DE102014212685A1 - Production of cermets with selected binders - Google Patents

Abstract

A method is described for producing a precursor (30) for a sintered product (40), comprising the steps: i. Providing a first component, a second component and at least one third component, ii. Mix in step i. provided components and forming a shaped body, iii. Treating the molding from step ii. in an oxidative atmosphere, wherein the precursor (30) of a sintered product (40) is obtained, the third component comprising at least one methylcellulose, water and an additive, the methylcellulose having a fiber content of less than 5% by weight based on the total mass of methyl cellulose, wherein at least 90% of the fibers have a size of less than 150 microns. Furthermore, a method for producing a precursor (30) for a sintered product (40), comprising the steps: i) providing a first component, a second component and at least one third component, ii). Mix in step i). provided components and forming a shaped body, iii) .Treating the shaped body from step ii). in a protective atmosphere, wherein the precursor (30) of a sintered product (40) is obtained, wherein the third component includes 2,2,4-trimethylpentane-1,3-diol monoisobutyrate.

Description

The invention relates to a method for producing a precursor for a sintered product, comprising the steps: i. Providing a first component, a second component and at least one third component, ii. Mix in step i. provided components and forming a shaped body, iii. Treating the molding from step ii. in an oxidative atmosphere, whereby the precursor of a sintered product is obtained, the third component including at least one methylcellulose, water and an additive. Furthermore, the invention relates to a method for producing a precursor for a sintered product, comprising the steps i). Providing a first component, a second component and at least one third component, ii). Mix in step i). provided components and forming a shaped body, iii). Treating the molding from step ii). in a protective atmosphere, whereby the precursor of a sintered product is obtained, wherein the third component includes 2,2,4-trimethylpentane-1,3-diol monoisobutyrate. Furthermore, the invention relates to a precursor of a sintered product prepared by one of the two previous methods. Moreover, the invention relates to a process for producing a sintered product, at least including the steps of: I. providing a precursor for a sintered product as described above, II. Treating the precursor at a temperature in a range of 800 to 2000 ° C to obtain the sintered product becomes. The invention also relates to a sintered product obtainable by the above-described process for producing a sintered product. Furthermore, the invention relates to a device comprising a sintered product according to the invention.

Sintered products are used in many fields in which, for example, a high resistance of the sintered product to chemicals such as acids or bases or high resistance to heat is required. Variants of sintered products are different compositions of on the one hand ceramic components and on the other hand metallic or metal-like components which have an electrical conductivity. In this way, the applicable as insulators ceramics can be equipped with an electrical conductivity. Sintered products, which are a combination of ceramics and metals, are also referred to as cermets. The prior art describes processes for producing sintered products, in particular cermets, which are either very time-consuming, expensive or polluting.

Generally, it is an object of the present invention to at least partially overcome the disadvantages of the prior art.

Another object is to provide a method for producing a precursor for a sintered product, which method is inexpensive and efficient.

Another object is to provide a precursor of a sintered product which can be converted into a sintered product with as few steps as possible.

A further object is to provide a precursor of a sintered product which can be converted to a stable sintered product when heated.

A further object is to provide a precursor of a sintered product which forms as few pores and / or as small as possible, preferably no pores, upon heating.

Another object is to provide a method of producing a sintered product that is inexpensive and efficient.

Yet another object is to provide a method for producing a sintered product, which leads to a stable sintered product in as few steps as possible.

Another object is to provide a sintered product having improved electrical properties.

A further object is to provide a sintered product which has the longest possible service life, in particular in aggressive solutions and is stable under high pressure.

A further object is to provide a device with a sintered product according to the invention which has the longest possible service life, in particular in aggressive solutions and is stable under high pressures. Among devices are in this context in particular Lamp pins, lamp electrodes, electrical feedthroughs, objects with the aforementioned components, such as cardiac pacemaker understood.

A contribution to the solution of at least one of the objects mentioned above is provided by the objects of the category-forming claims. The subject matters dependent on the categorie forming claims dependent claims represent preferred embodiments.

• i. Bereitstellen einer ersten Komponente, einer zweiten Komponente und mindestens einer dritten Komponente,
• ii. Mischen der in Schritt i. bereitgestellten Komponenten und Bilden eines Formkörpers,
• iii. Behandeln des Formkörpers aus Schritt ii. in einer oxidativen Atmosphäre, wobei der Vorläufer eines Sinterprodukts erhalten wird,

wobei die dritte Komponente zumindest eine Methylcellulose, Wasser und ein Additiv beinhaltet, wobei die Methylcellulose einen Faseranteil von weniger als 5 Gew.-% bezogen auf die Gesamtmasse an Methylcellulose aufweist, wobei mindestens 90 % der Fasern eine Größe von weniger als 150 µm aufweisen. A first subject of the present invention is a process for producing a precursor for a sintered product, comprising the steps:

• i. Providing a first component, a second component and at least a third component,
• II. Mix in step i. provided components and forming a shaped body,
• iii. Treating the molding from step ii. in an oxidative atmosphere, whereby the precursor of a sintered product is obtained,

wherein the third component includes at least one methylcellulose, water and an additive, wherein the methylcellulose has a fiber content of less than 5 wt .-% based on the total mass of methylcellulose, wherein at least 90% of the fibers have a size of less than 150 microns.

The first component may include any substance that may help increase the electrical conductivity of the precursor for the sintered product, and preferably also the sintered product to be formed. Preferably, the first component first contains a metal. The metal is preferably selected from the group consisting of platinum, palladium, iridium, niobium, molybdenum, titanium, cobalt, zirconium, rhodium, ruthenium, chromium, tantalum, tungsten, a titanium alloy, a tantalum alloy, a tungsten alloy or a mixture of at least two thereof. Preferably, the first component first comprises molybdenum. The first component includes first a metal preferably in an amount in a range of 90 to 100 wt%, or preferably in a range of 92 to 99 wt%, or preferably in a range of 95 to 98 wt%. %, in each case based on the total weight of the first component. Preferably, the first component comprises molybdenum in an amount ranging from 95 to 98% by weight, based on the total weight of the first component.

The second component may include any substance that helps to obtain a sintered product from the precursor for a sintered product by heating. The second component is, for example, a starting material for a sinterable substance. Preferably, the second component comprises a starting material for a ceramic selected from the group consisting of an oxide ceramic, a silicate ceramic, a non-oxide ceramic or a mixture of at least two thereof.

The oxide ceramic is preferably selected from the group consisting of a metal oxide, a semi-metal oxide or a mixture thereof. The metal of the metal oxide may be selected from the group consisting of aluminum, beryllium, barium, calcium, magnesium, sodium, potassium, iron, zirconium, titanium or a mixture of at least two thereof. The metal oxide is preferably selected from the group consisting of aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), zirconium oxide (ZrO ₂ ), yttrium oxide (Y ₂ O ₃ ), aluminum titanate (Al ₂ TiO ₅ ) or a mixture of at least two hereof. The semimetal of the semimetal oxide is preferably selected from the group consisting of boron, silicon, arsenic, tellurium or a mixture of at least two thereof.

