Porous ceramic and method of making the same

Abstract

A kind of porous ceramic, including loose layer and dense layer, the surface of the loose layer is liquid-permeable surface, the surface of the dense layer is atomized surface, several in the vertical direction extend finger-shaped holes are formed in the loose layer, the pore size of the finger-shaped hole becomes small on the side close to the liquid-permeable surface, the finger-shaped hole does not penetrate the dense layer downward, several capillary holes are also formed in the loose layer and the dense layer, the pore size of the capillary hole is less than the pore size of the finger-shaped hole, the capillary hole is interconnected and connects several finger-shaped holes, the thickness of the loose layer is greater than the thickness of the dense layer, atomized liquid is infiltrated into the porous ceramic from the liquid-permeable surface.This application also includes the manufacturing method of porous ceramic.

Description

Technical Field

[0001] This application relates to the fields of materials and electronic atomization, and more particularly to a porous ceramic and its manufacturing method. Background Technology

[0002] Existing atomizing devices are widely used in smoking enthusiasts, medical atomization, and other fields. The key to atomizing products lies in the use of the atomizer coil. Current atomizer coils generally include cotton coils and ceramic coils. Cotton coils are made of organic cotton and have the advantage of high e-liquid fidelity, but they are prone to burning. Ceramic coils, on the other hand, are easier to assemble and have stable performance, making them more widely used. Both cotton and ceramic coils are prone to leakage. When the capillary pores in a ceramic coil are larger, the e-liquid penetration efficiency is high, but leakage is more likely. If the pore size is smaller, e-liquid penetration is difficult, leading to dry burning. Chinese Patent Application No. 201910740263.9 discloses a ceramic core that solves the aforementioned technical problems. It is manufactured using a casting process, specifically employing three different ceramic slurries, which are layered and cast to obtain green bodies, which are then sintered. This results in three layered structures with different pore sizes. The larger pores on the seepage surface are suitable for rapid seepage of the atomized liquid, while the smaller pores on the atomization surface prevent the passage of large molecules, achieving a liquid-blocking effect and preventing leakage of the atomized liquid. Meanwhile, the aforementioned technical solutions generally use a method of removing pore-forming agents by sintering to form the pore structure. However, the pore structure produced by this method has a high dead-pore rate (dead pores refer to internally non-connected pores that do not conduct liquid).

[0003] However, the above manufacturing methods are complex, requiring multiple casting processes or additional slurry coating processes, which increases the number of uncontrollable factors in the process, leading to a significant increase in yield and cost. Summary of the Invention

[0004] Therefore, it is necessary to provide a porous ceramic manufacturing method that is simple and controllable in terms of high liquid conductivity, fast liquid conduction speed, and manufacturing process.

[0005] To address the aforementioned technical problems, this application provides a porous ceramic comprising a loose layer and a dense layer. The surface of the loose layer is a liquid-permeable surface, and the surface of the dense layer is an atomizing surface. A plurality of finger-shaped pores extending vertically are formed within the loose layer. The diameter of the finger-shaped pores decreases near the liquid-permeable surface and does not penetrate the dense layer downwards. A plurality of capillary pores are also formed within the loose and dense layers. The diameter of the capillary pores is smaller than that of the finger-shaped pores, and the capillary pores are interconnected and connect to a plurality of the finger-shaped pores. The thickness of the loose layer is greater than the thickness of the dense layer. Atomized liquid permeates into the porous ceramic from the liquid-permeable surface.

[0006] Preferably, the loose layer further includes a finger-shaped pore layer and a microporous layer. The finger-shaped pore layer is located between the dense layer and the microporous layer. A plurality of micropores are formed in the microporous layer, and the micropores penetrate upward through the permeation surface and communicate with the finger-shaped pores.

[0007] Preferably, the micropores are connected to each other through the capillaries.

[0008] Preferably, the dense layer also forms a pore structure other than capillary pores. The pore size of the pore structure in the dense layer is between 10-35 μm, the pore size of the finger pores is between 80-300 μm, the pore size of the micropores in the microporous layer is between 30-80 μm, the pore size of the capillary pores is between 5-35 μm, the porosity of the porous ceramic is between 50%-68%, and the porosity of the loose layer is greater than that of the dense layer.

