Porous ceramic as well as preparation method and application thereof

Abstract

The invention discloses porous ceramic as well as a preparation method and application thereof, and belongs to the technical field of porous materials. The porous ceramic comprises a lining with a porous structure and a surface layer with a porous structure, compared with the pore diameter of the lining, the pore diameter of the surface layer is smaller; the high-temperature salt in a molten state can enter the inside through small holes in the surface layer; the surface layer can prevent high-temperature salt in a molten state from leaking, and the lining provides a storage and phase change space for the high-temperature salt; the porosity of the lining is larger than that of the surface layer.

Description

Technical Field

[0001] The present invention belongs to the technical field of porous materials, and more specifically, relates to a porous ceramic and a preparation method and application thereof. Background Art

[0002] High-temperature salts such as nitrates, carbonates, chlorides, and sulfates offer advantages such as a wide heat storage temperature range (200-1000°C), high heat storage density, stable physical and chemical properties, and low price, making them ideal high-temperature heat storage materials. Their working principle is to store and release heat by absorbing (releasing) heat during the melting (solidification) process of the high-temperature salt. However, large-scale application of these heat storage materials faces two major challenges: first, the high-temperature salts are highly corrosive, easily corroding the packaging containers; second, the high-temperature salts have a low thermal conductivity of approximately 0.5 W / (m·K), resulting in poor heat transfer performance. Currently, an effective solution is to microencapsulate the high-temperature salts in porous ceramics, forming a shape-stable composite phase-change material. This composite heat storage material offers the following significant advantages: 1) The capillary force provided by the porous ceramic skeleton prevents leakage of the molten high-temperature salt, thus avoiding corrosion; 2) The porous ceramic skeleton provides a heat transfer channel for the high-temperature salt, enhancing heat transfer; and 3) The composite phase-change material can also directly contact the thermal fluid (typically air), effectively reducing the thermal resistance of the heat transfer interface.

[0003] The pore structure of porous ceramics will have an important impact on the comprehensive thermophysical properties of composite phase change materials. The pore structure of the porous ceramics not only needs to consider providing as much attachment space as possible for the high-temperature salt (under a certain volume), which helps to improve the heat storage density, but also needs to ensure that there is a sufficiently large capillary force to prevent the leakage of high-temperature salt, which helps to improve the load stability and heat transfer performance of the high-temperature salt, but at the same time limits the load amount of high-temperature salt (usually ≤50wt%). It can be seen from this that existing porous ceramics can never take into account the potential contribution to the structural stability, heat storage performance, and heat transfer performance of composite phase change materials. Summary of the Invention

[0004] 1. Problem to be solved

[0005] One of the purposes of the present invention is to provide a porous ceramic which is used as a matrix of a composite phase change material and has the advantages of structural stability and good heat storage performance;

[0006] The present invention also provides a method for preparing the porous ceramic.

[0007] 2. Technical solution

[0008] The technical solutions adopted in the present invention are as follows:

[0009] A first aspect of the present invention provides a porous ceramic, comprising:

[0010] An inner layer having a porous structure, and a surface layer having a porous structure;

[0011] The surface layer has pores of smaller diameter than the pores of the inner layer;

[0012] High-temperature salt in a molten state can enter the interior through the small holes in the surface;

[0013] The surface layer can prevent leakage of high-temperature salt in a molten state, and the inner layer provides space for storage and phase change of high-temperature salt;

[0014] The porosity of the inner layer is greater than the porosity of the surface layer.

[0015] As a preferred embodiment of any embodiment of the first aspect of the present invention, the porosity of the inner lining can be any value within any of the following numerical ranges: 78-88%, 79-88%, 80-88%, 78-87%, 79-87%, 80-87%, 78-86%, 79-86%, 80-86%, 78-85%, 79-85%, 80-85%, 78-84%, 79-84%, 80-84%, 78-83%, 79-83%, 80-83%, 78-82%, 79-82%, 80-82%.

[0016] As a preferred embodiment of any embodiment of the first aspect of the present invention, the porosity of the surface layer can be any value within any of the following numerical ranges: 50-75%, 52-75%, 55-75%, 58-75%, 60-75%, 62-75%, 65-75%, 67-75%, 70-75%.

[0017] As a preferred embodiment of any one of the first aspects of the present invention, the bulk density of the surface layer is greater than the bulk density of the inner layer; the bulk density of the surface layer is greater than the bulk density of the porous ceramic.

[0018] As a preferred embodiment of any embodiment of the first aspect of the present invention, the bulk density of the surface layer can be any value within the following numerical ranges: 0.7 to 0.85 g / cm 3 , 0.72~0.85g / cm 3 , 0.74~0.85g / cm 3 , 0.76~0.85g / cm 3 , 0.78~0.85g / cm 3 , 0.7~0.83g / cm 3 , 0.72~0.83g / cm 3 , 0.74~0.83g / cm 3 , 0.76~0.83g / cm3 , 0.78~0.83g / cm 3 , 0.7~0.8g / cm 3 , 0.72~0.8g / cm 3 , 0.74~0.8g / cm 3 , 0.76~0.8g / cm 3 , 0.78~0.8g / cm 3 .

[0019] As a preferred embodiment of any embodiment of the first aspect of the present invention, the bulk density of the inner lining can be any value within the following range: 0.45 to 0.65 g / cm 3 , 0.47~0.65g / cm 3 , 0.5~0.65g / cm 3 , 0.52~0.65g / cm 3 , 0.55~0.65g / cm 3 , 0.45~0.62g / cm 3 , 0.47~0.62g / cm 3 , 0.5~0.62g / cm 3 , 0.52~0.62g / cm 3 , 0.55~0.62g / cm 3 , 0.45~0.6g / cm 3 , 0.47~0.6g / cm 3 , 0.5~0.6g / cm 3 , 0.52~0.6g / cm 3 , 0.55~0.6g / cm 3 .

[0020] As a preferred embodiment of any embodiment of the first aspect of the present invention, the bulk density of the porous ceramic can be any value within the following numerical ranges: 0.6 to 0.75 g / cm 3 , 0.62~0.75g / cm 3 , 0.64~0.75g / cm 3 , 0.66~0.75g / cm 3 , 0.68~0.75g / cm 3 , 0.7~0.75g / cm 3 , 0.6~0.73g / cm 3 , 0.62~0.73g / cm 3 , 0.64~0.73g / cm 3 , 0.66~0.73g / cm 3 , 0.68~0.73g / cm3 , 0.7~0.73g / cm 3 .

[0021] As a preferred embodiment of any embodiment of the first aspect of the present invention, the porous ceramic has a bottom and a top according to the placement direction when in use;

[0022] The top portion has a surface layer, and the surface layer has a thickness t1;

[0023] The bottom portion has a surface layer, and the surface layer has a thickness t2;

[0024] From bottom to top, the maximum thickness of the inner lining is t3.

[0025] Furthermore, the t3 / t1 can be any value within any of the following numerical ranges: 2-5, 3-5, 3-4.

[0026] Furthermore, the t3 / t2 can be any value within any of the following numerical ranges: 2-5, 3-5, 3-4.

[0027] As a preferred embodiment of any one of the first aspects of the present invention, the inner pores are formed by the action of a porous structure pore-forming agent and a foaming agent.

[0028] A second aspect of the present invention provides a method for preparing a porous ceramic, the method comprising the steps of:

[0029] (A) preparing a first component and a second component;

[0030] The first component includes a skeleton material and a pore-forming agent;

[0031] The second component includes a framework material;

[0032] (B) using the first component and the second component as raw materials to obtain a molded body having the first component inside and the second component on the surface;

[0033] (C) performing a high-temperature sintering treatment on the molded body to obtain the porous ceramic.

[0034] As a preferred embodiment of any one of the second aspects of the present invention, the pore-forming agent of the first component includes a non-porous structure pore-forming agent.

[0035] As a preferred embodiment of any embodiment of the second aspect of the present invention, the pore-forming agent of the first component includes a pore-forming agent in a first particle size range and a pore-forming agent in a second particle size range; the first particle size range is 0.15 to 0.5 mm; and the second particle size range is 0.5 to 1 mm.

[0036] As a preferred embodiment of any embodiment of the second aspect of the present invention, the mass ratio of the pore-forming agent in the first particle size range to the pore-forming agent in the second particle size range is 1-5.