The silicate ceramic is preferably selected from the group consisting of a steatite (Mg ₃ [Si ₄ O ₁₀ (OH) ₂ ]), cordierite (Mg, Fe ²⁺ ) ₂ (Al ₂ Si) [Al ₂ Si ₄ O ₁₈ ]) , Mullite (Al ₂ Al _{2 + 2x} Si _2-2x O _10-x with x = oxygen _vacancies per unit cell), feldspar (Ba, Ca, Na, K, NH ₄ ) (Al, B, Si) ₄ O ₈ ) or a mixture of at least two of them.

The non-oxide ceramic may be selected from the group consisting of a carbide, a nitride or a mixture thereof. The carbide may be selected from the group consisting of silicon carbide (SiC), boron carbide (B ₄ C), titanium carbide (TiC), tungsten carbide ,. The nitride may be selected from the group consisting of silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), silicon aluminum oxynitride (SIALON) or a mixture of at least two thereof.

The second component preferably contains an oxide ceramic, preferably aluminum oxide (Al ₂ O ₃ ). Further preferably, the second component includes alumina in an amount in a range of 50 to 100 wt%, or preferably in a range of 70 to 100 wt%, or preferably in a range of 90 to 100 wt .-%, each based on the total weight of the second component. The particle size distribution of the second component, such as alumina, is preferably d ₂₀ = 0.2 μm, d ₅₀ = 0.4 μm, or d ₉₀ = 1 μm. This means that 20% of the total number of particles of the second component have a diameter of less than 0.2 μm, 50% of the particles have a diameter of less than 0.4 μm, and 90% of the particles have a diameter of less than 0.2 μm Have diameter of less than 1 micron. The particle sizes can be determined in various ways. For this purpose, optical methods are preferably used, such as electrical light scattering, condensation nucleus counting or laser diffraction. The particle size is preferably determined by means of laser diffraction.

The third component may include any substance that would be selected by one skilled in the art to facilitate mixing of the first and second components. Preferably, the third component includes a binder. The third component of step i. has at least one methylcellulose. The methylcellulose is preferably selected from the group consisting of hydroxypropylmethylcellulose (HPMC), hydroxyethylmethylcellulose (HEMC), ethylmethylcellulose (EMC) or a mixture thereof. The methylcellulose preferably includes hydroxypropylmethylcellulose (HPMC). Further preferably, the methylcellulose contains hydroxypropylmethylcellulose in a range of 80 to 100% by weight, or preferably in a range of 90 to 100% by weight, or preferably in a range of 95 to 100% by weight .-%, based on the total mass of methylcellulose. Preferably, the methylcellulose has a content of -OCH ₃ groups in a range of 20 to 40 wt .-%, or preferably in a range of 23 to 37 wt .-%, or preferably in a range of 25 to 35 wt .-% , based on the total mass of methylcellulose. Further preferably, the methylcellulose has a content of -OC ₃ H ₆ OH groups in a range of 1 to 12 wt .-%, or preferably in a range of 3 to 9 wt .-%, or preferably in a range of 4 to 8 Wt .-%, based on the total mass of methylcellulose.

As further binders, for example, thermoplastic or thermosetting polymers or waxes can be used. These can be used alone or as mixtures of binders of several such components. The thermoplastic polymer may be selected from the group consisting of acrylonitrile-butadiene-styrene (ABS), polyamides (PA), polylactate (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene (PE), Polypropylene (PP), polystyrene (PS), polyetheretherketone (PEEK) and polyvinylchloride (PVC) or a mixture of at least two of them. The thermosetting polymer may be selected from the group consisting of an aminoplast, an epoxy resin, a phenolic resin, a polyester resin or a mixture of at least two thereof. Waxes are hydrocarbon compounds that melt above 40 ° C without decomposition. These may also include polyesters, paraffins, polyethylenes or copolymers of at least two of them.

The third component preferably contains the binder in a range of 5 to 30 wt%, or preferably in a range of 6 to 25 wt%, or preferably in a range of 7 to 20 wt%, each based Total weight of the third component. The third component includes methylcellulose preferably in a range of 7 to 15 wt%, or in a range of 9 to 14 wt%, or in a range of 10 to 13 wt%, each based on the total weight of third component.

Furthermore, the third component from step i. for producing the precursor for a sintered product, water, preferably in an amount in a range of 65 to 95 wt .-%, or preferably in a range of 70 to 90 wt .-%, or preferably in a range of 75 to 85 wt. -%, in each case based on the total weight of the third component.

The water is preferably demineralized water.

The precursor of a sintered product preferably contains the additive in an amount in a range of 0.01 to 0.5 wt%, or preferably in a range of 0.02 to 0.2 wt%, or preferably in a range from 0.03 to 0.1 wt .-%, each based on the total weight of the precursor.

The additive may be any substance that would be selected by those skilled in the art as a precursor for a sintered product. The additive preferably includes a dispersant. The dispersant preferably contains at least one organic substance, preferably a surfactant. The organic substance preferably has at least one functional group. The functional group may be a hydrophobic or a hydrophilic functional group. The functional group may be selected from the group consisting of an ammonium group, a carboxylate group, a sulfate group, a sulfonate group, an alcohol group, a multiple alcohol group, an ether group or a mixture of at least two of them. The dispersant preferably has functional groups in a range of 1 to 100, or preferably in a range of 2 to 50, or preferably in a range of 2 to 30. Preferred dispersants are 64 & Zschimmer & Schwarz GmbH & Co KG under the trade name DISPERBYK ^®, for example DISPERBYK ^® 60, from Byk-Chemie GmbH, DOLAPIX CE.

The third component of the precursor of a sintered product preferably contains the additive in an amount in a range of 0.1 to 5 wt%, or preferably in a range of 0.2 to 2 wt%, or preferably in a range of 0.3 to 1 wt .-%, each based on the total weight of the third component.

The sum of all components of the third component always gives 100 wt .-% together.

The precursor for a sintered product after mixing preferably contains the first component in a range of 50 to 80% by weight, or preferably in a range of 55 to 70% by weight, or preferably in a range of 55 to 65% by weight. -%, in each case based on the total weight of the precursor. The precursor after mixing preferably contains the second component in a range of 9 to 40 wt%, or preferably in a range of 15 to 35 wt%, or preferably in a range of 18 to 30 wt%, each based on the total weight of the precursor. The precursor after mixing preferably contains the third component in a range of 5 to 25 wt.%, Or preferably in a range of 10 to 20 wt.%, Or preferably in a range of 12 to 20 wt. each based on the total weight of the precursor. The third component includes at least one methylcellulose, water and at least one additive. The precursor for a sintered product preferably contains methylcellulose in an amount in a range of 0.1 to 4.5% by weight, or preferably in a range of 0.5 to 3% by weight, or preferably in a range of 1 to 2 wt .-%, each based on the total weight of the precursor. The precursor for a sintered product preferably contains water in an amount in a range of 1 to 20 wt%, or preferably in a range of 2 to 19 wt%, or preferably in a range of 3 to 18 wt%. , in each case based on the total weight of the precursor. The precursor of a sintered product preferably contains the at least one additive in an amount in a range of 0.01 to 0.5 wt%, or preferably in a range of 0.02 to 0.2 wt%, or preferably in a range of 0.03 to 0.1 wt .-%, each based on the total weight of the precursor. The sum of the components of the first, second and third components in the precursor for a sintered product always gives 100 wt .-%.

