the metallic, ceramic and / or inorganic material is selected from the group consisting of aluminum, aluminum-based alloy, zinc or a zinc-based alloy, copper or a copper base Alloy, iron or an iron-based alloy, nickel or a nickel-based alloy, cobalt or a cobalt-based alloy, to which hard materials may have been added, and / or ceramic materials.

10. The method according to claim 8, characterized in that the blowing agent is selected metal hydrides of the main and subgroup metals, the decomposition point of which is below or near the softening point of the semi-finished product.

11. The method according to claim 1, characterized in that the thermally applied coating agent is selected from the group consisting of aluminum or an aluminum-based alloy, zinc or a zinc-based alloy, iron or an iron-based alloy, copper or a copper-based alloy, made of nickel or a nickel-based alloy, made of cobalt or a cobalt-based alloy, made of a hard material or a hard material mixture, made of a metallic hard material, a hard material-metal mixture and / or ceramic materials.

12. The method according to claim 1 or 11, characterized in that the thermal foaming is carried out continuously or discontinuously by heat sources or by means of electromagnetic radiation, preferably by means of ovens, induction ovens or lasers.

13. The method according to claim 1, 11 or 12, characterized in that the thermal foaming and / or heating of the coated semifinished product to temperatures between 200 ° C to 2000 ° C, preferably 500 ° C to 1500 ° C.

14. The method according to claim 13, characterized in that the thermal foaming takes place at normal pressure or a pressure of up to 4 bar.

15. The method according to claim 1 or 12 to 14, characterized in that the softening temperature of the coating agent or the coating is always selected so that it is more than 50 ° C, preferably 100 ° C, in particular 200 ° C above the softening temperature of the foamable semi-finished product lies.

16. The method according to claims 1 to 15, characterized in that the coating is further treated mechanically, thermally, chemically, thermochemically or by means of electromagnetic radiation and / or provided with polymeric coatings.

17. The method according to the preceding claims, in particular claims 1, 5, and / or 12, characterized in that the thermal coating and / or profiling takes place in a rotating unit.

18. The method according to claim 17, characterized in that a profile to be foamed, a reusable foam mold and / or a coated semi-finished foam is used as the rotating unit.

19. The method, characterized in that the pore structure and / or foam skin thickness are adjusted by means of the rotational speed with rotating foaming, also graded.

20. The method according to claim 17 to 19, characterized in that the rotating unit contains 0 to 35 wt .-%, preferably 5 to 25 wt .-% functional particles or inorganic fibers, based on the finished component, wherein the functional particles or inorganic fibers have a density different from that of metal foam, in particular a higher density or a lower density.

21. The method according to claim 17 - 20, characterized in that the melting temperature of the layer is chosen so that it is more than 400 ° C above the melting temperature of the foamable semi-finished product.

22. Component, in particular obtainable according to any one of claims 1 to 21, which on at least one of its surfaces has a coating of up to 2 cm, preferably 10 microns to 3000 microns made of a hard material, a hard material mixture, a metallic hard material, a hard metal Mixture or made of a ceramic material and wherein the foamed component in addition from a metallic material, in particular aluminum, aluminum-based alloy, zinc, zinc-based alloy, copper, copper-based alloy, iron, iron-based Alloy, nickel, nickel-based alloy, cobalt and / or a cobalt-based alloy.

23. Component according to claim 22, characterized in that it has an adhesive strength between the inner layer and the coating of 50 to 1000 MPa, preferably 50 to 300 MPa according to DIN EN 582.

24. Component according to claim 22 or 23, characterized in that it has a ceramic coating and the foamed component consists of a metallic material, an adhesive strength between the inner layer and the coating of 50 to 300 MPa, preferably 60-300 MPa according to DIN EN 582.

25. Component according to claim 22 or 23, characterized in that it has a hard material coating and the foamed component consists of a metallic material, an adhesive strength between the inner layer and the coating of 50 to 1000 MPa, preferably 50 to 100 MPa after DIN EN 582 has.

26. Use of the components according to claims 22 to 25 or obtained according to claims 1 to 21 for industrial series production, preferably in the automotive industry or construction industry.