[0037] As a preferred embodiment of any embodiment of the second aspect of the present invention, the pore-forming agent of the first component further comprises a porous structure pore-forming agent;

[0038] Calculated based on the total amount of the first component (skeleton material, non-porous structure pore-forming agent, porous structure pore-forming agent), the added amount of the porous structure pore-forming agent is 30-70 wt %.

[0039] As a preferred embodiment of any embodiment of the second aspect of the present invention, the particle size of the porous structure pore-forming agent does not exceed 100 microns.

[0040] As a preferred embodiment of any embodiment of the second aspect of the present invention, the usage ratio of the skeleton material and the pore-forming agent is 0.8 to 1.5.

[0041] As a preferred embodiment of any embodiment of the second aspect of the present invention, the first component further includes a sintering aid; the usage ratio of the skeleton material, pore-forming agent and sintering aid is (4-7):(4-7):(2-4).

[0042] As a preferred embodiment of any embodiment of the second aspect of the present invention, the second component further includes a sintering aid; the usage ratio of the skeleton material to the sintering aid is 2 to 5.

[0043] As a preferred embodiment of any embodiment of the second aspect of the present invention, the second component further includes a pore-forming agent; the amount ratio of the pore-forming agent is (4-15): (4-8): (2-4).

[0044] As a preferred embodiment of any embodiment of the second aspect of the present invention, the particle size of the pore-forming agent of the second component is less than or equal to 0.1 mm.

[0045] As a preferred embodiment of any embodiment of the second aspect of the present invention, in step (d), the holding time of the high-temperature sintering treatment is 1 to 4 hours.

[0046] As a preferred embodiment of any embodiment of the second aspect of the present invention, the holding temperature of the high-temperature sintering is 900-1300°C; preferably 1000-1200°C.

[0047] As a preference of any embodiment of the second aspect of the present invention, in step (d), the heating rate of the high temperature treatment is 2 to 10° C. / min.

[0048] As a preferred embodiment of any embodiment of the second aspect of the present invention, the skeleton material includes but is not limited to: steel slag, solid waste (blast furnace slag, fly ash, red mud, tailings), oxides (aluminum oxide, zirconium oxide, titanium oxide, silicon oxide), carbides (silicon carbide, boron carbide), nitrides (silicon nitride, aluminum nitride), mullite, zircon, and cordierite.

[0049] As a preferred embodiment of any embodiment of the second aspect of the present invention, the porous structure pore-forming agent includes but is not limited to: diatomaceous earth, kaolin, bentonite, and quartz.

[0050] As a preferred embodiment of any embodiment of the second aspect of the present invention, the non-porous structure pore-forming agent includes but is not limited to: inorganic pore-forming agents (calcium carbonate, calcite), organic pore-forming agents (corn starch, wheat starch, potato starch, carbon powder, coal powder).

[0051] As a preferred embodiment of any embodiment of the second aspect of the present invention, the sintering aid includes but is not limited to: waste glass, sodium feldspar, and potassium feldspar.

[0052] As a preferred embodiment of any embodiment of the second aspect of the present invention, the preparation method can prepare the porous ceramics described in any embodiment of the first aspect of the present invention.

[0053] A third aspect of the present invention provides a method for preparing a porous ceramic, the method comprising the steps of:

[0054] (a) preparing a slurry containing a first component; the first component includes a skeleton material, a pore-forming agent, a curing agent, a sintering agent, a binder, a foaming agent, a foam stabilizer, and a solvent;

[0055] Wherein, the content of the sintering aid can be 0;

[0056] (b) preparing a slurry containing a second component;

[0057] The second component includes a skeleton material, a pore-forming agent, a curing agent, a sintering aid, a binder, and a solvent;

[0058] Wherein, the content of the sintering aid can be 0;

[0059] (c) foaming and curing the slurry containing the first component to obtain a molded body containing the first component;

[0060] (d) applying a slurry containing the second component to the surface of the molded body containing the first component and curing the slurry to obtain a molded body coated with the second component;

[0061] (e) subjecting the molded body coated with the second component to a high-temperature sintering treatment to obtain the porous ceramic;

[0062] What needs to be explained above is the order of steps (a), (b), and (c). It only requires that step (a) be before step (c), and no other requirements are required.

[0063] As a preferred embodiment of the third aspect of the present invention, the solid content of the first component slurry can be any value selected from any of the following numerical ranges: 28-50wt%, 30-50wt%, 32-50wt%, 34-50wt%, 28-48wt%, 30-48wt%, 32-48wt%, 34-48wt%, 28-46wt%, 30-46wt%, 32-46wt%, 34-46wt%, 28-44wt%, 3 0~44wt%, 32~44wt%, 34~44wt%, 28~42wt%, 30~42wt%, 32~42wt%, 34~42wt%, 28~40wt%, 30~40wt%, 32~40 wt%, 34~40wt%, 28~38wt%, 30~38wt%, 32~38wt%, 34~38wt%, 28~36wt%, 30~36wt%, 32~36wt%, 34~36wt%.

[0064] As a preferred embodiment of any embodiment of the third aspect of the present invention, based on the total amount of the skeleton material, pore-forming agent, curing agent, sintering aid and solvent, the solid content of the skeleton material, pore-forming agent, curing agent and sintering aid can be any value within the following numerical ranges: 28-50wt%, 30-50wt%, 32-50wt%, 34-50wt%, 28-48wt%, 30-48wt%, 32-48wt%, 34-48wt%, 28-46wt%, 30-46wt%, 32-46wt%, 34~46wt%, 28~44wt%, 30~44wt%, 32~44wt%, 34~44wt%, 28~42wt%, 30~42wt%, 32~42wt%, 34~42wt%, 28~40wt%, 30~4 0wt%, 32~40wt%, 34~40wt%, 28~38wt%, 30~38wt%, 32~38wt%, 34~38wt%, 28~36wt%, 30~36wt%, 32~36wt%, 34~36wt%.

[0065] As a preferred embodiment of any embodiment of the third aspect of the present invention, based on the total amount of the skeleton material, pore-forming agent, curing agent and solvent, the solid content of the skeleton material, pore-forming agent and curing agent can be any value within any of the following numerical ranges: 28-50wt%, 30-50wt%, 32-50wt%, 34-50wt%, 28-48wt%, 30-48wt%, 32-48wt%, 34-48wt%, 28-46wt%, 30-46wt%, 32-46wt%, 34-46wt%, 28-44wt%, 30- 44wt%, 32~44wt%, 34~44wt%, 28~42wt%, 30~42wt%, 32~42wt%, 34~42wt%, 28~40wt%, 30~40wt%, 32~40wt%, 34~40wt%, 28~38w t%, 30~38wt%, 32~38wt%, 34~38wt%, 28~36wt%, 30~36wt%, 32~36wt%, 34~36wt%, 28~32wt%, 30~32wt%, 32~32wt%, 34~32wt%.

[0066] It should be noted that, as mentioned above, the solid content of the first component slurry will affect the foaming effect and the foam stabilization effect. Too high a solid content will lead to excessive slurry viscosity, which will have the adverse effect of difficult foaming and cause the problem of low porosity. Too low a solid content will lead to too low slurry viscosity, which will have the adverse effect of unstable foam and cause the problem of long curing cycle and unstable pore structure.

[0067] As a preferred embodiment of any embodiment of the third aspect of the present invention, in step (a), the mass ratio of the skeleton material, the pore-forming agent, and the foaming agent is (6-7.5): (0.8-2.5): 0.06.

[0068] As a preferred embodiment of any embodiment of the third aspect of the present invention, in step (b), the mass ratio of the framework material to the pore-forming agent is (6-9): (3-5.5).

[0069] As a preferred embodiment of any of the third aspects of the present invention, in the first component, the mass ratio of the skeleton material, pore-forming agent, curing agent, sintering aid, binder, foaming agent and foam stabilizer is (650-800):(80-250):(80-130):(0-130):(50-70):(4-8):(1-3).

[0070] As a preferred embodiment of any of the third aspects of the present invention, in the first component, the mass ratio of the skeleton material, pore-forming agent, curing agent, sintering aid, binder, foaming agent and foam stabilizer is (650-800):(80-130):(80-130):(0-130):(50-70):(4-8):(1-3).

