EP4304857A1 - Procédé et dispositif de fabrication de céramiques et produit céramique - Google Patents

Procédé et dispositif de fabrication de céramiques et produit céramique

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Publication number
EP4304857A1
EP4304857A1 EP22714404.5A EP22714404A EP4304857A1 EP 4304857 A1 EP4304857 A1 EP 4304857A1 EP 22714404 A EP22714404 A EP 22714404A EP 4304857 A1 EP4304857 A1 EP 4304857A1
Authority
EP
European Patent Office
Prior art keywords
ceramic
light
ceramic product
less
starting material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22714404.5A
Other languages
German (de)
English (en)
Inventor
Lukas PORZ
Wolfgang Rheinheimer
Michael Scherer
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Technische Universitaet Darmstadt
Original Assignee
Technische Universitaet Darmstadt
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE102021130349.4A external-priority patent/DE102021130349A1/de
Application filed by Technische Universitaet Darmstadt filed Critical Technische Universitaet Darmstadt
Publication of EP4304857A1 publication Critical patent/EP4304857A1/fr
Pending legal-status Critical Current

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    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/64Burning or sintering processes
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    • C04B35/00Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/62218Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining ceramic films, e.g. by using temporary supports
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D67/00Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0039Inorganic membrane manufacture
    • B01D67/0041Inorganic membrane manufacture by agglomeration of particles in the dry state
    • B01D67/00411Inorganic membrane manufacture by agglomeration of particles in the dry state by sintering
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01D71/02Inorganic material
    • B01D71/024Oxides
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B18/00Layered products essentially comprising ceramics, e.g. refractory products
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    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00Ohmic-resistance heating
    • H05B3/0033Heating devices using lamps
    • H05B3/0038Heating devices using lamps for industrial applications
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    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01D2325/00Details relating to properties of membranes
    • B01D2325/02Details relating to pores or porosity of the membranes
    • B01D2325/022Asymmetric membranes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • C04B2235/656Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
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Definitions

  • the present invention relates to a method and an apparatus for producing ceramics and a ceramic product.
  • furnaces For the production of ceramics by compacting ceramic powder by sintering at high temperatures, particularly temperature-resistant furnaces and a large amount of energy as well as long process times are necessary. Furnaces are built from particularly temperature-resistant materials and are heated using a great deal of energy. The ceramic inside the furnace heats up and the sintering process is carried out. However, the temperature resistance of these furnaces is also limited, so that in some cases sintering aids (for example with S1 3 N 4 ) have to be used in order to lower the sintering temperature. In general, the process times are in the range of hours and a lot of energy is required.
  • the object is achieved by the invention according to a first aspect in that a method for producing ceramics (with or without dislocations), the method comprising: Radiation of light onto a ceramic starting material in order to heat it up at least in certain areas and thereby produce a ceramic product, with the radiation of light simultaneously, i.e. at the same time, on an area of at least 0.1 mm 2 and/or on more than 20% of the Surface of the ceramic starting material takes place and the power density of the incident light is less than 800 W / cm 2 is proposed.
  • the irradiation of light can, for example, take place simultaneously on more than 20%, on at least 35%, at least 50%, at least 65%, at least 80%, at least 90%, at least 95%, or at least 99% of the surface of the ceramic starting material on the entire area.
  • Light can be radiated in, for example, simultaneously on an area of at least 0.1 mm 2 , at least 0.2 mm 2 , at least 0.5 mm 2 , at least 0.01 cm 2 , at least 0.02 cm 2 , at least 0.05 cm 2 , at least 0.1 cm 2 , at least 0.2 cm 2 , at least 0.5 cm 2 , or at least 1.0 cm 2 , in particular at least 60%, at least 70%, at least 80%, at least 90% , at least 95%, at least 98%, or at least 99% of the area of the ceramic starting material, for example over the entire area.
  • the irradiation of light takes place in particular for a time of at least 0.1 seconds, at least 0.5 seconds, at least 1 second, preferably at least 5 seconds, preferably at least 20 seconds, and/or a maximum of 10 minutes, preferably a maximum of 8 minutes. preferably at most 5 minutes, preferably at most 3 minutes, preferably at most 1 minute, preferably at most 30 seconds, preferably at most 10 seconds.
  • the irradiation of light with a power density of less than 800 W/cm 2 serves in particular to sinter the volume body.
  • the method according to the invention can also include a further step of irradiating light with a higher power density for a significantly shorter time onto the ceramic starting material in order to heat it up at least in certain areas and thereby produce a ceramic product, the irradiation of light simultaneously, i.e.
  • the power density of the incident light is at least 800 W/cm 2 , for example at least 1000 W/cm 2 , at least 2000 W/cm 2 , at least 4000 W/cm cm 2 , at least 10000 W/cm 2 , at least 15000 W/cm 2 , at least 50000 W/cm 2 , or at least 400000 W/cm 2 , preferably at most 750,000 W/cm 2 , at most 20000 W/cm 2 , at most 8000 W /cm 2 , not more than 10000 W/cm 2 , not more than 7000 W/cm 2 , or not more than 5000 W/cm 2 .
  • the further step of irradiating light takes place in particular for significantly shorter times, for example for a maximum of 100 milliseconds (ms), a maximum of 50 ms, a maximum of 40 ms, a maximum of 30 ms, a maximum of 25 ms, or a maximum of 20 ms, and/or at least 0, 5 ms, at least 1 ms, at least 2 ms, at least 5 ms, or at least 10 ms.
  • the further irradiation of light can also be referred to as a flash of light in view of the short duration.
  • the irradiation of light in the further step can, for example, take place simultaneously on at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 98%, or at least 99% of the surface of the ceramic starting material, in particular over the entire area Surface.
  • the irradiation of light in the further step can, for example, be carried out simultaneously on an area of at least 0.1 mm 2 , at least 0.2 mm 2 , at least 0.5 mm 2 , at least 0.01 cm 2 , at least 0.02 cm 2 , at least 0.05 cm 2 , at least 0.1 cm 2 , at least 0.2 cm 2 , at least 0.5 cm 2 , or at least 1.0 cm 2 , in particular at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 98%, or at least 99% of the area of the ceramic starting material, for example over the entire area.
  • the surface is therefore irradiated more intensely for a very short time before or after, preferably during the sintering process in addition to lighting for the sintering of the volume body.
  • a flash from a Xe flash lamp with a high power density in particular at least 800 W/cm 2 , for example at least 1000 W/cm 2 , at least 1500 W/cm 2 , at least 2000 W/cm 2 , at least 2500 W/cm 2 at least 3000 W/cm 2 , at least 3500 W/cm 2 , at least 4000 W/cm 2 , or about 4350 W/cm 2
  • a short time in particular a maximum of 50 ms, a maximum of 40 ms, a maximum of 30 ms, a maximum of 25 ms, or a maximum of 10 ms, for example about 20 ms
  • the surface can be heated to a significantly greater extent than the underlying volume material.
  • a layer with different properties is formed on the surface.
  • This preferably has a texture and has a higher density and grain size than the solid.
  • this layer can be used to generate directional grain growth in the volume body. In English, this type of control over grain growth is referred to as "templated grain growth".
  • a thermal or shrinkage misfit between the layer and the bulk is reduced, particularly prevented, by the use of the flash while the bulk is itself at high temperature, with the ceramic being particularly good at relieving stress at high temperatures.
  • the process time and the energy consumption can be drastically reduced and on the other hand the parameters of the heating rate can be controlled very reliably, in particular adjusted and/or actively regulated. In this way, it is possible to specifically control how quickly the powder is heated up at which point. In particular, heating can take place simultaneously over a large area and the process can be implemented as a continuous process.
  • the ceramic material can be heated particularly quickly by lighting. A high heating rate can be achieved in the ceramic material in the irradiated areas.
  • the proposed method thus enables in particular a much more direct control of the power density and thus of the temperature in the ceramic material.
  • the process is surprisingly much easier to carry out than the conventional production of ceramics.
  • aspects can be realized that are impossible with conventional sintering or can only be achieved with great effort, in particular one or more of the following aspects.
  • a grain size gradient and/or texturing can be generated by different temperature profiles on the surface and inside the ceramic.
  • the method can include a temporal and/or spatial power density profile.
  • a preferred power density profile over time includes, for example, a power density in a range of 800 W/c 2 to 20,000 W/cm 2 , e.g. 4350 W/cm 2 for a period of 0.2 to 200 ms, e.g. 20 ms, followed by or parallel to a further power density in a range of 10 W /cm 2 to ⁇ 800 W/cm 2 , for example 130 W/cm 2 for a period of 1 second to 2 minutes, for example 10 seconds.
  • the high first power density leads to the formation of the densely sintered surface layer. Due to the shortness with which the first power density is currently being used, the densely sintered layer is limited to a thin surface layer.
  • the thickness of the surface layer can be, for example, in a range from 10 to 20 ⁇ m.
  • Ceramic products with a dense surface layer and a porous volume underneath are particularly suitable for use in fuel cells. Grain size and texture each affect the functional and mechanical properties such as conductivity and susceptibility to cracking.
  • Nanoporosity can also be produced with the method according to the invention.
  • Nanopores are pores with a Martin diameter of less than 1 pm, i.e. in the nanometer range, which can be quantified by means of microstructure analysis, i.e. for example the evaluation of TEM micrographs.
  • a ceramic product according to the invention can contain nanopores. This is especially true when the ceramic product is T1O2, BaTiOs, YSZ (Yttria-stabilized zirconia) or Lio . sLaojTiOs as a material.
  • the method according to the invention also enables sintering at extremely high temperatures, for example at temperatures in a range from 500° C. to 3200° C., since there is no limitation of the temperature maximum by a furnace.