[0009] Preferably, the diameter of the finger-shaped pores is between 80-200 μm, the diameter of the capillary pores is between 5-30 μm, and the porosity of the porous ceramic is 50%.

[0010] Preferably, the diameter of the finger-shaped pores is between 100-300 μm, the diameter of the capillary pores is between 5-30 μm, and the porosity of the porous ceramic is 53%.

[0011] Preferably, the diameter of the finger-shaped pores is between 50-150 μm, the diameter of the capillary pores is between 10-35 μm, and the porosity of the porous ceramic is 58.5%.

[0012] Preferably, the thickness of the porous ceramic is 1-3 mm, the thickness of the dense layer is between 0.02-0.3 μm, and the thickness of the dense layer is not related to the thickness of the porous ceramic.

[0013] Preferably, the thickness of the porous ceramic is 2 mm.

[0014] Preferably, the thickness of the porous ceramic is 3 mm.

[0015] To address the aforementioned technical problems, this application also provides a method for manufacturing porous ceramics, comprising the following steps:

[0016] S10. Preparation of slurry: Mix 54-62 wt% of ceramic powder and pore-forming agent, 1-2 wt% of dispersant and 32-39 wt% of organic solvent and ball mill for 5 hours, then add 4-5.5 wt% of binder and mix evenly to obtain slurry.

[0017] S20, Casting: The slurry is cast onto the support plate;

[0018] S30, Phase transformation: The support plate and the slurry cast on it are immersed in water together. The slurry solidifies instantly after being immersed in water and forms the dense layer on the surface of the slurry in contact with water. The support plate and the slurry on it are soaked in water for no less than 12 hours. During this period, the organic solvent is replaced by water to form several gaps and obtain a green body.

[0019] S40, Sintering and Shaping: The solidified green body is placed in a sintering furnace, and the temperature is first slowly raised to 800°C and held for 2 hours. Then the temperature inside the furnace is raised to 1300-1550°C and held for 4 hours to obtain the porous ceramic. During this process, the gaps will shrink to form a capillary structure.

[0020] Preferably, the organic solvent is pure NMP (N-methylpyrrolidone) or NMP containing a small amount of non-solvent water (1-10 vt%); the dispersant is one or more of PVP (polyvinylpyrrolidone), DSP (disodium hydrogen phosphate), and TEOA (triethanolamine); the pore-forming agent includes one or more of starch, graphite, sawdust, and sucrose; the binder is one or more of PESF (polyphenylene ether sulfone), PES (polyether sulfone), PVB (polyvinyl butyral), and PMMA (polymethyl methacrylate); and the ceramic powder is one or more of alumina, silicon dioxide, titanium dioxide, kaolin, calcium carbonate, silicon carbide, talc, feldspar, cordierite, and diatomaceous earth.

[0021] Preferably, the volume ratio of the pore-forming agent to the ceramic powder in the mixture of the pore-forming agent and the ceramic powder is 0.3-0.45.

[0022] Preferably, the ceramic slurry comprises 58.5 wt% of a mixture of ceramic powder and pore-forming agent, 1.5 wt% of dispersant polyvinylpyrrolidone, 35 wt% of organic solvent N-methylpyrrolidone, and 5 wt% of binder polyethersulfone.

[0023] Preferably, the ceramic powder and the pore-forming agent are mixed at a volume ratio of 1:0.3 to obtain a mixture of ceramic powder and pore-forming agent, wherein the ceramic powder comprises: 75wt% alumina fine powder, 10wt% silica fine powder, 10wt% kaolin fine powder, and 5wt% titanium dioxide fine powder.

[0024] Preferably, the ceramic slurry comprises 58.5 wt% of a mixture of ceramic powder and pore-forming agent, 1.5 wt% of dispersant polyvinylpyrrolidone, 35 wt% of organic solvent N-methylpyrrolidone, and 5 wt% binder polyethersulfone; the ceramic powder and pore-forming agent are mixed at a volume ratio of 1:0.35 to obtain the mixture of ceramic powder and pore-forming agent, wherein the ceramic powder comprises: 85 wt% fine alumina powder, 10 wt% fine silica powder, and 5 wt% fine titanium dioxide powder.

