Ultra-high speed, high temperature sintering equipment

Abstract

The present invention relates to an ultra-high speed, high temperature sintering apparatus comprising first and second thermally conductive substrates comprising carbon spaced apart from one another to provide a space for receiving sintering substrates, the first and second thermally conductive substrates being disposed between third and fourth thermally conductive substrates, and heating means for heating the third and fourth thermally conductive substrates, thereby heating the third and fourth thermally conductive substrates, respectively, wherein the third and fourth thermally conductive substrates independently comprise one or more metal nitrides and / or metal oxides.

Description

[Technical Field]

[0001] The present invention relates to a sintering apparatus, and more particularly to an ultra-high speed, high temperature sintering apparatus. [Background technology]

[0002] Conventional sintering methods are typically carried out in so-called bulk furnaces, which are heated to a required sintering temperature that depends on the material composition to be sintered. The drawbacks of such bulk furnaces include long heating and cooling times (i.e., slow heating and cooling rates), difficulty in controlling the temperature and heat distribution (i.e., temperature uniformity), high energy consumption (due to long heating times), and increased total processing time. This leads to non-uniform sintering and, therefore, limited sinter quality. It also leads to low throughput (low number of sintered bodies produced in a given time), making these sintering techniques less suitable for industrial-scale application.

[0003] Recently, new sintering methods, such as microwave-assisted sintering, spark plasma sintering, and flash sintering, and improved sintering equipment have been developed. However, microwave-assisted sintering is highly dependent on the microwave absorption characteristics of the material being sintered, limiting its applicability. Spark plasma sintering equipment requires a mold to compress the material during sintering, limiting the shape and scalability of the sintered components. Furthermore, the pressure required makes it unsuitable for sintering complex three-dimensional structures. Flash sintering equipment can heat at rates up to 10,000°C / min, but requires expensive platinum electrodes. Furthermore, flash sintering equipment is not well suited for sintering components with complex shapes, such as three-dimensional structures.

[0004] CN208567515 discloses a sintering apparatus including, from the inside to the outside, a furnace body including a graphite heating body, an electrical insulating layer which is heat-insulating heat-resistant rock wool, and an insulating layer which first includes a hard graphite felt and then an aluminum silicate fiber layer.

[0005] US2007 / 0202455 discloses a sintering apparatus including a muffle with heaters or heating elements on either side in parallel. The muffle and heaters or heating elements are surrounded by multiple insulating layers made of carbon. The heaters may be made of graphite or may be carbon elements. Another embodiment discloses a carbon element that functions as both a muffle and a heater.

[0006] Another recently developed sintering equipment is the ultra-high speed, high temperature sintering equipment.

[0007] WO2020 / 236767 discloses a high-speed, high-temperature sintering apparatus and method. The substrate to be sintered is placed between two thermally conductive carbon elements, with the distance between each element and the substrate being 0 mm to 10 mm. The thermally conductive carbon elements are heated to a temperature of 500°C to 3000°C by an electric current, and sintering is carried out within 1 second to 1 hour by heating the substrate with the heated thermally conductive carbon elements.

[0008] A drawback of the above-described ultra-high-speed, high-temperature sintering apparatus is that it is difficult to sinter self-standing substrates, i.e., substrates without a support or carrier. For flat, self-standing substrates in particular, it is difficult to maintain the flatness of the substrate during sintering using the above-described apparatus. That is, sintered substrates obtained using the above-described apparatus tend to bend when sintered without a carrier or carrier, resulting in bowing and cracking, and cracks may occur when attempting to flatten the sintered substrate after sintering. Summary of the Invention

[0009] The present invention aims to overcome one or more of the above-mentioned drawbacks. It is an object of the present invention to provide a sintering apparatus that can shorten the sintering time and / or improve the control of sintering conditions, particularly the sintering temperature. It is also an object of the present invention to provide a sintering apparatus that can achieve more uniform sintering. A further object is to provide a sintering apparatus that can sinter thin substrates, i.e., having a thickness of less than 100 μm, and / or flat substrates, without damaging or deforming the sintered substrate, i.e., maintaining flatness. A further object is to provide a sintering apparatus that consumes less energy.

[0010] The term "substrate" as part of the sintering device is used in this disclosure for a component or layer of the sintering device, especially a layer having a sheet-like shape.

[0011] Advantageously, the sintering machine is an ultra-high-speed, high-temperature sintering machine. The term "ultra-high-speed sintering" is used in the present disclosure for a sintering machine that can be heated at a heating rate of at least 50°C / s and, optionally, cooled at a cooling rate of at least 50°C / s. The term "high-temperature sintering machine" is used in the present disclosure for a sintering machine that can be heated to a temperature of at least 750°C, preferably at least 900°C, for example, between 750°C and 1400°C, more preferably between 900°C and 1250°C.

[0012] According to one aspect of the present invention, a sintering apparatus is disclosed as set forth in the claims.

[0013] The sintering apparatus according to the present disclosure includes a first thermally conductive substrate and a second thermally conductive substrate spaced apart from each other, thereby providing a space for receiving a substrate, i.e., an article or object, to be sintered.

[0014] The first and second thermally conductive substrates are disposed between the third and fourth thermally conductive substrates, i.e., the third and fourth thermally conductive substrates are disposed on the outer surfaces of the first and second thermally conductive substrates, respectively.

[0015] The first and second thermally conductive substrates comprise carbon.

[0016] The third thermally conductive substrate and the fourth thermally conductive substrate each independently comprise one or more metal nitrides and / or metal oxides. Advantageously, the third and fourth thermally conductive substrates each independently comprise one or more single-crystal metal nitrides and / or single-crystal metal oxides.

[0017] Advantageously, the (single crystal) metal nitride comprises (single crystal) boron nitride and / or (single crystal) aluminium nitride. Advantageously, the (single crystal) metal oxide comprises (single crystal) alumina and / or (single crystal) sapphire, such as single crystal sapphire.