Providing the first component, the second component and at least the third component in step i. can be done in any way that the skilled person would choose for this purpose. Preferably, the provision of the first, second and third components is selected so that mixing of the components is possible after the provision. Further preferably, the first and second components are provided ground.

The mixing in step ii. can be done in any manner that the skilled person would choose for this purpose. Preferably, the mixing is carried out in a manner that the first, the second and the third component are mixed as homogeneously as possible. The mixing can be done for example by mixing or grinding. The mixing can be done by means of a stirring means, such as a stirring blade or other stirring tool, which is moved in a vessel. The grinding can be carried out by means of grinding tools, as known to those skilled in the art for such purposes. These may, for example, be movable grinding rams which grind the mixture in a vessel. Preferably, the mixing takes place in a ball mill with a roller block, a kneader or a combination of both. Preferably, the first are first mixed with the second component and / or homogenized and then mixed with the third component.

The at least three components can be mixed together, or alternatively brought together in several mixing steps. Several mixing steps can take place between the addition of the various components. The components are preferably mixed successively. It is preferable to first mix the first component with the second component in a ball mill on a roller block with Al ₂ O ₃ spheres. This mixing step may be followed by another mixing step, for example in a kneader. The powder mixture is preferably processed in a double-Z kneader. The addition of the components of the third component, such as the methylcellulose, the water and the additive, can take place together or in succession. Preferably, the addition of the third component consisting of the methylcellulose, the water and an additive takes place together to the mixture of first and second component. After addition of the third component, the mixture is again preferably mixed and / or homogenized in a kneader.

According to the invention, the mixture in step ii. formed into a shaped body. The shaped body can have any shape that would be selected by the person skilled in the art. The shaped body preferably has a shape selected from the group consisting of a polygon, a cuboid, a cube, a cone, a cylinder, a strand, a pyramid or a combination of at least two thereof. The forming of the shaped body can be carried out by any means which would be used by a person skilled in the art to form a shaped body. Forming of the molded article may be, for example, pressing, extrusion, bonding, or a combination of at least two thereof. As a molded body is a body, preferably consisting of the mixture of step ii. which maintains its shape under normal conditions, even during movements such as lifting, transporting, dropping, or a combination of at least two of them.

The molding is inventively in step iii. treated in an oxidative atmosphere. An oxidative atmosphere means an atmosphere in which potentially at least one constituent of one of the components of step ii. under the conditions of treatment from step iii. is oxidatively altered. In the oxidation of this component, the oxidation state of at least one atom of the component increases by at least one. At least one component of the oxidative atmosphere is thereby reduced. In the reduction, the oxidation state of at least one atom of the oxidative atmosphere decreases by at least one. Preferably, at least one component of the shaped article is oxidized during the treatment in an oxidative atmosphere. Further preferably, a constituent of the third component is oxidized by the oxidative atmosphere. Further preferably, the methylcellulose and the additive are oxidized in the oxidative atmosphere. The oxidative atmosphere is preferably a fluid. The fluid may be a gas or a liquid or a mixture thereof. Preferably, the oxidative atmosphere includes a gas. In the oxidative atmosphere treatment, preferably the methyl cellulose and the additive are oxidized. The oxidation products, mainly carbon dioxide and water, preferably escape during the treatment in an oxidative atmosphere.

The treatment of the molding from step ii. in an oxidative atmosphere in step iii. may include several other steps. In addition, treating in an oxidative atmosphere may be preceded or followed by one or more steps. These further steps may be carried out under the oxidative atmosphere or under a non-oxidative atmosphere. The further steps may be selected from the group consisting of an extrusion step, a drying step or a combination thereof.

Preferably, the mixture is extruded in an extrusion step to at least one shaped body. The extrusion step preferably takes place after mixing in step ii. and before treating in an oxidative atmosphere in step iii. instead of. Extrusion can be done in any extruder that is useful for extruding such blends. Preferably, the extruder is selected from a single screw extruder, multiple screw extruder, a pin extruder, a planetary roller extruder, or a combination of at least two thereof. Preferably, the extrusion is carried out in a screw extruder.

In addition or as an alternative to the extrusion step, drying of the at least one shaped body can take place in a drying step of the mixture. Depending on the size and type of the extruded shaped body, the drying conditions can be adapted with regard to drying temperature, humidity and pressure, and optionally further parameters. The drying step may be selected from the group consisting of drying at a constant humidity, drying at elevated temperature, drying at a reduced pressure, or a combination of at least two thereof.

Following the mixing in step ii., Or optionally already during the mixing, according to the invention the treatment of the mixture or of the shaped article takes place in step iii. in an oxidative atmosphere. The oxidative atmosphere preferably includes a gas selected from the group consisting of air, oxygen, hydrogen, nitrogen, a noble gas, or a mixture thereof. The noble gas is preferably helium, neon, argon or krypton or a mixture of at least two thereof. Preferably, the oxidative atmosphere includes oxygen in an amount in a range of 1 to 30% by volume, or in a range of 2 to 25% by volume, or in a range of 5 to 20% by volume based on Total volume of the oxidative atmosphere. Alternatively, the atmosphere may be hydrogen in a range of 0.1 to 4% by volume, or in a range of 0.2 to 3% by volume, or in a range of 0.3 to 2% by volume to the total volume of the atmosphere. The oxidative atmosphere preferably has nitrous gases of less than 3% by volume, or preferably less than 2% by volume, or preferably 0% by volume, based on the total volume of the oxidative atmosphere. Most preferably, the oxidative atmosphere has no nitrous gases.

The treatment in step iii. of the shaped body from step ii. can be done at elevated temperature. Preferably, at least part of the treatment of the molded article takes place at a temperature in a range of 30 to 800 ° C, or in a range of 100 to 600 ° C, or in a range of 150 to 450 ° C. In the treatment of the molded article at elevated temperature preferably escapes at least a portion of the binder. There are different temperature profiles when treating in step iii. of the shaped body from step ii. possible. The treatment of the shaped body in an oxidative atmosphere can be carried out either by introducing the shaped body from step ii. take place in a preheated oxidative atmosphere or by slow stepwise or steadily increased heating of the molding from step ii. in an oxidative atmosphere. The treatment in step iii is preferred. of the shaped body from step ii. made in one step to a temperature in a range of 250 to 400 ° C. Preference is given to treating the shaped body from step ii. over a period of time in a range of 1 to 180 minutes, preferably in a range of 10 to 120 minutes, or preferably in a range of 20 to 100 minutes.

According to the invention, the methylcellulose has a fiber content of less than 5 wt .-%, preferably less than 3 wt .-%, or preferably less than 2 wt .-%, each based on the total mass of methylcellulose. At least 90% of the fibers have a size of less than 150 μm, preferably less than 100 μm, or preferably less than 50 μm, or preferably less than 30 μm. The size of the fibers is determined by observing the mixture in the microscope. To determine the size, circles are drawn around the fiber. The diameter of the smallest circle that can be pulled around the fiber corresponds to the size of the fiber. Preferably, the fibers have an elongated extent.

In particular, fibers can be present in methylcelluloses obtained from natural, renewable resources. The fibers are generally insoluble in water. This can lead to the fact that when heating the precursor of a sintered product, the fibers are degraded only at higher temperatures than the non-fibrous methylcellulose. The fibers that are not in step iii. are oxidized, remain in the precursor for a sintered product. However, at higher temperatures the fibers also char. At these points of the precursor arise pores.

