Porous ceramic, preparation method thereof and atomization device

Abstract

The invention belongs to the technical field of atomizers, and relates to a preparation method of porous ceramic, which comprises the following steps: ball-milling and sieving ceramic aggregate magnesium oxide to obtain superfine magnesium oxide powder, adding hydroxyapatite, a sintering aid, glass powder and a pore forming agent, and fully and uniformly mixing to obtain mixed powder; mixing the mixed powder with a binder, and uniformly stirring to obtain a formed material; forming the formed material by adopting dry pressing forming to obtain a ceramic green body; and drying the ceramic green body, heating and sintering to obtain the porous ceramic doped with hydroxyapatite. The invention further relates to the porous ceramic and an atomization device. According to the technical scheme provided by the invention, the sintering temperature can be reduced, and the porosity and the bending strength can be improved.

Description

Technical Field

[0001] This application relates to the field of atomizer technology, and more specifically, to a porous ceramic, its preparation method, and an atomizing device. Background Technology

[0002] The atomizer coil is the core technology of an atomizer, determining to a certain extent the fineness of the atomized liquid and the accuracy of flavor reproduction. Currently, most commercially available atomizer coils are porous ceramic coils. Compared to traditional atomization methods, porous ceramics, due to their abundant micropores and special sintering process controlling porosity, allow for arbitrary adjustment of the aerosol particle size. These ceramics possess characteristics such as low thermal conductivity, low density, and low specific heat capacity. Furthermore, due to their material properties, the liquid exhibits a more uniform temperature field during atomization, resulting in more complete atomization per unit time and providing users with a better experience through higher atomization efficiency.

[0003] Current porous ceramics are mainly made of magnesium oxide as the main material, with the addition of certain binders and pore-forming agents, and are then injection molded and sintered. Magnesium oxide has obvious defects such as high sintering temperature, high thermal conductivity, and poor heat concentration during atomization, resulting in ceramics with poor affinity for e-liquid and poor flavor reproduction. Summary of the Invention

[0004] The technical problem to be solved by this application is the existing problem of high sintering temperature, high thermal conductivity and non-concentrated heat during atomization of porous ceramics.

[0005] To address the aforementioned technical problems, this application provides a method for preparing porous ceramics, employing the following technical solution: Magnesium oxide, a ceramic aggregate, is ball-milled and sieved to obtain ultrafine magnesium oxide powder. Hydroxyapatite, sintering aid, glass powder, and pore-forming agent are then added and thoroughly mixed to obtain a mixed powder. The mixed powder is mixed with the binder and stirred evenly to obtain the molded material; The material is formed by dry pressing to obtain a ceramic green body; The ceramic green body is dried and then sintered at a higher temperature to obtain porous ceramics doped with hydroxyapatite.

[0006] To address the aforementioned technical problems, this application also provides a porous ceramic, which is prepared using the method described above.

[0007] To address the aforementioned technical problems, this application also provides an atomizing device comprising the aforementioned porous ceramic.

[0008] Compared with the prior art, this application has the following main advantages: This application utilizes the sintering process of magnesium oxide and hydroxyapatite to promote crystal transformation and generate a β-TCP phase, thereby improving the affinity of the porous ceramic and reducing its thermal conductivity. The addition of sintering aids and glass powder lowers the sintering temperature, improving crystal formation and mechanical properties. The addition of pore-forming agents promotes the formation of ceramic pore structures, ensuring high porosity. The addition of binders enhances the bonding force between powder particles, improving the formability and stability of the green body. The prepared porous ceramic exhibits low sintering temperature, high porosity, strong adsorption capacity for e-liquid, low thermal conductivity, high flexural strength, and uniform pore size distribution. Attached Figure Description

[0009] To more clearly illustrate the solutions in this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0010] Figure 1 This is a flowchart of an embodiment of the method for preparing porous ceramics according to this application. Detailed Implementation

[0011] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings of this application are used to distinguish different objects, not to describe a particular order.