[0018] Preferably, the first thermally conductive substrate is at least partially in contact with the third thermally conductive substrate. Alternatively or additionally, preferably, the second thermally conductive substrate is at least partially in contact with the fourth thermally conductive substrate. "At least partially in contact" in the present invention means that the two substrates are in contact, i.e., in contact with each other, over at least a portion of the surfaces of the opposing substrates.

[0019] The sintering apparatus further comprises heating means. The heating means is arranged or provided for heating the third thermally conductive substrate and / or the fourth thermally conductive substrate during use of the apparatus. The heating means is arranged such that, during use, it is possible to heat the third and / or fourth thermally conductive substrate at a heating rate of at least 50°C / s. The heating means is arranged such that, during use, it is possible to heat the third and / or fourth thermally conductive substrate to a temperature of 750°C to 1400°C, preferably 900°C to 1250°C. The heating means is arranged such that, during use, heating the third and / or fourth thermally conductive substrate heats the first and / or second thermally conductive substrate, respectively.

[0020] Advantageously, the sintering apparatus further comprises a first conductor on the outer surface of the third thermally conductive substrate. Alternatively or additionally, advantageously, the sintering apparatus further comprises a second conductor on the outer surface of the fourth thermally conductive substrate.

[0021] Advantageously, when first and second conductors are provided, the first and second conductors together at least partially, preferably entirely, enclose the first, second, third and fourth thermally conductive substrates and the space (i.e., the space between the first and second thermally conductive substrates).

[0022] Advantageously, the first and second conductors comprise carbon. Examples of carbon-containing conductors include, but are not limited to, graphite, carbon fiber, carbon nanotubes, or a combination of two or more thereof. The first and second conductors can have the same or different compositions.

[0023] Advantageously, the sintering apparatus further includes first support means provided on an outer surface of the first conductor. Alternatively or additionally, advantageously, the sintering apparatus further includes second support means provided on an outer surface of the second conductor. Advantageously, the first support means and the second support means, if provided, each independently include a thermally and electronically insulating ceramic substrate and at least one metallic support component. Advantageously, the support means are arranged so that the metallic support component contacts the thermally and electronically insulating ceramic substrate and the conductor. In other words, if first and second support means are provided, the metallic support component is arranged so that it contacts the surface of the first and second conductors facing the thermally and electronically insulating ceramic substrate and support means (i.e., the outer surface of each conductor). Advantageously, the support means are arranged so that the metallic support component and the thermally and electronically insulating ceramic substrate mechanically support the conductor.

[0024] Advantageously, the thermally and electrically insulating ceramic substrate comprises alumina (ie, aluminum oxide).

[0025] Advantageously, the metal bearing component comprises tungsten or an alloy thereof. Non-limiting examples of alloys comprising tungsten are tungsten nickel iron alloy, tungsten nickel copper alloy and tungsten carbide alloy.

[0026] Advantageously, when the sintering apparatus comprises a first conductor and / or a second conductor, the heating means comprises means for inducing an electric current in the first conductor and / or the second conductor. Advantageously, in use when an electric current is induced in the first conductor and / or the second conductor, the third and / or fourth thermally conductive substrate is heated, advantageously by Joule heating. Joule heating is also known as resistive heating or ohmic heating. Advantageously, when an electric current is induced in the first and / or second conductor (in use of the apparatus), ohmic or resistive losses in the first and / or second conductor are dissipated in the form of heat, and the third and / or fourth thermally conductive substrate is heated.

[0027] Advantageously, the sintering device further comprises a third conductor and a fourth conductor in addition to the first and / or second conductor. Advantageously, the third conductor is provided at a proximal end of the first conductor and / or at a proximal end of the second conductor. Advantageously, the fourth conductor is provided at a distal end of the first conductor and / or at a distal end of the second conductor.

[0028] For example, if the sintering device includes only the first (or second) conductor, the third conductor is provided at the proximal end of the first (or second) conductor, and the fourth conductor is provided at the distal end of the first (or second) conductor. For example, if the sintering device includes first and second conductors, the third conductor is provided at the proximal end of the first conductor and the proximal end of the second conductor, and the fourth conductor is provided at the distal end of the first conductor and the distal end of the second conductor.

[0029] Advantageously, when the sintering apparatus comprises third and fourth conductors provided as described above, the heating means comprises means for inducing a current in the third and fourth conductors. Advantageously, in use when inducing a current in the third and fourth conductors, a current is induced in the first and / or second conductor to heat the third and / or fourth thermally conductive substrates.

[0030] Advantageously, the third and fourth conductors independently comprise copper, a copper alloy, silver, a silver alloy, tungsten, a tungsten alloy, or a combination of two or more thereof.

[0031] Alternatively or additionally to the heating means comprising means for inducing an electric current, the heating means advantageously comprises an infrared (IR) light source.

[0032] Advantageously, when the heating means comprises an IR light source, the sintering apparatus further comprises one or more lenses, suitably arranged such that, in use, the lenses are able to focus the IR light towards the third and / or fourth conductive substrate.

[0033] The heating means may be arranged to heat the third and fourth thermally conductive substrates independently of each other. For example, the heating means may be arranged to heat the third and fourth thermally conductive substrates according to the same heating profile, in use, such as at the same heating rate and / or the same temperature. Alternatively, the heating means may be arranged to heat the third and fourth thermally conductive substrates, in use, for example at different temperatures and / or different heating rates.

[0034] Advantageously, the sintering apparatus further comprises means for monitoring the temperature. Advantageously, the sintering apparatus further comprises means for monitoring the temperature of the space between the first and second thermally conductive substrates. Alternatively or additionally, advantageously, the sintering apparatus further comprises means for monitoring the temperature of the third and / or fourth thermally conductive substrates. Advantageously, the means for controlling the temperature comprises an infrared (IR) camera.