[0071] Furthermore, in the first component, the mass ratios of the skeleton material, pore-forming agent, curing agent, sintering aid, binder, foaming agent and foam stabilizer are preferably (650-800):(80-130):(80-130):(80-130):(50-70):(4-8):(1-3), (700-750):(90-110):((90-110):((90-110):(55-65):(5-7):2.

[0072] As a preferred embodiment of any embodiment of the third aspect of the present invention, the solid content of the second component slurry can be any value within any of the following numerical ranges: 40-70wt%, 42-70wt%, 45-70wt%, 47-70wt%, 50-70wt%, 52-70wt%, 54-70wt%, 56-70wt%, 58-70wt%, 60-70wt%.

[0073] As a preferred embodiment of any embodiment of the third aspect of the present invention, based on the total amount of the skeleton material, pore-forming agent, curing agent, sintering aid and solvent, the solid content of the skeleton material, pore-forming agent, curing agent and sintering aid can be any value within any of the following numerical ranges: 40-70wt%, 42-70wt%, 45-70wt%, 47-70wt%, 50-70wt%, 52-70wt%, 54-70wt%, 56-70wt%, 58-70wt% and 60-70wt%.

[0074] As a preferred embodiment of any embodiment of the third aspect of the present invention, based on the total amount of the skeleton material, pore-forming agent, curing agent, and solvent, the solid content of the skeleton material, pore-forming agent, curing agent, and sintering aid can be any value within any of the following numerical ranges: 40-70wt%, 42-70wt%, 45-70wt%, 47-70wt%, 50-70wt%, 52-70wt%, 54-70wt%, 56-70wt%, 58-70wt%, and 60-70wt%.

[0075] It should be noted that the solid content of the second component slurry described herein will affect the coating effect (wrapping degree and / or uniformity and / or leakage prevention ability) of the slurry containing the second component on the molded body containing the first component. Too much solid content will have an adverse effect on the uniformity of coating the slurry containing the second component on the molded body containing the first component, affecting the uniformity of the thickness of the surface layer of the porous ceramic obtained in the end and the leakage prevention effect; too low solid content will result in the number of operations of coating the slurry containing the second component on the molded body containing the first component, and will also affect the uniformity and leakage prevention ability of the surface layer of the porous ceramic obtained in the end.

[0076] As a preferred embodiment of any of the third aspects of the present invention, in the second component, the mass ratio of the skeleton material, pore-forming agent, curing agent, sintering aid and binder is (20-30):(10-20):(0-8):((0-8):(1-6).

[0077] Furthermore, in the second component, the mass ratios of the skeleton material, pore-forming agent, curing agent, sintering aid and binder are preferably (20-30):(10-20):(2-8):((2-8):(1-6), (22-18):(12-15):(3-7):(2-8):(7-6) in sequence.

[0078] As a preferred embodiment of any embodiment of the third aspect of the present invention, in step (d), the operation of "coating the slurry containing the second component on the surface of the molded body containing the first component and curing" can be repeated multiple times;

[0079] It is preferably repeated 1 to 8 times; more preferably repeated 2 to 5 times; and most preferably repeated 2 to 3 times.

[0080] It should be noted that the number of repetitions described herein will affect the porosity of the porous ceramic finally obtained, the loading rate of high-temperature salt when used as a composite phase change material, and the utilization rate of pores when used as a composite phase change material. Too many or too few repetitions will cause the porosity of the porous ceramic, the loading rate of high-temperature salt when used as a composite phase change material, and the utilization rate of pores when used as a composite phase change material to decrease. From the perspective of obtaining as high a porosity of the porous ceramic as possible, the loading rate of high-temperature salt when used as a composite phase change material, and the utilization rate of pores when used as a composite phase change material, while taking into account the leakage prevention ability when used as a composite phase change material, based on the solid content of the aforementioned slurry containing the second component, it is preferably repeated 2 to 3 times.

[0081] As a preferred embodiment of any embodiment of the third aspect of the present invention, the porous ceramic has a bottom and a top according to the placement direction when in use;

[0082] The top portion has a molded body containing a second component, and the molded body containing the second component has a thickness t1;

[0083] The bottom portion has a molded body containing a second component, and the molded body containing the second component has a thickness t2;

[0084] The maximum thickness of the shaped body containing the first component from the bottom to the top is t3.

[0085] As a preferred embodiment of any embodiment of the third aspect of the present invention, the t3 / t1 can be any value selected from any of the following numerical ranges: 2-5, 2.2-5, 2.4-5, 2.6-5, 2.8-5, 3-5, 3.2-5, 3.4-5, 3.6-5, 2-4.8, 2.2-4.8, 2.4-4.8, 2.6-4.8, 2.8-4.8, 3-4.8, 3.2-4.8, 3.4-4.8, 3.6-4.8, 2-4.5, 2.2- 4.5, 2.4~4.5, 2.6~4.5, 2.8~4.5, 3~4.5, 3.2~4.5, 3.4~4.5, 3.6~4.5, 2~4.2, 2.2~4.2, 2.4~4.2, 2.6~4.2, 2.8~4.2, 3~4.2, 3.2~4.2, 3.4~4.2, 3.6~4.2, 2~4, 2.2~4, 2.4~4, 2.6~4, 2.8~4, 3~4, 3.2~4, 3.4~4, 3.6~4.

[0086] As a preferred embodiment of any embodiment of the third aspect of the present invention, the t3 / t2 can be any value selected from any of the following numerical ranges: 2-5, 2.2-5, 2.4-5, 2.6-5, 2.8-5, 3-5, 3.2-5, 3.4-5, 3.6-5, 2-4.8, 2.2-4.8, 2.4-4.8, 2.6-4.8, 2.8-4.8, 3-4.8, 3.2-4.8, 3.4-4.8, 3.6-4.8, 2-4.5, 2.2- 4.5, 2.4~4.5, 2.6~4.5, 2.8~4.5, 3~4.5, 3.2~4.5, 3.4~4.5, 3.6~4.5, 2~4.2, 2.2~4.2, 2.4~4.2, 2.6~4.2, 2.8~4.2, 3~4.2, 3.2~4.2, 3.4~4.2, 3.6~4.2, 2~4, 2.2~4, 2.4~4, 2.6~4, 2.8~4, 3~4, 3.2~4, 3.4~4, 3.6~4.

[0087] It should be noted that the inventors' research has found that when porous ceramics are used as the matrix for composite phase-change materials, leakage of high-temperature salt is more likely to occur at the "top" or "bottom" during use. Based on this, and in accordance with the present invention's solution, the inventors have further discovered that when t3 / t1 and t3 / t2 meet the aforementioned requirements, leakage can be effectively avoided while also ensuring that the resulting porous ceramics have optimal porosity, optimal high-temperature salt loading when used as a composite phase-change material, and optimal pore utilization when used as a composite phase-change material.

[0088] As a preferred embodiment of any embodiment of the third aspect of the present invention, said (a) includes (a.1) and (a.2), wherein:

[0089] (a.1) Prepare a mixture containing a binder, a foaming agent, and a foam stabilizer;

[0090] (a.2) contacting the framework material, pore-forming agent, curing agent, and sintering aid with the mixed solution.

[0091] It should be noted that, in the process of "preparing a slurry containing the first component" as described herein, the "skeleton material, pore-forming agent, curing agent, sintering aid" and the "binder, foaming agent, foam stabilizer" are added separately and then mixed, which is conducive to the obtained porous ceramics having optimal porosity.

[0092] As a preference of any embodiment of the third aspect of the present invention, in step (c), the curing includes a sealing curing stage and a non-sealing curing stage.

[0093] It should be noted that the inventors' research has found that, in the method for preparing the porous ceramic of the present invention, maintaining both the sealed and non-sealed curing stages during the formation of the molded body containing the first component promotes the structural stability of the resulting porous structure. However, attempts to eliminate the sealed curing stage ultimately resulted in partial collapse of the pore structure.

[0094] As a preference of any embodiment of the third aspect of the present invention, in step (c), after the foaming is completed, a sealing curing stage is first performed, and then a non-sealing curing stage is performed.

[0095] As a preference of any embodiment of the third aspect of the present invention, in step (c), the sealing and curing stage lasts for 30 to 60 hours.

[0096] As a preference of any embodiment of the third aspect of the present invention, in step (c), the temperature of the sealing and curing stage is 15-30°C.