  • the ceramic products produced can achieve improved thermal stability, in particular at high temperatures of, for example, greater than 1400°C.
  • the extremely high process temperatures make it possible to dispense with sintering aids and to generate larger grains and thus achieve better creep resistance.
  • the creep rate is proportional to 1/grain size 2 (Nabarro-Herring creep) or 1/grain size 3 (Coble creep).
  • the temperature in the ceramic starting material and/or the ceramic product can be, for example, in a range from 500° C. to 3200° C., in particular in a range from 1000° C.
  • the ceramic is heated to at least 1800°C or even significantly higher, e.g. 2500°C, during the sintering process.
  • insulation made of expandable graphite is used, for example.
  • such an extremely high temperature can be reached in an ordinary atmosphere without great technical effort.
  • materials can be produced with a particularly coarse starting powder or with particularly high sintering and melting temperatures. This can speed up, cheapen and simplify the production of ceramics such as silicon carbide, silicon nitride, boron carbide, boron nitride or magnesium oxide.
  • ceramic products can be produced with significantly more homogeneous material properties, for example with regard to grain size, phase composition, porosity, number and size of microcracks, or conductivity.
  • this is due to the thermal decoupling of the green body by insulation from the substrate, for example by floating on a gas membrane.
  • the simultaneous, area illumination has the advantage that lateral temperature gradients (such as those that occur in selective laser sintering, for example, in which an area is not illuminated simultaneously, but instead the area is scanned point by point) are eliminated or at least significantly reduced are, whereby the material properties and their homogeneity are improved.
  • the process time is radically reduced in comparison to selective laser sintering, since with the method of the present invention entire components can be sintered in one go within seconds. Due to the extreme reduction in process time and the simplified handling, development can take place much faster. In particular, small series, such as in the production of sputter targets or PLD targets (English: “Pulsed Laser Deposition (PLD)”), can be cheaper and simplified.
  • PLD Pulsed Laser Deposition
  • Using light instead of an oven can reduce process time by a factor of 1000.
  • an energy saving of, for example, 20% to 99% can be achieved.
  • An energy saving can be transferred to a corresponding CO 2 saving.
  • Another advantage is that electric current can be used that can be purchased sustainably. Gas/oil are not available on a large scale CO2 neutral. Even thicker ceramics, for example those with a thickness in the range from 0.1 mm to 20 mm, in particular from 0.5 mm to 10 mm or from >1 mm to 5 mm, can be prepared within seconds with an energy saving of at least 90%. getting produced. In particular, an energy saving can be achieved with a simultaneously shortened delivery time.
  • the ceramic starting material can in particular have a thickness of at least 0.001 mm, at least 0.01 mm, at least 0.1 mm, at least 0.5 mm, at least 1.0 mm or at least 2.0 mm.
  • the thickness is, for example, in a range from 0.1 to 12.0 mm, in particular from 0.2 to 10.0 mm, from 0.5 to 8.0 mm, from 1.0 to 5.0 mm, or from 1.0 to 4.0mm.
  • the ceramic starting material is preheated to an average temperature, for example 50% of the maximum temperature during the sintering process. This significantly reduces the temperature range by which heating has to be carried out particularly quickly. As a result, a larger material thickness can be successfully processed and, in particular, homogeneous material inserts can be produced.
  • the preheating step can also take place at lower heating rates over longer periods of time than the actual sintering step. Furthermore, a significantly lower power density is required here than for sintering and it is conceivable to use a conventional furnace for the preheating step or to combine the step with the burning out of binder materials.
  • the radiation of heat from the ceramic is reduced by suitable mirrors.
  • a mirror for example elliptical or parabolic, which is coated with gold, for example, in order to reflect the radiated infrared radiation in particular, can be used to throw the emitted radiation back onto the ceramic being produced. This allows reducing the power needed to maintain the temperature. This can improve energy efficiency with long exposure times.
  • At least two sides are illuminated.
  • material thicknesses are from 0.1 to 12.0 mm, in particular from 0.2 to 10.0 mm, from 0.5 to 8.0 mm, from 1.0 to 5.0 mm, or from 2.0 to 4.0 mm, for example about 4 mm. It is preferably illuminated from two sides and a preheating step is used.
  • dislocations can optionally be produced at least locally.
  • a high density of such dislocations in ceramics can be particularly advantageous for their performance.
  • Dislocations allow the functional and mechanical properties of ceramics to be improved and/or specifically adjusted.
  • the properties of a ceramic, which can be influenced, in particular improved, with dislocations include the following:
  • Ceramics such as the tendency to interdiffuse when co-sintering different phases in a layered composite (e.g. capacitors, piezoelectric actuators, solar cells, solid-state batteries, fuel cells and electrolysis cells) or the homogeneity when depositing metallic lithium (lithium dendrite growth). ) in new batteries can be influenced, in particular improved, by dislocations.
  • a layered composite e.g. capacitors, piezoelectric actuators, solar cells, solid-state batteries, fuel cells and electrolysis cells
  • homogeneity when depositing metallic lithium (lithium dendrite growth). ) in new batteries can be influenced, in particular improved, by dislocations.
  • the process thus makes it possible to influence ceramics, depending on their later application, with regard to the number and density of the introduced dislocations and thereby in turn to influence the properties of the ceramic, especially its functional and mechanical properties, as they were mentioned above, for example, in a targeted manner discontinue and/or improve.
  • dislocations can replace and/or complement chemical doping. This can reduce the complexity of the materials, which allows for less complex raw material supply chains and more sustainable and economical production. At the same time, this also offers potential for easier recycling. Furthermore, good mechanical deformability of the ceramic after sintering can be achieved with the proposed method. This property can be used for secondary shaping, which requires plastic deformability, in particular bending, buckling, deep-drawing, forging and/or extrusion.
  • the proposed method can thus lead to a significant improvement in the properties of known ceramics.
  • the method can be implemented with comparatively little technical effort. Since the process places only low demands on the technical framework, it can also be easily integrated into existing production processes. Since the method works contact-free (it does not require any contacting of the sample body like "flash sintering"), its implementation is particularly easy. Existing production processes can therefore also be retrofitted very easily and inexpensively in order to use the proposed method there.
  • the light source can be selected from a large number of even conventional light sources. As a result, the method can be implemented in a particularly cost-effective manner. The method can also be used for a large number of different geometries of the specimen. In particular, processes with continuous material transport through the illuminated zone are possible. The proposed method is therefore very well suited for mass production.
  • a controlled and/or controllable temperature profile can preferably be set within the ceramic.
  • this can be a spatial temperature profile within the ceramic.
  • gradients can optionally be created in certain properties of the ceramic, that is, the values of the properties change gradually with location. It is also possible to produce ceramic products with property gradients using a time-dependent power density profile of the irradiation.
  • products with a high density surface layer of, for example, greater than 90% or greater than 95%, in particular without open or percolating porosity, and an underlying volume with low density with percolating porosity and thus gas permeability can be produced.
  • Such products are of interest, for example, for use in fuel cells or for water splitting.
  • the surface layer is gas-tight due to its high density, while the volume underneath represents a good reaction space due to its porosity.
  • the proposed method it is possible for the first time to produce dislocations with a sufficient number and density in a ceramic to achieve the properties influence, in particular improve, ceramics for demanding applications.
  • the method optionally enables the creation of dislocations under controlled conditions and is therefore also reproducible.
  • the method works particularly well with short wavelengths in particular. It is otherwise known that additives provide better absorption at long wavelengths and better results in selective laser sintering. However, it is better not to have to use additives, some of which are disadvantageous. Surprisingly, significantly more energy is absorbed when the process is carried out in a nitrogen atmosphere. Here, the oxygen vacancies have a similar effect to an absorbing additive.
  • the process is preferably carried out in a nitrogen atmosphere.
  • the method is preferably free of absorbent additives.
  • visible light and/or UV light can be used.
  • light in the infrared spectral range can also be used.
  • the temperature profile within the ceramic can be very precisely monitored, in particular controlled.
  • the efficiency can be set particularly reliably.
  • Blue laser light is particularly preferably used as a continuous wave (not pulsed, English: “continuous wave”), in particular laser light with a wavelength in a range from 200 nm to 700 nm, for example 300 nm to 600 nm or 400 nm to 500 nm.
  • a laser with a wavelength of 450 nm corresponds to a photon energy of 2.7 eV. If the photon energy is greater than the band gap, then the material absorbs almost 100% of the light, otherwise it is almost transparent (see glass).
  • the band gap is between 2 and 5 eV. For most relevant oxides between 2.7 and 3.8 eV. However, the band gap decreases with temperature and is reduced by about 1 eV at 1200°C. This means that for most oxides, around 2 eV is sufficient to achieve high efficiency at the maximum process temperature.
  • Red lasers with a wavelength of 800 nm (1.5 eV) are disadvantageous. The light is not efficiently absorbed, requiring 10 to 20 times more power. CO2 lasers with a wavelength of 10000 nm (0.15 eV) have even greater problems with effective absorption.
  • the photon energy is therefore preferably at least 2 eV and is in particular in a range from 2 eV to 5 eV, for example from 2.5 eV to 4.0 eV or from 2.7 eV to 3.8 eV. More than one wavelength is preferably used simultaneously in order to avoid a sudden change in absorption efficiency, which preferably increases the mechanical stability and the homogeneity.
  • the incident light is absorbed by the ceramic or the green body, in particular at or near the surface onto which the light falls, with the interior of the material also being able to be heated by heat transfer from the surface.
  • thin green bodies are used, with targeted switching off of the light also enabling very high cooling rates.
  • Layered composites and composites can also be sintered using this process, in particular solid-state batteries, actuators, capacitors and fuel cells.
  • a green body can, for example, designate the ceramic before the sintering process, and therefore the ceramic starting material.
