DE102021130349A1 - Process and device for the production of ceramics and ceramic product - Google Patents

Abstract

The present invention relates to a method and an apparatus for producing ceramics with dislocations and a ceramic product.

Description

The present invention relates to a method and an apparatus for producing ceramics and a ceramic product.

State of the art

It is known from the prior art that ceramics are regularly produced from ceramic powder, which is then connected by sintering. During sintering, the temperature is increased, causing the components of the powder to combine to form the finished ceramic. The powder is typically heated in sintering furnaces to obtain the ceramic. This also applies to so-called functional ceramics. These fall into a special class of ceramic materials that have special technical properties.

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 (e.g. with Si 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.

There is therefore still a desire to make ceramics and their production more efficient.

It is therefore the object of the present invention to specify a method and a device with which the disadvantages of the prior art can be overcome and which in particular allow more efficient ceramics to be produced. It is also an object of the present invention to specify a ceramic that overcomes the disadvantages of the prior art.

Description of the invention

• Einstrahlen von Licht auf ein keramisches Ausgangsmaterial, um dieses zumindest bereichsweise aufzuwärmen und dadurch ein keramisches Produkt zu erzeugen, wobei das Einstrahlen von Licht simultan, also gleichzeitig, auf einer Fläche von mindestens 0,1 mm² und/oder auf mehr als 20% der Fläche des keramischen Ausgangsmaterials erfolgt und wobei die Leistungsdichte des eingestrahlten Lichtes weniger als 800 W/cm² beträgt.

The object is achieved by the invention according to a first aspect in that a method for producing ceramics, 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 suggested.

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.

In addition to the irradiation of light described above, 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. at the same time, on more than 50% of the surface of the ceramic starting material and 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 , at most 7000 W/cm ² , or at most 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.

In a preferred embodiment, 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. For example, with 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 ) for 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. As a result, 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. Furthermore, 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".

Preferably, 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.

• • Erzeugung eines Korngrößengradienten,
• • Erzeugung einer Texturierung,
• • Erzeugung einer verbesserten Temperaturbeständigkeit, insbesondere bei besonders hohen Temperaturen,
• • Erzeugung homogener Materialeigenschaften,
• • Reduktion der Prozesszeit,
• • Genauere Kontrollierbarkeit des Prozesses, insbesondere Realisierung sehr schneller Profile,
• • Energieersparnis, insbesondere im Kleinserienbereich, selbst bei der Herstellung dickerer Keramiken, und/oder
• • Beschleunigung, Vergünstigung, Vereinfachung von Entwicklung, insbesondere von Kleinserien.

By using light to heat the powder material, on the one hand 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. At the same time, the process is surprisingly much easier to carry out than the conventional production of ceramics. At the same time, 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.

• • Generation of a grain size gradient,
• • Creation of a texturing,
• • Generation of improved temperature resistance, especially at particularly high temperatures,
• • generation of homogeneous material properties,
• • Reduction of the process time,
• • More precise controllability of the process, in particular the realization of very fast profiles,
• • Energy savings, especially in small series, even when producing thicker ceramics, and/or
• • Acceleration, discounts, simplification of development, especially of small series.

A grain size gradient and/or texturing can be generated by different temperature profiles on the surface and inside the ceramic. For example, the method can include a temporal and/or spatial power density profile. A favorite temporal lei The power density profile comprises, for example, a power density in a range from 800 W/cm ² to 20,000 W/cm ² , for example 4350 W/cm ² for a period of 0.2 to 200 ms, for example 20 milliseconds, followed by or in parallel with a further power density in a range from 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. This allows a ceramic product to be produced which has a grain size gradient and/or a texturing. In particular, it is possible to obtain a ceramic product containing a porous volume under a densely sintered surface layer. The high first power density leads to the formation of the densely sintered surface layer. Due to the short time with which the first power density is 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 μm. 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.

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. As a result, 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. Depending on the primary diffusion path, the creep rate is proportional to 1/grain size ² (Nabarro-Herring creep) or 1/grain size ³ (Coble creep). This opens up new areas of application for ceramic products in which conventionally manufactured ceramics can only be used to a limited extent due to their lower temperature stability increased by a factor of 100 to 1000, thus extending the service life of the ceramic by a similar amount.

With the present method, a temperature of at least 1400 °C, at least 1500 °C, at least 1600 °C, at least 1700 °C, at least 1800 °C, at least 1900 °C, or at least 2000 °C is achieved in the ceramic starting material and/or in the ceramic product °C reached. 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. to 3000° C., from 1200° C. to 2800° C., from 1400 °C to 2700°C, from 1500°C to 2600°C, from 1600°C to 2500°C, from 1700°C to 2400°C, from 1800°C to 2300°C, from 1900°C to 2200° C, or from 2000°C to 2100°C.

In a preferred embodiment, the ceramic is heated to at least 1800°C or even significantly higher, e.g. 2500°C, during the sintering process. In this case, insulation made of expandable graphite is used, for example. In particular, such an extremely high temperature can be reached in an ordinary atmosphere without great technical effort. As a result, 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.

With the method of the invention, 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. On the one hand, this is due to the thermal decoupling of the green body by insulation from the substrate, for example by floating on a gas membrane. On the other hand, 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.

In addition, 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.

The use of light instead of an oven can come with a reduction in process time connected by a factor of 1000. In addition, an energy saving of, for example, 20% to 99% can be achieved. An energy saving can be translated into a corresponding CO ₂ saving. Another advantage is that electric power can be used, which can be purchased sustainably. Gas/oil are not available on a large scale CO ₂ 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.

In a preferred embodiment, 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.

In a preferred embodiment, 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.

In a preferred embodiment, at least two sides are illuminated.

In a particularly preferred embodiment, 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.

The process also makes it possible to produce complete components, such as multilayer capacitors, in a single sintering process.

• • die Beständigkeit der Keramik gegen Risse;
• • die Verformbarkeit der Keramik, insbesondere die Hochtemperaturverformbarkeit;
• • die Bruchzähigkeit der Keramik;
• • das Verschleißverhalten der Keramik;
• • die katalytische Aktivität der Keramik;
• • die elektro-optischen Eigenschaften der Keramik;
• • die elektrische, ionische und/oder thermische Leitfähigkeit der Keramik; und
• • ferroelektrische und/oder halbleitende Eigenschaften der Keramik.