[0012] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0013] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0014] This application provides a method for preparing porous ceramics, see [link to relevant documentation]. Figure 1 As shown, it includes the following steps: Step S10: The ceramic aggregate magnesium oxide is ball-milled and sieved to obtain ultrafine magnesium oxide powder. Hydroxyapatite, sintering aid, glass powder and pore-forming agent are added and mixed thoroughly to obtain a mixed powder.

[0015] Magnesium oxide, as a primary ceramic aggregate, directly affects the mechanical properties and pore structure of the final ceramic product due to its particle size and purity. Ball milling of magnesium oxide effectively reduces particle size and increases its specific surface area, thereby improving mixing uniformity and reactivity with other components. Sieving further ensures the consistency of powder particle size. Ultrafine magnesium oxide powder improves the compactness of subsequent ceramic green bodies and enhances the density of porous ceramics.

[0016] Furthermore, the above-mentioned step of ball milling and sieving the ceramic aggregate magnesium oxide to obtain ultrafine magnesium oxide powder includes: High-purity magnesium oxide was obtained as ceramic aggregate by dry ball milling to obtain ball-milled powder; the powder was then sieved through a 300-mesh sieve and ball-milled to obtain ultrafine magnesium oxide powder.

[0017] In this embodiment, high-purity magnesium oxide with a purity of not less than 98% is selected to avoid the influence of impurities on ceramic properties. A rotary ball mill can be selected for dry ball milling, with the milling time controlled at 6 to 8 hours and the rotation speed set at 300 rpm to ensure that the magnesium oxide particles are thoroughly ground. After ball milling, the powder is sieved through a 300-mesh screen to remove larger particles, obtaining ultrafine magnesium oxide powder with a uniform particle size distribution. During dry ball milling, the grinding media and ball-to-material ratio can be adjusted according to equipment conditions to improve grinding efficiency. For example, zirconia balls can be used as the grinding media, with a ball-to-material ratio controlled at 1:1.

[0018] Dry ball milling and sieving of high-purity magnesium oxide can significantly improve the flowability of the powder, making it easier to improve the uniformity of subsequent mixing with other materials.

[0019] Next, hydroxyapatite, sintering aid, glass powder and pore-forming agent are added to the ultrafine magnesium oxide powder and mixed thoroughly to obtain a mixed powder.

[0020] Among them, hydroxyapatite, as a bioactive material, can react with magnesium oxide during sintering to form a specific phase (β-TCP phase), which improves the biocompatibility of ceramics and thus enhances the affinity between ceramics and e-liquid; the sintering aid can react with magnesium oxide at high temperature to form a low-melting-point phase, which promotes the bonding between particles, thereby reducing the overall sintering temperature and saving energy; glass powder forms a liquid phase during sintering, filling the gaps between particles and further enhancing the density and strength of ceramics; and the pore-forming agent decomposes or volatilizes at high temperature to form a porous structure.

[0021] When hydroxyapatite powder is added to ultrafine magnesium oxide powder, it is necessary to ensure that the particle size of the hydroxyapatite powder and the magnesium oxide powder are matched to avoid stratification.

[0022] The glass powder used is a medium-low temperature lead-free glass powder with a softening point of 600-700℃. During the sintering process, the medium-low temperature lead-free glass powder can soften and form a liquid phase, filling the gaps between particles and promoting grain growth and crystal transformation.

[0023] In some embodiments, the mixed powder comprises, by mass percentage, 40%-50% magnesium oxide, 10%-20% hydroxyapatite, 6%-15% sintering aid, 3%-8% glass powder, and 30%-40% pore-forming agent. The proportions of the mixed powder can be adjusted according to the performance requirements of the target ceramic.

[0024] In some embodiments, the sintering aid is selected from at least two of calcium carbonate, kaolin, and tourmaline. Calcium carbonate decomposes at high temperatures to form calcium oxide, which forms a solid solution with magnesium oxide, thus lowering the sintering temperature. Kaolin provides silicon and aluminum, enhancing the thermal stability of the ceramic. Tourmaline, as a natural mineral material, releases negative ions and promotes particle dispersion, reducing powder agglomeration and improving uniformity during mixing.