In a preferred embodiment of the method, the oxidative atmosphere comprises a gas selected from the group consisting of oxygen, air or a mixture thereof.

In a further preferred embodiment of the method, the additive comprises a dispersant consisting of an organic substance having at least one functional group. The organic substance may be any organic substance having at least one carbon atom. Preferably, the organic substance has a number of carbon atoms in a range of 1 to 1,000,000, preferably in a range of 10 to 500,000, or preferably in a range of 20 to 100,000. The functional group may be a hydrophobic or a hydrophilic functional group. The functional group may be selected from the group consisting of an ammonium group, a carboxylate group, a sulfate group, a sulfonate group, an alcohol group, a multiple alcohol group, an ether group or a mixture of at least two of them. Preferred dispersants are under the trade names DISPERBYK ^® from Byk-Chemie GmbH, DOLAPIX CE 64 & Zschimmer & Schwarz GmbH & Co KG.

In a preferred embodiment of the process, the methylcellulose has a viscosity in a range of 15,000 to 45,000 mPas, preferably 20,000 to 40,000 mPas, or preferably 25,000 to 35,000 mPas. The conditions for determining the viscosity can be found in the test methods.

In a preferred embodiment of the process, the methylcellulose has less than 0.2% by weight, preferably less than 0.1% by weight or preferably less than 0.05% by weight, of non-incinerable constituents, in each case based on the total mass methylcellulose. Non-incinerable constituents are understood as meaning the parts of a mixture which, when treated at temperatures up to 1200 ° C., remain as residue in the sintered product. The non-incinerable constituents may, inter alia, be inorganic compounds, such as, for example, salts, metal oxides or silicates. A non-incinerable component of the methylcellulose may be, for example, sodium chloride or sodium hydroxide. For example, a conductivity measurement, as described in the test methods, can serve as detection method.

Another object of the present invention is a precursor of a sintered product obtainable by the method described above.

• I. Bereitstellen eines Vorläufers für ein Sinterprodukt nach dem zuvor beschriebenen Verfahren,
• II. Behandeln des Vorläufers mit einer Temperatur in einem Bereich von 800 bis 2200 °C, bevorzugt in einem Bereich von 1000 bis 2000 °C, oder bevorzugt in einem Bereich von 1200 bis 1800 °C,

wobei das Sinterprodukt erhalten wird. A further subject of the present invention is a process for producing a sintered product, at least comprising:

• I. providing a precursor for a sintered product according to the method described above,
• II. Treating the precursor at a temperature in a range of 800 to 2200 ° C, preferably in a range of 1000 to 2000 ° C, or preferably in a range of 1200 to 1800 ° C,

wherein the sintered product is obtained.

The provision of the precursor for the sintered product can be made in any manner that would be used by one skilled in the art to further process the precursor for a sintered product into a sintered product. The provision of the precursor is preferably carried out in a vessel which withstands heating to temperatures of up to 2200 ° C. for a period of at least 24 hours without deformation and preferably without chemical changes. The treatment time depends on the size and geometry of the precursor.

The treatment of the precursor at a temperature in a range of 800 to 2200 ° C can be done in any device designed to provide such temperatures. Preferably, the treatment is carried out in a high-temperature furnace. The treatment of the precursor preferably takes place at a final temperature in a range of 70 to 95% of the melting temperature of that constituent of the precursor having the lowest melting point. The treatment of the precursor may take place directly following the treatment of step iii. of the shaped body from step ii. the previously described method for producing a precursor. Alternatively, the two treatments may be timed out. Preferably, the treatment of the precursor takes place directly after the treatment of the molding of step iii. of the previously described process for the preparation of a precursor. When the treatment of the precursor is carried out immediately after the treatment of the shaped article, the treatment of the precursor preferably takes place in the same atmosphere as the treatment of the shaped article.

Preferably, the treatment of the precursor takes place under a protective atmosphere or a reductive atmosphere. The change of the oxidative atmosphere to the protective or reductive atmosphere preferably occurs during heating to a final temperature during the treatment of the precursor. In this change of atmosphere is preferably gas that forms the protective atmosphere, passed into the oven, with the aim of replacing the gas space in the oven, a so-called "rinsing". For this purpose, the gas forming the protective atmosphere is preferably introduced into the furnace to at least three times the volume of the furnace. Preferably, the treatment of the precursor takes place immediately after the step of treating the mixture at a temperature in a range of 800 to 2200 ° C.

Alternatively, treating the precursor may also take place in one step with treating the mixture at a temperature in a range of 800 to 2200 ° C. This is preferred if the constituents of the precursor are not prone to oxidation by oxygen.

• i). Bereitstellen einer ersten Komponente, einer zweiten Komponente und mindestens einer dritten Komponente,
• ii). Mischen der in Schritt i). bereitgestellten Komponenten und Bilden eines Formkörpers,
• iii). Behandeln der Mischung aus Schritt ii). in einer Schutzatmosphäre, wobei der Vorläufer eines Sinterprodukts erhalten wird, wobei die dritte Komponente 2,2,4-Trimethylpentan-1,3-diol-monoisobutyrat beinhaltet.

Another, in particular a third aspect of the present invention is a further process for the preparation of a precursor for a sintered product, comprising the steps:

• i). Providing a first component, a second component and at least a third component,
• ii). Mix in step i). provided components and forming a shaped body,
• iii). Treating the mixture from step ii). in a protective atmosphere, whereby the precursor of a sintered product is obtained, wherein the third component includes 2,2,4-trimethylpentane-1,3-diol monoisobutyrate.

The first component for the preparation of the precursor according to the third aspect of the present invention may include any substance which increases its precursor for a sintered product, increasing the conductivity of the precursor for the sintered product and, preferably, the sintering product to be formed. Preferably, the first component first contains a metal. The metal is preferably selected from the group consisting of platinum, palladium, iridium, niobium, molybdenum, titanium, cobalt, zirconium, rhodium, ruthenium, chromium, tantalum, tungsten, a titanium alloy, a tantalum alloy, a tungsten alloy or a mixture of at least two thereof. Preferably, the first component first comprises molybdenum. The first component includes first a metal preferably in an amount in a range of 90 to 100 wt%, or preferably in a range of 92 to 99 wt%, or preferably in a range of 95 to 98 wt%. %, in each case based on the total weight of the first component.

The second component in the further process for producing the precursor may include any substance which contributes to the sintering product precursor by heating a sintered product receive. The second component is, for example, a starting material for a sinterable substance. Preferably, the second component comprises a starting material for a ceramic selected from the group consisting of an oxide ceramic, a silicate ceramic, a non-oxide ceramic or a mixture of at least two thereof.

The oxide ceramic is preferably selected from the group consisting of a metal oxide, a semi-metal oxide or a mixture thereof. The metal of the metal oxide may be selected from the group consisting of aluminum, beryllium, barium, calcium, magnesium, sodium, potassium, iron, zirconium, titanium or a mixture of at least two thereof. The metal oxide is preferably selected from the group consisting of aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), zirconium oxide (ZrO ₂ ), yttrium oxide (Y ₂ O ₃ ), aluminum titanate (Al ₂ TiO ₅ ) or a mixture of at least two hereof. The semimetal of the semimetal oxide is preferably selected from the group consisting of boron, silicon, arsenic, tellurium or a mixture of at least two thereof.