In a further aspect, at least locally dislocations can be produced with the method of the invention. A high density of such dislocations in ceramics is particularly important for their performance. Dislocations allow the functional and mechanical properties of ceramics to be improved and/or specifically adjusted. The properties of a ceramic that can be influenced, in particular improved, with dislocations include the following:

• • the resistance of ceramics to cracks;
• • the deformability of the ceramic, in particular the high-temperature deformability;
• • the fracture toughness of the ceramic;
• • the wear behavior of the ceramic;
• • the catalytic activity of the ceramic;
• • the electro-optical properties of the ceramic;
• • the electrical, ionic and/or thermal conductivity of the ceramic; and
• • ferroelectric and/or semiconducting properties of the ceramic.

But also secondary properties of 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.

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.

Furthermore, 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.

By radiating in light, a controlled and/or controllable temperature profile can preferably be set within the ceramic. For example, this can be a spatial temperature profile within the ceramic. As a result, a particularly good and reliable control of dislocations with a very high dislocation density can be achieved, which in turn enables a corresponding control of the properties of the ceramic. Also, 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. For example, 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.

With the proposed method it is possible for the first time to produce dislocations with a sufficient number and density in a ceramic in order to be able to influence, in particular improve, the properties of the ceramic even for demanding applications. The method enables dislocations to be generated 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.

For example, visible light and/or UV light can be used. Alternatively or additionally, light in the infrared spectral range can also be used. By radiating in light, for example in the visible and/or UV range, the temperature profile within the ceramic can be very precisely monitored, in particular controlled. By choosing the right wavelength, in particular by choosing the spectral range (UV, VIS, IR), 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, for example, 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). For most ceramics lies the band gap 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. CO ₂ lasers with a wavelength of 10,000 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.

In principle, 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. In a particularly suitable embodiment, 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.

In one embodiment, the ceramic starting material has a foil-like geometry. For example, adaptive (laser) optics can be used and the light output can be controlled precisely and quickly. Thus, 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 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. For example, particularly in the case of small thicknesses of the ceramic, for example a thickness of less than 1 mm, 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.

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.

With the proposed method, the use of sintering furnaces, which are conventionally used to heat the starting material, can be completely or at least partially dispensed with. This brings with it a number of important advantages: An enormous amount of energy can be saved, since entire furnaces no longer have to be heated up and cooled down again. The irradiation of light also enables an extremely dynamic temperature profile in the ceramic. The sluggish heating and cooling behavior of the furnace can be overcome. In contrast to heating bands, ovens or electricity, a very efficient control of the temperature of the ceramic can therefore be exercised.

In one embodiment, the ceramic material is sintered by means of a sintering furnace or in some other way before the start of the light irradiation and/or after the end of the light irradiation. This means that the proposed method can only be switched on when a high dislocation density is required, for example.

• • Keramiken nahezu beliebiger Geometrien, vor allem quaderförmige Geometrien mit Dicken unter 1 mm oder auch mit Dicken von 1 mm bis 5 mm, lassen sich mit dem Verfahren sintern.
• • Das Verfahren arbeitet berührungslos.
• • Das Verfahren ist skalierbar.
• • Das Verfahren kann besonders viel Fläche gleichzeitig behandeln.
• • Das Verfahren ist das erste industriell skalierbare Herstellungsverfahren für Keramiken, wie keramische Membranen, welche ihre herausragenden Eigenschaften durch die erzeugten Versetzungen erhalten.
• • Das Verfahren erreicht sehr kurze Prozesszeiten bei nur geringem technologischen Aufwand.
• • Das Verfahren, insbesondere der mit diesem verbundene Sinterprozess, kann direkt in bestehende industrielle Foliengießanlagen integriert werden.
• • Das Verfahren ermöglicht eine sehr hohe Anzahl und eine sehr hohe Dichte von Versetzungen.
• • Das Verfahren ist auch für die Massenproduktion gut skalierbar und einfach umzusetzen (beispielsweise können gut verfügbare Leuchten verwendet werden).
• • Die Prozessführung im Labormaßstab kann besonders ähnlich zur industriellen Prozessführung gestaltet werden, wodurch Weiterentwicklungen besonders schnell realisiert werden können und Qualitätskontrollen vereinfacht werden.
• • Das Verfahren kann sogar in bestehenden Anlagen nachgerüstet werden, da nur wenig Technik notwendig ist.
• • Das Verfahren kann als kontinuierlicher Prozess gestaltet werden.
• • Es ist eine erhebliche Energieeinsparung bei der Herstellung möglich, da keine Öfen notwendig sind, die aufgeheizt und wieder abgekühlt werden müssen. Nur das Material selbst wird erwärmt.
• • Das Verfahren ist gut reproduzierbar und kontrollierbar wodurch auch ungewünschte Nebeneffekte, wie eine Leitfähigkeitsänderung durch Punktdefekte im keramischen Material, vermieden werden, da sehr definierte Verfahrensparameter herrschen - im Gegensatz etwa zu der Situation beim Flash-Sintering. Dadurch wird das Verfahren in seiner Komplexität reduziert.

The proposed method preferably has the following advantageous features and properties, which can be used alone, all together and/or in any combination:

• • Ceramics of almost any geometry, especially cuboid geometries with a thickness of less than 1 mm or with a thickness of 1 mm to 5 mm, can be sintered with the process.
• • The process works without contact.
• • The process is scalable.
• • 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 get their outstanding properties from the dislocations created.
• • The method achieves very short process times with only little technological effort.
• • The process, in particular the associated sintering process, can be integrated directly into existing industrial film casting systems.
• • The process 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 process can even be retrofitted in existing plants, since little technology is required.
• • The procedure 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 is easily reproducible and controllable, which also avoids undesirable side effects such as a change in conductivity due to point defects in the ceramic material, since very defined process parameters prevail - in contrast to the situation with flash sintering. This reduces the complexity of the method.

The method 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.

Of course, the person skilled in the art understands that during the irradiation of the light, 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. In addition, the transitions between illuminated and non-illuminated areas can optionally be designed as a gradient.

In one embodiment, 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 using this process can be particularly efficient due to their high dislocation density. For example, functional ceramics can be produced with the method. When using 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" 3rd edition Peter M. Anderson, John P. Hirth and Jens Lothe, Cambridge University Press". Dislocations within the meaning of the present application are preferably one-dimensional crystal defects in the material, which are preferably can be generated during production.