[0025] In the mixed powder, by mass percentage, calcium carbonate accounts for 3%-6%, kaolin for 3%-5%, and tourmaline for 3%-5%. The selection and proportion of sintering aids can be adjusted according to the actual situation.

[0026] In one possible implementation, the calcining aid is a combination of calcium carbonate, kaolin, and tourmaline. The tourmaline powder needs to be pretreated, for example, by calcining at 500°C for 1 hour, to remove surface organic impurities and improve its activity. During mixing, the tourmaline is first premixed with calcium carbonate and kaolin before being added to the ultrafine magnesium oxide powder to ensure the effective dispersion of the tourmaline.

[0027] In some embodiments, the pore-forming agent is selected from at least one of polymethyl methacrylate, wood chips, starch, polyvinyl alcohol, and polystyrene; the average particle size of the pore-forming agent is 50-100 μm. The pore-forming agent decomposes or burns at high temperature, leaving pores, thereby achieving high porosity in the ceramic material.

[0028] In one possible implementation, the pore-forming agent is selected as polymethyl methacrylate particles with a decomposition temperature between 300-400℃ and an average particle size controlled at 60-80μm, so as to form pores of uniform size.

[0029] If sawdust or starch is used as a pore-forming agent, pretreatment is required, such as drying and sieving, to remove moisture and impurities.

[0030] The amount of pore-forming agent added is adjusted according to the target porosity. For example, when the porosity requirement is 60%, the proportion of pore-forming agent can be increased to 40%.

[0031] In some embodiments, the mixing process of the powders can be carried out using a three-dimensional mixer or a V-type mixer, with a stirring time of 2-4 hours and a rotation speed of 40-60 r / min. During the mixing process, different components can be added in stages. For example, ultrafine magnesium oxide powder and sintering aid can be mixed first, followed by the addition of hydroxyapatite, and finally glass powder and pore-forming agent, to gradually improve uniformity. After mixing is completed, the proportion of each component can be sampled and tested to ensure consistent distribution.

[0032] Step S20: Mix the powder with the binder and stir until homogeneous to obtain the molded material.

[0033] The binder can be selected from one or more combinations of paraffin wax, beeswax, polyethylene, and polyvinyl alcohol. In this embodiment, an aqueous solution of polyvinyl alcohol is selected as the binder, which can enhance the bonding force between powder particles and improve the moldability and stability of the green body.

[0034] Specifically, the mixed powder is mixed with a polyvinyl alcohol aqueous solution and stirred until homogeneous to obtain the molding material. The concentration and amount of the polyvinyl alcohol aqueous solution need to be adjusted according to the characteristics of the mixed powder to ensure that the molding material has suitable viscosity and flowability.

[0035] In some embodiments, the mass percentage concentration of the polyvinyl alcohol aqueous solution is 0.9-1.0%, and the mass of the polyvinyl alcohol aqueous solution is 5-7% of the mass of the mixed powder.

[0036] By optimizing the concentration of the polyvinyl alcohol aqueous solution, the molding material can be made to have good flowability, thereby achieving uniform mixing and providing sufficient strength for the green body. The mass of the polyvinyl alcohol aqueous solution in the mixed powder is adjusted according to the hygroscopicity and particle characteristics of the mixed powder to improve the bonding effect.

[0037] In one possible implementation, the preparation of the polyvinyl alcohol aqueous solution needs to be carried out at room temperature, and the stirring speed is controlled at 100 r / min for 30 min during dissolution to ensure that the polyvinyl alcohol is completely dissolved.

[0038] In this embodiment, uniform stirring ensures that the binder fully coats the mixed powder particles, forming a molding material with certain fluidity and adhesiveness. A uniform molding material ensures structural consistency of the green preform during the molding process, avoiding localized defects.

