WO2008071184A2

WO2008071184A2 - Composite material made of metal and ceramic, and method for production thereof

Info

Publication number: WO2008071184A2
Application number: PCT/DE2007/002287
Authority: WO
Inventors: Christos G. Aneziris; Piotr Scheller; Horst Biermann
Original assignee: Technische Universität Bergakademie Freiberg
Priority date: 2006-12-12
Filing date: 2007-12-12
Publication date: 2008-06-19
Also published as: DE112007000923B4; DE102007044160A1; DE112007000923A5; WO2008071184A3

Abstract

The invention relates to composite materials made of metal and ceramic, and production methods thereof, which can be used in areas where materials with high mechanical stresses are appropriate According to the invention, the composite material consists of at least one metallic and at least one ceramic material, at least one metallic and/or ceramic material consisting of a material which is capable of a change of volume via a phase transformation in the solid state. The composite material is produced by infiltration of a porous green or fired ceramic-shaped body with a molten melt, or by a shaping method from at least one ceramic and/or metallic material with subsequent sintering, wherein at least one metallic and/or ceramic component consists of a material which is capable of a change of volume via a phase transformation in the solid state. The inventive composite materials are characterized by an excellent strength and toughness with simultaneous large energy absorption capability and reduced density, and are suitable in particular for energy absorption components, crash-stressed components and stiffening structural components, chassis components, and high-strength and wear-resistant components.

Description

Composite material of metal and ceramic and method for its production

The invention relates to composites of metal and ceramic and their manufacturing processes that are applicable in the field of material use with high mechanical stresses. Furthermore, the invention relates to the use of these composite materials, in particular as an energy absorption component.

Are known metal-ceramic materials, cermets, which consist of a metallic and a ceramic phase. They are characterized by a particularly high hardness and wear resistance. Due to their lower bending strength, these materials are limited in use.

Cermets are produced by powder metallurgy, but according to GB 21 48 270 A can also be obtained by infiltration of porous SiC ceramics with molten aluminum at 700 ° C. and a pressure of 46 MN / m ² .

DE 39 14 010 C2 discloses a method for producing metal-ceramic composite materials, in which a porosity of defined porosity of a plurality of layers is infiltrated with Al melt.

DE 34 30 912 A1 describes an exhaust gas catalytic converter in which a green body is shaped from silicon carbide and a metallic silicon alloy and auxiliary substances by means of customary shaping processes, is cooled in a defined manner in a reaction firing and subsequently in the temperature range of demixing of the metal alloy.

From DE 43 00 477 Al honeycomb body with a plurality of separated by partitions extending channels of ceramic and metallic material are known which find particular application for electrically heatable converters in motor vehicles. Such honeycomb bodies are available by extrusion from metal and ceramic powders and subsequent sintering. Slots for electrically insulating subdivision should then be introduced into the honeycomb body.

It is known that stainless austenitic steels are distinguished in addition to a high corrosion resistance usually by a good cold workability. Both the cold working and the energy absorbing capacity of these austenitic steels can be increased by a so-called TRJP effect (transformation-induced plasticity). It is then achieved relatively high tensile strengths and at the same time relatively high elongation at break. So far, stainless cold-formable austenitic steels with TRIP effect can only be characterized by special properties. Thus, these steels have a tensile strength of about 520 to 850 MPa and at the same time elongation at break of about 60 to 45%. A stainless steel with chromium contents of 17 to 18% and nickel contents of 8 to 10%, such as. As the steel X5 CrNi 18 10 (1.4301), is a typical representative with TRIP effect. The cold working and energy absorbing capacity, the tensile strength and the elongation at break of said steels are raised by a TRIP or TWIP (Twinning Induced Plasticity) or by the superposition of the TRIP and TWIP effect.

If the austenite transforms into ε- and / or α'-martensite during a mechanical stress induced deformation, a TRIP effect is observed. As a result, the plastic deformation capacity and the tensile strength increase. By twinning, these property changes can be enhanced. It is then observed a high hardenability. At relatively low 0.2% Dehngrenzen then relatively high tensile strengths are achieved, so that usually a low yield ratio is registered.