[0097] As a preference of any embodiment of the third aspect of the present invention, in step (c), the duration of the non-sealing curing stage is 30 to 60 hours.

[0098] As a preference of any embodiment of the third aspect of the present invention, in step (c), the temperature of the non-sealed curing stage is 15-30°C.

[0099] As a preference of any embodiment of the third aspect of the present invention, in step (c), the foaming time is 1 to 3 hours.

[0100] As a preference of any embodiment of the third aspect of the present invention, in step (c), the foaming temperature is 15 to 30°C.

[0101] As a preference of any embodiment of the third aspect of the present invention, in step (c), stirring is performed during the foaming process, and the stirring speed is 700 to 900 revolutions per minute (r / min).

[0102] Furthermore, in step (c), stirring is performed during the foaming process, and the stirring speed is preferably 720-880 r / min and 750-850 r / min, respectively.

[0103] It should be noted that the stirring speed during the foaming process described herein will affect the porosity of the porous ceramics finally obtained. Appropriate rotation speed and time are conducive to the porous ceramics having optimal porosity.

[0104] As a preference of any embodiment of the third aspect of the present invention, in step (c), the curing further includes a drying stage.

[0105] As a preference of any embodiment of the third aspect of the present invention, in step (c), the drying time is 15 to 30 hours.

[0106] As a preference of any embodiment of the third aspect of the present invention, in step (c), the drying temperature is 40-80°C.

[0107] As a preference of any embodiment of the third aspect of the present invention, in step (d), the curing comprises: drying the slurry containing the second component after coating is completed.

[0108] As a preference of any embodiment of the third aspect of the present invention, in step (d), the drying time is 5 to 60 minutes.

[0109] As a preference of any embodiment of the third aspect of the present invention, in step (d), the drying temperature is 60-100°C.

[0110] As a preferred embodiment of any embodiment of the third aspect of the present invention, in step (e), the holding time of the high-temperature sintering treatment is 1 to 4 hours.

[0111] As a preferred embodiment of any embodiment of the third aspect of the present invention, in step (e), the holding temperature of the drying treatment is 1000-1300°C; preferably 1000-1200°C.

[0112] As a preference of any embodiment of the third aspect of the present invention, in step (e), the heating rate of the high temperature treatment is 2 to 10° C. / min.

[0113] As a preferred embodiment of any embodiment of the third aspect of the present invention, in step (a), the pore-forming agent has a particle size of less than or equal to 100 microns; preferably a particle size of 60 to 75 microns.

[0114] As a preferred embodiment of any embodiment of the third aspect of the present invention, in step (b), the pore-forming agent has a particle size of less than or equal to 100 microns; preferably a particle size of 60 to 75 microns.

[0115] As a preferred embodiment of any embodiment of the third aspect of the present invention, in step (a.1), the preparation of the mixed liquid includes the steps of: (a.11) preparing a solution containing a binder and stirring it; (a.12) contacting the foaming agent and the foam stabilizer with the solution and stirring it to obtain a mixed liquid.

[0116] It should be noted that, in the aforementioned process ("preparation of a slurry containing the first component", the "skeleton material, pore-forming agent, curing agent, sintering aid" and the "binder, foaming agent, foam stabilizer" are added separately and then mixed), further adding the "binder" and the "foaming agent, foam stabilizer" separately and then mixing them is more conducive to obtaining a porous ceramic with an optimal porosity.

[0117] As a preference of any embodiment of the third aspect of the present invention, in step (a.11), the stirring speed is 500 to 700 revolutions per minute (r / min).

[0118] As a preference of any embodiment of the third aspect of the present invention, in step (a.11), the stirring temperature is 40 to 70°C.

[0119] As a preference of any embodiment of the third aspect of the present invention, in step (a.12), the stirring speed is 500 to 700 revolutions per minute (r / min).

[0120] As a preference of any embodiment of the third aspect of the present invention, in step (a.12), the stirring temperature is 15 to 60°C.

[0121] As a preferred embodiment of any embodiment of the third aspect of the present invention, in the first component, the pore former includes a porous structure pore former and / or a non-porous structure pore former; preferably, the pore former is a porous structure pore former.

[0122] It should be noted that in the present invention, the first component forming the porous ceramic "inner lining" is ensured to have a "lining" containing both large and small pores through the combination of a pore-forming agent and a foaming agent. This not only increases the load capacity of the phase change material, but also enhances heat transfer (stepped pore microflow) through the composition of large and small pores within the lining. The pore-forming agent is preferably a porous structure pore-forming agent to ensure the aforementioned inner pore structure.

[0123] As a preferred embodiment of any embodiment of the third aspect of the present invention, in the second component, the pore-forming agent includes a porous structure pore-forming agent and / or a non-porous structure pore-forming agent;

[0124] Preferably, the pore-forming agent is a non-porous structure pore-forming agent.

[0125] As a preferred embodiment of any embodiment of the third aspect of the present invention, in the first component, the particle size of the pore-forming agent does not exceed 100 microns.

[0126] As a preferred embodiment of any embodiment of the third aspect of the present invention, in the second component, the particle size of the pore-forming agent does not exceed 100 microns.

[0127] It should be noted that in the present invention, the combination of a pore-forming agent and a foaming agent in the first component forming the porous ceramic "inner layer" ensures the formation of an "inner layer" containing both large and small pores. Furthermore, the pore-forming agent controls the porous ceramic "surface layer" to have relatively small pores overall, which also promotes a certain degree of microfluidity between the "inner layer" and the "surface layer," thereby enhancing heat transfer.

[0128] As a preferred embodiment of any embodiment of the third aspect of the present invention, in the first component, the amount of the pore-forming agent added can be any value within the following numerical ranges, calculated based on the total amount of the skeleton material, the pore-forming agent, the curing agent, and the sintering aid: 5-15wt%, 6-15wt%, 7-15wt%, 8-15wt%, 9-15wt%, 10-15wt%, 5-14wt%, 6-14wt%, 7-14wt%, 8-14wt%, 9 ~14wt%, 10~14wt%, 5~13wt%, 6~13wt%, 7~13wt%, 8~13wt%, 9~13wt%, 10~13wt%, 5~12wt%, 6~12wt%, 7~12wt%, 8~12wt%, 9~12wt%, 10~12wt%, 5~11wt%, 6~11wt%, 7~11wt%, 8~11wt%, 9~11wt%, 10~11wt%.

[0129] As a preferred embodiment of any embodiment of the third aspect of the present invention, in the first component, the amount of the pore-forming agent added can be any value within the following numerical ranges, calculated based on the total amount of the skeleton material, the pore-forming agent, and the curing agent: 5-15wt%, 6-15wt%, 7-15wt%, 8-15wt%, 9-15wt%, 10-15wt%, 5-14wt%, 6-14wt%, 7-14wt%, 8-14wt%, 9-1 4wt%, 10~14wt%, 5~13wt%, 6~13wt%, 7~13wt%, 8~13wt%, 9~13wt%, 10~13wt%, 5~12wt%, 6~12wt%, 7 ~12wt%, 8~12wt%, 9~12wt%, 10~12wt%, 5~11wt%, 6~11wt%, 7~11wt%, 8~11wt%, 9~11wt%, 10~11wt%.

[0130] It should be noted that the "amount of pore former added" mentioned herein will affect the strength of the obtained porous ceramics. Too much or too little "amount of pore former added" is not conducive to the strength of the porous ceramics.

[0131] As a preferred embodiment of any embodiment of the third aspect of the present invention, the skeleton material includes but is not limited to: steel slag, solid waste (blast furnace slag, fly ash, red mud, tailings, oxides (aluminum oxide, zirconium oxide, titanium oxide, silicon oxide), carbides (such as silicon carbide, boron carbide), nitrides (silicon nitride, aluminum nitride), mullite, zircon, and cordierite.

[0132] As a preferred embodiment of any embodiment of the third aspect of the present invention, the porous structure pore-forming agent includes but is not limited to: diatomaceous earth, kaolin, bentonite, and quartz.

[0133] As a preferred embodiment of any embodiment of the third aspect of the present invention, the non-porous structure pore-forming agent includes but is not limited to: inorganic pore-forming agents (calcium carbonate, calcite), organic pore-forming agents (corn starch, wheat starch, potato starch, carbon powder, coal powder).