[0039] In one possible implementation, the mixing process of the molding materials can be carried out using a low-speed mixer for 1 to 2 hours at a speed of 20 to 40 rpm. During mixing, the polyvinyl alcohol aqueous solution can be slowly added to the mixed powder first to avoid local agglomeration caused by adding it all at once. After mixing is completed, the uniformity of the material can be checked visually or by sampling to ensure that there is no obvious stratification or agglomeration.

[0040] Step S30: The material is formed by dry pressing to obtain a ceramic green body.

[0041] Dry pressing, a common ceramic forming process, effectively improves the structural stability of green bodies. Through dry pressing, the material is transformed into a ceramic green body with a certain strength and shape, providing a foundation for subsequent drying and sintering. During dry pressing, the control of pressure and holding time directly affects the density and strength of the green body. Hydraulic or mechanical presses can be used for forming equipment, and the mold design must consider the size and shape requirements of the green body.

[0042] In some possible implementations, dry pressing is used to apply a pressure of 400-600 MPa to the molding material and hold the pressure for 5-10 minutes to obtain a ceramic green body.

[0043] During dry pressing, the density of the green body can be further optimized by adjusting the pressure and holding time. A dense green body structure can reduce uneven shrinkage and crack formation during sintering, ensuring the consistency of the final ceramic material's properties.

[0044] In one possible implementation, the formed ceramic green body should be placed on a drying tray to avoid direct contact with a humid environment. The placement of the ceramic green body should ensure even pressure distribution, for example, by laying it flat to avoid localized pressure caused by stacking. After placement, the ceramic green body can be allowed to air dry or be dried at a low temperature to remove some moisture, preparing it for subsequent high-temperature drying.

[0045] Step S40: After drying the ceramic green body, it is heated and sintered to obtain porous ceramics doped with hydroxyapatite.

[0046] Through drying and high-temperature sintering processes, ceramic green bodies are transformed into porous ceramic materials with specific pore structures and mechanical properties. The drying process removes moisture and volatile substances from the ceramic green bodies, preventing cracks from forming during sintering; the sintering process, through high-temperature reactions, forms crystalline and porous structures, improving the ceramic's performance.

[0047] Furthermore, the steps described above, including drying the ceramic green body and then sintering it at a higher temperature to obtain porous ceramics doped with hydroxyapatite, include: The ceramic green body is dried in a drying oven at 70-90℃ for 4-6 hours to obtain a dried green body. The dried green body is heated at a preset heating rate until the target sintering temperature is reached, and then held at that temperature. The green body is then cooled in the furnace to obtain porous ceramics doped with hydroxyapatite. The preset heating rate is 5-10℃ / min; the target sintering temperature is 750-820℃; and the holding time is 2-4h.

[0048] The drying process is carried out in a constant temperature drying oven, with the temperature controlled at 70-90℃ for 4-6 hours, to ensure that the moisture evaporates slowly and avoid stress concentration caused by rapid drying.

[0049] The sintering process is carried out in a programmable temperature controlled furnace. The preset heating rate and holding time need to be adjusted according to the material ratio and target performance. After sintering, the furnace is cooled to room temperature to avoid thermal stress cracking caused by rapid cooling. After the holding period, microscopic observation revealed that uniform pores were formed inside the ceramic, and the grains were tightly bonded, indicating that the sintering parameters were set reasonably and the structural transformation was successfully achieved.

[0050] During the sintering process, Ca3(PO4)2 generated by the sintering of magnesium oxide and hydroxyapatite can form a β-TCP phase, which can significantly improve the biocompatibility and activity of ceramics, thereby enhancing their affinity with e-liquid. At the same time, the transformation of crystal form during the sintering process can reduce the thermal conductivity of porous ceramics.

