Nanoporous ceramics for atomization core and manufacturing method thereof

Abstract

The present invention provides a nanoporous ceramic for an atomizing core and a manufacturing method thereof, which includes 1 to 60 parts by weight of nanosilica, 10 to 80 parts by weight of ceramic powder, 1 to 50 parts by weight of a pore-forming agent, and 1 to 40 parts by weight of a sintering aid. The manufacturing method includes the following steps: (1) weighing the raw materials (nanosilica, ceramic powder, pore-forming agent, and sintering aid) and mixing them in a ball mill; (2) baking and drying the milled raw materials to obtain a mixed powder material; (3) heating paraffin wax until it is molten, adding the mixed powder material while stirring, and stirring for another 1 to 8 hours after the addition is complete to obtain a paraffin wax slurry; (4) pouring the paraffin wax slurry into a pre-prepared mold, cooling it to form a mold, and releasing it to obtain a wax mold; (5) preheating the wax mold and dewaxing it to obtain a dewaxed sample; and (6) sintering the dewaxed sample and cooling it to obtain a nanoporous ceramic. This method advantageously solves the problems of conventional techniques, such as the inability to achieve both high porosity and high strength, and the tendency for impurities and heavy metals to precipitate.

Description

[Technical Field]

[0001] The present invention relates to the technical field of atomizing cores, and more particularly to nanoporous ceramics for atomizing cores and a manufacturing method thereof. [Background technology]

[0002] Atomizing cores are primarily used in electronic atomizing devices to heat and atomize the liquid to be atomized into an aerosol, vapor, or mist that can be inhaled by the user. The liquid to be atomized may be smoke liquid or a solution containing a drug for health or medical use.

[0003] Current atomizing cores include heating elements based on porous ceramics, which are typically sintered at relatively low temperatures using a porous ceramic substrate sintering process. Conventional porous ceramic atomizing cores and their manufacturing methods use a mixture of ground and polished ceramic powders, and add low-softening-point glass powder or quartz sand to lower the sintering temperature. However, the resulting products are vulnerable to thermal shock. Furthermore, ceramics can suffer from cracking and oil leakage after repeated use. If the structure is unstable, impurities and heavy metals within the ceramic can easily precipitate and be mixed into the liquid being atomized, potentially posing a risk to human health. Furthermore, due to the low sintering temperature, measures to reduce porosity are typically used to ensure the structural strength of the product. However, if the product's porosity is low, carbon deposition and unpleasant odors can easily occur during use. Summary of the Invention [Problem to be solved by the invention]

[0004] The technical problem that the present invention aims to solve is to provide nanoporous ceramics for atomization cores and a method for manufacturing the same, in order to solve the drawback of conventional technologies that high porosity and high strength cannot be achieved at the same time, and the problem that when the strength and structure are unstable, impurities and heavy metals inside the ceramics are likely to precipitate and mix into the liquid to be atomized, causing harm to the human body. [Means for solving the problem]

[0005] The technical solution of the present invention is a nanoporous ceramic for atomization cores, characterized by comprising 1 to 60 parts by weight of nanosilica, 10 to 80 parts by weight of ceramic powder, 1 to 50 parts by weight of a pore-forming agent, and 1 to 40 parts by weight of a sintering aid.

[0006] Preferably, the composition contains 5 to 40 parts by weight of nanosilica, 20 to 70 parts by weight of ceramic powder, 5 to 30 parts by weight of a pore-forming agent, and 1 to 20 parts by weight of a sintering aid.

[0007] Preferably, the nanosilica contains colloidal nanosilica or powdered nanosilica, and the primary particle diameter of the nanoparticles is 10 to 150 nm. The amount of colloidal nanosilica is expressed as a value converted to its solid silica content.

[0008] Preferably, the ceramic powder includes at least one of kaolin, diatomaceous earth, alumina, silicon nitride, silicon carbide, quartz sand, glass sand, clay, and feldspar powder.

[0009] Preferably, the pore-forming agent includes at least one of graphite, starch, wheat flour, soybean flour, polystyrene microspheres, polymethyl methacrylate microspheres, carbonates, ammonium salts, sucrose, and fibers, and the particle size of the pore-forming agent is 1 to 200 μm.

[0010] Preferably, the pore-forming agent is flake graphite having a particle size of 1 to 20 μm.

[0011] Preferably, the sintering aid includes at least one of boron oxide, boric acid, oleic acid, stearic acid, sodium silicate, calcium oxide, iron oxide, and titanium oxide.