[0134] As a preferred embodiment of any embodiment of the third aspect of the present invention, the curing agent includes but is not limited to: gypsum (i.e. calcium sulfate hemihydrate (CaSO4·0.5H2O) and cement.

[0135] As a preferred embodiment of any embodiment of the third aspect of the present invention, the sintering aid includes but is not limited to: waste glass, sodium feldspar, and potassium feldspar.

[0136] As a preferred embodiment of any embodiment of the third aspect of the present invention, the binder includes but is not limited to: PVA (polyvinyl alcohol), xanthan gum, polypropylene alcohol, and sodium carboxymethyl cellulose.

[0137] As a preferred embodiment of any embodiment of the third aspect of the present invention, the foaming agent includes but is not limited to: SDS (sodium dodecyl sulfate), sodium dodecylbenzene sulfonate (SDBS), and soap.

[0138] As a preferred embodiment of any embodiment of the third aspect of the present invention, the foam stabilizer includes but is not limited to: CTAB 12 (dodecyltrimethylammonium bromide), CTAB 16 (cetyltrimethylammonium bromide), acrylamide, polyvinyl alcohol, cellulose, starch.

[0139] As a preferred embodiment of any embodiment of the third aspect of the present invention, the preparation method can prepare the porous ceramics described in any embodiment of the first aspect of the present invention.

[0140] The fourth aspect of the present invention provides a porous ceramic as in any embodiment of the first aspect of the present invention, or a porous ceramic prepared by the method of any embodiment of the second aspect of the present invention, or an application of a porous ceramic prepared by the method of any embodiment of the third aspect of the present invention, for use as a matrix of a composite phase change material. BRIEF DESCRIPTION OF THE DRAWINGS

[0141] Figure 1 The porous ceramic model provided by the present invention;

[0142] Figure 2 Foam diagram of the preparation of the liquid phase in Example 1 of the present invention;

[0143] Figure 3 The slurry containing the first component after foaming in Example 1 of the present invention;

[0144] Figure 4 The slurry containing the first component in Example 1 of the present invention is subjected to the "sealing and curing stage" treatment;

[0145] Figure 5 The molded body containing the first component after curing and drying according to Example 1 of the present invention;

[0146] Figure 6 The slurry containing the second component in Example 1 of the present invention;

[0147] Figure 7 A diagram showing the process of coating a slurry containing the second component on the surface of a molded body containing the first component and curing to obtain a molded body coated with the second component in Example 1 of the present invention;

[0148] Figure 8 In Example 1 of the present invention, the composite phase change material is prepared using the porous ceramics A-1 to A-4 obtained after high-temperature sintering as a matrix;

[0149] Figure 9 In Example 1 of the present invention, the composite phase change material is prepared using the porous ceramic A-3 obtained after high-temperature sintering as a matrix;

[0150] Figure 10 Actual image of the ceramic obtained from the lining formula of Example 2;

[0151] Figure 11 Actual image of the ceramic obtained from the surface layer formulation of Example 2;

[0152] Figure 12 The inner materials a1, a2, a3, a4, and a5 of the porous ceramic prepared in Example 7;

[0153] Figure 13 The inner materials of the porous ceramic prepared in Example 8 are C10, C20, D10, D20, C5D5, and C10D10;

[0154] Figure 14 The porous ceramic samples C20 / B3, C10 / B3, and C5D5 / B3 prepared in Example 9;

[0155] Figure 15 The composite phase change materials NaNO3 / C20, NaNO3 / D10, NaNO3 / C5D5, NaNO3 / C20 / B3, NaNO3 / C10 / B3, and NaNO3 / C5D5 / B3 prepared in Example 9;

[0156] Figure 16 The inner material of the porous ceramic and the loading rate of the porous ceramic sample to high temperature salt in Example 10

[0157] Figure 17 XRD pattern (a) of the chemical compatibility analysis of NaNO3 / C20 / B3 in Example 10; XRD pattern (b) of the chemical compatibility analysis of NaNO3 / D10 / B3; XRD pattern (c) of the chemical compatibility analysis of NaNO3 / C5D5 / B3;

[0158] Figure 18 DSC graphs of the phase change behavior of pure phase change material NaNO3, composite phase change materials NaNO3 / C20, NaNO3 / D10, and NaNO3 / C5D5 during melting and solidification in Example 10 (a); specific heat capacity of composite phase change materials NaNO3 / C20 / B3, NaNO3 / D10 / B3, and NaNO3 / C5D5 / B3 in the temperature range of 100°C to 380°C (b);

[0159] Figure 19In Example 10, the specific heat capacity (a) of the composite phase change material NaNO3 / C20 / B3 in the temperature range of 100℃~380℃, the specific heat capacity (b) of NaNO3 / D10 / B3 in the temperature range of 100℃~380℃, and the specific heat capacity (c) of NaNO3 / C5D5 / B3 in the temperature range of 100℃~380℃. DETAILED DESCRIPTION

[0160] All documents cited herein are incorporated herein by reference in their entirety, and if the meanings expressed in these documents are inconsistent with those of the present invention, the present invention shall prevail. In addition, various terms and phrases used in the present invention have the general meanings known to those skilled in the art. Even so, the present invention still intends to provide a more detailed description and explanation of these terms and phrases herein. If the terms and phrases mentioned are inconsistent with the generally known meanings, the meanings expressed in the present invention shall prevail.

[0161] When items are described by using the conjunction terms "... and / or..." etc., the description should be understood to include any one and all combinations of one or more of the associated listed items.

[0162] In general, the use of the term "about" indicates an approximate value that can vary depending on the desired properties obtained by the disclosed subject matter and will be interpreted in a context-dependent manner based on function. Therefore, one of ordinary skill in the art will be able to interpret a certain degree of difference on a case-by-case basis. In some cases, the number of important figures used when expressing a particular value can be a representative technique for determining the difference allowed by the term "about". In other cases, a gradient in a range of values ​​can be used to determine the range of differences allowed by the term "about". Further, all ranges in this disclosure are inclusive and combinable, and reference to a value stated in a range includes every value within that range.

[0163] In the present invention, the term "comprising" or "containing" means that various components can be used together in the composition of the present invention. Therefore, the terms "consisting mainly of..." and "consisting of..." are included in the terms "comprising" or "containing".

[0164] Unless defined otherwise, 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 invention belongs; and the terms used herein include any and all combinations of one or more of the associated listed items.

[0165] Unless otherwise specified, any feature disclosed in this specification may be replaced by other equivalent or alternative features having similar purposes. Unless otherwise specified, each feature is merely an example of a series of equivalent or similar features. The description is merely to help understand the present invention and should not be considered as a specific limitation of the present invention. Where specific conditions are not specified in the examples, the conditions are carried out according to conventional conditions or manufacturer recommendations. Reagents or instruments used without manufacturer's indication are conventional products that can be purchased.

[0166] The porosity in the examples herein was tested using the boiling method.

[0167] The present invention will be further described below with reference to specific embodiments.

[0168] Example 1

[0169] 1. Raw material formula and dosage

[0170] Table 1. Raw material formula of slurry containing the first component

[0171]

[0172] Note: The solvent is water

[0173] Table 2. Raw material formula of slurry containing the second component

[0174]

[0175] Note: The solvent is water

[0176] 2. Preparation Process

[0177] Raw material pretreatment: steel slag, diatomaceous earth, calcium carbonate, gypsum, waste glass, SDS, CTAB 12 Grind and pass through a 200-mesh sieve for later use;

[0178] 1. Preparation of a Molded Body Containing the First Component

[0179] 1) Preparation of PVA solution: 10 wt% PVA was mixed with water and stirred at 80°C and 600 rpm for 2 h to prepare a 10 wt% PVA solution;

[0180] 2) Preparation of liquid phase (taking the total volume of the solution as 30 ml, PVA, SDS, CTAB 12 For external doping): 0.06g SDS, 0.02g CTAB 12 6g PVA solution was poured into 14.1g water and stirred at 55℃ and 600r / min for 30min to obtain the following Figure 2 Foam solution shown;

[0181] 3) preparing a slurry containing the first component: thoroughly mixing 7.35 g of steel slag, 1.05 g of diatomaceous earth, 1.05 g of plaster of Paris, and 1.05 g of waste glass in a mortar to obtain a solid phase, and mixing the solid phase with the foam solution to obtain a slurry containing the first component;