The silicate ceramic is preferably selected from the group consisting of a steatite (Mg ₃ [Si ₄ O ₁₀ (OH) ₂ ]), cordierite (Mg, Fe ²⁺ ) ₂ (Al ₂ Si) [Al ₂ Si ₄ O ₁₈ ]) , Mullite (Al ₂ Al _{2 + 2x} Si _2-2x O _10-x with x = oxygen _vacancies per unit cell), feldspar (Ba, Ca, Na, K, NH ₄ ) (Al, B, Si) ₄ O ₈ ) or a mixture of at least two of them.

The non-oxide ceramic may be selected from the group consisting of a carbide, a nitride or a mixture thereof. The carbide may be selected from the group consisting of silicon carbide (SiC), boron carbide (B ₄ C), titanium carbide (TiC), tungsten carbide. The nitride may be selected from the group consisting of silicon nitride (Si ₃ N ₄ ), aluminum nitride (AlN), silicon aluminum oxynitride (SIALON) or a mixture of at least two thereof.

The second component in the further process for the preparation of the precursor preferably contains an oxide ceramic, preferably aluminum oxide (Al ₂ O ₃ ). Further preferably, the second component comprises alumina in an amount ranging from 50 to 100% by weight, or preferably in a range from 70 to 100% by weight, or preferably in a range from 90 to 100% by weight. %, in each case based on the total weight of the second component. The particle size distribution of the second component, such as alumina, is preferably d ₂₀ = 0.2 μm, d ₅₀ = 0.4 μm, and d ₉₀ = 1 μm. This means that 20% of the total number of particles have a diameter of less than 0.2 μm, 50% of the particles have a diameter of less than 0.4 μm, and 90% of the particles have a diameter of less than 1 μm exhibit. The particle sizes can be determined in various ways. For this purpose, optical methods are preferably used, such as electrical light scattering, condensation nucleus counting or laser diffraction. The particle size is preferred by means of laser diffraction. The particle size is preferably determined by means of laser diffraction.

The third component in the further process for preparing the precursor may include any substance that would be selected by one skilled in the art to facilitate mixing of the first and second components. Preferably, the third component comprises a binder, for example, 2,2,4-trimethylpentane-1,3-diol monoisobutyrate. The third component according to the invention comprises at least 2,2,4-trimethylpentane-1,3-diol monoisobutyrate. Further preferably, the third component comprises 2,2,4-trimethylpentane-1,3-diol monoisobutyrate in a range of from 95 to 100% by weight, based on the total weight of the third component. The third component preferably comprises 2,2,4-trimethylpentane-1,3-diol monoisobutyrate as pure substance. This is then present in a proportion by weight of more than 99 wt .-%, based on the total weight of the third component.

Providing the first component, the second component and at least the third component in step i). The further method can be carried out in any way that would be selected by the person skilled in the art for this purpose. Preferably, the provision of the first, second and third components is selected so that mixing of the components is possible after the provision. Further preferably, the first and second components are provided ground.

The mixing in step ii). can be done in any manner that the skilled person would choose for this purpose. Preferably, the mixing is carried out in a manner that the first, the second and the third component are mixed as homogeneously as possible. The mixing can be done for example by mixing or grinding. The mixing can be done by means of a stirring means, such as a stirring blade or other stirring tool, which is moved in a vessel. The grinding can be carried out by means of grinding tools, as known to those skilled in the art for such purposes. It can do this For example, they are mobile grinding rams that grind the mixture in a vessel. Preferably, the mixing takes place in a ball mill with a roller block, a kneader or a combination of both. Preferably, the first are first mixed with the second component and / or homogenized and then mixed with the third component.

The at least three components can be mixed together, or alternatively brought together in several mixing steps. Several mixing steps can take place between the addition of the various components. The components are preferably mixed successively. This mixing step may be followed by another mixing step, for example in a kneader. The powder mixture is preferably processed in a double-Z kneader. The addition of the components of the third component, such as the 2,2,4-trimethylpentane-1,3-diol monoisobutyrate and optionally the additive, can take place together or in succession. Preferably, the addition of the third component, consisting of 2,2,4-trimethylpentane-1,3-diol monoisobutyrate and optionally an additive, takes place together to the mixture of first and second component. After addition of the third component, the mixture is preferably again mixed or homogenized in a kneader.

The mixture is in step iii). treated in a protective atmosphere. A protective atmosphere is an atmosphere in which, as far as possible, no chemical reaction or reaction takes place between the protective atmosphere and the components of the precursor for a sintered product. A chemical reaction is understood to mean a reaction of at least one component which is accompanied by a change in the oxidation state of the component. Preferably, the oxidation state of none of the components of the precursor of the sintered product changes during the treatment of the precursor under a protective atmosphere. Only the third component escapes from the precursor to a sintered product or decomposes.

Preferably, a protective atmosphere is understood as meaning an inert atmosphere. Treating the mixture from step ii). in a protective atmosphere may involve several further steps.

According to the invention, the mixture in step ii). formed into a shaped body. The shaped body can have any shape that would be selected by the person skilled in the art. The shaped body preferably has a shape selected from the group consisting of a polygon, a cuboid, a cube, a cone, a cylinder, a strand, a pyramid or a combination of at least two thereof. The forming of the shaped body can be carried out by any means which would be used by a person skilled in the art to form a shaped body. Forming of the molded article may be, for example, pressing, extrusion, bonding, or a combination of at least two thereof. The shaped body is a body, preferably consisting of the mixture from step ii). which maintains its shape under normal conditions, even during movements such as lifting, transporting, dropping, or a combination of at least two of them. The mixture from step ii) is preferred. extruded into at least one molding in an extrusion step. The extrusion step preferably takes place after mixing and before treatment. The extrusion step may take place in a protective atmosphere. The extrusion step preferably takes place under normal pressure in air. Extrusion can be done in any extruder suitable for extruding such mixtures. Preferably, the extruder is selected from a single-screw extruder, multi-screw extruder, a pin extruder and a planetary roller extruder, or a combination of at least two thereof. Preferably, the extrusion is carried out in a screw extruder.

Following the mixing in step ii), or optionally also already during the mixing, according to the invention the treatment of the mixture or of the shaped body takes place in a protective atmosphere. A protective atmosphere is an atmosphere in which as little as possible components of the components are oxidatively converted. The protective atmosphere is preferably a fluid. The fluid may be a gas or a liquid or a mixture thereof. Preferably, the protective atmosphere includes a gas.

In a further preferred embodiment of the further method, the protective atmosphere comprises a gas selected from the group consisting of nitrogen, hydrogen, carbon dioxide, helium, neon, argon, krypton, xenon and radon or a mixture of at least two thereof. When the main constituent of the protective atmosphere is not hydrogen, the protective atmosphere may further include hydrogen in a range of 0.1 to 4% by volume, or in a range of 0.2 to 3% by volume, or in a range of 0.3 to 2 vol .-%, each based on the total volume of the protective atmosphere include. The protective atmosphere preferably has nitrous gases of less than 3% by volume, or preferably less than 2% by volume, based on the total volume of the protective atmosphere. Most preferably, the oxidative atmosphere has no nitrous gases.