[0025] Preferably, the ceramic slurry comprises 62 wt% of a mixture of ceramic powder and pore-forming agent, 1.5 wt% of dispersant polyvinylpyrrolidone, 32 wt% of organic solvent N-methyl-pyrrolidone, and 4.5 wt% of binder polyethersulfone; the ceramic powder and pore-forming agent are mixed at a volume ratio of 1:0.3 to obtain the mixture of ceramic powder and pore-forming agent, wherein the ceramic powder comprises: 43 wt% alumina fine powder, 41% corundum powder, 15 wt% silicon carbide fine powder, and 1 wt% calcium carbonate fine powder.

[0026] Preferably, the ceramic slurry comprises 54.5 wt% of a mixture of ceramic powder and pore-forming agent, 1.5 wt% of dispersant polyvinylpyrrolidone, 39 wt% of organic solvent N-methyl-pyrrolidone, and 5 wt% binder polyethersulfone; the ceramic powder and pore-forming agent are mixed at a volume ratio of 1:0.45 to obtain the mixture of ceramic powder and pore-forming agent, wherein the ceramic powder comprises: 55.6 wt% fine alumina powder, 35.7% quartz sand powder, 6.7% fine silica powder, and 2 wt% fine calcium carbonate powder.

[0027] This application, through a slurry formulation and the incorporation of a phase inversion casting process into the manufacturing method, enables the production of porous ceramics with both dense and porous layers in a single casting process. Compared to existing technologies, this significantly simplifies the manufacturing process, reduces costs, and improves process controllability. Furthermore, the porous ceramics of this application also feature several large-diameter finger-like pores within the porous layer, which can greatly increase oil retention and accelerate oil conduction. Attached Figure Description

[0028] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0029] Figure 1 This is a cross-sectional schematic diagram of the porous ceramic of this application;

[0030] Figure 2 This is a SEM image of the porous ceramic cross-sectional structure obtained in Embodiment 1 of this application;

[0031] Figure 3 SEM image of the porous ceramic cross-sectional structure obtained in Embodiment 2 of this application.

[0032] Figure 4 SEM image of the porous ceramic cross-sectional structure obtained in Example 3 of this application.

[0033] Figure 5 This is a SEM image of the porous ceramic cross-sectional structure obtained in Example 4 of this application. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them.

[0035] Please see Figure 1 , Figure 2 The image shown is a cross-sectional schematic diagram and electron microscope image of the porous ceramic of this application. The porous ceramic of this application includes a loose layer 11 and a dense layer 12. The loose layer 11 includes a finger-shaped pore layer 111 and a microporous layer 112 located on the upper side of the finger-shaped pore layer 111.

[0036] The thickness of the porous ceramic is between 1 and 3 mm, and the thickness of the dense layer 12 is between 0.02 and 0.3 μm. The thickness of the dense layer 12 is not related to the overall thickness of the porous ceramic.

[0037] The finger-shaped pore layer 111 has a plurality of finger-shaped pores 113 extending in the vertical direction. The diameter of the finger-shaped pores 113 gradually decreases from bottom to top and extends into the microporous layer 112. The microporous layer 112 has a plurality of micropores 114 that communicate with the finger-shaped pores 113. In one embodiment, the plurality of micropores 114 communicate with one finger-shaped pore 113.

[0038] The porous ceramic as a whole possesses various interconnected pore structures. The pore diameters of the pore structures within the dense layer 12 are between 10-35 μm, the pore diameters of the finger-shaped pores 113 are between 80-300 μm, and the pore diameters of the micropores 114 within the microporous layer 112 are between 30-80 μm. The porous ceramic also contains several capillaries that connect all the finger-shaped pores 113, preventing them from becoming isolated pore structures and facilitating the flow of liquid within them. Similarly, the micropores 114 within the microporous layer 112 are interconnected by capillaries. The formation of these capillaries is due to the special manufacturing process of the porous ceramic of this application, which will be described in detail below. The outer surface of the microporous layer 112 serves as the permeation surface, and the outer surface of the dense layer 12 serves as the atomization surface. The atomized liquid permeates downwards from the permeation surface through the pore structure to one side of the atomization surface. It should be noted that the top of the finger-shaped pores 113 extends upward through the microporous layer 112, but the pore diameter of the finger-shaped pores 113 in the microporous layer 112 is close to the pore diameter of the micropores 114 in the microporous layer; the finger-shaped pores 113 extend regularly in the vertical direction and do not extend laterally. The extension pattern of the capillaries is relatively random, and the pore diameter is relatively small, ranging from 5-35 μm.