[0182] 4) Foaming: Stir the slurry containing the first component at 800 r / min for 2 h at room temperature to complete foaming, and obtain Figure 3 The slurry containing the first component after the foaming is completed is shown;

[0183] 5) Sealing and curing: Reference Figure 4 As shown, the slurry was poured into a mold, sealed with plastic wrap, and cured at room temperature for 48 hours;

[0184] 6) Non-sealed curing: After the sealing curing is completed, remove the insurance film and carry out room temperature curing for 48 hours in the non-sealed state;

[0185] 7) Drying: After the non-sealed curing is completed, place it in an oven (60°C) and dry it for 24 hours to obtain the following Figure 5 The shaped body shown contains a first component;

[0186] 2. Preparation of a molded body coated with a second component

[0187] 1) Preparation of PVA solution: 10 wt% PVA was mixed with water and stirred at 80°C and 600 rpm for 2 h to prepare a 10 wt% PVA solution;

[0188] 2) Prepare a slurry containing the second component: (taking the total volume of the solution as 30 ml, PVA is added externally) Pour 12g of PVA solution into 4.2g of water and stir evenly; then thoroughly mix 7.5g of steel slag, 4.5g of calcium carbonate, 1.5g of gypsum, and 1.5g of waste glass in a mortar, pour into the above solution, and stir at 600r / min for 30min at room temperature to obtain the following: Figure 6 The slurry shown contains a second component;

[0189] 3) Preparation of a molded body coated with a second component: Figure 7 As shown in the figure, the molded body containing the first component is immersed in the slurry containing the second component for 10 seconds, taken out and placed in an oven (80°C) for drying for 10 minutes, which is a coating process; the operation can be repeated as needed; 4) High-temperature sintering: The molded body coated with the second component is placed in a muffle furnace, heated to 1100°C at 5°C / min, and then kept warm for 2 hours to obtain porous ceramics.

[0190] It should be noted that after the first coating in step 3) of this embodiment is completed, the thickness of the surface layer of the porous ceramic obtained after the final treatment in step 4) is about 1 to 1.5 mm;

[0191] In this embodiment, the following Figure 1 The porous ceramic samples A-1 to A-3 and the porous ceramic inner material A-4 are shown:

[0192] The porous ceramic inner material A-4 obtained after 0 coatings does not have a "surface layer" material; in terms of method, after completing "1. Preparation of a molded body containing the first component", the "4) high-temperature sintering" process is directly carried out, and the "1) preparation of a PVA solution, 2) preparation of a slurry containing the second component, and 3) preparation of a molded body coated with the second component" in "2. Preparation of a molded body coated with the second component" are not repeated;

[0193] Porous ceramic sample after 2 coatings (A-3);

[0194] Porous ceramic sample (A-2) after three coatings;

[0195] Porous ceramic sample (A-1) after 5 coatings.

[0196] 3. Basic performance test

[0197] 1) In addition, taking the porous ceramic lining material A-4 as an example, the key parameters of the porosity tested by the boiling method in this embodiment are shown in Table 3 below:

[0198] Table 3. Performance test of porous ceramic lining material A-4

[0199] <![CDATA[Dry weight (m1) / g]]> <![CDATA[Floating weight (m2) / g]]> <![CDATA[Wet weight (m3) / g]]> Porosity (P) / % <![CDATA[Body density (ρ) g / cm 3 > 3.6 2.4 8.64 80.8 0.58

[0200] 4. Preparation and performance testing of composite phase change materials

[0201] 1) In this embodiment, the porous ceramic samples A-1 to A-3 and the inner material A-4 of the porous ceramic are used as the matrix to prepare the following Figure 8 The composite phase change material shown is as follows: Sodium nitrate is used as the phase change material, heated to 340°C (molten state), the porous ceramic is immersed in molten sodium nitrate for 2 hours, and then taken out and cooled to room temperature with the furnace to obtain a composite phase change material. The loading rate of the porous ceramic for high-temperature salt and the pore utilization rate of the porous ceramic when loading high-temperature salt are tested.

[0202] 2) The performance test of the porous ceramic samples is shown in Table 4 below:

[0203] Table 4. Performance test of porous ceramic samples

[0204] sample Porosity (P) / % <![CDATA[Apparent density (ρ) / g / cm 3 > Loading rate / wt% Porosity utilization (solid / liquid) A-1 71.5％ 0.71 60.3 66.8％ / 78.8％ A-2 72.3％ 0.74 61.6 72.7％ / 85.9％ A-3 74.4％ 0.69 65.2 76.9％ / 90.9％ A-4 80.8％ 0.58 66.5 63.1％ / 74.7％

[0205] In addition, according to the test, in this embodiment, the porosity (P) of the surface layer formed by the slurry containing the second component coated on the surface of the molded body containing the first component is 73.3%, and the bulk density (ρ) is 0.78 g / cm 3 .

[0206] As can be seen from Table 4, A-3 is the porous ceramic with the best performance currently obtained. The following are other relevant information parameters of sample A-3:

[0207] Reference Figure 9 As shown, according to the placement direction during use, the porous ceramic has a bottom and a top; the top has a molded body containing the second component, and the molded body containing the second component has a thickness t1; the bottom has a molded body containing the second component, and the molded body containing the second component has a thickness t2; from the bottom to the top, the maximum thickness of the molded body containing the first component is t3;

[0208] The top and bottom surface layers (also called shells, formed by coating the slurry containing the second component twice) of sample A-3 have thicknesses t1 and t2 of 3 mm, and the inner layer (also called core, formed by curing and drying the slurry containing the first component) t3 has a thickness of 11 mm.

[0209] Example 2

[0210] This embodiment provides a method for preparing porous ceramics. Specifically,

[0211] The porous ceramic surface layer (such as Figure 11 As shown), inside (as Figure 10 The raw materials and amounts are as follows:

[0212] Lining formula: 50% steel slag + 50% calcium carbonate (0.15-0.5mm) + 30% waste glass

[0213] Surface layer formula: 100% steel slag + 30% waste glass

[0214] Preparation method: Fabric according to the following structure, with the lining formula in the middle and the surface formula around; press at 10MPa for 1min; keep warm at 1100℃ for 2h.

[0215] The performance test of the prepared samples is shown in Table 5 below:

[0216] Table 5. Performance test of samples prepared in Example 2

[0217] structure Porosity (P) / % <![CDATA[Body density (ρ) / g / cm 3 > Inside 52.4 1.36 surface layer 46.6 1.41

[0218] Example 3

[0219] The preparation method of the porous ceramic inner material provided in this embodiment is basically the same as that of the porous ceramic inner material A-4 in Example 1, with the only difference being that "5) Sealing and Curing" is directly replaced by "6) Non-Sealing and Curing". Specifically:

[0220] In this example, after "4) foaming," the material was directly cured at room temperature for 96 hours in an unsealed state. Then, "7) drying" was performed to obtain a molded body containing the first component. The remaining steps were the same as those for preparing porous ceramic lining material A-4 in Example 1, ultimately yielding porous ceramic lining material B-1.

[0221] Testing of the porous ceramic inner material B-1 revealed that it had a partially collapsed pore structure and a porosity of less than 60%.

[0222] Example 4

[0223] This example provides a method for preparing a porous ceramic lining material. This method is essentially the same as the preparation of porous ceramic lining material A-4 in Example 1, differing only in the stirring speed and stirring time during step "4) foaming." Specifically: Porous ceramic lining material B-2: stirring speed 600 r / min, stirring time 1 hour;

[0224] Porous ceramic lining material B-3: stirring speed 600 r / min, stirring time 2 h;

[0225] Porous ceramic lining material B-4: stirring speed 1000 r / min, stirring time 1 h;

[0226] Porous ceramic lining material B-5: stirring speed 1000 r / min, stirring time 2 h;

[0227] Porous ceramic lining material B-6: stirring speed 800 r / min, stirring time 3 h.

[0228] Example 5

[0229] This embodiment provides a method for preparing the inner material of porous ceramics, which is basically the same as the preparation of the inner material A-4 of the porous ceramics in Example 1, with the only difference being that the following operations are performed to replace the "step 2) preparation of the liquid phase" and "step 3) preparation of the slurry containing the first component" in "1. Preparation of a molded body containing the first component" in Example 1.