The product of tensile strength and maximum elongation can be used as an index for assessing the cold formability of the steels. The product of maximum elongation and tensile strength in the austenitic TRIP steels is in the range of approx. 25,000 to 38,000 MPa%, in the TRIP / TWIP steels in excess of 38,000 to 57,000 MPa% and in the LIP (Light Steel with Induced Plasticity) - Steels over 57,000 MPa%. The energy absorption capacity of the TRIP and TRIP / TWIP steels reaches values of 0.45 to 0.5 J / mm ^"3 , that is to say, in the case of a crash load, these steels have a large expansion reserve, which is not the case for the LIP steels Both cold workability and energy absorption capacity are achieved in the austenitic TRIP and TRIP / TWIP steels by influencing the austenitic structure as a result of mechanical stress in the process of cold forming, thereby reducing the austenite microstructure, especially in terms of formation from stacking faults and twins, and influences the formation of strain-induced martensite. One of the martensitic-like phase transformation has zirconia materials. It is known that zirconia crystallizes in three modifications possessing different thermal and mechanical properties. At room temperature, the monoclinic phase which is present as mineral baddelyite in nature is stable. When warming up, the monoclinic changes to the tetragonal phase at 117O ⁰ C, which in turn converts to the cubic modification at 2370 ⁰ C. The conversion tetragonal to monoclinic during cooling is associated with a volume increase of about 6%.

The conversion and the resulting volume change are reversible, so that the change in modification proceeds in a hysteresis due to the heating and cooling process. The transformation temperature depends primarily on the grain size. The volume increase in the transformation from tetragonal to monoclinic can cause such stresses in the material that the elastic absorption capacity is exceeded and cracks occur, which can lead to failure of the material. This transformation (tetragonal to monoclinic) is also known as martensitic transformation.

With the help of suitable stabilizers, which are installed in the grid, the high-temperature phase can be shifted metastable to room temperature. The volume jump is thereby completely or partially prevented. One speaks of fully stabilized (only the cubic phase present), partially stabilized (there may be all three modifications) and unstabilized (monoclinic only) zirconia. Through targeted material optimization (addition of certain stabilizers and additives and special heating processes), the percentage degree of stabilization (volume fractions of the cubic and tetragonal phase) can be set so that certain properties, such. B. greater fracture toughness (conversion-reinforced, zirconia-containing materials), volume increase, be improved. As stabilizers, the oxides of alkaline earth metals such as MgO and CaO and rare earth metals such as Y ₂ O ₃ and CeO ₂ are used. With the same degree of stabilization, the stabilizers have different effects on microstructure and properties. Furthermore, the powder preparation and the manner of addition of the stabilizer can have considerable effects on the properties and in particular on the corrosion resistance.

Zirconias are fired depending on Enddichteanforderung between 1550 ^0C and 1850 ^0C. In the production of low-porous materials (total porosity <10%) sintering temperatures above 1700 ⁰ C are selected. At high monoclinic proportion over 30% tried one on the basis of sintering auxiliary phases, such. B. SiO ₂ . TiO ₂ and Fe ₂ O ₃ , porosities less than 20% at economic maximum sintering temperatures below 1700 ⁰ C to realize.

Since the nature and degree of stabilization are primarily responsible for the properties of the zirconia materials, thermal and chemical destabilization processes are listed.

The change of the free energy ΔG _tm in the transformation from tetragonal to monoclinic of a particle in a matrix can be calculated by the following formula:

ΔG _tm = - ΔG _C + ΔU _d + ΔU _S. (1 )

ΔG _C describes the change of the chemical energy, ΔU _d the change of the distortion energy and ΔU _S the change of the surface energy. The temperature and the chemical composition significantly influence the chemical energy ΔG _C. The distortion energy ΔU _d , on the other hand, strongly depends on the elastic properties of the monoclinic phase and the surrounding matrix. Furthermore, tetragonal intrinsic tensions and external stresses have a large influence on the distortion energy. Thus, different thermal expansion coefficients of particles and matrix (Δα = ατ _e irα _Mat ri _x ) by an additional deformation energy (Δα * ΔT) either stabilize or destabilize the tetragonal phase at a production temperature> equilibrium temperature of the pure zirconia. The surface energy U _s is dependent on the particle size, so that above a critical particle size, the transformation from tetragonal to monoclinic occurs spontaneously. Finally, zirconium dioxides can also be mechanically destabilized.