In a preferred embodiment of the further process, the 2,2,4-trimethylpentane-1,3-diol monoisobutyrate contains less than 1% by weight, based on the total weight of the further precursor of impurities. Preferably, the 2,2,4-trimethylpentane-1,3-diol monoisobutyrate has impurities in a range of 0.05 to 1 wt.%, Preferably in a range of 0.1 to 0.8 wt.%, or preferably in a range of 0.2 to 0.7 wt .-%, based on the total mass of 2,2,4-trimethylpentane-1,3-diol monoisobutyrat on. Impurities can be understood as meaning all substances which do not correspond to 2,2,4-trimethylpentane-1,3-diol monoisobutyrate. As a rule, impurities are organic compounds.

In a preferred embodiment of at least one of the methods described above, the precursor comprises the third component in a range of from 0.3 to 25% by weight, based on the total weight of the further precursor.

In a preferred embodiment of at least one of the methods described above, the first component is selected from the group consisting of: platinum, palladium, iridium, niobium, molybdenum, titanium, cobalt, zirconium, rhodium, ruthenium, chromium, tantalum, tungsten, a titanium Alloy, a tantalum alloy, a tungsten alloy or a mixture of at least two thereof. Further preferably, the first component comprises an alloy selected from the group consisting of a platinum alloy, a titanium alloy, a tantalum alloy and a tungsten alloy or a mixture of at least two thereof. Preferably, the first component includes a platinum alloy.

In a preferred embodiment of at least one of the methods described above, the second component is selected from the group consisting of: alumina, zirconia, magnesia, aluminum nitride, aluminum titanate or a mixture of at least two thereof.

• a. 50 bis 90 Gew.-% die erste Komponente,
• b. 9 bis 40 Gew.-% die zweite Komponente,
• c. 0,3 bis 25 Gew.-% die dritte Komponente,
• d. Rest Wasser,

jeweils bezogen auf die Gesamtmasse des weiteren Vorläufers, wobei die Summe der Gewichtsprozente 100 ergibt.In a preferred embodiment of at least one of the methods described above, the precursor contains within a range of

• a. 50 to 90% by weight of the first component,
• b. 9 to 40% by weight of the second component,
• c. 0.3 to 25% by weight of the third component,
• d. Rest of water,

in each case relative to the total mass of the further precursor, the sum of the percentages by weight being 100.

In a preferred embodiment of at least one of the methods described above, the precursor is at least during a part of step iii. or step iii). treated at a temperature in a range of 250 ° C to 400 ° C.

Another object of the present invention is a precursor of a sintered product obtainable by the further method described above.

• I. Bereitstellen eines Vorläufers für ein Sinterprodukt nach dem zuvor beschriebenen Verfahren zur Herstellung eines weiteren Vorläufers für ein Sinterprodukt,
• II. Behandeln des weiteren Vorläufers mit einer Temperatur in einem Bereich von 800 bis 2200 °C, bevorzugt in einem Bereich von 1000 bis 2000 °C, oder bevorzugt in einem Bereich von 1200 bis 1800 °C,

wobei das Sinterprodukt erhalten wird. A further subject of the present invention is a process for producing a sintered product, at least comprising:

• I. providing a precursor for a sintered product according to the previously described method for producing a further precursor for a sintered product,
• II. Treating the further precursor at a temperature in a range of 800 to 2200 ° C, preferably in a range of 1000 to 2000 ° C, or preferably in a range of 1200 to 1800 ° C,

wherein the sintered product is obtained.

The provision of the precursor for the sintered product can be made in any manner that would be used by one skilled in the art to further process the precursor for a sintered product into a sintered product. The provision of the precursor is preferably carried out in a vessel which withstands heating to temperatures of up to 2200 ° C. for a period of at least 120 minutes without deformations and preferably without chemical changes. The providing may be selected from the group consisting of providing in a frit, a sheet metal, a metal crucible and a ceramic crucible or a combination of at least two thereof.

The treatment of the precursor at a temperature in a range of 800 to 2200 ° C can be done in any device designed to provide such temperatures. This is preferred Handle in a high temperature oven. The treatment of the precursor preferably takes place at a final temperature in a range of 70 to 95%, the melting temperature of that constituent of the precursor having the lowest melting point. The treatment of the precursor may take place directly following the treatment of step iii. of the shaped body from step ii. the previously described further process for the preparation of a precursor. Alternatively, the two treatments may be timed out. Preferably, the treatment of the precursor takes place directly after the treatment of the molding of step iii. of the previously described process for the preparation of a precursor.

Further preferably, the treatment takes place in step iii). the shaped body from step ii). according to the further process for producing a precursor together with treating the precursor at a temperature in a range of 800 to 2200 ° C according to the method of producing a sintered product. This is preferably done by the molding of step ii). directly after completion of step ii) is treated at a temperature in a range of 800 to 2200 ° C. When the treatment of the precursor is carried out immediately after the treatment of the shaped article, the treatment of the precursor preferably takes place in the same atmosphere as the treatment of the shaped article. Further preferred is the treatment according to step iii). already performed as part of step II. of the process for producing the sintered product.

Preferably, the treatment of the precursor takes place under a protective atmosphere or a reductive atmosphere. Should the protective atmosphere in treatment II. Be different from that in the treatment of step iii). so it is preferable to pass gas, which is the protective atmosphere into the oven, with the aim of replacing the gas space in the oven, a so-called "rinsing". For this purpose, the gas forming the protective atmosphere is preferably introduced into the furnace to at least three times the volume of the furnace. Preferably, the treatment of the precursor takes place immediately after the step of treating the mixture at a temperature in a range of 800 to 2200 ° C.

Preferably, the treatment of the precursor is carried out at a temperature in a range of 800 to 2200 ° C. The treatment in step II. Can be done directly at the final temperature or it can start at low temperatures, such as in a range of 100 to 800 ° C and slowly raised from there to the final temperature in a range of 800 to 2200 ° C. Treatment of the precursor at a temperature in the range of 800 to 2200 ° C is preferably followed by a cooling step. In the cooling step, the temperature is gradually or continuously brought from the final temperature to room temperature.

Another object of the present invention is a sintered product obtainable by the previously described method for producing a sintered product.

The sintered product preferably has an electrical conductivity of at least 20%, preferably at least 60%, more preferably of at least 70%, or preferably of at least 80%, of the conductivity of the first component. Preferably, the electrical conductivity is in a range of 1 × 10 ⁶ to 50 × 10 ⁶ S / m, or preferably in a range of 5 × 10 ⁶ to 40 × 10 ⁶ S / m, or preferably in a range of 10 × 10 ⁶ up to 30 · 10 ⁶ S / m. Furthermore, the sintered product preferably has a thermal expansion coefficient which deviates less than 20%, preferably less than 10% from the thermal expansion coefficient of the second component. Particularly preferred is a coefficient of linear expansion α in a range from 0.1 × 10 ^-6 / K to 20 × 10 ^-6 / K, or preferably in a range from 0.2 × 10 ^-6 / K to 15 × 10 ^-6 / K, or preferably in a range of 0.5 × 10 ^-6 / K to 10 × 10 ^-6 / K, measured at 25 ° C. Thus, the sintered product is particularly suitable for applications in which a current flow must be ensured in an environment with high temperature fluctuations.