[0012] Another technical solution of the present invention is: Step (1) of weighing nanosilica, ceramic powder, pore-forming agent, and sintering aid as raw materials according to the formulation, mixing them in a ball mill, and ball milling; Step (2) of baking and drying the ball-milled mixed raw material in step (1) and ball-milling to obtain a dried mixed powder material; (3) heating the paraffin wax until it is in a molten state, adding the mixed powder material while stirring, and after the addition is completed, stirring for another 1 to 8 hours to obtain a paraffin wax slurry; Step (4) of injecting the paraffin wax slurry into a mold prepared in advance, cooling it to form a shape, and then releasing it to obtain a wax mold; (5) preheating and dewaxing the wax pattern to obtain a dewaxed sample; and (6) subjecting the dewaxed sample to a sintering process including heating, maintaining the temperature, and cooling to obtain nanoporous ceramics.

[0013] Preferably, in step (1), the rotation speed of the ball mill is 150 to 500 rpm, the ball milling time is 1 to 10 hours, and the diameter of the abrasive is 1 to 50 mm.

[0014] Preferably, in step (2), the baking and drying temperature is 60 to 150°C, the drying time is at least 1 hour, the melting point of the paraffin wax is 50 to 120°C, and the amount of paraffin wax added is 10 to 60% by weight of the mixed powder material.

[0015] Preferably, in step (5), the dewaxing temperature is 400 to 800°C and the dewaxing time is 2 to 12 hours.

[0016] Preferably, in step (6), the sintering step is carried out at a temperature of 600 to 1500° C., with a temperature increase rate of 1 to 10° C. / min and a temperature retention time of 2 to 12 hours.

[0017] Preferably, in step (6), the sintering process is carried out in a protective atmosphere, and the protective atmosphere is one or more of a reducing atmosphere with hydrogen, an inert atmosphere. [Effects of the Invention]

[0018] Beneficial effects Nanosilica material is introduced into the porous ceramic manufacturing process at a specified ratio. Nanoscale silica is mixed with a micron-sized ceramic powder matrix in a specified ratio, and a micro-nanocomposite structure is formed during the sintering process through a hardening reaction. Nanosilica has a very large specific surface area and a high concentration of hydroxyl groups on its surface, which effectively reduces the sintering temperature during the solid-state reaction with the ceramic powder. Furthermore, the material maintains high strength even under conditions of high porosity. The nanosilica's surface structure, which contains a high concentration of hydroxyl groups, promotes the solid-state reaction between the ceramic powder and improves the conversion efficiency of aluminosilicate. The formation of a micro-nanocomposite structure improves the structural stability of the porous ceramic skeleton, resulting in a porous ceramic skeleton with high strength, low sintering temperature, and maintained high porosity. The porosity can be adjusted by adjusting the amount of pore-forming agent added within the range of 30-65%, enabling the production of products with excellent thermal shock resistance and stable performance. Based on the premise of high strength and stable internal structure, nanoporous ceramics are not easily broken, which solves the problem of cracks and oil leakage caused by repeated use of ceramics. Furthermore, because the ceramic structure is stable, impurities and heavy metals are not easily precipitated during use of the product, which solves the problem of impurities and heavy metals exceeding standard values. Furthermore, because of the high porosity, carbon is easily accumulated during use of the product, which solves the problem of unpleasant odors.

[0019] The present invention will now be described in more detail with reference to examples.

[0020] The nanoporous ceramic for atomizing core of the present invention contains 1 to 60 parts by weight of nanosilica, 10 to 80 parts by weight of ceramic powder, 1 to 50 parts by weight of pore-forming agent, and 1 to 40 parts by weight of sintering aid. To obtain better effects, it may contain 5 to 40 parts by weight of nanosilica, 20 to 70 parts by weight of ceramic powder, 5 to 30 parts by weight of pore-forming agent, and 1 to 20 parts by weight of sintering aid.

[0021] Here, nanosilica refers to colloidal or powdered nanosilica, with a primary particle diameter of 10-150 nm. The amount of colloidal nanosilica is expressed as a value converted to solid silica. Nanosilica and micron-sized ceramic powder form a micro-nano composite structure through a curing reaction during the sintering process. Nanosilica's extremely large specific surface area and abundant hydroxyl groups on its surface effectively reduce the sintering temperature during the solid-state reaction with the ceramic powder. Nanosilica also maintains high porosity and achieves high strength. The high strength and stable internal structure of this nanoporous ceramic make it less likely to crack and less likely to precipitate impurities or heavy metals during use.

[0022] The ceramic powder includes at least one of kaolin, diatomaceous earth, alumina, silicon nitride, silicon carbide, quartz sand, glass sand, clay, and feldspar powder.

[0023] The pore-forming agent includes at least one of graphite, starch, wheat flour, soybean flour, polystyrene microspheres, polymethyl methacrylate microspheres, carbonates, ammonium salts, sucrose, and fibers, and the particle size of the pore-forming agent is 1 to 200 μm.