  • the term leaves open whether the starting material is, for example, a film or a pressed powder and what its geometry is.
  • the ceramic starting material has a foil-like geometry.
  • adaptive (laser) optics can be used so that the light output can be controlled quickly and precisely.
  • dislocations can be introduced into the ceramic at the same time during the compaction taking place in the course of the sintering process. Due to the rapid heating and/or cooling rates that can be controlled in this way, dislocations can optionally be introduced into the ceramic to a large extent, which is not usually possible in a furnace, for example, due to its thermal inertia. The dislocations can then improve a large number of functional and mechanical properties of the ceramic.
  • the cooling rate can be controlled by switching off the irradiation; in particular, very high cooling rates can also be achieved as a result. This is a design parameter that is not traditionally available.
  • a high cooling rate can thus preferably be achieved by switching off the light source and thus by ending the supply of thermal power.
  • This enables a fast cooling time compared to conventional ovens. Since no conventional oven is optionally used, the thermal inertia of the oven is eliminated. As a result, the ceramic accounts for almost all of the thermal inertia. Accordingly, the thermal inertia can be particularly low in the case of thin ceramics. As a result, fast and precise temperature profiles can be run. It can be advantageous if the cooling with light is actively controlled in such a way that an aging step, ie direct holding at elevated temperatures, is provided. In particular, an aging step can be carried out at a temperature in a range from, for example, 300° C. to 1000° C.
  • a aging step can be particularly advantageous in the case of functional ceramics in order to equilibrate the point defects and thus obtain a stable profile of the temperature-dependent electrical conductivity of the ceramic product.
  • the provision of an aging step can also be used to minimize possible thermal shock effects or the resulting cracks in the ceramic product.
  • the cooling temperature is actively regulated and the cooling rate in the temperature range from, for example, 800° C. to 100° C.
  • the cooling rate in the temperature range from 800° C. to 100° C. is preferably over a range of at least 100 K in a range from 5 to 60 K/min, more preferably from 10 to 20 K/min.
  • the cooling rate in the temperature range from 800° C. to 100° C. is preferably at least 5 K/min, more preferably at least 10 K/min, over a range of at least 100 K.
  • the cooling rate in the temperature range from 800° C. to 100° C. over a range of at least 100 K is preferably at most 1 K/s, more preferably at most 20 K/min.
  • the method is particularly well suited for the sintering of electrolyte layers and/or layer composites for fuel cells, electrolytic cells and solid-state batteries as well as ceramic sensors.
  • the ceramic material before the start of the irradiation with light and/or after the end of the irradiation with light, the ceramic material is sintered by means of a sintering furnace or in some other way sintered. This means that the proposed method can only be switched on when a high dislocation density is required, for example.
  • the proposed method preferably has the following advantageous features and properties, which can be used alone, all together and/or in any combination:
  • the process can treat a particularly large area at the same time.
  • the process is the first industrially scalable manufacturing process for ceramics, such as ceramic membranes, which optionally obtain their outstanding properties from the dislocations produced.
  • the process in particular the associated sintering process, can be integrated directly into existing industrial film casting systems.
  • the process optionally enables a very high number and a very high density of dislocations.
  • the method is also easily scalable for mass production and easy to implement (for example, readily available lights can be used).
  • Process control on a laboratory scale can be designed in a particularly similar way to industrial process control, which means that further developments can be implemented particularly quickly and quality controls are simplified.
  • the method can be designed as a continuous process. • Significant energy savings are possible during production, since no ovens are required that have to be heated up and cooled down again. Only the material itself is heated.
  • the process can be used particularly well for the production of ceramics in one or more of the following areas: fuel cell technology,
  • Electrolytic cells solid-state batteries, sensors, solid-state batteries, hydrogen technology, solar cells, catalysis technology, capacitors and actuators.
  • the transition from the ceramic starting material to the ceramic product is fluid as a result of the sintering process.
  • the invention preferably makes it possible to set the temperature in such a way, in particular to minimize a lateral variation in the temperature profile, that no large local gradients arise in the ceramic starting material. This makes the sintered material more tear-resistant.
  • the transitions between illuminated and non-illuminated areas can optionally be designed as a gradient.
  • an area of 1 cm 2 or more, preferably 250 cm 2 or more, and/or 2000 cm 2 or less, preferably 100 cm 2 or less, of the material is illuminated simultaneously.
  • the ceramics produced with the process can be particularly efficient due to their optionally high dislocation density.
  • functional ceramics can be produced with the method.
  • functional ceramics there is an interest in ceramics that are as efficient as possible, since this benefits the entire system (e.g. a battery).
  • a functional ceramic is preferably understood to mean a ceramic with special functional properties, for example with regard to capacitors, sensors or battery membranes. It differs, for example, from structural ceramics, which define their added value through their structure and mechanical properties. Dislocations are defined in relevant specialist literature, e.g. "Theory of dislocations"
  • Dislocations within the meaning of the present application are preferably one-dimensional crystal defects in the material, which can preferably be generated during production.
  • the ceramic starting material is heated in certain areas at a heating rate of (a) 1 K/s or more, preferably 10 K/s or more, preferably 100 K/s or more, preferably 1000 K/s or more, (b) 10000 K/s or less, preferably 5000 K/s or less, preferably 1000 K/s or less, and/or (c) between 10 and 5000 K/s, preferably between 100 and 2000 K/s, preferably between 100 and 1500 K/s, preferably between 100 and 1000 K/s.
  • a heating rate of (a) 1 K/s or more, preferably 10 K/s or more, preferably 100 K/s or more, preferably 1000 K/s or more, (b) 10000 K/s or less, preferably 5000 K/s or less, preferably 1000 K/s or less, and/or (c) between 10 and 5000 K/s, preferably between 100 and 2000 K/s, preferably between 100 and 1500 K/s, preferably between 100 and 1000 K/s.
  • a high number and a high density of dislocations in the ceramic product can optionally be achieved by achieving appropriate heating rates in the ceramic material through the irradiation of light.
  • the heating rate is a maximum of 2500 K/s, preferably a maximum of 500 K/s, preferably a maximum of 150 K/s, preferably a maximum of 50 K/s, preferably a maximum of 50 K/s.
  • the heating rate can alternatively or additionally also be 1 K/s or be more.
  • the heating rate is between 1 K / s and 5000 K / s, preferably between 50 K / s and 1000 K / s, preferably between 50 K / s and 800 K / s, preferably between 100 K / s and 600 K/ s.
  • the target temperature is reached with a heating rate of more than 500 K/s in less than 5 seconds, preferably in less than 1 second, even more preferably in less than 0.1 seconds.
  • the target temperature is stabilized within less than 10 seconds, preferably less than 5 seconds, more preferably less than 2 seconds, even more preferably less than 1 second, with an accuracy of +/- 20K.
  • the cooling rate is between 25,000 K/s and 50 K/s, preferably between 1000 K/s and 50 K/s.
  • the cooling rate from the sintering temperature to a temperature of 1000° C. is preferably very fast.
  • the cooling rate from the sintering temperature to a temperature of 1000° C. is preferably in a range from 50 K/s to 1000 K/s, for example from 100 K/s to 500 K/s, or from 150 K/s to 250 K/s. s.
  • the cooling rate can also be dependent on the thickness.
  • the quotient of the cooling rate and the material thickness can be in a range between 25000 K/(mm*s) and 10 K/(mm*s), preferably between 1000 K/(mm*s) and 50 K/(mm*s ) lie. If light with greater power densities is further irradiated for very short times, significantly higher heating rates can occur, for example up to 5,000,000 K/s, up to 1,000,000 K/s, or up to 500,000 K/s. With the flash of light, for example, a dense layer can be produced on a porous substrate.
  • the heating rate is detectable at the illuminated surface.
  • the heating rate can then be controlled by measuring the temperature change at the illuminated surface. This can preferably be done without contact using a suitable pyrometer. Other methods of temperature measurement are also possible, for example using thermocouples, resistive temperature sensors or indirect measurement methods based on the properties of the material to be sintered.
  • the power density selected during heating is higher than is then necessary to maintain the temperature, in order to make the heating rate as high and constant as possible.
  • the power density is preferably increased during heating in order to achieve a heating rate that is as uniform as possible.
  • the power density of the incident light can be directly controlled as a parameter.
  • This control can optionally also include setting a heating rate that varies locally and/or over time.
  • the power density parameter is also easily accessible by measurement.
  • the heating rate is controlled based on the power density of the incident light.
  • the power density is between 2 W/cm 2 and 750 W/cm 2 , preferably between 4 W/cm 2 and 500 W/cm 2 , even more preferably between 5 W/cm 2 and 200 W/cm 2 , or between 10 and 150 W/ cm2 .
  • the power density is less than 800 W/cm 2 , for example not more than 750 W/cm 2 , not more than 700 W/cm 2 , not more than 650 W/cm 2 , not more than 600 W/cm 2 , not more than 550 W/cm 2 , not more than 500 W / cm 2 , not more than 450 W / cm 2 , not more than 400 W / cm 2 , not more than 350 W / cm 2 , not more than 300 W / cm 2 , not more than 250 W / cm 2 , not more than 200 W / cm 2 , not more than 150 W / cm 2 , not more than 100 W/cm 2 , or not more than 75 W/cm 2 .
  • the power density can be at least 1 W/cm 2 , at least 2 W/cm 2 , at least 4 W/cm 2 , at least 5 W/cm 2 , at least 10 W/cm 2 , at least 20 W/cm 2 , at least 30 W/cm cm 2 , at least 40 W/cm 2 , at least 50 W/cm 2 , or at least 60 W/cm 2 .