[0039] The overall porosity of the porous ceramic in this application is between 50% and 68%. The porosity of the loose layer 11 is greater than that of the dense layer 12.

[0040] When the porous ceramic of this application is applied to atomizing products, such as when the People's Republic of China Patent No. 202110430799.8 is applied to the field of electronic cigarettes, the atomizing liquid passes downward through the microporous layer 112 from the liquid-permeable surface of the microporous layer 112 and enters the finger-shaped holes 113. The atomizing liquid in the finger-shaped holes 113 will continue to permeate into the dense layer 12. The pore structure in the dense layer has a small pore size, which can prevent the atomizing liquid from passing downward through the dense layer by utilizing the surface tension of the liquid, thereby avoiding oil leakage. The finger-shaped holes 113 in the porous layer 11 greatly improve the porosity of the porous ceramic and the permeation speed of the atomizing liquid, so that the atomizing liquid in the dense layer can be quickly replenished after atomization. At the same time, the microporous layer 112 above the finger-shaped holes 113 also has a small pore size structure, which makes it easy for the atomizing liquid to not flow out of the porous ceramic when the product is inverted, thus playing a role in locking in oil.

[0041] The method for manufacturing porous ceramics in this application includes the following steps:

[0042] S10, Prepare the slurry;

[0043] In this step, the slurry comprises the following components by mass: 54-62 wt% of a mixture of ceramic powder and pore-forming agent, 1-2 wt% of dispersant, 32-39 wt% of organic solvent and 4-5.5% of binder.

[0044] The volume ratio of the pore-forming agent to the ceramic powder in the mixture is 0.3-0.45. The pore-forming agent includes one or more of starch, graphite, sawdust, and sucrose. The ceramic powder is one or more of alumina, silicon dioxide, titanium dioxide, kaolin, calcium carbonate, silicon carbide, talc, feldspar, cordierite, and diatomaceous earth.

[0045] The organic solvent is pure NMP (N-methylpyrrolidone) or NMP containing a small amount of non-solvent water (1-10 wt%); the dispersant is one or more of PVP (polyvinylpyrrolidone), DSP (disodium hydrogen phosphate), and TEOA (triethanolamine); the binder is one or more of PESF (polyphenylene ether sulfone), PES (polyether sulfone), PVB (polyvinyl butyral), and PMMA (polymethyl methacrylate).

[0046] In this step, the ceramic powder is first mixed with a pore-forming agent, then a dispersant and an organic solvent are added. After ball milling for more than 5 hours, a binder is added and the mixture is mixed for more than 15 hours to obtain a uniform slurry.

[0047] S20, casting;

[0048] In this step, the prepared slurry is cast onto a support plate, with a preferred thickness of 1-3 mm. The support plate is a glass plate or other smooth-surfaced material.

[0049] S30, phase transformation;

[0050] The slurry cast onto the support plate is immersed in water along with the support plate. Upon immersion in water, the slurry solidifies instantly, forming a dense layer 12 on the surface of the slurry in contact with the water. This dense layer 12 can be understood as a film. The slurry is soaked in water for at least 12 hours. During the soaking process, the organic solvent is displaced by the water to obtain a green body, forming several pores within the solidified slurry. No dense layer is formed on the side of the green body that contacts the support plate; instead, a microporous layer 112 is formed on the side of the green body that contacts the support plate.

[0051] S40, slice and demold;

[0052] This step involves cutting the obtained green blank according to the set dimensions, and then demolding it through a demolding table to obtain a green blank of the specified size. This step is optional.