Alternatively or additionally, it can also be provided that 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.

Appropriate heating rates in the ceramic material due to the irradiation of light are achieved, a high number and a high density of dislocations can be realized in the ceramic product.

Optionally, 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.

For example, in one embodiment, 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.

For example, in one embodiment, 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. For example, 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.

As an alternative or in addition, the cooling rate is between 25000 K/s and 50 K/s, preferably between 1000 K/s and 50 K/s. The cooling rate can in particular also depend on the thickness. For example, 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.

In one embodiment, 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. In a preferred embodiment, 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.

In order to control the heating rate, the power density of the incident light, for example, 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.

Therefore, in one embodiment, the heating rate is controlled based on the power density of the incident light. Optionally, 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 . For example, 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 .

Significantly higher power densities can also be irradiated for short periods, as described above (flash of light).

A mathematical consideration shows that 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.

In this case, 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. at For example, with a very high power density, the ceramic can be heated, which is then quickly adjusted to a lower value that corresponds to the current temperature. As a result, the ceramic can be heated very quickly, with the maximum temperature being reached quickly and, in particular, very precisely. As a result, for example, 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. Furthermore, 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.

Optionally, the change in power density is between 1%/s and 100,000%/s, preferably from 100%/s and 10,000%/s. In particular, 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.

Optionally, 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.

Alternatively or additionally, it can also be provided that 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.

Due to the short period of time, the process is also particularly suitable for large-scale production.

Optionally, the period is a maximum of 10 minutes, preferably a maximum of 1 minute, preferably a maximum of 10 seconds,

For example, in one embodiment, 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.

Alternatively or additionally, it can also be provided that 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.

For example, the dislocation densities given are those that are generated locally. In other words: For example, the dislocation densities given are dislocation densities that are sufficient for the at least locally generated dislocations.

This can mean that the irradiation of light and the heating of the material result in larger-scale dislocations than the at least locally generated dislocations, with the larger-scale dislocations not all satisfying the specified dislocation densities and therefore not counting among the locally generated dislocations. For example, further dislocations can exist around the locally generated dislocations (with corresponding dislocation densities), but they have a lower density.

For example, the dislocation densities relate to an area of 1 µm 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.

1. (i) die Leistungsdichte des eingestrahlten Lichtes (a) zwischen 1 W/cm² und 750 W/cm², weiter bevorzugt zwischen 5 W/cm² und 150 W/cm² liegt, und/oder (b) einen definierten oder definierbaren Zielwert mit einer Genauigkeit von besser als 10%, besser als 5%, besser als 2% oder besser als 1% in weniger als 5 Sekunden, bevorzugt in weniger als 2 Sekunden, weiter bevorzugt in weniger als 1 Sekunde, weiter bevorzugt in weniger als 0,5 Sekunden, weiter bevorzugt in weniger als 0,1 Sekunde, erreicht und danach stabilisiert wird;
2. (ii) und/oder
3. (iii) die Leistungsdichte und/oder das Temperaturprofil frei gestaltet werden kann bzw. können.

Alternatively or additionally, it can also be provided that
the locally generated dislocations are within the area of the ceramic material heated by the light;

1. (i) 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;
2. (ii) and/or
3. (iii) the power density and/or the temperature profile can be designed freely.

Consequently, the entire area of the ceramic material heated by the light does not have to have dislocations. And/or also shows areas with dislocations that do not meet the conditions imposed on the locally generated ones.

Alternatively or additionally, it can also be provided that 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 body 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.

In one embodiment, the ceramic starting material is provided in the form of an endless belt and/or moved relative to the light source. As a result, even large areas can be processed, in particular sintered, quickly and economically, and therefore quickly and cheaply.

1. (i) die Dicke des keramischen Ausgangsmaterial zwischen 0,00005 mm und 15,0 mm, vorzugsweise zwischen 0,001 mm und 10,0 mm, vorzugsweise 0,1 mm bis 5 mm vorzugsweise zwischen 0,5 mm und 4,0 mm, beträgt;
2. (ii) das keramische Ausgangsmaterial SrTiO₃, und/oder TiO₂ als Material aufweist oder daraus besteht und/oder wobei das keramische Produkt eine keramische Membran aufweist oder darstellt; und/oder
3. (iii) das keramische Ausgangsmaterial eines oder mehrere der folgenden Materialien aufweist:
   1. (a) Ein beliebiges keramisches Material, insbesondere ein nichtmetallischanorganisches Material mit kristallinem Aufbau;
   2. (b) Eine Keramik mit Perowskitstruktur, Spinellstruktur, Zinkblendestruktur, Wurzitstruktur, Natriumchloridstruktur, oder Fluoridstruktur;
   3. (c) Eine Keramik auf Basis von Bariumtitanat, Bariumzirkonat, Blei-Zirkonat-Titanat, Titanoxid, Siliziumkarbid, Siliciumnitrid, Borcarbid, Bornitrid, Zirkondiborid, Nickeloxid, Zinkoxid, Zirkoniumoxid, Strontiumtitanat, Magnesiumoxid, Lithium-Lanthan-Titanat, Lithium-Lanthan-Zirkonat, Lithium-Lanthan-Tantalat, Lithium-Cobalt-Oxid, Lithium-Mangan-Oxid, Lithium-Nickel-Mangan-Oxid und/oder Aluminiumoxid, jeweils mit beliebigen Dotierungszusätzen und/oder Sinteradditiven sowie Mischungen aus mehreren diesen Materialien;
   4. (d) Ein beliebiges Metall; oder/und
   5. (e) Ein oder mehrere Materialien aus der Gruppe aufweisend: Silber, Lithium, Palladium, Platin, Gold, Nickel, Titan, Aluminium, Kupfer, Eisen, Niob, Chrom, Vanadium, Iridium, Tantal, Osmium, Rhenium, Molybdän, Wolfram, Magnesium oder eine Legierung aus mehreren dieser Metalle.
   6. (f) Ein beliebiges nichtmetallisches anorganisches Material, welches überwiegend keine kristalline Struktur aufweist und welches mit Hilfe eines Sinterprozesses seine Form erhält.
   7. (g) Silikatfasern, Borosilikatglas und Tetraborsilizid.