  • the maximum temperature of the ceramic in particular of the green body, can depend approximately on the 4th root of the power density as soon as a sample temperature has adjusted according to the power density of the incident light. For example, 5 W/cm 2 corresponds to approximately 750° C. and 200 W/cm 2 corresponds to approximately 1750° C. for an exemplary ceramic test body, in particular a green body. If the power density is above the power density required for the current temperature, the ceramic heats up. If the power density is reduced, the ceramic cools down. At high temperatures, a large part of the power density is used to compensate for the thermal energy radiated by the ceramic.
  • the power density is controlled in particular with a good temporal resolution, as a result of which very precisely defined power density profiles or temperature profiles are made possible.
  • the ceramic can be heated with a very high power density, which is then quickly adjusted to a lower value that corresponds to the current temperature.
  • the ceramic can be heated very quickly, with the maximum temperature being reached quickly and, in particular, very precisely.
  • the time in which the temperature is increased from 90% to 100% of the target temperature can be significantly reduced, in particular minimized, compared to conventional methods such as a conventional oven, and at the same time the target temperature can be prevented from being exceeded.
  • the technical control of the power density thus enables almost any temperature profile, in particular with rapid temperature changes.
  • the local (and/or temporal) variation of the temperature profile allows locally varying properties and dislocation densities to be set in the ceramic material. This enables the user to design the temperature profile much more freely. In this way, complex temperature profiles are preferably also possible.
  • the power density can preferably be switched on and off with a particularly short time delay, or it can be dosed as desired.
  • the switching speeds that can be achieved are determined by the lights and the optics used and can be, for example, 1 second or less, preferably 1 millisecond or less. "Switching speed" preferably means the time required to switch the lighting on and off again. Alternatively or in addition, the switching can also be controlled by the optics, while the lamp shines continuously, for example.
  • the change in power density is between 1%/s and 100,000%/s, preferably from 100%/s and 10,000%/s.
  • these rates of change can be achieved in the range from 50% to 100%, preferably from 75% to 100%, more preferably from 90% to 100% of the sintering temperature.
  • the power density can be reduced by more than 80% in less than 10 s, preferably in less than 1 s, preferably less than 10 ms, and preferably switched off completely.
  • the ceramic starting material is heated, in particular in certain areas, by irradiating light for a period of (a) at least 0.25 seconds, preferably at least 3 seconds, preferably at least 20 seconds, and/ or (b) a maximum of 10 minutes, preferably a maximum of 8 minutes, preferably a maximum of 5 minutes, preferably a maximum of 3 minutes, preferably a maximum of 1 minute, preferably a maximum of 30 seconds, preferably a maximum of 10 seconds, preferably a maximum of 5 seconds, preferably a maximum of 3 seconds, preferably a maximum 1 second, done.
  • the process is also particularly suitable for large-scale production.
  • the period is a maximum of 10 minutes, preferably a maximum of 1 minute, preferably a maximum of 10 seconds,
  • the period of time is between 0.1 second and 10 minutes, preferably between 1 second and 1 minute, preferably between 2 seconds and 30 seconds.
  • the locally generated dislocations have a density of 10 5 /cm 2 or more, preferably 10 6 /cm 2 or more, preferably 10 7 /cm 2 or more, preferably 10 8 /cm 2 or more, preferably 10 9 /cm 2 or more, preferably 10 10 /cm 2 or more, preferably 10 11 /cm 2 .
  • the method is not only particularly easy to implement, but also allows correspondingly high dislocation densities.
  • the dislocation densities given are those that are generated locally.
  • the dislocation densities given are dislocation densities that are sufficient for the at least locally generated dislocations.
  • dislocation densities relate to an area of 1 pm 2 , 1 cm 2 or 1 m 2 of the ceramic. For larger areas, the density can be tested locally at ten representative locations, for example.
  • the power density of the incident light is (a) between 1 W/cm 2 and 750 W/cm 2 , more preferably between 5 W/cm 2 and 150 W/cm 2 , and/or (b) a defined or definable one Target value with an accuracy of better than 10%, better than 5%, better than 2% or better than 1% in less than 5 seconds, preferably in less than 2 seconds, more preferably in less than 1 second, more preferably in less than 0.5 seconds, more preferably less than 0.1 second, and thereafter stabilized; and or
  • the power density and/or the temperature profile can be designed freely.
  • the invention also relates to ceramic products without dislocations.
  • the ceramic starting material has at least one ceramic layered composite, at least one ceramic composite material and/or at least one ceramic powder, and/or in the form of a foil, an endless strip, a preferably cuboid or round compact and /or is provided as a solid.
  • the ceramic starting material can be handled particularly well and safely by being provided as a compact or as a solid.
  • a compact can, for example, comprise or represent ceramic material in powder form pressed to form a ceramic body.
  • a green body within the meaning of the present application can be a blank made of ceramic powder before sintering, which is produced, for example, by means of pressing processes.
  • a Green bodies within the meaning of the present application can also be a blank before sintering, which is produced by means of liquid-based methods such as slip casting.
  • a green body within the meaning of the present application can also be a blank before sintering, which is produced using cast foils.
  • the ceramic starting material is provided in the form of an endless belt and/or moved relative to the light source.
  • the thickness of the ceramic starting material is between 0.00005 mm and 15.0 mm, preferably between 0.001 mm and 10.0 mm, preferably between 0.1 mm and 5 mm, preferably between 0.5 mm and 4.0 mm ;
  • the ceramic starting material has or consists of SrTi0 3 and/or PO2 as material and/or wherein the ceramic product has or is a ceramic membrane;
  • the ceramic starting material comprises one or more of the following materials:
  • sintering processes can be carried out at high temperatures in non-metallic-inorganic materials. This is also possible when a crystalline structure is predominantly absent.
  • ceramic or glass fibers can be sintered into a solid and highly porous block.
  • One example is the composite of highly porous embedded glass fiber with a dense top layer, which is used as a heat protection tile for spacecraft re-entry into the atmosphere.
  • These components are known from the space shuttle, for example, and will also be used in new and future space vehicles such as the SpaceX Starship.
  • the heat transfer medium With lighting as the heat transfer medium, the starting material can be produced particularly quickly and in an energy-saving manner.
  • the cover layer and the volume body can be heated differently.
  • the production temperature is not limited by an oven, which means that it can be set higher. As a result, the choice of material can be improved, which enables higher operating temperatures.
  • Ceramics with preferred thicknesses are relevant for common applications. Ceramics with preferred thicknesses can be sintered with simple and readily available lamps and a high dislocation density can be achieved. Because the heating of the ceramic material by the light used can then be controlled particularly well. It is therefore preferable that the method is used for manufacturing thin ceramics.
  • the thickness of the finished ceramic may differ from that of the ceramic starting material. For example, a reduction in thickness of, for example, 40% takes place during the sintering process.
  • the thickness of the ceramic starting material is preferably 20 mm or less, 5 mm or less, preferably 2 mm or less, preferably 1.0 mm or less, preferably 0.1 mm or less, preferably 0.02 mm or less less, preferably 0.01 mm or less, preferably 0.005 mm or less.
  • the thickness is 0.0002 mm or more, preferably 0.002 mm or more, preferably 0.01 mm or more, preferably 0.05 mm or more, preferably 0.1 mm or more, for example 0.2 mm or more, 0 .5 mm or more, or 1.0 mm or more.
  • the ceramic can have a thickness of between 0.001 mm and 5 mm, in particular between 0.01 mm and 2 mm.
  • the ceramic product can have a membrane, in particular a thin membrane.
  • This membrane, in particular thin membranes, can preferably have the thicknesses mentioned above.
  • At least one surface, in particular a side surface, preferably the main side surface, of the ceramic starting material is illuminated, preferably completely or partially, by the light.
  • the ceramic material can even be completely heated in one operation and thereby processed in its entirety, in particular sintered and/or provided with dislocations.
  • the main side surface is preferably to be understood as meaning the side surface of the ceramic starting material with the largest surface area, such as in particular a compact or solid body.
  • the light is irradiated in parallel and/or sequentially, in particular with a relative, preferably continuous, displacement of the ceramic material relative to the incident light, onto a number of areas, in particular surface areas, of the ceramic starting material, in order thereby to places to create dislocations in the ceramic product;
  • a defined geometry in particular with a large area, is generated by the irradiation in a heated zone, which is square or whose shape can be configured freely by the user;
  • the temperature profile can be controlled locally and/or as it varies over time.
  • the irradiation takes place in parallel, several light sources can be used, for example. Large areas can thus also be quickly processed, in particular heated, and/or high heating rates can be achieved even over a large area and/or the volume regions located underneath.
  • the irradiation takes place in such a way that the temperature profile generated in the ceramic material varies locally in order to obtain temperature gradients and/or patterns of dislocation densities.
  • a local power density variation can be carried out for this purpose.
  • (i) has wavelengths in the visible wavelength range or in the non-visible wavelength range, in particular in the UV range or in the visible range, preferably has only those
  • At least one light source in particular having at least one light-emitting diode, at least one Xe flash lamp, at least one laser, at least one UV lamp, at least one medium-pressure UV lamp and/or at least one metal vapor lamp, at least one halogen lamp, at least one infrared heater, is emitted,
  • (iii) is directed by an optic onto the ceramic starting material and/or, preferably onto the area to be heated, is focused, and/or
  • each light source may preferably be an individual type of light source. Because the light is radiated in from outside and impinges on a surface of the ceramic starting material, a volume area adjoining the surface also heats up very reliably.
  • the light can be radiated in from above, from below and from both sides, particularly in the case of a flat ceramic.
  • the light can only be irradiated from one side.
  • the side from which no light is radiated can be open or covered or provided with a mirror.
  • a design in horizontal or vertical orientation is possible, as well as any angle.