[0053] S50, sintered molding;

[0054] The solidified green body is placed in a sintering furnace and held at 550–700°C for 3–6 hours, then heated to 1300–1550°C for 2.5–5 hours to obtain the porous ceramic of this application. During the sintering process, the pore-forming agent is burned off, and the gaps formed in the phase transformation step shrink, ultimately forming the porous ceramic structure of this application. The shrinkage of the gaps forms the capillaries in the porous ceramic of this application. The pore size in the dense layer 12 (i.e., the film coating) is smaller than the pore size in the loose layer 11.

[0055] The porous ceramic, porous ceramic manufacturing method and atomizing device of this application can form a dense layer 12 and a loose layer 11 on the vertical sides of the porous ceramic in one casting process. Compared with the preparation of porous ceramics with different pore sizes by multiple castings using different formulas, the process of this application is simpler and more practical, with a shorter manufacturing cycle, lower manufacturing cost and higher product process controllability.

[0056] Meanwhile, the porous ceramic formulation of this application contains an organic solvent. By immersing the cast product in water, the organic solvent is displaced and gaps are formed. During sintering, these gaps shrink to form capillaries that connect the entire porous ceramic. The presence of these gaps allows the pore structures within the porous layer to connect with each other, increasing the ratio of open pores (pores that can connect to the liquid) and reducing closed pores (pores that exist independently and have problems such as not being able to seep liquid).

[0057] Meanwhile, the finger-shaped holes 113 have a teardrop-shaped structure with a small opening at the top. Alternatively, the presence of the microporous layer 112 can prevent the atomized liquid that has seeped into the finger-shaped holes 113 from flowing out, thus locking in the oil and preventing the atomized liquid from flowing out after entering, which would affect the oil guiding speed. The presence of the dense layer 12 can prevent leakage, thereby ensuring the safety of the product.

[0058] The present invention will be further described in detail below through specific embodiments:

[0059] Example 1

[0060] S10. Slurry preparation: Using 75wt% alumina fine powder, 10wt% silica fine powder, 10wt% kaolin fine powder, and 5wt% titanium dioxide fine powder as ceramic powder raw materials, 30vol% pore-forming agent is added according to the mixing density of the ceramic powder to form a mixture of ceramic powder and pore-forming agent; 1.5wt% dispersant polyvinylpyrrolidone and 35wt% organic solvent N-methyl-pyrrolidone are added to the 58.5wt% ceramic powder and pore-forming agent mixture, ball milling is performed for 5 hours, then 5wt% binder polyethersulfone is added, and the mixture is mixed for another 15 hours to obtain a uniform slurry;

[0061] S20, Casting: Adjust the casting blade to 1.6mm, pour the evenly mixed slurry into the trough, and cast to obtain a wet film strip;

[0062] S30, Phase transformation: The wet film is cured in pure water at 15°C for 20 hours to obtain a wet preform; in this step, the organic solvent is replaced by pure water and forms irregular gaps, and a dense layer is formed on the surface of the wet preform that is in contact with water.

[0063] S40. Green body processing: Then, according to the requirements, cut it into a certain shape and size, and dry it for 40 hours in an environment with a temperature of 25℃ and a relative humidity of 45% to obtain the green body.

[0064] S50, Sintering: The green body is placed in a sintering furnace, and the furnace temperature is increased to 800℃ at a rate of 0.5℃ / min. The temperature is held for 2 hours to remove the binder, and then increased to 1500℃ at a rate of 2℃ / min. The temperature is held for 4 hours to sinter, and porous ceramics are obtained.

[0065] Example 2:

[0066] S10. Slurry preparation: Using 85wt% alumina fine powder, 10wt% silica fine powder, and 5wt% titanium dioxide fine powder as ceramic powder raw materials, 35vol% pore-forming agent is added according to the mixing density of the ceramic powder to form a mixture of ceramic powder and pore-forming agent; 1.5wt% dispersant polyvinylpyrrolidone and 35wt% organic solvent N-methyl-pyrrolidone are added to the 58.5wt% mixture of ceramic powder and pore-forming agent, ball milling is performed for 5 hours, and then 5wt% binder polyvinyl butyral is added and mixed for another 15 hours to obtain a uniform slurry;

[0067] S20, Casting: Adjust the casting blade to 2.5mm, pour the evenly mixed slurry into the trough, and cast to obtain a wet film strip;

[0068] S30, Phase transformation: The wet film is cured in pure water at 15°C for 20 hours to obtain a wet preform; in this step, the organic solvent is replaced by pure water and forms irregular gaps, and a dense layer is formed on the surface of the wet preform that is in contact with water.