[0035] The sintering apparatus of the present invention has the advantage of being able to achieve a high heating rate of at least 50°C / s. A further advantage of the sintering apparatus of the present invention is that it can uniformly sinter a wide variety of substrates in a short period of time, without being limited thereto.

[0036] Furthermore, the sintering apparatus of the present invention is particularly suited to sintering thin and / or substantially flat substrates as well as free-standing substrates, which is achieved by the combination of heated third and fourth thermally conductive substrates comprising one or more metal nitrides and / or metal oxides, and first and second thermally conductive substrates comprising carbon disposed between the substrate (i.e., article or object) to be sintered and the third and fourth thermally conductive substrates. [Brief explanation of the drawings]

[0037] Aspects of the present invention will now be described in more detail with reference to the accompanying drawings, in which like reference numbers refer to like features, and in which: [Figure 1] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 2] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 3] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 4] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 5] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 6] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 7] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 8] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 9] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 10] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 11] 1 to 11 show various sintering apparatuses according to the present invention in a schematic manner. [Figure 12] 12A and 12B show SEM images at different resolutions of a cross section of an inorganic substrate sintered by a prior art device. [Figure 13]13A and 13B show SEM images at different resolutions of the cross section of an inorganic substrate sintered by the sintering apparatus of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] 1 shows a schematic diagram of a sintering apparatus 100 according to a first embodiment of the present disclosure. The sintering apparatus 100 has a substantially horizontal arrangement. The sintering apparatus 100 includes a first thermally conductive substrate 2 and a second thermally conductive substrate 3 spaced apart from each other to provide a space 101. In use of this apparatus, an object to be sintered, for example an inorganic substrate, is advantageously placed within the space 101, i.e., between the first (2) and second (3) thermally conductive substrates.

[0039] The first (2) and second (3) thermally conductive substrates are disposed between the third thermally conductive substrate 4 and the fourth thermally conductive substrate 5. In other words, the third (4) and fourth (5) thermally conductive substrates surround or enclose the first (2) and second (3) thermally conductive substrates.

[0040] Advantageously, the first (2) and second (3) thermally conductive substrates, independently of one another, comprise or consist essentially of carbon. Examples of carbon-containing thermally conductive substrates include, but are not limited to, graphite, carbon fiber, carbon nanotubes, or combinations of two or more thereof. The first (2) and second (3) thermally conductive substrates can have the same composition or different compositions. The first (2) and second (3) thermally conductive substrates, independently of one another, can be substantially flat. Alternatively, they can independently have a shape conforming to the shape of the object to be sintered. Advantageously, the first (2) and second (3) thermally conductive substrates, independently of one another, have a thickness of 0.5 μm to 20 mm, preferably 1 μm to 10 mm.

[0041] The third (4) and fourth (5) thermally conductive substrates can have the same or different compositions. Advantageously, the third (4) and fourth (5) thermally conductive substrates comprise or consist essentially of a metal nitride or metal oxide. Non-limiting examples of metal nitrides include boron nitride or aluminum nitride. Non-limiting examples of metal oxides include aluminum oxide or sapphire, such as single crystal sapphire. Advantageously, the metal nitride comprises or consists essentially of a single crystal metal nitride. Advantageously, the metal oxide comprises or consists essentially of a single crystal metal oxide. The inventors have discovered that single crystal metal nitrides and single crystal metal oxides can better withstand, i.e., exhibit no significant damage or degradation, the high heating rates (50°C / s or greater) and high cooling rates (-50°C / s or greater) that can be achieved by the sintering apparatus of the present disclosure compared to non-single crystal metal nitrides and metal oxides.

[0042] Advantageously, at least a portion, preferably the entire surface of the third (4) and / or fourth (5) thermally conductive substrate is polished.

[0043] The third (4) and fourth (5) thermally conductive substrates may, independently of one another, be substantially flat, or may, independently of one another, have a shape that conforms to or matches the shape of the object to be sintered. Advantageously, the third (4) and fourth (5) thermally conductive substrates, independently of one another, have a thickness of 0.5 μm to 20 mm, preferably 1 μm to 10 mm.

[0044] The present inventors have surprisingly discovered that by using the third (4) and fourth (5) thermally conductive substrates described above, it is possible to sinter the substrate while maintaining its original shape or geometry. In particular, the sintering apparatus of the present invention is capable of sintering flat substrates, even thin substrates (i.e., having a thickness of 100 μm or less), thereby maintaining their flatness during sintering. That is, when sintering flat substrates using the sintering apparatus of the present disclosure, bending of the substrate is prevented.

[0045] Furthermore, sufficient support is provided for the object to be sintered without the need for a support means such as a tray for the substrate to be sintered during sintering. Thus, the sintering apparatus of the present invention allows for the sintering of free-standing substrates such as free-standing thin membranes.

[0046] Surprisingly, the inventors have discovered that by using first (2) and second (3) thermally conductive substrates that contain carbon and that are disposed between the substrate to be sintered and the third (4) and fourth (5) thermally conductive substrates during use of the apparatus, it is possible to avoid solid-state reactions that may occur between the substrate to be sintered and the third (4) and fourth (5) thermally conductive substrates. Such solid-state reactions are usually undesirable because they adversely affect sintering quality. Therefore, the sintering apparatus of the present invention is able to avoid such reactions, thereby improving sintering quality.

[0047] The sintering apparatus 100 of Figure 1 further includes a first conductor 6 and a second conductor 7. Advantageously, the first (6) and second (7) conductors have a surface area equal to or greater than the surface area of ​​the third (4) and fourth (5) thermally conductive substrates, respectively.