In the case of MgO-stabilized zirconium dioxide materials, increasing de-stabilization becomes evident with higher Fe ₂ O ₃ , TiO ₂ and SiO ₂ fractions. These phase portions may already be present as impurities in the powder, are present as slag constituents or are added as sintering aids. They extract the stabilizer from the zirconium dioxide, form new mixed phases with the MgO and settle primarily at the grain boundaries. The destabilizing effect of SiO _{2 is} significantly higher than that of Fe ₂ O ₃ and TiO ₂ . The latter two can also be incorporated into the lattice and substitute the MgO. Similar phenomena also occur in CaO-stabilized zirconia, with the SiO ₂ leading to a greater reduction in stabilization compared to the MgO-stabilized zirconia. stabilized leads. Y ₂ θ ₃ -stabilized zirconium dioxides show the greatest resistance to SiO ₂ . It is found that with higher SiO 2 impurity levels higher cubic proportions are formed. The liquid glass phase (SiO ₂ ) kinetically promotes the diffusion of yttrium ions into the zirconia lattice. During destabilization during the cooling phase of the fire, silicon and yttrium enrichments are present separately at the grain boundaries. It does not form a mixed phase. The thermal destabilization is clearly evident at different cooling rates and in particular for MgO-stabilized zirconium dioxides. The smaller the cooling rate, the greater the destabilization. This is not only found at low sintering temperatures of 1550-1600 ° C, but it is characterized at higher fires (1750-1850 ° C, very dense structure without sintering aid) significantly. The literature shows that in partially stabilized zirconium dioxide materials (PSZ) in addition to the cubic phase convertible tetragonal parts in the form of finely crystalline precipitates in the cubic grains are present. These metastable, tetragonal, zirkondioxi danteiles can increase the structure of the martensitic transformation (volume increase) and create micro-cracks in the microstructure, which are responsible for a certain plasticity.

The reinforcement in pure ceramic products is essentially due to the crack-shielding effect caused by the change in volume and shape of the martensitic transformation. This leads to a lowering of the stress concentration at the crack tip. This type of energy dissipation is analogous to the crack tip plasticity observed in ductile metals. The essential reinforcement mechanism is based on the direct crack shield resulting from stress-induced martensitic transformation in a zone (process zone) prior to the advanced crack (stress-induced transformation toughening). Another mechanism is the formation and propagation of matrix microcracks triggered by the stress field existing around already converted monoclinic zirconia particles. In this case, it is a thermal conversion during cooling from the production temperature (microcrack toughening). Another reinforcing effect which does not shield the crack tip from externally applied stress but reduces the driving force for crack propagation is caused by crack deflection. Cracks can be deflected by local residual stress around already transformed monoclinic particles, or directly by tetragonal particles (crack deflection toughening). An important technological aspect of stress-induced transformation is the generation of lasting ones Surface compressive stresses by grinding or sanding (surface transformation strengthening).

The invention has for its object to provide composite materials of metal and ceramic, which use the property of the phase transformation of the components to improve the mechanical end properties and are therefore particularly suitable for energy absorption components, stiffening structural components, wear and strength components.

According to the invention the object is achieved by a composite of at least one metallic and at least one ceramic material, wherein at least one metallic and / or ceramic material consists of a material which is capable of a volume change via a phase transformation in the solid state.

The composite material according to the invention thus obtains improved mechanical properties such that at least one of the material components undergoes a change in volume via a phase transformation during production and / or during subsequent mechanical and / or thermal treatment and / or in the application. The change in volume due to phase transformation in the solid state results in a tensioning of the matrix of the composite material and targeted building up of compressive stresses in the composite material.

According to an advantageous embodiment of the invention, the .Verbundwerkstoff consists of at least one metallic and at least one ceramic material, which are capable of a volume change via a phase transformation in the solid state. The volume change of the ceramic material generates and / or amplifies the phase transformation of the metallic material in the composite material. These composites achieve even higher strength properties.