  • a light source preferably has: one or more light-emitting diodes, one or more lasers (in particular with a wavelength in a range from 200 nm to 700 nm, for example 300 nm to 600 nm or 400 nm to 500 nm), one or more Xe flash lamps (in particular in quasi-continuous multi-pulse operation), one or more UV lamps, in particular one or more medium-pressure UV lamps and/or one or more metal vapor lamps or one or more halogen lamps or infrared lamps.
  • one or more light-emitting diodes one or more lasers (in particular with a wavelength in a range from 200 nm to 700 nm, for example 300 nm to 600 nm or 400 nm to 500 nm), one or more Xe flash lamps (in particular in quasi-continuous multi-pulse operation), one or more UV lamps, in particular one or more medium-pressure UV lamps and/or one or more metal vapor lamps or one or more halogen lamps or inf
  • the invention can be implemented using a laser as the light source.
  • a laser can also be used in addition to and/or simultaneously with another light source in order to be able to produce patterns with nuances.
  • a diode laser preferably made up of a plurality of diodes, in particular diode stacks, with a homogeneous intensity distribution is preferably used here.
  • the object is achieved by the invention according to a second aspect in that a
  • the device in particular (i) for producing ceramics (with or without dislocations), (ii) for carrying out the method according to the first aspect of the invention and/or (iii) set up to carry out the method according to the first aspect of the invention , the device having at least one receptacle for receiving a ceramic starting material and at least one light source for radiating light onto the ceramic starting material received or that can be accommodated in the holder, with the device preferably being set up to radiate the light onto the ceramic starting material in order to heat it up at least in certain areas and thereby produce a ceramic product, and wherein the holder has a Has insulation is proposed.
  • the insulation should be sufficiently stable even against the illumination for the necessary process time.
  • the thermal conductivity of the insulation at 1400°C can be less than 400 W/(m*K), at most 50 W/(m*K), at most 20 W/(m*K), at most 10 W/(m*K). ), not more than 5 W/(m*K), not more than 2 W/(m*K), not more than 1 W/(m*K), not more than 0.5 W/(m*K), or not more than 0.25 W /(m*K).
  • the thermal conductivity of the insulation can be, for example, at least 0.01 W/(m*K), at least 0.05 W/(m*K), at least 0.1 W/(m*K), or at least 0.2 W/( m*K).
  • the density of the insulation can be, for example, in a range from 0.05 to 0.25 g/cm 3 , in particular in a range from 0.10 to 0.15 g/cm 3 , for example around 0.12 g/cm 3 .
  • the insulation preferably allows a maximum of 50 W/cm 2 , a maximum of 15 W/cm 2 , or a maximum of 5 W/cm 2 heat flow from the ceramic starting material and/or the ceramic product.
  • Ceramic wool or expandable graphite for example, can be used as insulation. Expandable graphite is particularly preferred because it reacts less with the ceramic than ceramic wool.
  • Advantageous insulation can also include or consist of a noble metal.
  • a noble metal high-melting precious metals are particularly preferred.
  • the insulation may include or consist of a material selected from the group consisting of iridium, platinum, rhodium, ruthenium, osmium, rhenium, tungsten, tantalum, molybdenum, hafnium, and alloys of two or more thereof. Iridium and platinum and alloys thereof are particularly preferred. Iridium is very particularly preferred.
  • the insulation can be in the form of a wool, a net and/or a foil.
  • the insulation preferably comprises a material selected from the group consisting of one or more noble metals, expandable graphite, ceramic wool, in particular aluminum oxide, and combinations of two or more thereof.
  • the insulation preferably has a thickness in a range from 0.25 to 5.0 cm, from 0.5 to 3.0 cm, from 0.75 to 2.5 cm, or from 1.0 to 2.0 cm .
  • the thickness of the insulation may be at least 0.25 cm, at least 0.5 cm, at least 0.75 cm, or at least 1.0 cm.
  • the thickness of the insulation can be, for example, at most 5.0 cm, at most 3.0 cm, at most 2.5 cm, or at most 2.0 cm.
  • the insulation can also be realized in the form of a gas film.
  • the insulation can include or consist of a gas film.
  • gas can flow through holes in a metal plate, forming a gas film on which the ceramic then floats.
  • the insulation ensures a particularly homogeneous temperature distribution, which in turn is associated with particularly homogeneous material properties.
  • the insulation enables the method to be carried out at comparatively low power densities, since an unwanted loss of energy can be avoided or at least drastically reduced.
  • expandable graphite is particularly well suited. Expandable graphite is not suitable for conventional sintering in the furnace as it would burn up completely. However, expandable graphite withstands the short sintering times and relatively low power densities of the present invention excellently.
  • a gas film on which the ceramic floats can also serve as an insulating base. The amount of heat dissipated by the substrate is a dynamic quantity as the temperature changes. In case a target temperature is held for many seconds, a 1 cm thick copper pad with a thermal conductivity of 400 W/mK could dissipate about 6000 W/cm 2 .
  • the thermal radiation emitted by the ceramic can be reflected back onto the ceramic during sintering using a mirror system.
  • a mirror system for example, a parabolically or elliptically shaped and/or gold-coated mirror can be used.
  • the device can have a plurality of light sources. If the device comprises multiple light sources, each light source can preferably be an individual type of light source.
  • the illumination described in relation to the first aspect of the invention for example in the form of a compact, and received or can be received in the receptacle can be carried out with a plurality of light sources.
  • the device can also have an optical system. This allows the lighting of the material to be adjusted.
  • the optics can have lenses, mirrors and/or the like.
  • the device can also have control means that make it possible to determine the heating rate of the heating, the irradiation period and/or the illuminated area and the irradiation of the light, in particular with regard to the heating rate, the period of time and/or the illuminated area area to control accordingly, in particular to regulate and/or control.
  • the method is implemented using a particularly flexible device.
  • the small size, comparable to a shoebox, and the possibility of operating the device with a standard socket connection (230 V, 16A in Germany) enables cost-effective use, e.g. on the table, in dental laboratories, small art workshops or in glove boxes, which are used in laboratories for air-sensitive materials be used.
  • a stack of light-emitting diodes is attached as a central component within a housing that protects the environment from the light used. These illuminate the ceramic product, which is positioned on a changeable insulation. This can be easily removed, which is made possible, for example, by a pull-out drawer.
  • the light-emitting diodes preferably emit UV light, preferably with a wavelength of 375 nm or 450 nm.
  • the light-emitting diodes are connected to a water-cooled thermal sink, whereby the emitted light can be bundled with micro-lenses and lenses to improve power density. They are preferably arranged above the ceramic and can alternatively or additionally be attached at other angles.
  • the temperature is read out by a suitable pyrometer, with an active control circuit preferably being present between the pyrometer data and the power density.
  • the power supply, control and cooling of the light-emitting diodes can be accommodated in the same housing or alternatively installed in a separate box with a connection through cables and hoses.
  • the peak load of the power supply can be significantly reduced by using a suitable intermediate energy store.
  • a power of at least 4 kW is required for a power density of 50 W/cm 2 on an area of 80 cm 2 . This exceeds the maximum power of an ordinary socket.
  • an energy storage device can provide 8 kW for 30 seconds and then be recharged over a few minutes with significantly less power.
  • an ordinary car starter battery can be used, which allows several lights before it has to be charged.
  • the processing space is preferably designed in such a way that the base can be replaced by other devices.
  • a pad with insulation in a gas-tight chamber. This can let the light shine in through a quartz glass window on the upper side, but can specifically control the atmosphere, for example with a continuous gas flow with a gas such as air, oxygen, argon, nitrogen or forming gas.
  • a fused silica disk also protects the device from contamination.
  • the object is achieved by the invention according to a third aspect in that a ceramic product (with or without dislocations), in particular manufactured and / or manufacturable with the method according to the first aspect of the invention and / or with the device according to the second aspect of the Invention, which in particular has an at least partially sintered microstructure is proposed.
  • the ceramic product can have a sintered microstructure.
  • the ceramic product may have a partially sintered microstructure or a fully sintered microstructure.
  • the ceramic product can, for example, at least locally, have dislocations with a density of 10 5 / cm 2 or more, preferably 10 6 / cm 2 or more, preferably 10 7 / cm 2 or more, preferably 10 8 /cm 2 or more, preferably 10 9 /cm 2 or more, preferably 10 10 /cm 2 or more, preferably 10 11 /cm 2 .
  • a ceramic product that has such a high dislocation density can be produced for the first time ever using a method according to the invention.
  • the local dislocation density is preferably 10 9 /cm 2 or more, particularly 10 10 /cm 2 or more.
  • a ceramic product according to the invention can contain nanopores. This applies in particular if the ceramic product PO2, BaTiCh, YSZ (Yttria-stabilized zirconia) or Lio . sLao TiOs has as a material.
  • the ceramic product preferably has a porosity such that in a transmission electron microscopic (TEM) image on an area of 100 ⁇ m 2 there are at least 2 nanopores, more preferably at least 4 nanopores, more preferably at least 8 nanopores, more preferably at least 10 nanopores, more preferably at least 12 nanopores, more preferably at least 15 nanopores, more preferably at least 20 nanopores are present, especially when the sample thickness is 250 nm.
  • TEM transmission electron microscopic
  • the number of nanopores can be, for example, at most 150 nanopores, at most 100 nanopores, at most 75 nanopores, at most 50 nanopores, at most 40 nanopores, or at most 30 nanopores on an area of 100 ⁇ m 2 , in particular with a sample thickness of 250 nm
  • Nanopores preferably range from 2 to 150 nanopores, from 4 to 150 nanopores, from 8 to 100 nanopores, from 10 to 75 nanopores, from 12 to 50 nanopores, from 15 to 40 nanopores, or from 20 to 30 nanopores on one Area of 100 pm 2 , especially with a sample thickness of 250 nm.