[0048] Advantageously, the first conductor 6 and the second conductor 7 each comprise or consist essentially of carbon. Examples of conductors comprising carbon include, but are not limited to, graphite, carbon fiber, carbon nanotubes, or a combination of two or more thereof. Advantageously, the first conductor 6 and the second conductor 7 each comprise or consist essentially of a nonwoven carbon material, such as carbon felt.

[0049] The sintering apparatus 100 further comprises a heating means 102. The heating means is connected to a first conductor 6 and a second conductor 7. The connection may be any electrical connection known in the art, which in use transfers electrical current from the heating means 102 to the first (6) and second (7) conductors, i.e., induces electrical current in the conductors 6, 7. A power supply 103 is provided for generating the electrical current. The power supply 103 may be a direct current (DC) power supply or an alternating current (AC) power supply.

[0050] In use, when a substrate to be sintered is placed in the space 101 of the sintering apparatus 100, the power supply 103 generates an electric current which is induced in the first conductor 6 and the second conductor 7 by the heating means 102. The electric current flows through the conductors 6, 7 and the resistive losses in the material of the conductors 6, 7 are transferred as heat. This heat heats the third (4) and fourth (5) thermally conductive substrates, thereby heating the first (2) and second (3) thermally conductive substrates and therefore the substrate to be sintered.

[0051] The sintering machine makes it possible to obtain heating rates of 50° C. / s or more, for example at least 60° C. / s, or even 70° C. / s or more, i.e. the sintering machine is an ultrafast sintering machine.

[0052] Advantageously, the sintering apparatus is capable of achieving a cooling rate of 50°C / s or more, for example at least 60°C / s, or even 70°C / s or more, i.e., of cooling the article or object to a temperature at least 50°C lower than the temperature of the article or object the second before.

[0053] Advantageously, the sintering apparatus 100 further comprises means 104 for monitoring the temperature within the sintering apparatus 100. Advantageously, the means 104 for monitoring the temperature comprise an IR sensor and / or an IR camera. Advantageously, the means 104 for monitoring the temperature are capable of measuring and controlling the temperature so that the temperature is maintained at a predetermined value or within a predetermined range.

[0054] The means for monitoring temperature 104 may be arranged to monitor the temperature within the space 101, i.e., of the object to be sintered during sintering. Alternatively or additionally, the means 104 may be arranged to monitor the temperature of one or more of the first (2), second (3), third (4) or fourth (5) thermally conductive substrates.

[0055] Advantageously, the sintering device further comprises cooling means (not shown), which advantageously make it possible to cool the space, i.e. the sintered substrate, at a cooling rate of at least -50°C / s.

[0056] Advantageously, the sintering apparatus is arranged in a glove box (not shown) which, in use, is filled with an inert gas, in other words, the sintering apparatus is advantageously arranged to carry out the sintering process in an inert atmosphere, such as an atmosphere containing argon, nitrogen or helium.

[0057] The third thermally conductive substrate 4 can be provided at a distance from the first thermally conductive substrate 2 and / or from the first conductor 6. Advantageously, each distance is individually 0.05 mm to 25 mm, for example, 0.1 mm to 20 mm, 0.2 mm to 15 mm, or 0.25 mm to 10 mm, etc. Alternatively, the third thermally conductive substrate 4 can be at least partially in contact with the first thermally conductive substrate 2 (e.g., can be at least partially touching) and / or can be at least partially in contact with the first conductor 6.

[0058] The fourth thermally conductive substrate 5 can be provided at a distance from the second thermally conductive substrate 3 and / or from the second conductor 7. Advantageously, each distance is individually 0.05 mm to 25 mm, for example, 0.1 mm to 20 mm, 0.2 mm to 15 mm, or 0.25 mm to 10 mm, etc. Alternatively, the fourth thermally conductive substrate 5 can be at least partially in contact with the second thermally conductive substrate 3 and / or at least partially in contact with the second conductor 7.

[0059] 2 shows a sintering apparatus 110. In contrast to the sintering apparatus 100 of FIG. 1, the third thermally conductive substrate 4 contacts the first thermally conductive substrate 2 and the first conductor 6 over its entire surface area. In other words, the third thermally conductive substrate 4 is sandwiched between the first thermally conductive substrate 2 and the first conductor 6. Furthermore, the fourth thermally conductive substrate 5 also contacts the second thermally conductive substrate 3 and the second conductor 7 over its entire surface area.

[0060] Optionally, the first conductor 6 may at least partially surround the third thermally conductive substrate 4 (not shown). Additionally, and further optionally, the first conductor 6 can at least partially surround the first thermally conductive substrate 2, the space 101, and even the second (3) and fourth (5) thermally conductive substrates. Similarly, optionally, the second conductor 7 may at least partially surround the fourth thermally conductive substrate 5 (not shown). Additionally, and further optionally, the second conductor 7 can at least partially surround the second thermally conductive substrate 3, the space 101, and even the first (2) and third (4) thermally conductive substrates.

[0061] In other words, the first conductor 6 and / or the second conductor 7 may be a coating, for example a wrapping or envelope, which surrounds the space 101 and the thermally conductive substrates 2, 3, 4, 5, while still providing an opening through which the substrate to be sintered can be provided within the space.

[0062] An advantage of the first conductor 6 and / or second conductor 7 partially surrounding at least one or more thermally conductive substrates 2, 3, 4, 5 and optionally space 101 is that a more uniform and / or higher heating rate can be obtained.

[0063] Figure 3 shows a sintering apparatus 120 according to a further embodiment of the present invention. The sintering apparatus 120 includes first (2), second (3), third (4), and fourth (5) thermally conductive substrates and first (6) and second (7) conductors, as disclosed in Figure 2, providing a space 101 between the first (2) and second (3) thermally conductive substrates.

[0064] The sintering apparatus 120 further includes a first heating means 102a connected to the second conductor 7 and a first power supply 103a. The sintering apparatus 120 further includes a second heating means 102b connected to the first conductor 6 and a second power supply 103b. The power supplies 103a, 103b can be as described above.