[0051] In one possible implementation, a programmable temperature-controlled box furnace is used for sintering, with a fixed heating rate of 5°C / min to avoid thermal stress caused by rapid heating. The target sintering temperature is adjusted according to the type of pore-forming agent and the proportion of sintering aids. For example, when the proportion of pore-forming agent is high, the temperature can be set to 780°C, with a holding time of 3 hours to ensure complete decomposition of the pore-forming agent. During sintering, it is necessary to ensure a stable atmosphere inside the furnace to avoid the impact of oxidation or reduction reactions on the material properties.

[0052] In some possible implementations, the furnace cooling process needs to be carried out naturally inside the sintering furnace, with the cooling rate controlled at 2-5℃ / min. This avoids the direct entry of external air into the furnace, which would cause localized rapid cooling. This can effectively avoid the thermal stress caused by rapid cooling, thereby reducing the generation of internal cracks in the ceramic and maintaining the integrity of the ceramic structure.

[0053] This application also provides a porous ceramic, which is prepared by the preparation method described above.

[0054] The porous ceramics produced have a porosity of 58-67%, an average pore size of 17-30 μm, and a flexural strength of 30-60 MPa.

[0055] The porous ceramic sinter prepared by the above method has the advantages of low sintering temperature, high porosity, strong adsorption capacity for e-liquid, low thermal conductivity, high bending strength, and uniform pore size distribution.

[0056] This application also provides an atomizing device comprising the porous ceramic described above.

[0057] When the atomizing device is an electronic cigarette atomizer, specifically when porous ceramics are used in electronic cigarette atomizers, the low thermal conductivity and high oil absorption rate of porous ceramics optimize the atomization effect. Specifically, low thermal conductivity reduces heat loss and improves energy utilization efficiency; high oil absorption rate ensures uniform liquid adsorption and release, improving atomization uniformity.

[0058] The following specific embodiments will be used to illustrate the contents of this application in more detail and to further elaborate on this application, but these embodiments are by no means intended to limit this application.

[0059] Example 1 This embodiment provides a method for preparing porous ceramics, including the following steps: (1) Pretreatment High-purity magnesium oxide ceramic aggregate was dry ball-milled at a ratio of 1:1, with the high-purity magnesium oxide having a purity greater than 99%; then it was passed through a 300-mesh sieve to obtain ultrafine magnesium oxide powder.

[0060] (2) Powder mixing Add sintering aids (calcium carbonate, kaolin), hydroxyapatite, medium- and low-temperature lead-free glass powder, and polymethyl methacrylate (pore-forming agent) with an average particle size of 50 μm to the above-mentioned ultrafine magnesium oxide powder. After thorough mixing, a mixed powder is obtained. The powder contains, by mass percentage, 40% magnesium oxide, 10% hydroxyapatite, 5% kaolin (sintering aid), 5% calcium carbonate, 5% medium- and low-temperature lead-free glass powder, and 35% polymethyl methacrylate.

[0061] (3) Ceramic green body forming The above-mentioned mixed powder is mixed with a polyvinyl alcohol aqueous solution, and after stirring and mixing evenly, it is dry-pressed to obtain a ceramic green body; The polyvinyl alcohol aqueous solution has a mass percentage concentration of 1.0% and its mass is 6% of the mass of the mixed powder.

[0062] (4) Sintering of porous ceramics The ceramic green body was dried in an 85°C drying oven for 4 hours, and then heated in a programmable temperature controlled box furnace at a rate of 5°C / min to reach 760°C and held for 2 hours. After cooling to room temperature in the furnace, porous ceramics were obtained.

[0063] Example 2 This embodiment provides a method for preparing porous ceramics, including the following steps: (1) Pretreatment High-purity magnesium oxide ceramic aggregate was dry ball-milled at a ratio of 1:1, with the high-purity magnesium oxide having a purity greater than 99%; then it was passed through a 300-mesh sieve to obtain ultrafine magnesium oxide powder.