[0069] S40. Green body processing: Then, according to the requirements, cut it into a certain shape and size, and dry it for 40 hours in an environment with a temperature of 25℃ and a relative humidity of 45% to obtain the green body.

[0070] S50, Sintering: The green body is placed in a sintering furnace, and the furnace temperature is increased to 800℃ at a rate of 0.5℃ / min. The temperature is held for 2 hours to remove the binder, and then increased to 1450℃ at a rate of 2℃ / min. The temperature is held for 4 hours to sinter, and porous ceramics are obtained.

[0071] Example 3:

[0072] In this embodiment, a method for preparing porous ceramics with a straight pore gradient structure is as follows:

[0073] S10. Slurry preparation: Using 43wt% alumina fine powder, 41wt% corundum powder, 15wt% silicon carbide fine powder, and 1wt% calcium carbonate fine powder as ceramic powder raw materials, 30vol% pore-forming agent is added according to the mixing density of the ceramic powder to form a mixture of ceramic powder and pore-forming agent; 1.5wt% dispersant polyvinylpyrrolidone and 32wt% solvent N-methyl-pyrrolidone are added to the 62wt% mixture of ceramic powder and pore-forming agent, ball milling is performed for 5 hours, and then 4.5wt% binder polyethersulfone is added and mixed for another 15 hours to obtain a uniform slurry;

[0074] S20, Casting: Adjust the casting blade to 2.5mm, pour the evenly mixed slurry into the trough, and cast to obtain a wet film strip;

[0075] S30, Phase transformation: The wet film is cured in pure water at 30°C for 20 hours to obtain a wet preform; in this step, the organic solvent is replaced by pure water and forms irregular gaps, and a dense layer is formed on the surface of the wet preform that is in contact with water.

[0076] S40. Green body processing: Then, according to the requirements, cut it into a certain shape and size, and dry it for 40 hours in an environment with a temperature of 25℃ and a relative humidity of 45% to obtain the green body.

[0077] S50, Sintering: The green body is placed in a sintering furnace, and the furnace temperature is increased to 800℃ at a rate of 0.5℃ / min. The temperature is held for 2 hours to remove the binder, and then increased to 1500℃ at a rate of 2℃ / min. The temperature is held for 4 hours to sinter, and porous ceramics are obtained.

[0078] Example 4:

[0079] In this embodiment, a method for preparing porous ceramics with a straight pore gradient structure is as follows:

[0080] S10. Slurry preparation: Using 55.6 wt% alumina fine powder, 35.7% quartz sand powder, 6.7 wt% silica fine powder, and 2 wt% calcium carbonate fine powder as ceramic powder raw materials, 45 vol% pore-forming agent is added according to the mixing density of the ceramic powder to form a mixture of ceramic powder and pore-forming agent; 1.5 wt% dispersant polyvinylpyrrolidone and 39 wt% solvent N-methyl-pyrrolidone are added to the 54.5 wt% ceramic powder and pore-forming agent mixture, ball milling is performed for 5 h, then 5 wt% binder is added, and mixing is performed for another 15 h to obtain a uniform slurry;

[0081] S20, Casting: Adjust the casting blade to 2.0mm, pour the evenly mixed slurry into the trough, and cast to obtain a wet film strip;

[0082] S30, Phase transformation: The wet film is cured in water containing 1% NMP at 30°C for 20 hours to obtain a wet preform; in this step, the organic solvent is replaced by pure water and forms irregular gaps, and a dense layer is formed on the surface of the wet preform that is in contact with water.

[0083] S40. Green body processing: Then, according to the requirements, cut it into a certain shape and size, and dry it for 40 hours in an environment with a temperature of 25℃ and a relative humidity of 45% to obtain the green body.

[0084] S50, Sintering: The green body is placed in a sintering furnace, and the furnace temperature is increased to 800℃ at a rate of 0.5℃ / min. The temperature is held for 4 hours to remove the binder, and then increased to 1500℃ at a rate of 2℃ / min. The temperature is held for 4 hours to sinter, and porous ceramics are obtained.