[0065] The first heating means 102a is arranged, in use, to induce a current in the second conductor 7. The second heating means 102b is arranged, in use, to induce a current in the first conductor 6. Inducing a current in the conductors 6, 7 heats the adjacent thermally conductive substrates 5, 4. This in turn heats the thermally conductive substrates 3, 2 adjacent to the heated thermally conductive substrates 5, 4, and heats and sinters the object to be sintered.

[0066] Providing separate heating means 102a, 102b connected to different conductors 7, 6, respectively, advantageously allows different amounts or levels of current to be induced in each conductor. In other words, advantageously, the first heating means 102a and the second heating means 102b are arranged so that the fourth (5) and second (3) and third (4) and first (2) thermally conductive substrates can be heated to different temperatures, at different heating rates, and / or for different durations (i.e., different sintering times). This allows, for example, a sintered substrate having a first porosity at a first surface and a second porosity that differs from the first porosity at a second surface, such as the surface opposite the first surface. For example, a substrate having a porosity gradient throughout its thickness can be obtained. This is achieved because different sintering temperatures and / or different sintering times tend to result in different, i.e., lower or higher, porosities. For example, a two-layer dense-porous substrate can be obtained from a single substrate in this manner.

[0067] Figure 4 discloses a sintering apparatus 130 according to a further embodiment of the present invention. The sintering apparatus 130 includes first (2), second (3), third (4), and fourth (5) thermally conductive substrates and first (6) and second (7) conductors, as disclosed in Figure 2.

[0068] The sintering device 130 further comprises a third conductor 8 and a fourth conductor 9. Advantageously, the third (8) and fourth (9) conductors are -3 S / cm~75×10 4 Advantageously, the third (8) and fourth (9) conductors, independently of one another, comprise copper, a copper alloy, silver, a silver alloy, tungsten, a tungsten alloy, iron, an iron alloy, or a combination of two or more thereof.

[0069] Advantageously, the third conductor 8 is provided at the proximal end 60 of the first conductor 6 and at the proximal end 70 of the second conductor. Advantageously, the third conductor 8 is in at least partial, preferably total contact with the first conductor 6 at its proximal end 60 and / or in at least partial, preferably total contact with the second conductor 7 at its proximal end 70.

[0070] Advantageously, the fourth conductor 9 is provided at the distal end 61 of the first conductor 6 and at the distal end 71 of the second conductor. Advantageously, the fourth conductor 9 is in at least partial, preferably total contact with the first conductor 6 at its distal end 61 and / or in at least partial, preferably total contact with the second conductor 7 at its distal end 71.

[0071] Advantageously, the heating means 102 is connected to the third (8) and fourth (9) conductors and to a power supply 103 so that, in use, an electric current can be induced in the third (8) and fourth (9) conductors and thereby in the first (6) and second (7) conductors to heat the substrate to be sintered as described above.

[0072] Figure 5 discloses yet another embodiment of the sintering apparatus 140 of the present invention. The sintering apparatus 140 includes first (2), second (3), third (4), and fourth (5) thermally conductive substrates and first (6) and second (7) conductors, as disclosed in Figure 2.

[0073] The sintering device 140 further includes a third conductor including a first portion 81 and a second portion 82. The sintering device 140 further includes a fourth conductor including a first portion 91 and a second portion 92. Advantageously, the third and fourth conductors are 10 -3 S / cm~75×10 4 Advantageously, the third and fourth conductors, independently of one another, comprise copper, a copper alloy, silver, a silver alloy, tungsten, a tungsten alloy, iron, an iron alloy, or a combination of two or more thereof.

[0074] Advantageously, the first portion 81 of the third conductor is provided at, and in particular at least partially contacts, the proximal end 60 of the first conductor 6. Advantageously, the first portion 91 of the fourth conductor is provided at, and in particular at least partially contacts, the distal end 61 of the first conductor 6. The second heating means 102b is connected to the first portions 81, 91 and to a second power source 103B. The second heating means 102b is arranged to, in use, induce a current in the first portions 81, 91 and in this way in the first conductor 6, which causes Joule heating of the third (4) and first (2) thermally conductive substrates, as described above.

[0075] Advantageously, the second portion 82 of the third conductor is provided at, and in particular at least partially contacts, the proximal end 70 of the second conductor 7. Advantageously, the second portion 92 of the fourth conductor is provided at, and in particular at least partially contacts, the distal end 71 of the second conductor 7. First heating means 102a are connected to the second portions 82, 92 and to a first power supply 103a. The first heating means 102a is arranged to, in use, induce a current in the second portions 82, 92 and thus in the second conductor 7. This results in Joule heating of the fourth (5) and second (3) thermally conductive substrates, as described above.

[0076] 6 discloses a sintering apparatus 150 according to a further embodiment of the present disclosure. The sintering apparatus 150 includes first (2), second (3), third (4), and fourth (5) thermally conductive substrates, first (6) and second (7) conductors, heating means 102, and a power source 103, as disclosed in FIG.

[0077] The sintering apparatus 150 further comprises a first support means and a second support means. Advantageously, the first support means is provided on the outer surface of the first conductor 6, i.e., on the side of the first conductor 6 opposite to the side facing (or in contact with, in the case of FIG. 6 ) the third thermally conductive substrate 4. Advantageously, the second support means is provided on the outer surface of the second conductor 7.

[0078] Advantageously, each support means comprises a ceramic substrate 105. Advantageously, the ceramic substrate 105 is thermally and / or electrically insulating, preferably thermally and electrically insulating. Advantageously, the ceramic substrate 105 comprises or consists essentially of aluminium oxide.