  • Nanopores Two types can be distinguished in TEM images. There are pores that extend through the entire sample thickness. These pores appear white. Other pores do not extend through the entire sample thickness and therefore appear less white to light greyish. Both types of nanopores are counted for the evaluation of the number of nanopores according to the invention.
  • the number of observed nanopores depends on the sample thickness. In particular, the number of visible nanopores increases with sample thickness. However, even with a sample thickness of virtually zero, the void count itself is not zero. Even a minimally thin layer still shows a minimum of pores. Regardless of the sample thickness, the number of nanopores on an area of 100 ⁇ m 2 is preferably at least 2 nanopores, more preferably at least 4 nanopores, more preferably at least 8 nanopores, more preferably at least 10 nanopores, more preferably at least 12 nanopores, more preferably at least 15 nanopores , more preferably at least 20 nanopores.
  • the number of Nanopores per 250 nm sample thickness can be, for example, at most 150 nanopores, at most 100 nanopores, at most 75 nanopores, at most 50 nanopores, at most 40 nanopores, or at most 30 nanopores on an area of 100 ⁇ m 2 regardless of the sample thickness.
  • sample thickness refers to the thickness of the sample being examined.
  • the sample thickness can be significantly less than the thickness of the ceramic product.
  • the sample can be obtained from the ceramic product by cutting out a lamella with a focused ion beam or by mechanical polishing followed by thinning with argon ions.
  • the number of nanopores is determined in five image sections, each of which is at least 50 ⁇ m 2 in size.
  • the number of nanopores in the sample per 100 ⁇ m 2 is determined as the mean value from the corresponding values of the five image sections.
  • the image section can also have a size of more than 100 ⁇ m 2 or a size of less than 100 ⁇ m 2 .
  • the number of nanopores per 100 pm 2 can then be easily extrapolated by calculation.
  • Nanopores can exist parallel to larger pores. However, porosity with larger pores is not desired and is preferably minimized. Nanopores, on the other hand, offer amazing advantages. Nanopores can be associated with various advantages, for example an improvement in electrical conductivity, in particular for PO2, and/or an improvement in ionic conductivity, in particular for YSZ. The ionic or electrical conductivity can increase, for example, by 10% or more compared to a ceramic with an identical composition but without nanoporosity.
  • the ceramic product according to the invention preferably shows a higher saturation polarization compared to a conventionally sintered sample of the same powder.
  • the saturation polarization of a ceramic product according to the invention preferably exceeds the saturation polarization of a conventionally sintered ceramic product of the same composition by at least 10%, more preferably by at least 20%, more preferably by at least 30%, more preferably by at least 40%.
  • the saturation polarization of a ceramic product according to the invention can exceed the saturation polarization of a conventionally sintered ceramic product of the same composition, for example by at most 100%, by at most 80%, by at most 70% or by at most 60%.
  • the saturation polarization of a ceramic product according to the invention can exceed the saturation polarization of a conventionally sintered ceramic product of the same composition by, for example, 10% to 100%, 20% to 80%, 30% to 70% or 40% to 60%.
  • “conventional sintering” for the ceramic BaTiCh means sintering in oxygen at 1220° C. for 5 hours with a heating and cooling rate of 10 Kelvin per minute.
  • “conventional sintering” means more generally sintering to a density of greater than 90% in a conventional furnace with heating and cooling rates in the range of 1 to 200 Kelvin per minute.
  • a comparison is preferably suitable when the grain sizes of the compared ceramics do not differ by more than a factor of two.
  • the ceramic product according to the invention has a saturation polarization of more than 12 pC/cm 2 .
  • the saturation polarization of the ceramic product according to the invention is at least 14 pC/cm 2 , more preferably at least 15 pC/cm 2 , more preferably at least 16 pC/cm 2 , more preferably at least 17 pC/cm 2 , more preferably at least 17.5 pC/cm 2 .
  • the saturation polarization may be, for example, at most 50 pC/cm 2 , at most 40 pC/cm 2 , at most 30 pC/cm 2 , at most 25 pC/cm 2 , at most 20 pC/cm 2 , or at most 18.5 pC/cm 2 .
  • the saturation polarization is preferably in a range from >12 to 50 pC/cm 2 , from 14 to 40 pC/cm 2 , from 15 to 30 pC/cm 2 , from 16 to 25 pC/cm 2 , from 17 to 20 pC/cm 2 cm 2 or from 17.5 to 18.5 pC/cm 2 .
  • the values for the saturation polarization mentioned in this paragraph relate in particular to the case that the ceramic product comprises or consists of BaTiCh.
  • the ceramic product according to the invention shows a significantly narrower hysteresis curve than the comparison sample. Due to the significantly lower coercivity (the minimum in the elongation) it is easier to switch than the reference sample and is therefore more interesting for actuator applications, for example.
  • the coercive field strength of a ceramic product according to the invention is preferably at most 50%, more preferably at most 40%, more preferably at most 30%, more preferably at most 25% of the coercive field strength of a conventionally sintered ceramic product of the same composition.
  • the coercivity of a ceramic product according to the invention can be, for example, at least 2%, at least 5%, at least 10% or at least 15% of the coercivity of a conventionally sintered ceramic product of the same composition.
  • the coercivity of a ceramic product according to the invention may be, for example, 2% to 50%, 5% to 40%, 10% to 30% or 15% to 25% of the coercivity of a conventionally sintered ceramic product of the same composition.
  • the coercive field strength of the ceramic product according to the invention is preferably in a range from 0.005 to ⁇ 0.19 kV/mm, from 0.01 to 0.15 kV/mm, from 0.02 to 0.10 kV/mm, or from 0 03 to 0.05kV/mm.
  • the coercive field strength is preferably less than 0.19 kV/mm, more preferably at most 0.15 kV/mm, more preferably at most 0.10 kV/mm, more preferably at most 0.05 kV/mm.
  • the coercive field strength can be at least 0.005 kV/mm, at least 0.01 kV/mm, at least 0.02 kV/mm, or at least 0.03 kV/mm, for example.
  • the values for the coercive field strength mentioned in this paragraph relate in particular to the case that the ceramic product comprises or consists of BaTiCh.
  • the elongation of a ceramic product according to the invention preferably exceeds the elongation of a conventionally sintered ceramic product of the same composition by at least 15%, more preferably by at least 25%, more preferably by at least 50%, more preferably by at least 70%.
  • the elongation of a ceramic product according to the invention may exceed the elongation of a conventionally sintered ceramic product of the same composition, for example by at most 150%, at most 125%, at most 100% or at most 90%.
  • the saturation polarization of a ceramic product according to the invention can exceed the saturation polarization of a conventionally sintered ceramic product of the same composition by, for example, 15% to 150%, 25% to 125%, 50% to 100% or 70% to 90%.
  • the elongation of the ceramic product is preferably in a range from >0.07% to 0.20%, from 0.075% to 0.175%, from 0.10% to 0.15%, from 0.11% to 0.14% , or from 0.12% to 0.13%.
  • the elongation of the ceramic product is preferably greater than 0.07%, more preferably at least 0.075%, more preferably at least 0.10%, more preferably at least 0.11%, more preferably at least 0.12%.
  • the elongation of the ceramic product can be, for example, at most 0.20%, at most 0.175%, at most 0.15%, at most 0.14%, or at most 0.13%.
  • the ceramic products according to the invention preferably have a high domain wall density. This allows many ferro- and dielectric properties to be adjusted. For example, the high domain wall density can contribute to the increase in elongation.
  • the ceramic product can be in the form of a membrane, particularly a thin membrane.
  • Functional ceramics are used as thin membranes in fuel cells, electrolytic cells, sensors, solid-state batteries, gas separation membranes, actuators and capacitors, for example.
  • these thin Membranes can be stacked as multilayers and also contain layers such as metallic electrodes.
  • the product according to the invention can preferably be used in fuel cells, electrolytic cells, sensors and/or solid-state batteries.
  • the thickness of the ceramic product is between 0.00005 mm and 20 mm, the ceramic product comprising or being a ceramic membrane and/or the ceramic product comprising or consisting of SrTiCh, and/or T1O2 as material; and or
  • the ceramic product comprises one or more of the following materials:
  • the ceramic material may contain or consist of a material selected from the group consisting of PO2, BaTiCh, YSZ, Lio .3 Lao Ti0 3 and combinations of two or more thereof.
  • Ceramics with preferred thicknesses are relevant for common applications.
  • the thickness of the ceramic starting material is preferably 20 mm or less, preferably 10 mm or less, preferably 5 mm or less, preferably 2 mm or less, preferably 1 mm or less, preferably 0.5 mm or less , preferably 0.05 mm or less.
  • the thickness is 0.001 mm or more, preferably 0.005 mm or more, preferably 0.01 mm or more, preferably 0.05 mm or more, preferably 0.1 mm or more.
  • the ceramic can have a thickness of between 0.001 mm and 20 mm, in particular between 0.005 mm and 15 mm, from 0.1 to 10.0 mm, from 0.2 to 8.0 mm, from 0.5 to 6 .0 mm, or from 1.0 to 5.0 mm, for example from 2.0 to 4.0 mm.
  • the ceramic product can have a membrane, in particular a thin membrane.
  • This membrane, in particular thin membranes, can preferably have the thicknesses mentioned above.
  • the ceramic product can in particular have a grain size gradient, texturing, high temperature resistance, particularly homogeneous material properties, and/or nanoporosity.
  • the grain size can change, for example, by more than a factor of three in less than 50 pm, preferably by more than a factor of five in less than 20 pm, preferably by more than a factor of 15 in less than 10 pm, in one direction and at the same time vary less than a factor of two in an orthogonal direction.
  • the particle size can preferably change gradually, in particular as in FIG. 4, or in steps, in particular as in FIG.