The composite materials according to the invention can be based on metal or ceramic, ie the metallic or ceramic component predominates in the composite material. Preference is given to metallic based composite materials with a metallic content of at least 70 vol.%, Preferably at least 80 vol.%. The composite material according to the invention can be obtained according to an advantageous embodiment of the invention by infiltration with a metallic melt of a green or gehrannten ceramic molding. Porous ceramic structures in the green or fired state, such. B. foam structures, honeycomb structures, spherical structures, spaghetti structures or ceramic originally paper structures are infiltrated with molten metal. During infiltration and / or during cooling, the ceramic material is partially or fully converted and keeps the metallic component under tension by increasing the volume. In this case, both a forced infiltration, an activated infiltration, z. B. by the addition of activating elements based on Ni, Ti, Mg, Al, Si, or combinations of the two are used. According to the invention, this strain can lead to a conversion of the metallic component during and / or production or the ceramic or metallic component is only during use, for. B. by a blow, and an internal tension of the composite is caused.

The composite material according to the invention is obtainable according to a further advantageous embodiment of the invention by forming a mass of at least one ceramic and / or metallic material and auxiliaries and subsequent sintered fire. For this purpose, ceramic and metallic powder or granules are mixed. About a molding process with the addition of other additives, a semifinished product is formed at room temperature or at temperatures lower than the melting point of the metallic material and produced with a subsequent firing at temperatures less than the melting point of the metallic material of the composite material with its final properties.

The composite material according to the invention can also be obtained by film casting or slip casting of a mass of at least one ceramic and / or metallic powder and auxiliaries and subsequent sintering firing. Flexible green sheets are about the tape casting process at temperatures below 100 ⁰ C consisting produced from ceramic and metal powders, transferred to components by green machining, which receive their final properties for a subsequent firing. Before the fire, the foils remain flexibly deformable due to the containing plasticizers on an organic basis.

Advantageously, the ceramic material in the composite material according to the invention is present as a porous shaped body and has a foam, honeycomb, ball spaghetti or Paper texture on. The ball or spaghetti structures can be both hollow and full ceramics.

According to a further advantageous embodiment of the invention, the composite material according to the invention by pressing a mass of at least one ceramic and / or metallic powder or granules and optionally excipients and subsequent sintering at temperatures less than the melting point of the metallic material is available.

The ceramic material of the composite material according to the invention is selected from zirconia-containing materials, quartz or quartz-containing materials, alumium titanates. Barium titanates. Perovskite or spinel ceramics.

The ceramics capable of volume dependent phase transformation include, for example: As zirconium dioxides, zirconia-containing materials, quartz and quartz-containing materials, aluminum titanates, barium titanates and other perovskite ceramics and spinel ceramics. Particularly preferred are Y ₂ O ₃ and / or MgO and / or CeO ₂ - stabilized zirconia.

According to the invention, zirconium dioxides having a high monoclinic content of more than 50% can be used. According to the invention, non-stabilized synthetic or natural zirconium dioxide powders are also used for this purpose. In the case of a homogeneous distribution of zirconium dioxide granules and / or grains in a metallic melt or in a metallic powder mixture, ready-formed ceramic components can be dispensed with according to the invention.

The metallic materials of the composite according to the invention are iron, steel or their alloys or Mg, Al, Ni, Ti or Cu or their alloys or refractory metals or noble metals or their alloys. Metallic materials that are capable of volume change via phase transformation are TRIP (transformation induced plasticity) or TWIP (twinning induced plasticity) metals or metal alloys. Examples of TRIP steels that can be used for the composite materials according to the invention are, for. B. metastable austenitic steels Type X5CrNi 18.10 or austenitic-martensitic lightweight steels according to DE 10 2005 030 413 B3 or austenitic steels according to DE 10 2005 024 029 B3.

TRIP / TWIP metals or metal alloys for the composite materials according to the invention are advantageously selected from

- metastable austenitic steels type X5CrNi 18.10

- multiphase steels with TRIP effect type Fe-Al-C, Fe-Mn-C, Fe-Mn-Si-C,

- brasses (alpha-beta brasses) of type Cu Zn 40

- Shape memory alloys of the type nickel-titanium or nickel-titanium-iron (NiTiFe)

Tin bronzes of the type Cu Sn20 Aluminum bronzes of the type Cu AllO Fe5.