[0024] Preferably, the pore-forming agent is flake graphite with a particle size of 1 to 20 μm. When high strength is ensured by nanosilica, the pore-forming agent serves to adjust the porosity to a range of 30 to 65% by adjusting the amount of pore-forming agent added. The high porosity within the atomizing core allows the liquid to be atomized to easily penetrate, transmit, or flow during use of the atomizing core, and also makes it less likely that carbon will accumulate and cause an unpleasant odor.

[0025] The sintering aid includes at least one of boron oxide, boric acid, oleic acid, stearic acid, sodium silicate, calcium oxide, iron oxide, and titanium oxide.

[0026] The method for producing nanoporous ceramics for atomization cores of the present invention includes the steps of: Step (1) of weighing nanosilica, ceramic powder, pore-forming agent, and sintering aid as raw materials according to the formulation, mixing them in a ball mill, and ball milling; Step (2) of baking and drying the ball-milled mixed raw material in step (1) and ball-milling to obtain a dried mixed powder material; (3) heating the paraffin wax until it is in a molten state, adding the mixed powder material while stirring, and after the addition is completed, stirring for another 1 to 8 hours to obtain a paraffin wax slurry; Step (4) of injecting the paraffin wax slurry into a mold prepared in advance, cooling it to form a shape, and then releasing it to obtain a wax mold; (5) preheating and dewaxing the wax pattern to obtain a dewaxed sample; and (6) subjecting the dewaxed sample to a sintering process including heating, maintaining, and cooling to obtain nanoporous ceramics.

[0027] In step (1), the rotation speed of the ball mill is 150 to 500 rpm, the ball milling time is 1 to 10 hours, and the diameter of the abrasive is 1 to 50 mm.

[0028] In step (2), the baking and drying temperature is 60 to 150°C, the drying time is at least 1 hour, the melting point of the paraffin wax is 50 to 120°C, and the amount of paraffin wax added is 10 to 60% of the weight of the mixed powder material.

[0029] In step (5), the dewaxing temperature is 400 to 800°C, and the dewaxing time is 2 to 12 hours.

[0030] In step (6), the sintering temperature is 600 to 1500°C, the temperature rise rate is 1 to 10°C / min, and the temperature retention time is 2 to 12 hours.

[0031] In step (6), the sintering process is carried out in a protective atmosphere, which may be one or more of a hydrogen reducing atmosphere and an inert atmosphere. Sintering of the ceramic alone can be carried out in an air atmosphere. If heating is performed with an integrally sintered metal resistance wire, sintering must be carried out in a protective atmosphere to prevent oxidation of the metal resistance wire during sintering. The protective atmosphere may be a hydrogen reducing atmosphere or an inert atmosphere, and the inert atmosphere may include one or more of nitrogen gas and argon gas. The sintering atmosphere does not affect the performance of the nanoporous ceramic material of the present invention.

[0032] Embodiments of the present invention The present invention will be described in detail below with reference to specific examples. Example 1

[0033] Specifically, the nanoporous ceramic for the atomizing core in this embodiment of the present invention contains 15 parts by weight of nanosilica, 60 parts by weight of kaolin, 20 parts by weight of flake graphite with a particle diameter of 2 μm, 4 parts by weight of sodium silicate, and 1 part by weight of oleic acid. Example 2

[0034] Specifically, the method for manufacturing the nanoporous ceramic for the atomization core according to the embodiment of the present invention includes the following steps: (1) 15 parts by weight of nanosilica, which is a silica sol with a particle size of 150 nm, 60 parts by weight of 1000 mesh kaolin, 20 parts by weight of a pore-forming agent, which is flake graphite with a particle size of 2 μm, 4 parts by weight of sodium silicate, and 1 part by weight of oleic acid were weighed out, and the weighed components were placed in a ball mill and mixed and ball milled under the following conditions: ball mill rotation speed: 350 rpm, ball milling time: 10 hours, abrasive diameter: 10 mm. (2) The mixed raw material ball-milled in step (1) was baked in an oven at 60°C for 12 hours, and then ball-milled to obtain a dried mixed powder material. (3) 40% by weight of paraffin wax with a melting point of 60°C was weighed out relative to the total weight of the mixed powder material of step (2), the paraffin wax was heated until it became molten, and the mixed powder material was added while stirring. After the addition was completed, the mixture was further stirred and kneaded at 65°C for 6 hours to obtain a paraffin wax slurry. (4) The paraffin wax slurry was poured into a mold prepared in advance, cooled and molded, and then released to obtain a wax mold. (5) The wax mold was placed in a furnace in an air atmosphere, heated to 400°C, and dewaxed for 6 hours to obtain a dewaxed sample. (6) The above dewaxed sample was placed in a furnace in an air atmosphere and sintered under the following conditions: sintering temperature: 950°C, heating rate: 3°C / min, and heat retention time: 4 hours. After that, the temperature was lowered to room temperature to obtain nanoporous ceramics. Comparative Example Compared with Example 1 or Example 2, this comparative example differs in the following respects. Instead of 15 parts by weight of nanosilica, 15 parts by weight of quartz sand with a mesh of 1000 was used, which is irregularly distributed silicon oxide of the order of microns.