Alternatively or additionally, it can also be provided that

1. (i) 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 ;
2. (ii) the ceramic starting material comprises or consists of SrTiO ₃ and/or TiO ₂ as material and/or wherein the ceramic product comprises or is a ceramic membrane; and or
3. (iii) the ceramic starting material comprises one or more of the following materials:
   1. (a) Any ceramic material, especially a non-metallic inorganic material with a crystalline structure;
   2. (b) A ceramics having a perovskite structure, a spinel structure, a zincblende structure, a wurzite structure, a sodium chloride structure, or a fluoride structure;
   3. (c) A ceramic based on barium titanate, barium zirconate, lead zirconate titanate, titanium oxide, silicon carbide, silicon nitride, boron carbide, boron nitride, zirconium diboride, nickel oxide, zinc oxide, zirconium oxide, strontium titanate, magnesium oxide, lithium lanthanum titanate, lithium lanthanum zirconate, lithium lanthanum tantalate, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide and/or aluminum oxide, each with any doping additives and/or sintering additives and mixtures of several of these materials;
   4. (d) any metal; or and
   5. (e) One or more materials from the group comprising: silver, lithium, palladium, platinum, gold, nickel, titanium, aluminum, copper, iron, niobium, chromium, vanadium, iridium, tantalum, osmium, rhenium, molybdenum, tungsten, Magnesium or an alloy of several of these metals.
   6. (f) Any non-metallic inorganic material which is predominantly non-crystalline in structure and which is shaped by a sintering process.
   7. (g) Silicate fibers, borosilicate glass and tetraboron silicide.

With the method of the invention, sintering operations at high temperatures in non-metal metallic-inorganic materials are carried out. This is also possible when a crystalline structure is predominantly absent. For example, ceramic or glass fibers can be sintered into a solid and highly porous block. One example is the composite of highly porous bonded fiberglass with a dense top layer, which is used as a heat protection tile for spacecraft re-entering the atmosphere. These components are known from the space shuttle, for example, and will also be used in new and future spacecraft, such as the SpaceX Starhip. With lighting as the heat transfer medium, the starting material can be produced particularly quickly and in an energy-saving manner. Furthermore, the cover layer and the volume body can be heated differently. In addition, 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.

Those skilled in the art know that 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.

In one embodiment, 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. Optionally, 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. For example, the ceramic can have a thickness of between 0.001 mm and 5 mm, in particular between 0.01 mm and 2 mm.

In one embodiment, 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.

Alternatively or additionally, it can also be provided that 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.

As a result of the complete illumination, 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.

1. (i) das Licht parallel und/oder sequentiell, insbesondere unter relativer, vorzugsweise kontinuierlicher, Verschiebung des keramischen Materials relativ zu dem einfallenden Licht, auf mehrere Bereiche, insbesondere Oberflächenbereiche, des keramischen Ausgangsmaterials eingestrahlt wird, um dadurch parallel bzw. sequentiell an mehreren lokalen Orten Versetzungen im keramischen Produkt zu erzeugen;
2. (ii) die durch die Bestrahlung in einer aufgeheizten Zone eine definierte Geometrie, insbesondere mit einer großen Fläche, erzeugt wird, welche quadratisch ist oder vom Anwender in ihrer Form frei wählbar ausgestaltet werden kann;
3. (iii) die Bestrahlung mit einer Verzögerung von weniger als 10 Sekunden bevorzugt in weniger als 1 Sekunde, weiter bevorzugt in weniger als 0,1 Sekunde, bevorzugt von weniger als 0,01 Sekunde weiter bevorzugt von weniger als 1 Millisekunde, noch weiter bevorzugt von weniger als 0,1 Millisekunde um mehr als 90% reduziert werden kann, und/oder wobei durch das Abschalten der Bestrahlung eine Abkühlrate von mehr als 10 K/s, weiter bevorzugt von mehr als 50 K/s, noch weiter bevorzugt von mehr als 200K/s erreicht wird; und/oder
4. (iv) das Temperaturprofil lokal oder/und zeitlich variierend kontrolliert werden kann.

Alternatively or additionally, it can also be provided that

1. (i) 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;
2. (ii) 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;
3. (iii) irradiation with a delay of less than 10 seconds, preferably less than 1 second, more preferably less than 0.1 second, preferably less than 0.01 second, more preferably less than 1 millisecond, even more preferably of less than 0.1 millisecond can be reduced by more than 90%, and/or wherein switching off the irradiation results in a cooling rate of more than 10 K/s, more preferably more than 50 K/s, even more preferably more than 200K/s is reached; and or
4. (iv) the temperature profile can be controlled locally and/or as it varies over time.

If 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 even over a large area and/or which can be reached in the underlying volume areas.

Alternatively or additionally, it can also be provided that 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. For example, a local power density variation can be carried out for this purpose.

1. (i) Wellenlängen im sichtbaren Wellenlängenbereich oder im nicht-sichtbaren Wellenlängenbereich, insbesondere im UV-Bereich oder im sichtbaren Bereich, aufweist, vorzugsweise ausschließlich solche aufweist,
2. (ii) Von zumindest einer Lichtquelle, insbesondere aufweisend zumindest eine Leuchtdiode, zumindest eine Xe-Blitzlampe, zumindest einen Laser, zumindest eine UV-Lampe, zumindest einen Mitteldruck-UV-Strahler und/oder zumindest eine Metalldampflampe, zumindest eine Halogenlampe, zumindest einen Infrarotstrahler, ausgestrahlt wird,
3. (iii) von einer Optik auf das keramische Ausgangsmaterial gelenkt und/oder, vorzugsweise auf den aufzuwärmenden Bereich, fokussiert wird, und/oder
4. (iv) das keramische Ausgangsmaterial an der Oberfläche und/oder innerhalb eines an die Oberfläche angrenzenden Volumenbereichs erwärmt.

Alternatively or additionally, it can also be provided that the light

1. (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
2. (ii) From 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 emitter, is emitted,
3. (iii) is directed by an optic onto the ceramic starting material and/or, preferably onto the area to be heated, is focused, and/or
4. (iv) heating the ceramic starting material at the surface and/or within a volume region adjacent to the surface.

When the light is irradiated from multiple light sources, 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.

In this case, the light can be radiated in from above, from below and from both sides, particularly in the case of a flat ceramic. Alternatively, 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.

The invention can be implemented using a laser as the light source. For example, 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.

However, an advantage of a laser is that it can focus light strongly, which is what laser light sources are typically optimized for. However, this reduces the area that can be processed at the same time. Therefore, the laser beams for use in this invention should preferably be expanded first. A diode laser, preferably made up of a plurality of diodes, in particular diode stacks, with a homogeneous intensity distribution is preferably used here.