Advantageous embodiments of the inventive composite materials are metal-ceramic - combinations of

- Complex carbides (MAX phases) of the type Ti3 SiC2 with refractory metals W, Mo, Ta

Copper matrix and oxide ceramics (Al ₂ O ₃ , quartz, Al ₂ TiO ₅ , ZrO ₂₅ Y ₂ O ₃ )

Copper matrix and SiC or TiC and / or ZrC, HfC copper matrix and Si ₃ N ₄

- copper matrix and chromium, Cu up to 60% Cr, copper - silver

Aluminum bronze and oxide ceramics (Al ₂ O ₃ , ZrO ₂ )

Aluminum bronze and SiC or Si ₃ N ₄

- Copper matrix with oxide ceramics further reinforcing materials (WC particles, W fibers)

and or

Refractory metal and refractory metal combinations in combination with ceramics and phase-transformable ceramics: Mo - La ₂ O ₃ , Mo - HfC, Mo - Ti - Zr, Mo - Y ₂ O ₃ , Mo - W, W - Cu, W - WC, W - Ag, W - La ₂ O ₃ , W - CeO ₂ , W - thorium oxide, Ta - W.

According to the invention, the composite material of a metal and a ceramic but also consist of several metals and several ceramic materials. In the case of several metallic materials z. B. the composites subsequently subjected to a further molten metal and partially infiltrated.

Metal and ceramic enter into a good bond in the composite according to the invention. The reason for this is an in situ mixed spinel formation of ceramic and metal, z. Stabilized zirconia and metal or metal alloy elements, resulting in higher densification and strength of the composite.

According to the invention, the composite material of metal and ceramic is produced by infiltration of a porous green or fired ceramic molding with a molten metal or by a molding process of at least one ceramic and / or metallic material and optionally excipients with subsequent sintering firing, wherein at least one metallic and / or ceramic material a material that is capable of volume change through solid state phase transformation.

A preferred method is the infiltration process, as forced molten metal infiltration or as activated infiltration via the addition of metallic and / or inorganic additives or a combination of both. For this purpose, porous ceramic structures, such. As foam structures, honeycomb structures, spherical structures, spaghetti structures or ceramic originally paper structures according to the invention infiltrated with molten metal. During infiltration and / or during cooling, the ceramic material partially or fully converted and held by an increase in volume, the metallic component under tension. In this case, both a forced infiltration, an activated infiltration z. B. by the addition of activating elements based on Ni, Ti, Mg, Al, Si or combinations of the two are used. According to the invention, this strain can lead to a conversion of the metallic component or the ceramic component is only during use, for. B. by a blow, and an internal strain of the metallic component is caused. Finally, granules of a ceramic-based base can also contribute to infiltration. The granules may already have been pre-sintered or a partial sintering takes place during the infiltration of the molten metal.

A preferred method for producing the composite material according to the invention results from the plastic shaping and a subsequent sintering firing. For this purpose, ceramic and metallic powder or granules are mixed. About a F ormgebungs method with the addition of other additives, a semifinished product is formed at room temperature or at temperatures lower than the melting point of the metallic material and produced with a subsequent firing at temperatures less than the melting point of the metallic material of the composite material with its final properties.

With the help of plasticizers and other additives metallic and / or ceramic powders or granules are treated at temperatures below 100 ⁰ C to form a viscous, kneadable mass on an aqueous basis, which are formed by extrusion into green bodies. The temporary auxiliaries of the green bodies are burned out at temperatures during a subsequent heat treatment. This is followed by a sintering firing with or without pressure of the green body at temperatures less than the melting point of the metallic material.

Particularly preferred is the production of a honeycomb body. For this purpose, plasticizers and other additives are added to the metallic and ceramic powders at temperatures below 100 ^° C., and the mixture is worked up in a plastic, kneadable mass on a water-based basis in a kneader. This is followed by extrusion honeycomb production. After extrusion, the temporary adjuvants are burned out with a subsequent heat treatment and then by sintering firing with or without pressure, the composite body achieves its mechanical, thermal and chemical end properties. In accordance with the invention, phase-transformable metallic and phase-transformable ceramics are used to increase the mechanical properties so that at least one of the material components undergoes a volume change via a phase transformation during production and / or subsequent mechanical and / or thermal and / or chemical treatment and / or in the application case, and finally leads to the improved mechanical properties of the composite body.

Flour or semolina or cellulose or liquefier or wetting agent or combinations thereof are used according to the invention as further additives for the shapeable shaping.

A further embodiment of the method for producing the composite material according to the invention is that produced by a film casting at temperatures below 100 ⁰ C green sheets of ceramic and metallic powders and optionally auxiliaries and that subsequently a sintering at temperatures below the melting point of the metallic material of the green sheet or without pressure.