[0085] Table 1 below shows the relevant performance parameters of the porous ceramics obtained in Examples 1-4:

[0086]

[0087] Table 1

[0088] This application also includes an atomizing device in which the porous ceramic is used. The atomizing device includes a power supply system connected to the heating element 14, a liquid storage chamber, and the porous ceramic that seals the liquid storage chamber. The heating element 14 is disposed on the dense layer of the porous ceramic. The atomizing liquid in the liquid storage chamber seeps into the porous ceramic from the surface of the loose layer. The dense layer 12 prevents the atomizing liquid from further penetrating downwards. The heating element 14 heats the porous ceramic and atomizes the atomizing liquid inside the porous ceramic to generate an aerosol.

[0089] The porous ceramic and manufacturing method of this application can produce porous ceramics with a dense layer 12 and a loose layer 11 through a single casting process. Compared with the prior art, this greatly simplifies the manufacturing process, reduces costs, and improves process controllability.

[0090] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0091] The above embodiments only illustrate preferred implementations of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A porous ceramic, characterized in that, The porous ceramic comprises a loose layer and a dense layer. The surface of the loose layer is a liquid-permeable surface, and the surface of the dense layer is an atomizing surface. Several finger-shaped pores extending vertically are formed within the loose layer. The diameter of the finger-shaped pores decreases near the liquid-permeable surface and does not penetrate the dense layer downwards. Several capillary pores are also formed within the loose and dense layers. The diameter of the capillary pores is smaller than that of the finger-shaped pores. The capillary pores are interconnected and connect several of the finger-shaped pores. The thickness of the loose layer is greater than that of the dense layer. The atomized liquid permeates into the porous ceramic from the liquid-permeable surface. The loose layer further includes a finger-shaped pore layer and a microporous layer. The finger-shaped pore layer is located between the dense layer and the microporous layer. The microporous layer has a plurality of micropores formed in the microporous layer. The micropores penetrate upward through the permeation surface and connect with the finger-shaped pores. The micropores are interconnected through the capillaries; a dense layer and a loose layer can be formed on the vertical sides of the porous ceramic through a single casting process. The diameter of the finger-shaped pores is between 80-300 μm, the diameter of the micropores in the microporous layer is between 30-80 μm, the diameter of the capillaries is between 5-35 μm, and the diameter of the finger-shaped pores in the microporous layer is close to the diameter of the micropores in the microporous layer.

2. The porous ceramic as described in claim 1, characterized in that, The dense layer also contains pore structures other than capillary pores. The pore size of the pore structures in the dense layer is between 10-35 μm. The porosity of the porous ceramic is between 50%-68%, and the porosity of the loose layer is greater than that of the dense layer.

3. The porous ceramic as described in claim 2, characterized in that, The diameter of the finger-shaped pores is between 80-200 μm, the diameter of the capillary pores is between 5-30 μm, and the porosity of the porous ceramic is 50%.

4. The porous ceramic as described in claim 2, characterized in that, The diameter of the finger-shaped pores is between 100-300 μm, the diameter of the capillary pores is between 5-30 μm, and the porosity of the porous ceramic is 53%.

5. The porous ceramic as described in claim 2, characterized in that, The diameter of the finger-shaped pores is between 50-150 μm, the diameter of the capillary pores is between 10-35 μm, and the porosity of the porous ceramic is 58.5%.

6. The porous ceramic as described in claim 2, characterized in that, The thickness of the porous ceramic is 1-3 mm, and the thickness of the dense layer is between 0.02-0.3 μm. The thickness of the dense layer is not related to the thickness of the porous ceramic.