Because with the present invention, large surface areas can be irradiated simultaneously and almost homogeneously. This means that large areas can be processed quickly and economically. In particular, it is possible in this way to process an endless strip quickly and inexpensively.

• - zumindest eine Aufnahme zum Aufnehmen eines keramischen Ausgangsmaterial und
• - zumindest eine Lichtquelle zum Einstrahlen von Licht auf das in der Aufnahme aufgenommene oder aufnehmbare keramische Ausgangsmaterial,

wobei vorzugsweise die Vorrichtung dazu eingerichtet ist das Licht auf das keramische Ausgangsmaterial einzustrahlen, um dieses zumindest bereichsweise aufzuwärmen und dadurch ein keramisches Produkt zu erzeugen und wobei die Aufnahme eine Isolierung aufweist
vorgeschlagen wird.The object is achieved by the invention according to a second aspect in that a 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 ) which is set up to carry out the method according to the first aspect of the invention, comprising the device

• - At least one receptacle for receiving a ceramic starting material and
• - at least one light source for radiating light onto the ceramic starting material that is or can be received in the receptacle,

wherein the device is preferably set up to radiate the light onto the ceramic starting material in order to heat it up at least in regions and thereby produce a ceramic product, and wherein the receptacle has insulation
is suggested.

The insulation should be sufficiently stable even against the illumination for the necessary process time.

For example, 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 .

At a temperature of 1400° C., 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.

When performed in zero gravity, no pad and therefore no insulation is required.

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. The insulation ensures a particularly homogeneous temperature distribution, which in turn is associated with particularly homogeneous material properties. In addition, 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. It is surprising that 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 . In contrast, a ceramic wool with a thermal conductivity of 0.4 W/mK could only dissipate 6.4 W/cm ² . It becomes clear that the heat flow through the insulation is only a fraction of the lighting power density, while a metallic substrate allows many times the undesired heat flow.

To further improve the energy efficiency, especially with longer exposures, the thermal radiation emitted by the ceramic can be reflected back onto the ceramic during sintering using a mirror system. For this purpose, for example, a parabolically or elliptically shaped and/or gold-coated mirror can be used.

With the device according to the invention it is possible to produce ceramics with a high dislocation density. In particular, it is possible to produce ceramics with dislocations by carrying out the method according to the first aspect of the invention therewith.

The same advantages and the same areas of use therefore apply to the device as were also described above in relation to the first aspect of the invention.

In one embodiment, 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.

For example, 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. Alternatively or additionally, 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.

Alternatively or additionally, 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.

In a particularly preferred embodiment, the method is implemented using a particularly flexible device. The small size, comparable to a shoe box, and the possibility of operating the device with a normal socket connection (230 V, 16A in Germany) enables cost-effective use, for example on the table, in dental laboratories, small workshops or in glove boxes used in laboratories for air-sensitive materials.

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 microlenses and lenses in order to improve the 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. For example, an energy storage device can provide 8 kW for 30 seconds and then be recharged over a few minutes with significantly less power. Here, for example, 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. For example, it is possible to use 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, 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 at least partially sintered microstructure is proposed.

In particular, the ceramic product can have a sintered microstructure. For example, 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.

The same advantages and the same areas of use therefore apply to the ceramic product as were also described above in relation to the first aspect of the invention.

For example, 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. In particular, these thin membranes can be stacked as multilayers and can 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.

1. (i) die Dicke des keramischen Produkts zwischen 0,00005 mm und 20 mm beträgt, wobei das keramische Produkt eine keramische Membran aufweist oder darstellt und/oder wobei das keramische Produkt SrTiO₃, und/oder TiO₂ als Material aufweist oder daraus besteht; und/oder
2. (ii) das keramische Produkt eines oder mehrere der folgenden Materialien aufweist:
   1. (a) Ein beliebiges keramisches Material, insbesondere ein nichtmetallischanorganisches Material mit kristallinem Aufbau;
   2. (b) Eine Keramik mit Perowskitstruktur, Spinellstruktur, Zinkblendestruktur, Wurzitstruktur, Natriumchloridstruktur, oder Fluoridstruktur;
   3. (c) Eine Keramik auf Basis von Bariumtitanat, Bariumzirkonat, Blei-Zirkonat-Titanat, Titanoxid, Siliziumkarbid, Siliciumnitrid, Borcarbid, Bornitrid, Zirkondiborid, Nickeloxid, Zinkoxid, Zirkoniumoxid, Strontiumtitanat, Magnesiumoxid, Lithium-Lanthan-Titanat, Lithium-Lanthan-Zirkonat, Lithium-Lanthan-Tantalat, Lithium-Cobalt-Oxid, Lithium-Mangan-Oxid, Lithium-Nickel-Mangan-Oxid und/oder Aluminiumoxid, jeweils mit beliebigen Dotierungszusätzen und/oder Sinteradditiven sowie Mischungen aus mehreren diesen Materialien;
   4. (d) Ein beliebiges Metall; oder/und
   5. (e) Ein oder mehrere Materialien aus der Gruppe aufweisend: Silber, Lithium, Palladium, Platin, Gold, Nickel, Titan, Aluminium, Kupfer, Eisen, Niob, Chrom, Vanadium, Iridium, Tantal, Osmium, Rhenium, Molybdän, Wolfram, Magnesium oder eine Legierung aus mehreren dieser Metalle.
   6. (f) Ein beliebiges nichtmetallisches anorganisches Material, welches überwiegend keine kristalline Struktur aufweist und welches mit Hilfe eines Sinterprozesses seine Form erhält.
   7. (g) Silikatfasern, Borosilikatglas und Borsilizid.