A further embodiment of the method for producing the composite material according to the invention is that metallic and ceramic powders or granules and optionally excipients pressed and that subsequently takes place a sintering at temperatures less than the melting point of the metallic material of the compact.

The ceramics used are zirconium dioxides, zirconium dioxide-containing materials, quartz and quartz-containing materials, aluminum titanates, barium titanates or other perovskite ceramics and spinel ceramics. Y ₂ O ₃ and / or MgO and / or CeO ₂ -stabilized zirconia are particularly preferred.

The ceramics capable of volume dependent phase transformation include, for example: As zirconium dioxides, zirconia-containing materials, quartz and quartz-containing materials, aluminum titanates, barium titanates and other perovskite ceramics and spinel ceramics.

According to the invention, zirconium dioxides having a high monoclinic content of more than 50% can be used. According to the invention, non-stabilized synthetic or natural zirconium dioxide powders are also used for this purpose. In the case of a homogeneous distribution of zirconium dioxide granules and / or grains in a metallic melt or in a metallic powder mixture, ready-formed ceramic components can be dispensed with according to the invention. As metallic materials of the inventive composite iron, steel or their alloys or Mg, Al, Ni, Ti or Cu or their alloys or refractory metals or precious metals or their alloys are used. As metallic materials capable of volume change via phase transformation, TRIP (transformation induced plasticity) or TWIP (twinning induced plasticity) metals or metal alloys are used. Examples of TRIP steels that can be used for the inventive composite materials are, for. B. austenitic austenitic steels of the type XSCrNi 18.10 or austenitic-martensitic lightweight steels according to DE 10 2005 030 413 B3 or austenitic steels according to DE 10 2005 024 029 B3. TRIP / TWIP metals or metal alloys for the composite materials according to the invention are advantageously selected from

Metastable austenitic steels of the type XSCrNi 18.10

- multiphase steels with TRIP effect type Fe-Al-C, Fe-Mn-C, Fe-Mn-Si-C,

- brasses (alpha-beta brasses) of type Cu Zn 40

Tin bronzes of the type Cu Sn20 Aluminum bronzes of the type Cu AIlO FeS.

The composites of the invention may be metallic or ceramic based, i. H. the metallic or the ceramic part predominates in the composite material. Preference is given to metallic based composite materials with a metallic content of at least 70 vol.%, Preferably at least 80 vol.%.

The composite materials according to the invention are characterized by excellent strength and toughness combined with high energy absorption capacity and reduced density and are particularly suitable for crash-stressed components and stiffening structural components, chassis components, wear and strength components.

The composite materials according to the invention are particularly suitable for crash-impacted energy absorption components and, with the same installation space, allow higher energy consumption to be realized more cost-effectively and more easily. For this application is also advantageous that the Composite materials according to the invention are nonflammable and thermally stable and corrosion resistant. The invention therefore also includes energy-absorbing components based on the composite materials according to the invention, in which at least one metallic and / or ceramic material consists of a material which is capable of a volume change via a solid state phase transformation and in which the energy absorption component has a honeycomb geometry.

The honeycomb body geometry of the energy absorbing component is obtained by molding a mass of at least one ceramic and / or metallic powder or granules and auxiliaries and subsequent sintering firing. The ceramic component is selected from zirconia-containing materials, quartz or quartz-containing materials, aluminum titanates. Barium titanates. Perovskite or spinel ceramics and preferably selected from Y ₂ O ₃ and / or MgO and / or CeO ₂ - stabilized zirconia. The metallic material is a TRIP and / or TWIP metal or a TRIP and / or TWTP metal alloy and selected from iron, steel or their alloys or Mg, Al, Ni, Ti or Cu or their alloys or refractory metals or precious metals or their alloys.

The energy absorption components according to the invention have in situ spinels of stabilized zirconium dioxide and metals or metal alloy elements and thereby achieve high strength values. When using MgO-stabilized zirconia and TRIP and / or TWIP steels, sintering fires in situ form MgO-stabilized spinels from the MgO-stabilized ZrO ₂ and the alloying elements of the steel.

The energy absorption components according to the invention are suitable, for example, as bumper carriers, as frame parts (eg sills) or the like in vehicles, for example in motor vehicles for absorbing kinetic energy in the event of an impact, for example as a result of an accident. They have a high deformability while ensuring a sufficient static strength. The energy absorbing components can be made by forming a thin film and then sintering.