[0079] Advantageously, each support means further comprises at least one metal support component 106, preferably at least two, more preferably at least three, i.e. a plurality of metal support components 106. Advantageously, the metal support component 106 comprises or essentially consists of one or more metals and / or alloys thereof that can withstand sintering temperatures. In particular, the metal support component 106 comprises or essentially consists of one or more metals and / or alloys thereof that have a melting temperature of at least 1500°C, for example at least 1750°C or at least 2000°C, in order to avoid melting of the metal support component 106 during heating and sintering.

[0080] Advantageously, the metal support component 106 comprises or consists essentially of tungsten or an alloy thereof. Non-limiting examples of alloys comprising tungsten are tungsten nickel iron alloy, tungsten nickel copper alloy, and tungsten carbide alloy.

[0081] The metal support component 106 can have any shape that allows for placement of the metal support component 106 between the ceramic substrate 105 and the (first or second) conductors 6, 7 such that the metal support component 106 contacts both the ceramic substrate 105 and the conductors 6, 7. Non-limiting examples of shapes include a cylinder, a cube, a pyramid, and a sphere. Non-limiting practical examples of structures include a pin, a rod, and a cylinder.

[0082] Advantageously, the metal support component 106 is attached to the ceramic substrate 105. The attachment may be any type of attachment known in the art. Advantageously, the metal support component 106 is embedded in the ceramic substrate 105.

[0083] When in contact, the support means provides mechanical support to the conductor, and thus the thermally conductive substrate. The support means thus mechanically supports the substrate to be sintered in use of the sintering apparatus 150. This eliminates the need to provide the substrate to be sintered in the space 101 with a carrier or support structure. In other words, the sintering apparatus 150, including the support means, allows for the sintering of free-standing substrates.

[0084] Figure 7 discloses a sintering apparatus 160 according to a further embodiment of the present disclosure. The sintering apparatus 160 includes first (2), second (3), third (4), and fourth (5) thermally conductive substrates 5 and first (6), second (7), third (8), and fourth (9) conductors as disclosed in Figure 4. The sintering apparatus 160 further includes first and second support means as disclosed in Figure 6.

[0085] Figure 8 discloses a sintering apparatus 170 according to a further embodiment of the present disclosure. The sintering apparatus 170 includes first (2), second (3), third (4), and fourth (5) thermally conductive substrates, first (6) and second (7) conductors, first (102a) and second (102b) heating means, and first (103a) and second (103b) power sources, as disclosed in Figure 3. The sintering apparatus 170 further includes first and second support means as disclosed in Figure 6.

[0086] The sintering apparatus of the present invention can be provided in a substantially horizontal position, i.e., at a 90° angle relative to the Earth's gravitational field (as shown in Figures 1-8). The sintering apparatus can also be provided in a substantially vertical position, i.e., at a 0° angle relative to the Earth's gravitational field, as shown in Figure 9. The sintering apparatus can also be provided in any position between the substantially horizontal position (i.e., a 90° angle) and the substantially vertical position (i.e., a 0° angle).

[0087] 9 shows a sintering apparatus 180 similar to the sintering apparatus 150 of FIG. 6, but positioned in a vertical position (0° angle with respect to the Earth's gravitational field). The inventors have discovered that a vertical position facilitates the movement of particles within the object or substrate being sintered during sintering due to gravity. Such a vertical setup is particularly advantageous for sintering flat substrates such as films, foils, and membranes.

[0088] 10 illustrates a sintering apparatus 190 according to yet another embodiment. The sintering apparatus 190 includes a first (2) thermally conductive substrate in contact with a third (4) thermally conductive substrate, and a second (3) thermally conductive substrate in contact with a fourth (5) thermally conductive substrate. The thermally conductive substrates 2, 3, 4, and 5 are advantageously as described above. The sintering apparatus 190 further includes a means 104 for monitoring the temperature, which is advantageously as described above.

[0089] The sintering apparatus 190 further comprises heating means 10 comprising a light source. Advantageously, the light source is an infrared (IR) light source. The IR light source advantageously comprises one or more IR heaters. Particularly suitable IR heaters are short wave IR heaters and ceramic IR heaters. Advantageously, the IR heaters operate at 6 kW or less. Advantageously, the IR light source is operated at a temperature between 500°C and 1300°C, preferably between 600°C and 1000°C, most preferably between 650°C and 800°C, for example between 700°C and 750°C. Advantageously, the IR light source is switched on, i.e., the IR light source heats the thermally conductive substrates 2, 3, 4, 5 and / or the space between the first (2) and second (3) thermally conductive substrates for a time period between 5 seconds and 40 minutes, preferably between 10 seconds and 30 minutes, such as between 1 minute and 25 minutes, 2 minutes and 20 minutes, 5 minutes and 15 minutes, more preferably between 7 minutes and 10 minutes, such as between 9 minutes and 10 minutes. It will be understood that the optimal time period will depend on the IR light source, in particular its power.

[0090] The sintering apparatus 190 further comprises a lens 11 arranged between the light source 10 and the thermally conductive substrates 2, 3, 4, 5. Advantageously, the lens 11 is arranged such that, in use, it focuses light rays emitted from the light source, in particular IR light rays, towards the thermally conductive substrates 2, 3, 4, 5 and / or towards the space between the first (2) and second (3) thermally conductive substrates, thereby reducing energy (heat) losses and providing a more efficient sintering apparatus.

[0091] 11 shows a sintering apparatus 200 according to a further embodiment. The sintering apparatus 200 includes a first (2) thermally conductive substrate in contact with a third (4) thermally conductive substrate, and a second (3) thermally conductive substrate in contact with a fourth (5) thermally conductive substrate. The thermally conductive substrates 2, 3, 4, and 5 are advantageously as described above. The sintering apparatus 200 advantageously further includes first (6) and second (7) conductors as described above in contact with the third (4) and fourth (5) thermally conductive substrates, respectively.