• a) weniger als 5 Vol.-%, bevorzugt weniger als 4 Vol.-%, oder bevorzugt weniger als 3 Vol.-% Poren, jeweils bezogen auf das Gesamtvolumen des Sinterproduktes; mindestens 90 %, bevorzugt mindestens 92 %, oder bevorzugt mindestens 94 % der Poren weisen eine Größe von weniger als 150 µm, bevorzugt von weniger als 140 µm, oder bevorzugt von weniger als 130 µm auf,
• b) einen Kohlenstoffgehalt von weniger als 10 ppm, bevorzugt von weniger als 5 ppm bezogen auf das Gesamtgewicht des Sinterproduktes.

In a preferred embodiment of the sintered product, the sintered product has at least one, preferably both of the following properties:

• a) less than 5 vol .-%, preferably less than 4 vol .-%, or preferably less than 3 vol .-% pores, each based on the total volume of the sintered product; at least 90%, preferably at least 92%, or preferably at least 94% of the pores have a size of less than 150 μm, preferably less than 140 μm, or preferably less than 130 μm,
• b) a carbon content of less than 10 ppm, preferably less than 5 ppm, based on the total weight of the sintered product.

For the purposes of the invention, pores are holes in the sintered product which are larger than 5 μm in their greatest extent. The pores may have a size in a range of 6 to 500 μm. The pore size is preferably determined by means of manual measurement of scanning electron micrographs. The size of the pores is determined based on a cross section at the location of the pores with the greatest distance from a pore wall to the opposite pore wall. The size is measured directly through the pore.

The carbon content of the sintered product is determined by means of elemental analysis. A suitable analysis method is described in the test methods.

Another object of the present invention is a device comprising at least one sintered product according to one of the methods described above.

The device may be any device that would be selected by a person skilled in the art in order to use the sintered product. The sintered product can be used in the device for the targeted conduction of electrical currents. Thus, the sintered product can be installed in the device so that the sintered product is installed in the housing of the device to selectively initiate an electrical current through the sintered product into the interior of the device can be supplied without unwanted power to other components of the device , The sintered product is preferably resistant to acids or bases, preferably in a pH range of 1 to 13, preferably in a pH range of 1.5 to 12.5, or preferably in a pH range of 2 to 12. The sintered product is furthermore preferably gas-tight. The sintered product preferably withstands pressures in a range from 1 to 10 bar, preferably in a range from 1 to 9 bar. Furthermore, the sintered product is preferably weather resistant, which means that preferably no changes of physical or chemical properties of the sintered product in climatic changes such as temperatures in a range of -50 and 150 ° C, humidities in a range of 0 to 100% rel. Humidity, pressures in a range of 1 to 10 bar take place.

In a further preferred embodiment of the device, the device is selected from the group consisting of a lamp post, a lamp electrode, an electrical feedthrough or a cardiac pacemaker. The sintered product is preferably used in the device, such as the lamp pin, the lamp electrode or the cardiac pacemaker as an electrical conductor in an otherwise electrically insulating housing. The electrical feedthrough can be used for example in any device that is to separate a preferably hermetically sealed interior of its environment. The device can be used for example with the electrical feedthrough in an implantable medical device. For example, the electrical feedthrough may include an electrically insulating base body made of a ceramic or an electrically insulating polymer. Preferably, one or more electrical conduction elements, which contain the sintered product, are materially connected to the base body. These line elements preferably pass through the base body, so that an electrically conductive connection between the interior of the device and the outside space can be made.

EXAMPLES

Various blends were prepared for a precursor to a sintered product using a ball mill mixed with 1 cm diameter Al ₂ O ₃ spheres. The following Tables 1 to 3 list the compositions of three variants of precursors for a methylcellulose sintered product. The specified methylcellulose was acquired as Tylose under the trade name Tylose ^® E 409,002 of ShinEtsu SE Tylose GmbH% Co. KG. Table 4 shows a mixture for a precursor for a sintered product under variant 4 with 2,2,4-trimethylpentane-1,3-diol monoisobutyrate. The 2,2,4-trimethylpentane-1,3-diol monoisobutyrate was obtained from Sigma Aldrich Co. LLC. based.

From each of the mixture variants, a strand-shaped molded body (length = 20 cm, strand thickness = 0.8) was extruded. The moldings with mixtures according to Variant 1-3 were first at a temperature of 350 ° C for 30 min. and then treated at a temperature of 1750 ° C for 60 minutes, whereby the sintered products were obtained. The moldings according to variant 4 were treated at a temperature of 1750 ° C for 60 min, whereby the sintered products were also obtained. Variant 1 Table 1: Composition of a methylcellulose-containing precursor of a sintered product material Quantity [g] Proportion [% by weight] Mo (about 45% by volume) 33,90 56.76 Al ₂ O ₃ (about 55% by volume) 16.10 26,95 Tylose E409002 0.70 1.17 DISPERBYK ^® 0.03 0.05 water 9.00 15.07 total 59.73 100 Variant 2 Table 2: Composition of a methylcellulose-containing precursor of a sintered product material Quantity [g] Proportion [% by weight] Mo (about 60% by volume) 39,70 67.60 Al ₂ O ₃ (40% by volume) 10.30 17.54 Tylose E409002 0.70 1.19 DISPERBYK ^® 0.03 0.05 water 8.00 13.62 total 58.73 100 Variant 3 Table 3: Composition of a methylcellulose-containing precursor of a sintered product material Quantity [g] Proportion [% by weight] Mo (about 42% by volume) 32,55 54.04 Al ₂ O ₃ (about 58% by volume) 17.45 28.97 Tylose 0.70 1.16 DISPERBYK ^® 0.03 0.05 water 9.50 15.78 total 60.23 100 Variant 4 Table 4: Composition of a 2,2,4-trimethylpentane-1,3-diol monoisobutyrate-containing precursor of a sintered product material Quantity [g] Proportion [% by weight] Mo (about 42% by volume) 32,55 56.12 Al ₂ O ₃ (about 58% by volume) 17.45 30.09 2,2,4-trimethylpentane-1,3-diol monoisobutyrate 8.00 13.79 total 58,00 100.00

TEST AND TEST METHODS

• 1) Test Method for Viscosity Measurement: a) was measured with a viscometer Brookfield LV, spindle no. 4th b) it is a 2 wt .-% aqueous solution of the compound to be determined (for example, a methyl cellulose) prepared and determined at 20 ° C, at a speed of 12 / min.
• 2) Test method for the conductivity measurements of aqueous solutions: a) according to DIN 53114 Paper, cardboard and pulp; Determination of the conductivity of aqueous extracts; b) a solution was provided comprising: i) 0.5 g of methylcellulose; ii) 9.5 g of isopropanol pa; iii) 200 ml of distilled water (prepared by reverse osmosis).
• 3) Test Method for Incineration: DIN 54373 Testing of pulp, paper and cardboard; Determination of the acid-insoluble fraction in the incineration residue. Modification: Use of a methylcellulose as a test substance.
• 4) Test method for the particle size measurement of methyl cellulose: For this, 1 g of the methylcellulose was mixed with 50 ml of boiling, distilled water to form a gel. After three hours, the gel was homogenized and streaked between two slides. The size of the insoluble particles was then determined under a light microscope.
• 5) Method for Determining Particle Size of Inorganic Powders: The particle size of inorganic powders was determined by laser light scattering with a Mastersizer 2000 (Malvern Instruments Ltd., Great Britain).
• 6) Test Method for Pore Size: On the basis of a scan of a scanning electron microscope (SEM), images of the samples to be examined were produced at a magnification of 1: 500 to 1: 1000. At these, the diameter of the pore was manually measured at the widest point.
• 7) Test method for carbon content: The carbon content was measured using a Leco RC612 Elemental Analyzer.

characters

The following is in

1 a diagram of a method for producing a precursor for a sintered product according to the invention;

2 a schematic of a method for producing a sintered product;

3 a schematic representation of a precursor for a sintered product;

4 a schematic representation of a sintered product;

5 a schematic representation of an article with a sintered product
shown.