[0230] The specific operation is as follows: 7.35g steel slag, 1.05g diatomaceous earth, 1.05g gypsum, and 1.05g waste glass are fully mixed in a mortar to obtain a solid phase; the solid phase, 0.06g SDS, and 0.02g CTAB are mixed. 12, 6 g of PVA solution was poured into 14.1 g of water, and stirred at 55°C and 600 r / min for 30 min to obtain a slurry containing the first component;

[0231] The rest of the preparation was the same as that of sample A-4 in Example 1, and finally a porous ceramic lining material B-7 was obtained.

[0232] Example 6

[0233] This embodiment provides a method for preparing the inner material of a porous ceramic, which is basically the same as the preparation of the inner material A-4 of the porous ceramic in Example 1, except that the amount of diatomaceous earth used in the solid phase is different. Specifically:

[0234] Porous ceramic lining material B-8: Diatomaceous earth is used in a relatively low amount, such as 1%, and the remaining raw materials, amounts, and operations are the same as in Example 1;

[0235] Porous ceramic lining material B-9: In the solid phase, the proportion of diatomaceous earth is increased to 20 wt %, and the remaining raw materials, amounts, and operations are the same as in Example 1;

[0236] The porosities of the porous ceramic lining materials B2 to B9 prepared in Examples 4 to 6 above are shown in Table 6.

[0237] Table 6. Porosity of the inner materials B2 to B9 of the porous ceramics prepared in Examples 4 to 6

[0238] Porous ceramic lining material A-4 B-2 B-3 B-4 B-5 B-6 B-7 B-8 B-9 Porosity (P) / % 80.8 68 74 66 72 78 62 76 74

[0239] Example 7

[0240] This embodiment provides five porous ceramic lining materials containing a composite system of a foaming agent and a foam stabilizer in different ratios. The raw material formulas and amounts are shown in Tables 7 and 8.

[0241] Table 7. Solid phase raw material formula of slurry containing the first component

[0242]

[0243] Table 8. Liquid raw material formula of slurry containing the first component

[0244]

[0245] Note: The solvent is water

[0246] 1. Preparation process

[0247] Raw material pretreatment: steel slag, gypsum, waste glass, SDS, CTAB 12 Grind and pass through a 200-mesh sieve for later use;

[0248] 1. Preparation of a Molded Body Containing the First Component

[0249] 1) Preparation of liquid phase: Using water as solvent, a mixture containing SDS and CTAB at the concentrations shown in Table 8 was prepared. 12 The liquid phase was stirred at 55 °C and 600 r / min for 30 min;

[0250] 3) preparing a slurry containing the first component: thoroughly mixing steel slag, plaster of Paris, and waste glass in a mortar to obtain a solid phase, and mixing the solid phase with the foam solution to obtain a slurry containing the first component with a solid phase content of 35 wt%;

[0251] 4) Foaming: This step is the same as in Example 1;

[0252] 5) Sealing and curing: This step is the same as in Example 1;

[0253] 6) Non-sealed curing: This step is the same as in Example 1;

[0254] 7) Drying: This step is the same as in Example 1;

[0255] In summary, the inner materials a1, a2, a3, a4, and a5 of the porous ceramics are obtained respectively, wherein the morphologies of a1, a2, and a3 are as follows: Figure 12 shown.

[0256] 2. Basic performance test

[0257] In this embodiment, the performance tests of the porous ceramic lining materials a1, a2, a3, a4, and a5 are shown in Table 9 below:

[0258] Table 9. Performance test of porous ceramic lining materials a1, a2, a3, a4, and a5

[0259] sample Porosity (%) <![CDATA[Apparent density (g / cm 3 )]]> a1 65.7 1.2 a2 64.3 1.13 a3 76.3 0.58 a4 72.7 0.66 a5 67.5 0.99

[0260] Example 8

[0261] This example adopts a strict control experiment design to systematically investigate the effect of pore-forming agent type and content on the internal material structure and performance of porous ceramics. Based on the previously optimized ceramic slurry formula (solid content 35wt%, foaming agent and foam stabilizer ratio fixed at SDS:CTAB 12 =3:1), and six representative experimental systems were designed: the raw material formulas and dosages are shown in Tables 10 and 11.

[0262] Table 10. Liquid raw material formula of slurry containing the first component

[0263]

[0264] Table 11. Solid phase raw material formula of slurry containing the first component

[0265] sample Steel slag (wt%) Calcium carbonate (wt%) Diatomaceous earth (wt%) Plaster of Paris (wt%) Waste glass (wt%) C10 70 10 0 10 10 C20 60 20 0 10 10 D10 70 0 10 10 10 D20 60 0 20 10 10 C5D5 70 5 5 10 10 C10D10 60 10 10 10 10

[0266] 1. Preparation process

[0267] The raw material pretreatment and preparation process can refer to the section "1. Preparation of a molded body containing the first component" in Example 1. Finally, samples C10, C20, D10, D20, C5D5, and C10D10 of the inner material of the porous ceramic were obtained respectively, and their morphologies are as follows: Figure 13 shown.

[0268] 2. Basic performance test

[0269] In this embodiment, the performance tests of the porous ceramic lining material samples C10, C20, D10, D20, C5D5, and C10D10 are shown in Table 12 below:

[0270] Table 12. Performance test of porous ceramic lining materials C10, C20, D10, D20, C5D5, and C10D10

[0271]

[0272]

[0273] Example 9

[0274] In this embodiment, the inner material samples C20, D10, and C5D5 of the porous ceramic prepared in the aforementioned embodiment 8 are used as the core, and the slurry containing the second component shown in Table 13 below is used as the shell raw material to prepare porous ceramic samples (C20 / B3, C10 / B3, and C5D5 / B3).

[0275] Table 13. Raw material formula of slurry containing the second component

[0276]

[0277] Note: The solvent is water

[0278] 1. Preparation process

[0279] The raw material pretreatment and preparation process can be referred to in the "II. Preparation Process" section of Lining Material A-4 in Example 1. Finally, the porous ceramic samples (C20 / B3, C10 / B3, and C5D5 / B3) that underwent two coatings had top and bottom surface layers (also known as shells, formed by two coatings of the slurry containing the second component) with thicknesses t1 and t2 of 3 mm, respectively, and inner layers (also known as cores, formed by curing and drying the slurry containing the first component) t3 with a thickness of 11 mm.

[0280] Finally, the morphology of each sample is as follows Figure 14 shown.

[0281] 2. Basic performance test

[0282] The performance of the porous ceramic samples C20 / B3, C10 / B3 and C5D5 / B3 obtained in this embodiment was tested and shown in Table 14 below:

[0283] Table 14. Performance test of porous ceramics C20 / B3, C10 / B3, and C5D5 / B3

[0284] sample Porosity (%) <![CDATA[Body density (g / cm 3 )]]> C20 / B3 71.1 0.83 D10 / B3 73.1 0.79 C5D5 / B3 71.6 0.81

[0285] Example 10

[0286] Composite phase change material loading performance and leakage tests were performed on the porous ceramic lining material samples C20, D10, and C5D5 prepared in the aforementioned embodiment, as well as the porous ceramic samples C20 / B3, C10 / B3, and C5D5 / B3 prepared in the aforementioned embodiment.

[0287] The porous ceramic inner material samples C20, D10, C5D5 porous ceramic samples C20 / B3, C10 / B3 and C5D5 / B3 were prepared as the matrix. Figure 15 The composite phase change materials shown (NaNO3 / C20, NaNO3 / D10, NaNO3 / C5D5, NaNO3 / C20 / B3, NaNO3 / C10 / B3, NaNO3 / C5D5 / B3): Sodium nitrate is used as the phase change material, heated to 340°C (molten state), the porous ceramic is immersed in molten sodium nitrate for 2 hours, and then taken out and cooled to room temperature with the furnace to obtain a composite phase change material. The loading rate of the porous ceramic for high-temperature salt and the pore utilization rate of the porous ceramic when loading high-temperature salt are tested.

[0288] Furthermore, the composite material was subjected to 15 thermal cycle tests for leakage stability. The thermal cycle consisted of heating from 250°C to 350°C, holding at 350°C for 10 minutes, and then cooling to 250°C. This constituted one cycle, with both the heating and cooling rates being 5°C / min.