[0092] The sintering apparatus 200 further comprises first and second support means comprising a ceramic substrate 105 and at least one metallic support component 106. The first and second support means are advantageously as described above.

[0093] The sintering apparatus 200 further comprises an IR light source 10. The IR light source 10 is positioned such that, in use, the emitted IR light heats the conductors 6, 7 and the thermally conductive substrates 2, 3, 4, 5 and therefore also heats the substrate to be sintered. [Example]

[0094] Example 1 The reference porous substrate and the inventive porous substrate were prepared from green structures of the same composition, where the reference porous substrate was obtained by sintering using a prior art sintering device and the inventive porous substrate was obtained by sintering using the sintering device of the present invention.

[0095] First, Li as a pore-forming compound 6.25 Al0.25 La3Zr2O 12 3 g of aluminum-doped LLZO (or Al-LLZO), 0.075 g (2.5 wt%) of Li2CO3, 0.56 mL of plasticizer, 0.59 g of surfactant, and 2.07 g of polymethyl methacrylate (PMMA) were mixed with 5.9 mL of a solvent containing 5 vol% isopropanol, 87 vol% ethanol, and 8 vol% 1-propanol using a spatula and ball-milled at 165 rpm for 18 hours. A binder solution was prepared by adding 3 g of polyvinyl butyral to 8.89 mL of isopropanol. 2.51 g of the binder solution was added to the mixture (suspension) and ball-milled at 200 rpm for 2 hours.

[0096] The mixture was film-cast onto a glass substrate by tape casting. This was done twice to obtain two green structures (one for each sintering method). The resulting green structures were kept at ambient conditions for 1 hour to allow the solvent to evaporate, and then removed from the glass substrate.

[0097] The green structure was then placed between two alumina plates and debinding was carried out in air at 600 °C to completely remove the solvent (evaporation temperature below 150 °C), PMMA (at about 350 °C), and residual organic compounds such as binders and plasticizers (at about 600 °C).

[0098] The reference (sintered) LLZO substrate was obtained by placing the first green structure between two carbon foils and sandwiching it between two carbon plates, which was sintered at 1250 °C for 30 s in a nitrogen atmosphere.

[0099] SEM images of the cross-section of the obtained reference sintered LLZO substrate (Figures 12A and 12B at different magnifications) clearly showed that the obtained reference sintered LLZO substrate was not flat but highly curved. Also, several cracks were observed. The SEM images were recorded using a Hitachi TM3030 tabletop microscope at an accelerating voltage of 10 kV.

[0100] Similar results were obtained with a similar setup in a nitrogen atmosphere at temperatures between 1000°C and 1250°C for 30 seconds to 120 seconds.

[0101] The inventive (sintered) LLZO substrate was obtained by placing a second green structure of the same composition as the first green structure in an apparatus 160 shown in FIG.

[0102] The first (2) and second (3) thermally conductive substrates were essentially carbon foil. The third (4) and fourth (5) thermally conductive substrates were boron nitride plates. The boron nitride plates were rigid and substantially flat. The first (6) and second (7) conductors were essentially carbon and were carbon felt. Support means were provided on the exterior, including an alumina substrate 105 and a plurality of tungsten pins as metal support members 106. A third copper conductor 8 was provided at the proximal end of the first (6) and second (7) conductors, and a fourth copper conductor 9 was provided at the distal end of the first (6) and second (7) conductors. The third (8) and (9) conductors were connected to a power source 103 by an electronic circuit 102, which served as a heating means.

[0103] After the second green structure was placed between the carbon foils 2 and 3, the power supply 103 was turned on and a current was induced to flow through the carbon felt. The resistive losses of the current caused the boron nitride plate to heat, which heated the carbon foil and green structure to a temperature of 1250°C at a heating rate of about 60°C / s. After reaching a temperature of 1250°C, the temperature was maintained for 30 seconds by continuing to pass the current through the carbon felt.

[0104] SEM images of the cross-sections of the obtained sintered LLZO substrates of the invention (Figures 13A and 13B at different magnifications) clearly show that the sintered LLZO substrates of the invention are substantially flat. Similar results were obtained with the same equipment and setup for sintering at temperatures between 1000°C and 1250°C for times between 30 and 120 seconds.

[0105] Example 2 Further green structures according to Example 1 were sintered in an apparatus 190 according to Figure 10. The first (2) and second (3) thermally conductive substrates consisted essentially of carbon foil. The third (4) and fourth (5) thermally conductive substrates were boron nitride plates. The boron nitride plates were rigid and substantially flat.

[0106] The green structure was placed between carbon foils 2 and 3. An IR light source, including an IR heater operating at 6 kW, was used as the heating means. The IR irradiation heated the boron nitride plates 4 and 5 via thermal radiation, and the heat was transferred to the carbon foils 2 and 3 and the green structure. The boron nitride plates 4 and 5 were heated to 700°C for 550 seconds. The IR light source was then turned off, and the boron nitride plates, carbon foils, and sintered LLZO substrate were allowed to cool to room temperature.

[0107] The resulting sintered LLZO substrate was visually inspected and found to be substantially flat.