[0035] The porous ceramic substrates manufactured in Example 1 or Example 2 and Comparative Example were measured for compressive strength in accordance with the Chinese national standard for porous ceramics. The measurement results are shown in the table below. JPEG0007764478000001.jpg17164

[0036] From the above data, it can be seen that in the comparative example, except that the same amount of quartz sand was used instead of nanosilica, the other material components were exactly the same. When the monodispersed nanosilica was replaced with irregularly distributed micron-order silicon oxide, the strength of the produced porous ceramics was obviously reduced, which shows that nanosilica has higher activity in the sintering process and the structure of the ceramics obtained by solid-state reaction is stable. [Industrial Applicability]

[0037] The above is merely a preferred embodiment of the present invention, and any equivalent changes and modifications made based on the scope of the claims of the present invention are included in the scope of the claims of the present invention.

Claims

1. A method for producing nanoporous ceramics for atomization cores, comprising: Step (1) of weighing 5 to 15 parts by weight of nanosilica, 60 to 70 parts by weight of micron-order ceramic powder, 20 to 30 parts by weight of a pore-forming agent, and 1 to 5 parts by weight of a sintering aid as raw materials, mixing them in a ball mill, and ball milling; Step (2) of baking and drying the ball-milled mixed raw material in step (1) and ball-milling to obtain a dried mixed powder material; (3) heating the paraffin wax until it is in a molten state, adding the mixed powder material while stirring, and after the addition is completed, stirring for another 1 to 8 hours to obtain a paraffin wax slurry; Step (4) of injecting the paraffin wax slurry into a mold prepared in advance, cooling it to form a shape, and then releasing it to obtain a wax mold; (5) preheating and dewaxing the wax pattern to obtain a dewaxed sample; and (6) subjecting the dewaxed sample to a sintering process including heating, maintaining the temperature, and cooling to obtain nanoporous ceramics.

2. 2. The method for producing nanoporous ceramics for atomization cores according to claim 1, wherein in step (1), the rotation speed of the ball mill is 150 to 500 rpm, the ball milling time is 1 to 10 hours, and the diameter of the abrasive is 1 to 50 mm.

3. 2. The method for producing nanoporous ceramics for atomization cores according to claim 1, wherein in step (2), the baking and drying temperature is 60-150°C, the drying time is at least 1 hour, the melting point of the paraffin wax is 50-120°C, and the amount of paraffin wax added is 10-60% by weight of the mixed powder material.

4. 2. The method for producing nanoporous ceramics for atomization cores according to claim 1, wherein in step (5), the dewaxing temperature is 400-800°C, and the dewaxing time is 2-12 hours.

5. The method for producing nanoporous ceramics for atomization cores according to claim 1, characterized in that in step (6), the temperature of the sintering process is 600 to 1500 ° C, the heating rate is 1 to 10 ° C / min, and the heat-keeping time is 2 to 12 hours.

6. 2. The method for producing nanoporous ceramics for atomization cores according to claim 1, wherein in step (6), the sintering process is carried out in a protective atmosphere, and the protective atmosphere is one or more of a reducing atmosphere using hydrogen and an inert atmosphere.

7. The method for manufacturing nanoporous ceramics for atomization cores described in claim 1, characterized in that the nanosilica contains colloidal nanosilica or powdered nanosilica, the primary particle diameter of the nanoparticles is 10 to 150 nm, and the amount of colloidal nanosilica is expressed as a value converted into its solid silica content.

8. A method for producing nanoporous ceramics for atomization cores as described in claim 1, characterized in that the ceramic powder includes at least one of kaolin, diatomaceous earth, alumina, silicon nitride, silicon carbide, quartz sand, glass sand, clay, and feldspar powder.

9. The method for producing nanoporous ceramics for atomization cores as described in claim 1, characterized in that the pore-forming agent includes at least one of graphite, starch, wheat flour, soybean flour, polystyrene microspheres, polymethyl methacrylate microspheres, carbonates, ammonium salts, sucrose, and fibers, and the particle diameter of the pore-forming agent is 1 to 200 μm.

10. A method for producing nanoporous ceramics for atomization cores as described in Claim 9, characterized in that the pore-forming agent is flake graphite having a particle diameter of 1 to 20 μm.

11. A method for producing nanoporous ceramics for atomizing cores as described in claim 1, characterized in that the sintering aid contains at least one of boron oxide, boric acid, oleic acid, stearic acid, sodium silicate, calcium oxide, iron oxide, and titanium oxide.

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