7. The porous ceramic as described in claim 6, characterized in that, The porous ceramic has a thickness of 2 mm.

8. The porous ceramic as described in claim 6, characterized in that, The porous ceramic has a thickness of 3 mm.

9. A method for manufacturing porous ceramics as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S10. Preparation of slurry: Mix 54-62 wt% of ceramic powder and pore-forming agent, 1-2 wt% of dispersant and 32-39 wt% of organic solvent and ball mill for 5 hours, then add 4-5.5 wt% of binder and mix evenly to obtain slurry. S20, Casting: The slurry is cast onto a support plate; S30, Phase transformation: The support plate and the slurry cast on it are immersed in water together. The slurry solidifies instantly after being immersed in water and forms the dense layer on the surface of the slurry in contact with water. The support plate and the slurry on it are soaked in water for no less than 12 hours. During this period, the organic solvent is replaced by water to form several gaps and obtain a green body. S40, Sintering and Shaping: The solidified green body is placed in a sintering furnace, and the temperature is first slowly raised to 800°C and held for 2 hours. Then the temperature inside the furnace is raised to 1300-1550°C and held for 4 hours to obtain the porous ceramic. During this process, the gaps will shrink to form a capillary structure.

10. The method for manufacturing porous ceramics as described in claim 9, characterized in that, The organic solvent is pure NMP or NMP containing a small amount of non-solvent water (1-10 wt%); the dispersant is one or more of PVP, DSP, and TEOA; the pore-forming agent includes one or more of starch, graphite, sawdust, and sucrose; the binder is one or more of PESF, PES, PVB, and PMMA; and the ceramic powder is one or more of alumina, silicon dioxide, titanium dioxide, kaolin, calcium carbonate, silicon carbide, talc, feldspar, cordierite, and diatomaceous earth.

11. The method for manufacturing porous ceramics as described in claim 10, characterized in that, The volume ratio of the pore-forming agent to the ceramic powder in the mixture is 0.3-0.

45.

12. The method for manufacturing porous ceramics as described in claim 9, characterized in that, The ceramic slurry comprises 58.5 wt% of a mixture of ceramic powder and pore-forming agent, 1.5 wt% of dispersant polyvinylpyrrolidone, 35 wt% of organic solvent N-methylpyrrolidone, and 5 wt% of binder polyethersulfone.

13. The method for manufacturing porous ceramics as described in claim 12, characterized in that, The ceramic powder and the pore-forming agent are mixed at a volume ratio of 1:0.3 to obtain a mixture of ceramic powder and pore-forming agent. The ceramic powder includes: 75wt% alumina fine powder, 10wt% silica fine powder, 10wt% kaolin fine powder, and 5wt% titanium dioxide fine powder.

14. The method for manufacturing porous ceramics as described in claim 9, characterized in that, The ceramic slurry comprises 58.5 wt% of a mixture of ceramic powder and pore-forming agent, 1.5 wt% of dispersant polyvinylpyrrolidone, 35 wt% of organic solvent N-methyl-pyrrolidone, and 5 wt% of binder polyethersulfone; the ceramic powder and pore-forming agent are mixed at a volume ratio of 1:0.35 to obtain the mixture of ceramic powder and pore-forming agent, wherein the ceramic powder comprises: 85 wt% fine alumina powder, 10 wt% fine silica powder, and 5 wt% fine titanium dioxide powder.

15. The method for manufacturing porous ceramics as described in claim 9, characterized in that, The ceramic slurry comprises 62 wt% of a mixture of ceramic powder and pore-forming agent, 1.5 wt% of dispersant polyvinylpyrrolidone, 32 wt% of organic solvent N-methyl-pyrrolidone, and 4.5 wt% of binder polyethersulfone; the ceramic powder and pore-forming agent are mixed at a volume ratio of 1:0.3 to obtain the mixture of ceramic powder and pore-forming agent, wherein the ceramic powder comprises: 43 wt% fine alumina powder, 41% corundum powder, 15 wt% fine silicon carbide powder, and 1 wt% fine calcium carbonate powder.

16. The method for manufacturing porous ceramics as described in claim 9, characterized in that, The ceramic slurry comprises 54.5 wt% of a mixture of ceramic powder and pore-forming agent, 1.5 wt% of dispersant polyvinylpyrrolidone, 39 wt% of organic solvent N-methyl-pyrrolidone, and 5 wt% of binder polyethersulfone; the ceramic powder and pore-forming agent are mixed at a volume ratio of 1:0.45 to obtain the mixture of ceramic powder and pore-forming agent, wherein the ceramic powder comprises: 55.6 wt% fine alumina powder, 35.7% quartz sand powder, 6.7% fine silica powder, and 2 wt% fine calcium carbonate powder.

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