[0064] (2) Powder mixing Add sintering aids (calcium carbonate, kaolin), hydroxyapatite, medium- and low-temperature lead-free glass powder, and polymethyl methacrylate (pore-forming agent) with an average particle size of 100 μm to the above-mentioned ultrafine magnesium oxide powder. After thorough mixing, a mixed powder is obtained. The powder contains, by mass percentage, 40% magnesium oxide, 10% hydroxyapatite, 5% kaolin (sintering aid), 5% calcium carbonate, 5% medium- and low-temperature lead-free glass powder, and 35% polymethyl methacrylate.

[0065] (3) Ceramic green body forming The above-mentioned mixed powder is mixed with a polyvinyl alcohol aqueous solution, and after stirring and mixing evenly, it is dry-pressed to obtain a ceramic green body; The polyvinyl alcohol aqueous solution has a mass percentage concentration of 1.0% and its mass is 6% of the mass of the mixed powder.

[0066] (4) Sintering of porous ceramics The ceramic green body was dried in an 85°C drying oven for 4 hours, and then heated in a programmable temperature controlled box furnace at a rate of 5°C / min to reach 760°C and held for 2 hours. After cooling to room temperature in the furnace, porous ceramics were obtained.

[0067] Example 3 This embodiment provides a method for preparing porous ceramics, including the following steps: (1) Pretreatment High-purity magnesium oxide ceramic aggregate was dry ball-milled at a ratio of 1:1, with the high-purity magnesium oxide having a purity greater than 99%; then it was passed through a 300-mesh sieve to obtain ultrafine magnesium oxide powder.

[0068] (2) Powder mixing Add sintering aids (calcium carbonate, kaolin), hydroxyapatite, low-temperature lead-free glass powder, and polymethyl methacrylate (pore-forming agent) with an average particle size of 50 μm to the above-mentioned ultrafine magnesium oxide powder. After thorough mixing, a mixed powder is obtained. The powder contains, by mass percentage, 45% magnesium oxide, 20% hydroxyapatite, 5% kaolin (sintering aid), 5% calcium carbonate, 5% low-temperature lead-free glass powder, and 30% polymethyl methacrylate.

[0069] (3) Ceramic green body forming The above-mentioned mixed powder is mixed with a polyvinyl alcohol aqueous solution, and after stirring and mixing evenly, it is dry-pressed to obtain a ceramic green body; The polyvinyl alcohol aqueous solution has a mass percentage concentration of 1.0% and its mass is 6% of the mass of the mixed powder.

[0070] (4) Sintering of porous ceramics The above-mentioned ceramic green body was dried in a drying oven at 75℃ for 5 hours, and then heated in a programmable temperature controlled box furnace at a rate of 5℃ / min to reach 800℃ and held for 3 hours. After cooling to room temperature in the furnace, porous ceramics were obtained.

[0071] Example 4 This embodiment provides a method for preparing porous ceramics, including the following steps: (1) Pretreatment High-purity magnesium oxide ceramic aggregate was dry ball-milled at a ratio of 1:1, with the high-purity magnesium oxide having a purity greater than 99%; then it was passed through a 300-mesh sieve to obtain ultrafine magnesium oxide powder.

[0072] (2) Powder mixing Add sintering aids (calcium carbonate, kaolin), hydroxyapatite, medium- and low-temperature lead-free glass powder, and polymethyl methacrylate (pore-forming agent) with an average particle size of 50 μm to the above-mentioned ultrafine magnesium oxide powder. After thorough mixing, a mixed powder is obtained. In this mixed powder, by mass percentage, magnesium oxide accounts for 40%, hydroxyapatite accounts for 20%, kaolin sintering aid accounts for 3%, calcium carbonate accounts for 4%, medium- and low-temperature lead-free glass powder accounts for 8%, and polymethyl methacrylate accounts for 35%.

[0073] (3) Ceramic green body forming The above-mentioned mixed powder is mixed with a polyvinyl alcohol aqueous solution, and after stirring and mixing evenly, it is dry-pressed to obtain a ceramic green body; The polyvinyl alcohol aqueous solution has a mass percentage concentration of 1.0% and its mass is 6% of the mass of the mixed powder.