In 1 the process for producing a precursor for a sintered product according to the invention is shown schematically. In step i. or step i). 10 a first component is mixed together with the second component, in the proportions as in the variants 1 to 4, in a ball mill with Al ₂ O ₃ balls. The third component is added to this mixture in a double-Z kneader. The mixing takes place in step ii. or ii). 12 at room temperature and under normal pressure for 30 minutes instead. Subsequently, the mixture in a screw extruder within 30 min. extruded into strands. The extruded mixture is placed on a sheet 32 collected.

If the mixture or the molding is a mixture of one of the variants 1 to 3, the strands are stored at room temperature overnight. Subsequently, the strands are heated in an atmosphere with air or an atmosphere of 75 vol .-% nitrogen, 20 vol .-% oxygen, 5 vol .-% argon for 60 minutes in an oven at 350 ° C. After the 60 minutes, the precursor for a sintered product 30 be cooled at room temperature in air or directly from the process 2 be subjected. In this way, a precursor of a sintered product 30 obtained according to claim 1.

2 schematically shows as the precursor for a sintered product 30 out 1 in one step 20 on the same sheet 32 how the mixture is made 1 provided. The precursor from step iii. will be in step 22 sintered in a protective atmosphere of 100 vol .-% hydrogen at 1750 ° C. The precursor from step iii). will be in step 22 sintered in an atmosphere of 100 vol .-% nitrogen at 1750 ° C and a sintered product 40 receive.

If the mixture or the molding is a mixture of variant 4, then the strands become after extrusion in step iii). 14 in a protective atmosphere consisting of 100 vol .-% nitrogen heated to 1750 ° C in an oven. In this way, a sintered product 40 receive.

In 3 is a precursor 30 for a sintered product 40 on a sheet 32 shown.

In 4 is a sintered product 40 after the sintering process 2 shown.

5 shows a device 50 , for example a pacemaker, with a built-in sintered product 40 ,

LIST OF REFERENCE NUMBERS

10

 Step i./Step i).

12

 Step ii./Step ii).

14

 Step iii./Step iii)

20

 Step I.

22

 Step II.

30

 Precursor of a sintered product

32

 sheet

40

 sintered product

50

 contraption

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• DIN 53114 [0091]
• DIN 54373 [0091]

Claims (18)

A method for producing a precursor ( 30 ) for a sintered product ( 40 ), including the steps: i. Providing a first component, a second component and at least one third component, ii. Mix in step i. provided components and forming a shaped body, iii. Treating the molding from step ii. in an oxidative atmosphere, the precursor ( 30 ) of a sintered product ( 40 wherein the third component comprises at least one methylcellulose, water and an additive, the methylcellulose having a fiber content of less than 5% by weight based on the total mass of methylcellulose, wherein at least 90% of the fibers have a size of less than 150 μm. The method of claim 1, wherein the oxidative atmosphere includes a gas selected from the group consisting of oxygen, air or a mixture thereof. The method of claim 1 or 2, wherein the additive includes a dispersant that includes an organic substance having at least one functional group. The method of any one of the preceding claims, wherein the methylcellulose has a viscosity in a range of 15,000 to 45,000 mPas. The method of any one of the preceding claims, wherein the methylcellulose has less than 0.2% by weight of non-incinerable ingredients. A method for producing a precursor ( 30 ) for a sintered product ( 40 ), including the steps: i). Providing a first component, a second component and at least one third component, ii). Mix in step i). provided components and forming a shaped body, iii). Treating the molding from step ii). in a protective atmosphere, the precursor ( 30 ) of a sintered product ( 40 ), wherein the third component includes 2,2,4-trimethylpentane-1,3-diol monoisobutyrate. The method of any of claims 5 or 6, wherein the protective atmosphere comprises a gas selected from the group consisting of nitrogen, hydrogen, carbon dioxide, helium, neon, argon, krypton, xenon and radon, or a mixture of at least two thereof. The process according to any one of claims 6 or 7, wherein the 2,2,4-trimethylpentane-1,3-diol monoisobutyrate is less than 1% by weight, based on the total weight of the precursor ( 30 ) Contains impurities. The method according to any one of the preceding claims, wherein the precursor ( 30 ) the third component in a range of 0.3 to 25 wt .-%, based on the total weight of the precursor ( 30 ). The method of any one of the preceding claims, wherein the first component is selected from the group consisting of: platinum, palladium, iridium, niobium, molybdenum, titanium, cobalt, zirconium, rhodium, ruthenium, chromium, tantalum, tungsten or a mixture of at least two of that. The method of any one of the preceding claims, wherein the second component is selected from the group consisting of: alumina, zirconia, magnesia, aluminum nitride, aluminum titanate, or a mixture of at least two thereof. The method according to any one of the preceding claims, wherein the precursor ( 30 ) in a range of a. From 50% to 90% by weight of the first component, b. 9 to 40% by weight of the second component, c. 0.3 to 25% by weight of the third component, d. Balance of water, based in each case on the total weight of the precursor ( 30 ), the sum of the percentages by weight being 100. The method according to any one of the preceding claims, wherein the precursor ( 30 ) at least during a part of step iii. or step iii). is treated at a temperature in a range of 250 ° C to 400 ° C. A forerunner ( 30 ) of a sintered product ( 40 ) obtainable by a process according to any one of claims 1 to 13. A method for producing a sintered product ( 40 ), at least including: I. providing a precursor ( 30 ) for a sintered product ( 40 ) according to claim 14, II. treating the precursor ( 30 ) having a temperature in a range of 800 to 2200 ° C, the sintered product ( 40 ). A sintered product ( 40 ) obtainable according to claim 15. The sintered product ( 40 ) according to claim 16, wherein the sintered product ( 40 ) has at least one of the following properties: a) less than 5% by volume of pores, based on the total volume of the sintered product, wherein at least 90% of the pores have a size of less than 150 μm, b) a carbon content of less than 10 ppm based on the total weight of the sintered product ( 40 ) having. A device ( 50 ) comprising at least one sintered product ( 40 ) according to claim 16 or 17, or obtainable by a method according to claim 15. The device ( 50 ) according to claim 18, wherein the device ( 50 ) is selected from the group consisting of a lamp post, a lamp electrode, an electrical feedthrough, a pacemaker, or a combination of at least two thereof.

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