Alternatively or additionally, it can also be provided that

1. (i) the thickness of the ceramic product is between 0.00005mm and 20mm, wherein the ceramic product comprises or is a ceramic membrane and/or wherein the ceramic product comprises or consists of SrTiO ₃ , and/or TiO ₂ as material consists; and or
2. (ii) the ceramic product comprises one or more of the following materials:
   1. (a) Any ceramic material, especially a non-metallic inorganic material with a crystalline structure;
   2. (b) A ceramics having a perovskite structure, a spinel structure, a zincblende structure, a wurzite structure, a sodium chloride structure, or a fluoride structure;
   3. (c) A ceramic based on barium titanate, barium zirconate, lead zirconate titanate, titanium oxide, silicon carbide, silicon nitride, boron carbide, boron nitride, zirconium diboride, nickel oxide, zinc oxide, zirconium oxide, strontium titanate, magnesium oxide, lithium lanthanum titanate, lithium lanthanum zirconate, lithium lanthanum tantalate, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide and/or aluminum oxide, each with any doping additives and/or sintering additives and mixtures of several of these materials;
   4. (d) any metal; or and
   5. (e) One or more materials from the group comprising: silver, lithium, palladium, platinum, gold, nickel, titanium, aluminum, copper, iron, niobium, chromium, vanadium, iridium, tantalum, osmium, rhenium, molybdenum, tungsten, Magnesium or an alloy of several of these metals.
   6. (f) Any non-metallic inorganic material which is predominantly non-crystalline in structure and which is shaped by a sintering process.
   7. (g) Silicate fibers, borosilicate glass and boron silicide.

Ceramics with preferred thicknesses are relevant for common applications.

In one embodiment, 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. Optionally, 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. For example, 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.

In one embodiment, 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 and/or particularly homogeneous material properties.

The grain size can, for example, change in one direction by more than a factor of three to less than 50 μm, preferably by more than a factor of five to less than 20 μm, preferably by more than a factor of 15 to less than 10 μm, and at the same time by vary less than a factor of two in an orthogonal direction. The grain size can preferably change gradually, in particular as in 4 , or stepped, especially as in 7 , change. The difference in grain size preferably does not exceed a factor of 1000.

For example, the porosity can change in less than 5 μm from less than 5%, in particular no open porosity, to greater than 15%, in particular open, percolating porosity.

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.

Try

The method according to the invention enables a very high density of dislocations. To classify the following experiments with each results given by the inventors: (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 achieve dislocation densities of the order of even greater than or equal to 10 ¹⁰ /cm ² . The dislocation density can be improved by optimizing the temperature profile.

character list

Further features and advantages of the invention result from the following description, in which preferred embodiments of the invention are explained with the aid of schematic drawings.

• 1 eine Vorrichtung gemäß dem zweiten Aspekt der Erfindung in einer Seitenansicht;
• 2 ein keramisches Material, das in der Vorrichtung der 1 verwendet wird;
• 3 eine weitere Vorrichtung gemäß dem zweiten Aspekt der Erfindung in einer perspektivischen Ansicht;
• 4 eine lichtmikroskopische Aufnahme eines keramischen Produkts mit einem Korngrößengradienten;
• 5, 6, 7 eine elektronenmikroskopische Aufnahme eines keramischen Produkts mit Texturierung und sprunghaftem Dichtegradient;
• 8 Darstellung der Quantifizierung der Texturierung;
• 9 eine elektronenmikroskopische Aufnahme eines keramischen Produkts hergestellt aus zwei keramischen Ausgangsmaterialien;
• 10 eine elektronenmikroskopische Aufnahme eines Vielschichtkondensators hergestellt mit dem Verfahren der Erfindung;
• 11, 12 Temperatur-Zeit-Kurven der Herstellung eines keramischen Produkts mit dem Verfahren der Erfindung.
• 13 eine weitere Vorrichtung gemäß dem zweiten Aspekt der Erfindung in einer perspektivischen Ansicht;

show:

• 1 a device according to the second aspect of the invention in a side view;
• 2 a ceramic material used in the device of 1 is used;
• 3 another device according to the second aspect of the invention in a perspective view;
• 4 an optical micrograph of a ceramic product with a grain size gradient;
• 5 , 6 , 7 an electron micrograph of a ceramic product with texturing and an abrupt density gradient;
• 8th representation of quantification of texturing;
• 9 an electron micrograph of a ceramic product made from two ceramic starting materials;
• 10 an electron micrograph of a multilayer capacitor made by the method of the invention;
• 11 , 12 Temperature-time curves of the production of a ceramic product with the method of the invention.
• 13 another device according to the second aspect of the invention in a perspective view;

examples

Example 1: Green body made from pressed SrTiO ₃ powder

A disc-shaped green body made of SrTiO 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 approx. 0.12 g/cm ³ ..

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. In this case, the sintering temperature is preferably exceeded or fallen short of by less than 15.degree. Furthermore, after heating, 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. At the sintering temperature, the power density is preferably 170 W/cm ² when using a 450 nm wavelength diode laser stack.

The dislocation density can preferably be checked with dark-field transmission electron microscopy or electron channeling contrast imaging (ECCI).

Example 2:

A foil made of the material BaTiO ₃ 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.

During illumination, 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. In particular, the foil can be moved relative to the light source or the light source can be moved relative to the foil. As a result, the temperature profile or the power density can also be adjusted by the movement profile. Preferably, 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. In this case, the sintering temperature is preferably exceeded or fallen short of by less than 15.degree. Furthermore, after heating, 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. At the sintering temperature, the power density is preferably about 92 W/cm ² when using a diode laser stack with a wavelength of 450 nm.

Example 3:

A grain size gradient was created by laterally varying thermal contact with the substrate. The irradiation was homogeneous. Alternatively, 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 made of 99.99% pure TiO ₂ with a thickness of about 150 μm 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.

4 shows a correspondingly produced ceramic product with a grain size gradient.

Example 4:

A grain size gradient and texturing were created by different temperature profiles on the surface and inside the ceramic. A green body made of 99.99% pure TiO ₂ with a thickness of about 150 μm 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. In the first lighting step, no insulation was necessary because the temperature only reached the surface but not the volume. In the second illumination step, 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.

In this example, as in 5 , 6 and 7 shown, a virtually completely dense layer on the surface with a thickness of about 20 µm and a grain size of about 15 µm and a thicker layer underneath with significantly smaller grains and very high porosity. where is in 7 , showing a fracture surface after the first treatment step, to see that a large part of the grains extends through the entire thickness of the layer. Furthermore, the grains in this layer have a preferred orientation which is referred to as texturing. This texturing was determined using electron diffraction for more than 5000 grains and is in 8th presented and quantified. 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.

Furthermore, 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 intense illumination step, here the first step, can be performed during the longer and less intense illumination step whereby the overall processing can be done in one go, for example in 10 seconds or less.

Example 5:

With the method of the invention, two ceramic starting materials, TiO ₂ and BaTiO ₃ , which were pressed together as a powder in two layers, were sintered together into a ceramic product. A sharp interface was obtained. the 9 shows a correspondingly produced ceramic product.