[0074] (4) Sintering of porous ceramics The above-mentioned ceramic green body was dried in a drying oven at 70℃ for 6 hours, and then heated in a programmable temperature controlled box furnace at a rate of 5℃ / min to reach 820℃ and held for 2 hours. After cooling to room temperature in the furnace, porous ceramics were obtained.

[0075] Example 5 This embodiment provides a method for preparing porous ceramics, including the following steps: (1) Pretreatment High-purity magnesium oxide ceramic aggregate was dry ball-milled at a ratio of 1:1, with the high-purity magnesium oxide having a purity greater than 99%; then it was passed through a 300-mesh sieve to obtain ultrafine magnesium oxide powder.

[0076] (2) Powder mixing Add sintering aids (calcium carbonate, kaolin, and tourmaline), hydroxyapatite, low-temperature lead-free glass powder, and polymethyl methacrylate (porogen) with an average particle size of 50 μm to the above-mentioned ultrafine magnesium oxide powder. After thorough mixing, a mixed powder is obtained. The powder contains, by mass percentage, 40% magnesium oxide, 10% hydroxyapatite, 4% kaolin (sintering aid), 4% calcium carbonate, 3% tourmaline, 5% low-temperature lead-free glass powder, and 34% polymethyl methacrylate.

[0077] (3) Ceramic green body forming The above-mentioned mixed powder is mixed with a polyvinyl alcohol aqueous solution, and after stirring and mixing evenly, it is dry-pressed to obtain a ceramic green body; The polyvinyl alcohol aqueous solution has a mass percentage concentration of 1.0% and its mass is 6% of the mass of the mixed powder.

[0078] (4) Sintering of porous ceramics The ceramic green body was dried in an 85°C drying oven for 4 hours, and then heated in a programmable temperature controlled box furnace at a rate of 5°C / min to reach 760°C and held for 2 hours. After cooling to room temperature in the furnace, porous ceramics were obtained.

[0079] Comparative Example 1 This comparative example provides a method for preparing porous ceramics, including the following steps: (1) Pretreatment High-purity magnesium oxide ceramic aggregate was dry ball-milled at a ratio of 1:1, with the high-purity magnesium oxide having a purity greater than 99%; then it was passed through a 300-mesh sieve to obtain ultrafine magnesium oxide powder.

[0080] (2) Powder mixing Add sintering aids (calcium carbonate, kaolin), hydroxyapatite, low-temperature lead-free glass powder, and polymethyl methacrylate (pore-forming agent) with an average particle size of 50 μm to the above-mentioned ultrafine magnesium oxide powder. After thorough mixing, a mixed powder is obtained. The powder contains, by mass percentage, 50% magnesium oxide, 5% kaolin (sintering aid), 5% calcium carbonate, 5% low-temperature lead-free glass powder, and 35% polymethyl methacrylate.

[0081] (3) Ceramic green body forming The above-mentioned mixed powder is mixed with a polyvinyl alcohol aqueous solution, and after stirring and mixing evenly, it is dry-pressed to obtain a ceramic green body; The polyvinyl alcohol aqueous solution has a mass percentage concentration of 1.0% and its mass is 6% of the mass of the mixed powder.

[0082] (4) Sintering of porous ceramics The ceramic green body was dried in an 85°C drying oven for 4 hours, and then heated in a programmable temperature controlled box furnace at a rate of 5°C / min to reach 760°C and held for 2 hours. After cooling to room temperature in the furnace, porous ceramics were obtained.

[0083] The porous ceramics in Examples 1-5 and Comparative Example 1 were subjected to experimental testing and analysis. The test results are shown in Table 1.

[0084] Table 1

[0085] As can be seen from Table 1, porous ceramics with better comprehensive performance can be prepared by adopting the material formulation, process flow and sintering technology of this application that incorporates ultrafine magnesium oxide powder and hydroxyapatite. These ceramics have higher porosity and higher strength.