[0108] Nomenclature 2. First thermally conductive substrate 3. Second thermally conductive substrate 4. Third thermally conductive substrate 5. Fourth thermally conductive substrate 6. First Conductor 7. Second Conductor 8.Third Conductor 9. Fourth Conductor 10. Infrared (IR) light source 11. Lens 60. Proximal end of first conductor 61. Distal end of first conductor 70. Proximal end of second conductor 71. Distal end of second conductor 81. Third Conductor (First Part) 82. Third Conductor (Second Part) 91. Fourth Conductor (First Part) 92. The second part of the fourth conductor 100. Sintering equipment 101. Space between the first and second thermally conductive substrates 102. Means for inducing electric current 102a. Means for inducing electric current 102b. Means for inducing electric current 103.Power supply 103a.Power supply 103b.Power supply 104.Means for monitoring temperature 105. Thermal and electrical insulating ceramic substrates 106. Metal Support Components 110. Sintering equipment 120. Sintering equipment 130. Sintering equipment 140. Sintering equipment 150. Sintering equipment 160. Sintering equipment 170. Sintering equipment 180. Sintering equipment 190. Sintering equipment 200. Sintering equipment

Claims

1. - a first thermally conductive substrate substrate (2) and a second thermally conductive substrate substrate (3) spaced apart from each other, thereby providing a space (101) for receiving a substrate to be sintered; a third thermally conductive substrate (4) and a fourth thermally conductive substrate (5) between which the first thermally conductive substrate (2) and the second thermally conductive substrate (3) are provided; heating means (10, 102, 102a, 102b) for heating the third thermally conductive substrate (4) and / or the fourth thermally conductive substrate (5), thereby heating the first (2) and / or second (3) thermally conductive substrate, respectively; Including, the first (2) and second (3) thermally conductive substrates contain carbon; The third thermally conductive substrate (4) and the fourth thermally conductive substrate (5) each independently comprise one or more metal nitrides and / or metal oxides. Ultra-high speed, high temperature sintering equipment (100, 110, 120, 130, 140, 150, 160, 170, 180, 190).

2. 10. The sintering apparatus (100, 110, 120, 130, 140, 150, 160, 170, 180, 190) of claim 1, wherein the third (4) and fourth (5) thermally conductive substrates independently comprise one or more single crystal metal nitrides and / or single crystal metal oxides.

3. 10. The sintering apparatus (100, 110, 120, 130, 140, 150, 160, 170, 180, 190) according to any one of the preceding claims, wherein the metal nitride comprises boron nitride and / or aluminum nitride.

4. 10. The sintering apparatus (100, 110, 120, 130, 140, 150, 160, 170, 180, 190) according to any one of the preceding claims, wherein the metal oxide comprises alumina and / or sapphire.

5. 2. The sintering apparatus (110, 120, 130, 140, 150, 160, 170, 180, 190) of claim 1, wherein the first (2) thermally conductive substrate is at least partially in contact with the third (4) thermally conductive substrate and / or the second (3) thermally conductive substrate is at least partially in contact with the fourth (5) thermally conductive substrate.

6. 10. The sintering apparatus (100, 110, 120, 130, 140, 150, 160, 170, 190) according to any one of the preceding claims, further comprising a first conductor (6) on the outer surface of the third thermally conductive substrate (4) and / or a second conductor (7) on the outer surface of the fourth thermally conductive substrate (5), preferably wherein the first (6) and second (7) conductors comprise carbon.

7. 7. The sintering apparatus (100, 110, 120, 130, 140, 150, 160, 170, 190) according to claim 6, wherein the first conductor (6) and the second conductor (7) together at least partially, preferably entirely, surround the first (2), the second (3), the third (4) and the fourth (5) thermally conductive substrates and the space (101).

8. The sintering apparatus (150, 160, 170, 190) according to any one of claims 6 to 7, further comprising a first support means provided on an outer surface of the first conductor (6) and / or a second support means provided on an outer surface of the second conductor (7), wherein each of the first support means and the second support means independently comprises a thermally and electrically insulating ceramic substrate (105) and at least one metallic support component (106), and the support means are arranged such that the metallic support component (106) is in contact with the thermally and electrically insulating ceramic substrate (105) and the conductors (6, 7).

9. 9. The sintering apparatus (150, 160, 170, 190) of claim 8, wherein the thermally and electrically insulating ceramic substrate (105) comprises alumina.

10. The sintering apparatus (150, 160, 170, 190) of any one of claims 8 to 9, wherein the metal support component (106) comprises tungsten or an alloy thereof.

11. Sintering apparatus (100, 110, 120, 130, 140, 150, 160, 170) according to any one of claims 6 to 10, wherein the heating means (102, 102a, 102b) comprises means for inducing an electric current in the first (6) and / or the second conductor (7), thereby heating, in use, the third (4) and / or the fourth (5) thermally conductive substrate.

12. The heating means (102, 102a, 102b) further comprises a third conductor (8, 81, 82) at the proximal end (60) of the first conductor (6) and / or the proximal end (70) of the second conductor (7), and a fourth conductor (9, 91, 92) at the distal end (61) of the first conductor (6) and / or the distal end (71) of the second conductor (7), and the heating means (102, 102a, 102b) induces current in the third (8, 81, 82) and fourth conductors (9, 91, 92).

12. The sintering apparatus (130, 140) according to any one of claims 6 to 11, comprising means for conducting an electric current through the first (6) and / or second (7) conductors, whereby, in use, an electric current is induced in the first (6) and / or second (7) conductors to heat the third (4) and / or fourth (5) thermally conductive substrates, respectively, and preferably the third (8, 81, 82) and fourth (9, 91, 92) conductors comprise copper, tungsten, or a combination thereof.

13. The sintering apparatus (180, 190) according to any one of the preceding claims, wherein the heating means (10) comprises an infrared (IR) light source.

14. 14. The sintering apparatus (180, 190) of claim 13, further comprising one or more lenses (11).

15. 10. Sintering apparatus (120, 140, 160) according to any one of the preceding claims, wherein the heating means (10, 102a, 102b) are arranged so that, in use, they are able to heat the third (4) and fourth (5) thermally conductive substrates independently of each other.

16. 10. The sintering apparatus (100, 110, 120, 130, 140, 150, 160, 170, 180, 190) according to any one of the preceding claims, further comprising means (104) for monitoring the temperature of the space (101) between the first (2) and second (3) thermally conductive substrates, preferably wherein the means (104) for monitoring the temperature comprises an infrared (IR) camera.

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