Example 6:

A multilayer capacitor was manufactured by the method of the invention (see 10 ). The multilayer capacitor consists of ceramic BaTiO ₃ and thin layers of platinum electrodes. The layers of BaTiO ₃ 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.

10 shows a polished cross-section through the component thickness.

Example 7:

Example 7 relates to various temperature-time histories of the manufacture of a ceramic product using the method of the invention.

In 11 shows the temperature dependence of the absorption of the incident light. At high temperatures, there is increased absorption of longer wavelengths. The course of the temperature over time shows that initially at a temperature of around 800°C a temperature plateau almost forms with a significant slowdown in the temperature rise. As soon as a tipping point above 800°C was reached, the temperature rose massively to almost 1600°C. At temperatures below the tipping point, the absorption of light by the material is relatively low. Above 800°C, the incident light is absorbed significantly better. This example was performed on 1 mm thick pressed powder of lithium ion conductive Li _6.4 La ₃ Zr _1.4 Ta _0.6 O ₁₂ ceramic.

12 On the other hand, 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.

Detailed description of the figures

1 Figure 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 . In the present case, 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.

For this purpose, light 9 from the light source 7 is radiated onto a surface area 11a of the ceramic material 5 . The material of the surface area 11a and the underlying volume area is thereby heated and sintered. The heating takes place so quickly, that is, at such a high heating rate, that a high density of dislocations can be generated locally in the ceramic product that is obtained after sintering. The locally generated dislocations therefore exist in the heated area.

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 a high dislocation density is generated. The light irradiation is changed, for example, by means of an in 1 control and control unit, not shown, which may 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.

2 shows a top view of the (in 2 ceramic material 5 accommodated in receptacle 3 (not shown). The two surface areas 11a and 11b are shown therein, spaced apart for better visibility from the edge of the compact 5 are shown. 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.

For example, 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 .

For example, 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 area 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.

3 Figure 1 shows an embodiment of a device according to the second aspect of the invention, in which a ceramic material 5 in foil form is moved relative to the illumination. In particular, 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.

On one or two sides, light sources 13 of the same or (as in 3 provided) of different types installed. The light is directed onto the ceramic material 5 by optics 15 suitable for the respective light source 13 . are in 3 the beam path 17 and the illuminated zone 19 are schematically outlined.

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.

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 µm can be seen on the left-hand side. Significantly smaller grain sizes can be seen on the right-hand side. The scale bar is approx. 250 µm.

the 5 and 6 show electron micrographs of a ceramic product with a stepwise density gradient. Underneath a dense surface layer is a porous volume. The scale bar is 100 µm in 5 and 50 µm in 6 .

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 5 and 6 represents. A fracture surface is shown. Here it becomes clear that the grains of the dense layer extend through the entire layer thickness.

8th shows a quantification of the texture of titanium dioxide, which is also used in 5 and 6 is shown. The probability with which the crystal structure of the grains is oriented in a certain direction is shown. In the center of the circle is the 100 direction. At the edges of the circle, 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 outside to inside, the values for the lines are 0.71; 1; 1.41; 2; 2.83 and 4.

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 µm.

10 shows an electron micrograph of a multilayer capacitor manufactured with the method of the invention. Metallic conductor structures can be seen between the ceramic parts. The scale bar is 200 µm.

the 11 and 12 show temperature-time curves of the production of a ceramic product with the method of the invention. With 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.

Those disclosed in the foregoing description, claims and drawings th features can be essential for the invention in its various embodiments both individually and in any combination.

13 Figure 12 shows a device according to the second aspect of the invention.

The device has a power supply, an intermediate energy store, control technology and water cooling, which can be accommodated in a housing 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 fitted over 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.

Reference List

1

contraption

3

recording

5

ceramic material

7

light source

9

light

11a, 11b

surface area

13

light source

15

optics

17

beam path

19

Illuminated zone

21

Enclosure for power supply, intermediate energy storage, control technology and water cooling.

23

Connection for cables and hoses

25

Light shielding enclosure

27

Array of light-emitting diodes with water-cooled thermal sink

29

Device for easy changing of the ceramic material and insulation

31

Changeable insulation

33

ceramic material

35

cooling

37

pyrometer

Claims (19)