[0086] Obviously, the embodiments described above are only some embodiments of this application, not all embodiments. The accompanying drawings show preferred embodiments of this application, but do not limit the patent scope of this application. This application can be implemented in many different forms; rather, the purpose of providing these embodiments is to provide a more thorough and comprehensive understanding of the disclosure of this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or make equivalent substitutions for some of the technical features. Any equivalent structures made using the content of this application's specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the scope of patent protection of this application.

Claims

1. A method for preparing porous ceramics, characterized in that, Includes the following steps: Magnesium oxide, a ceramic aggregate, is ball-milled and sieved to obtain ultrafine magnesium oxide powder. Hydroxyapatite, sintering aid, glass powder, and pore-forming agent are then added and thoroughly mixed to obtain a mixed powder. The mixed powder is mixed with the binder and stirred evenly to obtain the molded material; The material is formed by dry pressing to obtain a ceramic green body; The ceramic green body is dried and then sintered at a higher temperature to obtain porous ceramics doped with hydroxyapatite.

2. The method for preparing porous ceramics according to claim 1, characterized in that, The step of ball milling and sieving the ceramic aggregate magnesium oxide to obtain ultrafine magnesium oxide powder includes: High-purity magnesium oxide is obtained as ceramic aggregate, and the high-purity magnesium oxide is processed by dry ball milling to obtain ball-milled powder; The ball-milled powder was sieved through a 300-mesh sieve to obtain the ultrafine magnesium oxide powder.

3. The method for preparing porous ceramics according to claim 1, characterized in that, In the mixed powder, by mass percentage, the magnesium oxide accounts for 40%-50%, the hydroxyapatite accounts for 10%-20%, the sintering aid accounts for 6%-15%, the glass powder accounts for 3%-8%, and the pore-forming agent accounts for 30%-40%.

4. The method for preparing porous ceramics according to claim 3, characterized in that, The sintering aid is selected from at least two of calcium carbonate, kaolin, and tourmaline, wherein, by mass percentage, the calcium carbonate accounts for 3%-6%, the kaolin accounts for 3%-5%, and the tourmaline accounts for 3%-5% of the mixed powder; The pore-forming agent is selected from at least one of polymethyl methacrylate, wood chips, starch, polyvinyl alcohol, and polystyrene; the average particle size of the pore-forming agent is 50-100 μm.

5. The method for preparing porous ceramics according to claim 1, characterized in that, The binder is selected from a polyvinyl alcohol aqueous solution; the step of mixing the mixed powder with the binder and stirring evenly to obtain the molding material includes: The mixed powder is mixed with the polyvinyl alcohol aqueous solution and stirred evenly to obtain a molding material; wherein the mass percentage concentration of the polyvinyl alcohol aqueous solution is 0.9-1.0%, and the mass of the polyvinyl alcohol aqueous solution is 5-7% of the mass of the mixed powder.

6. The method for preparing porous ceramics according to claim 1, characterized in that, The step of forming the material by dry pressing to obtain a ceramic green body includes: The material is subjected to a pressure of 400-600 MPa and held for 5-10 minutes by dry pressing to obtain a ceramic green body.

7. The method for preparing porous ceramics according to claim 1, characterized in that, The step of drying the ceramic green body and then sintering it at a higher temperature to obtain porous ceramic doped with hydroxyapatite includes: The ceramic green body is dried in a drying oven at 70-90℃ for 4-6 hours to obtain a dried green body. The dried green body is heated at a preset heating rate to reach the target sintering temperature and held at that temperature. The green body is then cooled in the furnace to obtain a porous ceramic doped with hydroxyapatite. The preset heating rate is 5-10℃ / min; the target sintering temperature is 750-820℃; and the holding time is 2-4h.

8. A porous ceramic, characterized in that, The porous ceramic is prepared by any one of claims 1 to 7.

9. The porous ceramic according to claim 8, characterized in that, The porous ceramic has a porosity of 58-67%, an average pore size of 17-30 μm, and a flexural strength of 30-60 MPa.

10. An atomizing device, characterized in that, Includes the porous ceramics described in claim 8 or 9.

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