  • the difference in grain size preferably does not exceed a factor of 1000.
  • the porosity can go from less than 5%, particularly no open porosity, to greater than 15%, particularly open, percolating porosity, in less than 5 ⁇ m.
  • the texturing can be so significant that more than 15% of the grains are aligned with a deviation of less than 15°, preferably more than 20% of the grains with a deviation of less than 10° from a preferred axis.
  • the ceramic product of the invention may also be a laminate, particularly a multi-layer laminate.
  • the present invention also relates to a layered composite comprising or consisting of the ceramic product of the invention.
  • the present invention also relates to a capacitor comprising or consisting of the ceramic product of the invention.
  • the present invention also relates to a solid state battery comprising or consisting of the ceramic product of the invention.
  • the present invention also relates to the use of the ceramic product of the invention as or in a capacitor or solid state battery.
  • the method according to the invention optionally enables a very high density of dislocations.
  • the following tests were carried out by the inventors with the results indicated in each case: (1.) Simple sintering of a ceramic cup led to a dislocation density of up to 10 5 /cm 2 . (2.) Mechanical deformation led to a dislocation density of up to 10 8 /cm 2 . (3.) Flash sintering resulted in a dislocation density of up to 10 10 /cm 2 . (4.)
  • the proposed method can optionally achieve dislocation densities with orders of magnitude even greater than or equal to 10 10 /cm 2 .
  • the dislocation density can be improved by optimizing the temperature profile.
  • Fig. 1 shows a device according to the second aspect of the invention in a
  • Figure 2 shows a ceramic material used in the device of Figure 1; 3 shows a further device according to the second aspect of the invention in a perspective view;
  • FIG. 13 shows a further device according to the second aspect of the invention in a perspective view
  • Fig. 14 Transmission electron micrograph of a ceramic product with nanopores.
  • Example 1 Green body made from pressed SrTiCh powder
  • a disc-shaped green body made of SrTi0 3 powder with 99.99% purity is pressed with a thickness of 1 mm and a diameter of 6.4 mm at a pressure of 700 MPa.
  • the initial particle size of the powder is approximately 400 nm.
  • the green body is then illuminated from one side, preferably from above. On the underside, the green body lies on a thin layer of very porous aluminum oxide wool, for example 1 cm to 2 cm thick, or alternatively on a 1 cm or 2 cm thick layer of expandable graphite with a density of about 0.12 g/cm 3 .
  • the green body With the illumination, the green body is heated at a heating rate of 100 K/s to 500 K/s to or near below or above the sintering temperature, 1875°C, and held at this temperature for 25 seconds.
  • the sintering temperature is preferably exceeded or fallen short of by less than 15.degree.
  • the sintering temperature is preferably stabilized in less than 6 seconds.
  • the lighting is then switched off and the green body is cooled back down to room temperature.
  • the cooling from the sintering temperature to less than 1000 °C takes less than 3 seconds.
  • a diode laser stack with a wavelength of 450 nm, Xe flash lamp, halogen lamp, UV medium-pressure lamp or infrared lamp is preferably used for the illumination.
  • the power density is preferably 170 W/cm 2 when using a 450 nm wavelength diode laser stack.
  • a foil made of the material BaTiO ß is produced by foil casting.
  • the average particle size is less than or equal to 250 nm.
  • the binder is first burned out. Temperature profiles which require temperatures well below the sintering temperature and often require times in the range from minutes to hours are known from the prior art for the corresponding binder. As an alternative to a conventional oven, this step can optionally also be carried out with the aid of irradiation, in which case the power density should be selected to be low, for example 80% lower. As soon as the binder has burned out, the foil is heated to the sintering temperature using lighting.
  • the foil can, for example, float on a thin film of gas over a reflective surface, or alternatively lie on a 1 cm thick layer of expandable graphite and be illuminated from above. Alternatively, it can hang vertically and be irradiated from two sides, with the power density then having to be applied from both sides.
  • the lateral measurement is only limited by the size of the light source.
  • the foil can be moved relative to the light source or the light source can be moved relative to the foil.
  • the temperature profile or the power density can also be adjusted by the movement profile.
  • the relative movement of the film and light source enables a continuous strip to be processed.
  • the foil is heated to or near below or above the sintering temperature of 1150° C. to 1550° C. by the irradiation at 400 K/s and is kept at this temperature for 30 seconds.
  • the sintering temperature is preferably exceeded or fallen short of by less than 15.degree.
  • the sintering temperature is preferably stabilized in less than 6 seconds, for example in less than 2 seconds.
  • the lighting is then switched off and the green body is cooled back down to room temperature.
  • the cooling from the sintering temperature to less than 900 °C takes less than 3 seconds.
  • a diode laser stack with a wavelength of 450 nm, Xe flash lamp, UV medium-pressure lamp, halogen lamp or infrared lamp is preferably used for the illumination.
  • the power density is preferably about 92 W/cm 2 when using a diode laser stack with a wavelength of 450 nm.
  • a grain size gradient was created by laterally varying thermal contact with the substrate.
  • the irradiation was homogeneous.
  • the thermal contact with the substrate can also be homogeneous and the radiation can vary, or both the thermal contact and the radiation can vary.
  • a green body of 99.99% pure T1O2 with a thickness of about 150 ⁇ m was pressed. This was placed on a copper base with contact only at a small point or small points. As a result, these areas were cooled, with significantly less heat dissipation taking place in the free-floating areas. In these areas, the grain size is significantly larger with gradients towards the colder areas. Illumination was performed with a 450 nm wavelength diode laser stack at 200 W/cm 2 for 10 s.
  • FIG. 4 shows a correspondingly produced ceramic product with a grain size gradient.
  • a grain size gradient and texturing were created by different temperature profiles on the surface and inside the ceramic.
  • a green body of 99.99% pure T1O2 with a thickness of about 150 ⁇ m was pressed.
  • the different temperature profiles were generated by a temporal power density profile with a first power density in a range of 4350 W/cm 2 for a period of 20 ms, followed by a second power density in a range of 100 W/cm 2 for a period of 10 s.
  • the first lighting step no insulation was necessary because the temperature only reached the surface but not the volume.
  • an approximately 2 cm thick layer of expandable graphite with a density of approximately 0.12 g/cm 3 was used as the insulating substrate.
  • a virtually completely dense layer is formed on the surface with a thickness of about 20 ⁇ m and a grain size of about 15 ⁇ m and a thicker layer underneath with significantly smaller grains and very great porosity.
  • FIG. 7 shows a fracture surface after the first treatment step, that a large part of the grains extends through the entire thickness of the layer.
  • the grains in this layer have a preferred orientation which is referred to as texturing. This texturing was determined by means of electron diffraction for more than 5000 grains and is shown and quantified in FIG. Alternatively, the quantification can be given by a probability of a certain orientation range, which was determined here as a 16% probability for an orientation with less than 15° deviation from the 100 axis.
  • the second illumination step created a porous layer under the dense layer over the entire remaining thickness. This is preferably characterized by an open porosity which is gas-permeable, with the layer having mechanical integrity.
  • a special feature is that this combination of a dense and a porous layer can be manufactured from a previously completely homogeneous green body. Furthermore, the short and intensive illumination step, here the first step, can be carried out during the longer and less intensive illumination step, so that the entire processing can take place in one go and, for example, in 10 seconds or less.
  • Example 5 With the method of the invention, two ceramic starting materials, T1O2 and BaTiCh, which were pressed together as a powder in two layers, were sintered together into a ceramic product. A sharp interface was obtained.
  • FIG. 9 shows a correspondingly produced ceramic product.
  • a multilayer capacitor was fabricated using the method of the invention (see Figure 10).
  • the multilayer capacitor consists of ceramic BaTiCh and thin layers of platinum electrodes.
  • the BaTiCh layers were produced by means of tape casting, with the platinum electrodes being produced by means of screen printing.
  • the binder materials required for tape casting were burned out in a conventional oven at medium temperature.
  • the raw component was then placed on an approximately 2 cm thick insulation made of expanded graphite and illuminated from above.
  • the power density was 47 W/cm 2 for 5 seconds followed by 75 W/cm 2 for 20 seconds followed by 47 W/cm 2 for another 10 seconds.
  • FIG. 10 shows a polished cross section through the component thickness.
  • Example 7 relates to various temperature-time histories of the manufacture of a ceramic product using the method of the invention.
  • FIG. 11 shows the temperature dependence of the absorption of the incident light.
  • This example was performed on 1 mm thick pressed powder of lithium ion conductive Li 6.4 La 3 Zn .4 Tao .6 0i 2 ceramic.
  • FIG. 12 shows the temperature-time profile of a sample without any appreciable temperature dependence of the absorption of the incident light. This temperature curve was recorded in the experiment in Example 1.
  • Example 8 A disk-shaped green body made of T1O2 powder with 99.99% purity is pressed with a thickness of 1 mm and a diameter of 6.4 mm at a pressure of 700 MPa. The initial particle size of the powder is approximately 300 nm. The green body is then illuminated from one side, preferably from above. On the underside, the green body lies on a thin layer of very porous aluminum oxide wool, for example 1 cm to 2 cm thick, or alternatively on a 1 cm or 2 cm thick layer of expandable graphite with a density of about 0.12 g/cm 3 .
  • the green body With the illumination, the green body is heated at a heating rate of 100 K/s to 500 K/s to or near below or above the sintering temperature, 1600°C, and held at this temperature for 10 to 30 seconds.
  • the sintering temperature is preferably exceeded or fallen short of by less than 15.degree.
  • the sintering temperature is preferably stabilized in less than 6 seconds.
  • the lighting is then switched off and the green body is cooled back down to room temperature.
  • the cooling from the sintering temperature to less than 1000 °C takes less than 3 seconds.