Process for the production of ceramics, the process comprising: irradiation of light onto a ceramic starting material in order to heat it up at least in regions and thereby produce a ceramic product, the irradiation of light being simultaneously applied to an area of at least 0.1 mm ² and/or takes place on more than 20% of the surface of the ceramic starting material, and the power density of the incident light is less than 800 W/cm ² . procedure after claim 1 , wherein the area-wise heating of the ceramic starting material with 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. Method according to one of the preceding claims, wherein the, in particular regionally, heating of the ceramic starting material by irradiating light for a period of (a) 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 (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 of 1 second. Method according to one of the preceding claims, wherein locally 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 method according to any one of the preceding claims, (i) wherein the locally generated dislocations are within the region of the ceramic material heated by the light; (ii) where the power density of the incident light is (a) between 1 W/cm ² and 750 W/cm ² , more preferably between 25 W/cm ² and 175 W/cm ² , and/or (b) a defined or definable target value is reached with an accuracy of better than 5% in less than 5 seconds, preferably better than 2% in less than 2 seconds, more preferably better than 1% in less than 0.5 seconds, and is then stabilized; and/or (iii) wherein the power density and/or the temperature profile can be designed freely. Method according to one of the preceding claims, wherein 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 film, an endless strip, a preferably cuboid compact and/or as a Solid is provided. Method according to any one of the preceding claims, (i) wherein the thickness of the ceramic starting material is between 0.00005 mm and 20 mm, preferably between 0.001 mm and 10 mm, preferably between 0.1 mm and 5 mm, preferably between 0.5 mm and is 4.0mm; (ii) wherein the ceramic starting material comprises or consists of SrTiO ₃ and/or TiO ₂ as material and/or wherein the ceramic product comprises or is a ceramic membrane; and/or (iii) wherein the ceramic starting material comprises one or more of the following materials: (a) any ceramic material, in particular a non-metallic inorganic material with a crystalline structure; (b) A ceramics having a perovskite structure, a spinel structure, a zincblende structure, a wurzite structure, a sodium chloride structure, or a fluoride structure; (c) A ceramic based on barium titanate, barium zirconate, lead zirconate titanate, titanium oxide, silicon carbide, silicon nitride, boron carbide, boron nitride, zirconium diboride, nickel oxide, zinc oxide, zirconium oxide, strontium titanate, magnesium oxide, lithium lanthanum titanate, lithium lanthanum zirconate, lithium lanthanum tantalate, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide and/or aluminum oxide, each with any doping additives and/or sintering additives and mixtures of several of these materials; (d) any metal; or/and (e) one or more materials from the group comprising: silver, lithium, palladium, platinum, gold, nickel, titanium, aluminum, copper, iron, niobium, chromium, vanadium, iridium, tantalum, osmium, rhenium, molybdenum , tungsten, magnesium or an alloy of several of these metals. (f) Any non-metallic inorganic material which is predominantly non-crystalline in structure and which is shaped by a sintering process. (g) One or more materials from the group: silicate fibers, borosilicate glass and boron silicide. Method according to one of the preceding claims, wherein at least one surface, in particular a side surface, preferably a main side surface, of the ceramic starting material is illuminated, preferably completely or partially, by the light. Method according to one of the preceding claims, (i) the light being radiated 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 local places to generate dislocations in the ceramic product; (ii) the irradiation in a heated zone generating a defined geometry, in particular with a large area, which is square or whose shape can be designed by the user to be freely selectable; (iii) wherein the irradiation continues with a delay of less than 10 seconds, preferably less than 1 second, more preferably less than 0.1 second, preferably less than 0.01 second, more preferably less than 1 millisecond preferably less than 0.1 millisecond is reduced by more than 90%, and/or wherein switching off the irradiation results in a cooling rate of more than 10 K/s, more preferably more than 50 K/s, even more preferably more than 200K/s is reached; and or (iv) the temperature profile being able to be controlled locally and/or in a time-varying manner. Method according to one of the preceding claims, wherein the light (i) has wavelengths in the visible wavelength range or in the non-visible wavelength range, in particular in the UV range or the visible range, preferably exclusively has such, (ii) wavelengths in the range from 200 to 700 nm has, preferably exclusively has such, (iii) At least one light source, in particular having at least one light-emitting diode, at least one laser, Xe flash lamp, at least one halogen lamp, at least one UV lamp, at least one medium-pressure UV lamp and/or at least a metal vapor lamp, at least one infrared emitter, is emitted, (iv) is directed by an optic onto the ceramic starting material and/or is focused, preferably onto the area to be heated, and/or (v) the ceramic starting material on the surface and/or inside of a volume adjacent to the surface is heated. Process according to one of the preceding claims, in which a temperature of at least 1800°C is reached in the ceramic starting material and/or in the ceramic product. Method according to one of the preceding claims, wherein the method additionally comprises a further irradiation of light, wherein the further irradiation of light takes place with a power density of at least 1500 W/cm ² and a maximum duration of 50 ms. Device, in particular (i) for the production of ceramics (with or without dislocations), (ii) for carrying out the method according to one of Claims 1 until 12 and/or (iii) which is set up to carry out the method according to any one of Claims 1 until 12 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 receptacle, with the device preferably being set up to radiate the light onto the ceramic starting material in order to heat this at least in regions and thereby to produce a ceramic product, and wherein the receptacle has insulation. device after Claim 13 , whereby the thermal conductivity of the insulation at 1400°C is at most 10 W/(m*K). Device according to one of Claims 13 and 14 , a. in which light-emitting diodes are mounted on a thermal sink and optionally provided with microlenses and/or lenses, in particular to illuminate a ceramic material in a handy housing that protects the surroundings from the light used, b. at which the light output can reach at least 5 W/cm ² , c. in which the processing room is modular and/or has replaceable insulation and/or the temperature can be read using a pyrometer and/or the light sources are separated from the ceramic material by a quartz glass pane, d. whereby an intermediate energy store enables light outputs of more than 3 kW although the electrical connected load is less than 3.6 kW, and/or e. a laser diode stack being used in addition or as an alternative to the arrangement of light-emitting diodes. Ceramic product, in particular manufactured and/or producible using the method according to one of Claims 1 until 12 and/or with the device according to one of Claims 13 until 15 . Ceramic product after Claim 16 , (i) wherein the thickness of the ceramic product is between 0.0005 mm and 20 mm, wherein the ceramic product comprises or is a ceramic membrane and/or wherein the ceramic product comprises or consists of SrTiO ₃ , and/or TiO ₂ as material consists; (ii) the ceramic product comprising one or more of the following materials: (a) any ceramic material, particularly a non-metallic inorganic material of crystalline structure; (b) A ceramics having a perovskite structure, a spinel structure, a zincblende structure, a wurzite structure, a sodium chloride structure, or a fluoride structure; (c) A ceramic based on barium titanate, barium zirconate, lead zirconate titanate, titanium oxide, silicon carbide, silicon nitride, boron carbide, boron nitride, zirconium diboride, nickel oxide, zinc oxide, zirconium oxide, strontium titanate, magnesium oxide, lithium lanthanum titanate, lithium lanthanum zirconate, lithium lanthanum tantalate, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide and/or aluminum oxide, each with any doping additives and/or sintering additives and mixtures of several of these materials; (d) any metal; or/and (e) one or more materials from the group comprising: silver, lithium, palladium, platinum, gold, nickel, titanium, aluminum, copper, iron, niobium, chromium, vanadium, iridium, tantalum, osmium, rhenium, molybdenum , tungsten, magnesium or an alloy of several of these metals; (f) Any non-metallic inorganic material which is predominantly non-crystalline in structure and which is shaped by a sintering process. (g) Silicate fibers, borosilicate glass and boron silicide. (iii) the ceramic product having at least locally 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 ; and/or (iv) the ceramic product having a grain size gradient, texturing, high temperature resistance and/or homogeneous material properties. Ceramic product according to one of Claims 16 and 17 , a. wherein the grain size varies by more than a factor of five in less than 50 µm in one direction and wherein the grain size varies by less than a factor of two in an orthogonal direction, b. wherein the porosity in less than 5 µm changes from less than 5%, in particular no open porosity, to greater than 15%, in particular with open, percolating porosity, and/or c. with more than 15% of the grains being oriented with a deviation of less than 15° from a preferential axis. Ceramic product according to one of Claims 16 until 18 , whereby the product represents a layered composite with several layers.

Images