With reference to attached figures and embodiments, the invention will be explained in more detail. Showing: Fig. 1 ceramic foam structure

Fig. 2 spaghetti structure

Fig. 3 Ceramic honeycomb body structure

Fig. 4 ceramic Granulathaufen

Fig. 5 REM-Aufhahme a honeycomb body

FIG. 6 shows SEM reception of the surface of the honeycomb body according to exemplary embodiment 3. FIG

FIG. 7 shows a REM image of the surface of the honeycomb body according to exemplary embodiment 3. FIG

Embodiment 1

By infiltration of a 3.5 wt.% MgO partially stabilized zirconia foam ceramic (Fig. 1, fired at 1600 ⁰ C for 2 h, activated after firing via spray coating with 10 wt.% Ti) with an austenitic CrNi - TRIP steel X5CrNi 18.10 according to the invention the product with maximum elongation and tensile strength of the composite of about 38,000 MPa% raised to 45,000 MPa%. The ceramic prior to molten metal infiltration consists of 10 vol.% Monoclinic phase fraction, 45 vol.% Tetragonal phase fraction and 45 vol.% Cubic moiety. After molten metal infiltration, the composite has an increased monoclinic content at room temperature, which is about 55% by volume. About the phase transformation of the ceramic, the metal matrix was braced. As the molding method, a melt infiltration of ordinary Schuamkeramik served at 1630 ⁰ C in an induction furnace under inert gas atmosphere.

According to exemplary embodiment 1, the spaghetti structures, honeycomb bodies or granules shown in FIGS. 2 to 4 can also be infiltrated with a molten metal. In this case, the ceramic phase transformation or during use in combination with the macrogeometry of the ceramic leads to the desired strain of the metal matrix. Exemplary embodiment 2 Honeycomb body

The following table contains a mixture for the production of a honeycomb body based on convertible steel and zirconium dioxide ceramic:

The grain size of the ceramic is between 1 to 7 microns and steel between 40 to 70 microns. The plastic mass is prepared in a kneader with about 18 wt.% Water at room temperature and then pressed in an extruder at room temperature through a mouthpiece with 300 cpsi (channels per square inch). The green honeycomb body is debindered at 350 ⁰ C in an oxidic atmosphere and then fired in argon at 1300 ⁰ C for 30 min. In Fig. 3, the honeycomb geometry is shown before and after the fire. With a weight saving of about 70%, according to the invention, the product of maximum elongation and tensile strength of the composite honeycomb body is raised from about 35,000 MPa% to 40,000 MPa%.

Exemplary embodiment 3 Honeycomb body

According to the recipe of embodiment 2, a honeycomb body is formed. The green honeycomb body is debindered at 350 ⁰ C in an oxidic atmosphere and then in Argon fired at 135O ° C for 30 min. For the firing process, a titanium cage is used. Obtained is a honeycomb body with 450 MPa cold compressive strength. At 222kN, a 50% compression is achieved without the honeycomb rupturing or breaking. Fig. 5 shows a cross section of the honeycomb body. 5 shows the surface of the honeycomb body and FIG. 6 shows an enlarged detail from FIG. 5. It can be seen that mixed spinels are formed in situ on the grain boundaries (Mg, Al, Cr, Mn, Fe, ZrJbO ₄ ) and ceramics enter into a good bond via the MgO-stabilized ZrO ₂ .

Claims

claims

1. Composite material of metal and ceramic, consisting of at least one metallic and at least one ceramic material, characterized in that at least one metallic and / or ceramic material consists of a material which is capable of a volume change via a phase transformation in the solid state.

2. A composite material according to claim 1, characterized in that at least one metallic and at least one ceramic material consist of a material which are capable of a change in volume via a phase transformation in the solid state and that in the composite material by volume change of the ceramic material, the phase transformation of the metallic material generated and / or reinforced in the composite material.

3. A composite material according to claim 1 or 2, characterized in that it is obtainable by infiltration with a metallic melt of a green or fired ceramic shaped body.

4. A composite material according to claim 1 or 2, characterized in that it is obtainable by molding a composition of at least one ceramic and / or metallic powder or granules and auxiliaries and subsequent sintering fire.