  • a diode laser stack with a wavelength of 450 nm, Xe flash lamp, halogen lamp, UV medium-pressure lamp or infrared lamp is preferably used for the illumination.
  • the power density is preferably 115 to 135 W/cm 2 using a 450 nm wavelength diode laser stack.
  • the nanoporosity can preferably be checked with transmission electron microscopy or in a micrograph of a polished surface in a scanning electron microscope.
  • FIG. 14 shows a transmission microscopy image on which nanopores can be seen and individual ones are marked.
  • Reference number 39 marks a pore which extends over the entire observed sample thickness. The total number of pores observed cannot be less than the number of this type of pore.
  • Reference number 41 marks a pore which only extends over part of the observed sample thickness.
  • BaTiOs powder was calcined by conventional solid-state synthesis from stoichiometrically weighed T1O2 (99.9%) and BaCO 3 (99.95%) at 885 °C for 4 hours.
  • the raw materials were first ground with an attritor and then with a planetary ball mill.
  • the samples were pressed as described in Example 8 and then the reference sample was sintered in oxygen at 1220°C for 5 hours with a heating and cooling rate of 10 Kelvin per minute.
  • the other sample was irradiated according to the method described with a xenon flash lamp with a power density of less than 800 W/cm 2 for 15 s.
  • the hysteresis curves of polarization and strain were measured in parallel with a Sawyer and Tower measurement circuit for polarization and an optical displacement sensor for strain. In addition, the measurement was carried out bipolar up to a field strength of 1.5 kV/mm or -1.5 kV/mm. Figures 15 and 16 were measured at a frequency of 100 Hz.
  • the solid lines marked with reference numerals 43 and 47 represent the measured polarization and strain of the sample sintered with the xenon flash lamp, reference numerals 45 and 49 those of the reference sample.
  • Example 10 one reference sample was sintered conventionally and one sample was sintered with the xenon flash lamp.
  • the ceramic according to the invention was post-treated with an aging step at 800° C., with the heating and cooling rate being 5 K/min. All other synthesis parameters can be taken from example 8 and 9.
  • the samples were then polished with diamond paste with a particle size of 15 ⁇ m, 6 ⁇ m, 3 ⁇ m, 1 ⁇ m and 0.25 ⁇ m and then vibration-polished for several hours.
  • a domain structure can also be visualized using transmission electron microscopy, as shown in FIG.
  • FIG. 1 shows a device 1 according to the second aspect of the invention.
  • the device 1 has a receptacle 3 which accommodates a powdery ceramic starting material 5 .
  • the receptacle 3 is a base on which the ceramic material 5 rests.
  • the ceramic material 5 is a cuboid or foil-like green body.
  • the device 1 also has a light source 7 .
  • the light source 7 is a halogen lamp that emits light in the infrared wavelength range.
  • the device 1 is set up to carry out the method according to the first aspect of the invention.
  • the incident light is then changed so that the light 9 from the light source 7 is incident on a surface region 11b of the ceramic material 5 and the ceramic material 5 is sintered there as well and optionally a high dislocation density is generated.
  • the light irradiation is changed, for example, by means of a monitoring and control unit, not shown in FIG. 1, which can have one or more sensors, such as temperature sensors and optical sensors.
  • the ceramic material 5 can then be removed in the form of the ceramic product then produced.
  • FIG. 2 shows a top view of the ceramic material 5 held by the holder 3 (not shown in FIG. 2).
  • the two surface areas 11a and 11b are shown therein, being shown at a distance from the edge of the compact 5 for better visibility.
  • the ceramic material 5 is thus sequentially first heated in the surface area 11a and then in the area 11b by light irradiation (to be more precise, of course, above all the underlying volume area of the material). While in the present case the incident light passes, so to speak, from the surface area 11a to the surface area 11b, other implementations are also possible.
  • light could be radiated onto the surface areas 11a and 11b at the same time. Either by using a second light source or by expanding the light from the light source 7 .
  • the green body 5 could also be moved continuously relative to the light cone 9 . Then the green body 5 could, viewed relatively, be moved into the light cone 9 and thus be illuminated in the surface region 11a after a certain time. While the relative movement continues, the green body 5 could be illuminated after a certain time in the surface area 11b and then the green body 5 could be moved out of the light cone 9 again when viewed relatively.
  • FIG. 3 shows an embodiment of a device according to the second aspect of the invention, in which a ceramic material 5 in sheet form is moved relative to the illumination.
  • the ceramic material 5 can be used in the form of an endless belt, in which case the ceramic material 5 can also be a layered composite.
  • Light sources 13 of the same type or (as envisaged in FIG. 3) of different types can be installed on one or two sides.
  • the light is directed onto the ceramic material 5 by optics 15 suitable for the respective light source 13 .
  • the beam path 17 and the illuminated zone 19 are sketched schematically in FIG. 3 .
  • the temperature profile is controlled individually by the shape of the respectively illuminated zone 19, the temporal variation of the intensity and by the relative movement of the beam path 17 or the light source 13 and the ceramic material. Furthermore, the temperature profile can be optimized by using several illuminated zones, which can also be used overlapping.
  • FIG. 4 shows an electron micrograph of a ceramic product with a grain size gradient. Large grain sizes with a diameter in the range of 100 pm can be seen on the left-hand side. Significantly smaller grain sizes can be seen on the right-hand side. The scale bar is about 250 pm.
  • Figures 5 and 6 show electron micrographs of a ceramic product having a stepwise density gradient. Underneath a dense surface layer is a porous volume. The scale bar is 100 pm in Figure 5 and 50 pm in Figure 6.
  • FIG. 7 shows an electron micrograph of a ceramic product in which only the surface has been treated, which is a precursor to the ceramic product in Figures 5 and 6. A fracture surface is shown. Here it becomes clear that the grains of the dense layer extend through the entire layer thickness.
  • FIG. 8 shows a quantification of the texture of titanium dioxide, which is also shown in FIGS. 5 and 6. It shows the probability with which the crystal structure of the grains is oriented in a certain direction.
  • the center of the circle is the 100 direction.
  • the orientation is 90° different from the 100° direction, with two orthogonal directions A1 and A2 being drawn in.
  • the black lines delimit areas in which there is a certain orientation probability.
  • the lines each represent numerical values of multiples of a statistical probability (English: "times random"). From the outside in, the values for the lines are 0.71; 1 ; 1.41; 2; 2.83 and 4.
  • FIG. 9 shows an electron micrograph of a ceramic product made from two ceramic starting materials. A sharp demarcation can be seen. The scale bar is 5 pm.
  • FIG. 10 shows an electron micrograph of a multilayer capacitor produced by the method of the invention. Metallic conductor structures can be seen between the ceramic parts.
  • the scale bar is 200 pm.
  • Figures 11 and 12 show temperature-time curves for the manufacture of a ceramic product by the method of the invention.
  • the arrangement used to measure the temperature consisting of a pyrometer for the temperature range from 500 °C to 3000 °C, no temperatures below 500 °C could be detected. A value of 500°C is therefore always shown in the curves for temperatures of ⁇ 500°C.
  • FIG 13 shows an apparatus according to the second aspect of the invention.
  • the device has a power supply, an energy buffer store,
  • Control technology and water cooling which can be accommodated in an enclosure 21.
  • This can be connected with cables and hoses to another light-shielding housing 25 in which light-emitting diodes and the ceramic material are located.
  • the light-emitting diodes 27 are arranged as densely as possible and, in addition to the power supply, are connected to a water-cooled thermal sink.
  • the arrangement of the light-emitting diodes 27 is mounted above a device for easy changing of the ceramic material 29. This consists of an exchangeable insulation 31 on which the ceramic material 33 can be placed.
  • the housing 25 can have a cooling system 35 by a fan, for example. Furthermore, the device can have a pyrometer 37 which can read the temperature of the surface of the ceramic.
  • Nanopores 39 and 41 are marked thereon as an example.
  • a nanopore 39 can extend over the entire observed sample thickness.
  • a nanopore 41 can also only make up part of the sample thickness.
  • the scale bar is 2 pm.
  • 16 shows a hysteresis curve of strain versus electric field for the inventive ceramic product 43, in this case BaTiOs, and a reference sample 45, also BaTiOs.
  • FIG. 17 shows an atomic force micrograph in the piezo mode of a ceramic according to the invention which was produced without an aging step.
  • the length of one side of the square images is 10 pm.
  • the contrast is created by deflecting a conductive atomic force microscope tip.
  • the inverse piezoelectric effect is used to map the domain structure.
  • FIG. 19 shows a hysteresis curve of the strain as a function of the electric field for the ceramic product according to the invention, in this case BaTiOs, without an aging step 51 and after an aging step 55 and a reference sample 53, also BaTiOs.

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Abstract

La présente invention concerne un procédé et un dispositif de fabrication de céramiques et un produit céramique. Le procédé comporte les étapes suivantes : application de lumière sur un matériau de départ céramique pour chauffer celui-ci au moins partiellement et produire ainsi un produit céramique, l'application de lumière étant effectuée simultanément sur une surface d'au moins 0,1 mm2 et/ou sur plus de 20 % de la surface du matériau de départ céramique, et la densité de puissance de la lumière appliquée étant inférieure à 800 W/cm2, le dispositif présentant : au moins un logement pour recevoir un matériau de départ céramique et au moins une source de lumière pour l'application de lumière sur le matériau de départ céramique logé ou pouvant être logé dans le logement, le dispositif étant de préférence conçu pour appliquer la lumière sur le matériau de départ céramique pour chauffer celui-ci au moins partiellement et produire ainsi un produit céramique, le logement présentant une isolation.
EP22714404.5A 2021-03-12 2022-03-11 Procédé et dispositif de fabrication de céramiques et produit céramique Pending EP4304857A1 (fr)

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