5. A composite material according to claim 1 or 2, characterized in that it is obtainable by casting foil casting or slip casting a mass of at least one ceramic and / or metallic powder or granules and auxiliaries and subsequent sintering fire.

6. Composite material according to one of claims 1 to 5, characterized in that the ceramic material is present in the composite material as a porous shaped body.

7. Composite material according to one of claims 1 to 5, characterized in that the composite material has a foam, honeycomb, ball spaghetti or paper structure.

8. A composite material according to claim 1 or 2, characterized in that it is obtainable by molding a mass of at least one ceramic and / or metallic powder and optionally adjuvants and subsequent sintering fire.

9. Composite material according to one of claims 1 to 8, characterized in that the ceramic material is selected from zirconia-containing materials, quartz or quartz-containing materials, aluminum titanates. Barium titanates. Perovskite or spinel ceramics.

10. A composite material according to any one of claims 1 to 9, characterized in that the metallic material is selected from iron, steel or their alloys or Mg, Al ₅ Ni, Ti or Cu or their alloys or refractory metals or precious metals or their alloys.

11. Composite material according to one of claims 1 to 9, characterized in that the metallic material is a TRIP and / or TWIP metal or a metal alloy.

12. A composite material according to any one of claims 1 to 11, characterized in that the composite contains in situ spinels of stabilized zirconia and metal or metal alloy elements.

13. A method for producing a composite material of metal and ceramic by infiltration of a porous green or fired ceramic molding with a molten metal or by a molding process of at least one ceramic and / or metallic material with subsequent sintering, characterized in that at least one metallic and or ceramic Component is made of a material that is capable of a volume change via a phase transformation in the solid state.

14. The method according to claim 13, characterized in that an enforced molten metal infiltration or by the addition of metallic and / or inorganic additives, an activated infiltration or a combination of both is performed.

15. The method according to claim 13, characterized in that with the aid of plasticizers and other additives metallic and / or ceramic powders or granules are treated at temperatures below 100 ⁰ C to form a viscous, kneadable mass on an aqueous basis, formed by extrusion into green bodies be burned out that the temporary auxiliaries of the green body with a subsequent heat treatment and then that a sintering fire takes place with or without pressure of the green body.

16. The method according to claim 15, characterized in that are added as further additives for the plastic molding flour or semolina or cellulose or plasticizers or wetting agents or combinations thereof.

17. The method according to claim 13, characterized in that produced by a film casting at temperatures below 100 ⁰ C green sheets of ceramic and metallic powders and optionally excipients and that subsequently a sintering fire of the green sheet with or without pressure.

18. The method according to claim 13, characterized in that metallic and ceramic powders or granules and optionally excipients pressed and that subsequently a sintering firing of the compact takes place.

19. The method according to any one of claims 13 to 19, characterized in that are used as ceramics, zirconium dioxides, zirconium dioxide-containing materials, quartz and quartz-containing materials, aluminum titanates, barium titanates, perovskite ceramics or spinel ceramics.

20. The method according to any one of claims 13 to 19, characterized in that as metallic materials iron, steel or their alloys or Mg, Al, Ni, Ti or Cu or their alloys or refractory metals or precious metals or their alloys.

21. The method according to any one of claims 13 to 20, characterized in that a TRIP and / or TWIP metal or a TRIP and / or TWIP metal alloy is used as the metallic material.

22. Use of a composite material according to one of claims 1 to 12 for crash-stressed components and stiffening structural components, chassis components, wear and strength components.

23. Energieabsorptionsbauteü consisting of at least one composite material according to one of claims 1 to 6 and 9 or 10, characterized in that the component has a honeycomb body geometry.

24. The energy absorption component according to claim 23, wherein the ceramic material is selected from Y ₂ O ₃ and / or MgO and / or CeO 3 -stabilized zirconium dioxide.

25. Energy absorption component according to claim 23 or 24, characterized in that the metallic material is a TRIP and / or TWIP metal or a TRIP and / or TWIP metal alloy.

26. Energy absorption component according to one of claims 23 to 25, characterized in that the honeycomb geometry is obtainable by molding a mass of at least one ceramic and / or metallic powder or granules and auxiliaries and subsequent sintering firing.

27. Energiebabsorptionsbauteil according to any one of claims 23 to 26, characterized in that the component via the MgO stabilization in situ spinels of the MgO-stabilized ZrO2 and the alloying elements of the steel.