[0289] Table 15. Test of the inner material of porous ceramics and the loading rate of porous ceramic samples to high temperature salt

[0290]

[0291]

[0292] As shown in Table 15, the test results fully demonstrate the significant advantages of the core-shell structure design: after cyclic testing, the loading rate of the high-temperature salt NaNO3 loaded on the porous ceramic lining material sample without a shell structure (such as C20) was reduced to 53.6%, while the loading rate of the porous ceramic sample C20-B3, which uses the same matrix but has a core-shell structure, was reduced to 57.3%. Particularly noteworthy is that the optimized porous ceramic samples D10-B3 and C5D5-B3 demonstrated excellent anti-leakage performance, with loading rates exceeding 60%.

[0293] In addition, in terms of the proportion of pore-forming agents, the porous ceramic samples (D10-B3, C5D5-B3) with a pore-forming agent addition amount of 10wt% have a higher loading rate than the porous ceramic sample C20-B3 with a pore-forming agent addition amount of 20wt%; the porous ceramic sample C5D5-B3 prepared by including both calcium carbonate and diatomaceous earth pore-forming agents has a higher loading rate than the porous ceramic sample D10-B3 prepared by including only diatomaceous earth as a single pore-forming agent.

[0294] Table 16. Test of the inner material of porous ceramics and the loading rate of porous ceramic samples to high temperature salt

[0295]

[0296] According to Table 16 and Figure 16 It can be seen that the porous ceramic sample with shell structure has a more stable loading rate;

[0297] like Figure 16As shown, the mass loss during thermal cycling exhibits a typical three-stage evolution pattern: the initial stage (0-5 cycles) is characterized by rapid weight loss, accounting for approximately 60% of the total weight loss, primarily due to the volatilization of the high-temperature salt NaNO3 from the surface and near-surface regions of the material; the intermediate stage (5-10 cycles) is characterized by a significant slowdown in the weight loss rate, entering a relatively stable weight loss phase; and the late stage (10-15 cycles) is characterized by a near-equilibrium state, with the weight loss trend becoming stable. Overall, the porous ceramic samples with a shell structure exhibit significantly lower mass loss than the inner material samples of the porous ceramic without a shell structure, indicating that the microporous shell design within the core-shell structure effectively controls the leakage rate to below 1%, demonstrating excellent long-term stability. The porous ceramic samples with a 10 wt% pore-forming agent addition (D10-B3 and C5D5-B3) exhibit relatively lower mass loss than the porous ceramic sample C20-B3 with a 20 wt% pore-forming agent addition. The mass losses of the porous ceramic sample C5D5-B3 prepared with both calcium carbonate and diatomaceous earth as two pore-forming agents, and the porous ceramic sample D10-B3 prepared with only diatomaceous earth as a single pore-forming agent, both do not exceed 0.5%. However, it is worth mentioning that the porous ceramic sample C5D5-B3 effectively regulates the pore distribution characteristics of the material due to the synergistic effect of the two pore-forming agents, calcium carbonate and diatomaceous earth, while ensuring a high loading rate (>60wt%), and significantly improves the anti-leakage performance.

[0298] Steel slag is an industrial solid waste with a complex chemical composition, which may cause chemical reactions with high-temperature salt-based phase change materials, thereby weakening the heat storage capacity of the composite phase change materials. Therefore, chemical compatibility is the most basic requirement for the preparation of solid waste-based composite phase change materials. The chemical compatibility can be judged by the mineral phase composition relationship between the composite phase change material, porous ceramic sample and phase change material. Specifically, when the diffraction peak of the composite phase change material happens to be the physical superposition of the diffraction peak of the porous ceramic sample and the phase change material, it can be determined that the porous ceramic sample and the phase change material are only physically combined and no chemical reaction occurs, and the composite phase change material has good chemical compatibility. Taking NaNO3 / C5D5 / B3 as an example, the mineral phase composition of the composite phase change material, porous ceramic sample and phase change material was further studied by XRD, such as Figure 17 As shown in the figure, the diffraction peak of NaNO3 / C5D5 / B3 is a physical superposition of the diffraction peaks of C5D5 / B3 and NaNO3. Therefore, the porous ceramic sample (C5D5 / B3) has good chemical compatibility with the high-temperature salt-based phase change material (NaNO3).

[0299] In addition, the phase change behavior of the composite phase change material during melting and solidification was investigated using a differential scanning calorimetry (DSC) system and compared with that of the pure phase change material ( Figure 18(a)). Experimental results show that the melting point and freezing point of pure sodium nitrate (NaNO3) are 309°C and 300°C, respectively, with corresponding melting and solidification enthalpies of 171.5 J / g and 170.1 J / g, respectively. The phase transition temperatures of the three composite phase change materials (NaNO3 / C20 / B3, NaNO3 / D10 / B3, and NaNO3 / C5D5 / B3) are essentially the same as those of pure sodium nitrate, but their phase transition enthalpies are significantly lower, with melting and solidification enthalpies of 99.7 J / g and 99.8 J / g, 109.2 J / g and 110.0 J / g, and 117.2 J / g and 117.4 J / g, respectively.

[0300] In addition, the sensible heat characteristics of the composite phase change material are closely related to its specific heat behavior. To this end, we further measured the specific heat capacity of the material in the temperature range of 100℃~380℃ ( Figure 18 (b) Figure 19 Based on this, the thermal storage density of the composite materials can be calculated in two ways: one is to superimpose the sensible and latent heat of the pure phase-change material NaNO₃ and the sensible heat of the porous ceramic sample; the other is to directly integrate the specific heat capacity of the composite material within the target temperature range. Using the latter method, we calculated that the thermal storage densities of the three composite phase-change materials within the range of 100°C to 380°C were 555.4 J / g, 617.1 J / g, and 577.6 J / g, respectively.

[0301] Any embodiment of any aspect of the invention may be combined with other embodiments, provided that no contradiction arises. In addition, in any embodiment of any aspect of the invention, any technical feature may be applicable to the technical feature in other embodiments, provided that no contradiction arises.

Claims

1. Porous ceramics, characterized in that The porous ceramic comprises: An inner layer having a porous structure, and a surface layer having a porous structure; The surface layer has a small pore size compared to the inner pore size; High-temperature salt in a molten state can enter the interior through the small holes in the surface; The surface layer can prevent leakage of high-temperature salt in a molten state, and the inner layer provides space for storage and phase change of high-temperature salt; The porosity of the inner layer is greater than the porosity of the surface layer; The bulk density of the surface layer is greater than the bulk density of the inner layer.

2. The porous ceramic according to claim 1, characterized in that The inner layer has a porosity of 78-88%; the surface layer has a porosity of 50-75%; The bulk density of the porous ceramic is 0.6 to 0.85 g / cm 3 The preferred bulk density of the porous ceramic is 0.6 to 0.75 g / cm 3 .

3. A method for preparing porous ceramics, characterized in that: The method comprises the steps of: (A) preparing a first component and a second component; The first component includes a skeleton material, a pore-forming agent, and a sintering aid, wherein the amount ratio of the skeleton material, the pore-forming agent, and the sintering aid is (4-7): (4-7): (2-4); The second component includes a skeleton material and a sintering aid, wherein the skeleton material and the sintering aid are used in a ratio of 1 to 5; (B) using the first component and the second component as raw materials to obtain a molded body having the first component inside and the second component on the surface; (C) performing a high-temperature sintering treatment on the molded body to obtain the porous ceramic; the holding time of the high-temperature sintering treatment is 1 to 4 hours; the holding temperature of the sintering treatment is 900 to 1300° C.; Wherein, the pore-forming agent includes a porous structure pore-forming agent and / or a non-porous structure pore-forming agent.

4. A method for preparing porous ceramics, characterized in that: The method comprises the steps of: (a) preparing a mixed solution containing a binder, a foaming agent, and a foam stabilizer; The skeleton material, pore-forming agent, curing agent, sintering aid and the mixed liquid are contacted and mixed to obtain the slurry containing the first component; wherein the content of the sintering aid can be zero; The solid content of the slurry containing the first component is 28 to 50 wt %; (b) preparing a slurry containing the second component with a solid content of 40 to 70 wt %; The second component includes a skeleton material, a pore-forming agent, a curing agent, a sintering agent, a binder, and a solvent; wherein the content of the sintering agent can be zero; (c) foaming and curing the slurry containing the first component to obtain a molded body containing the first component; (d) applying a slurry containing the second component to the surface of the molded body containing the first component and curing the slurry, repeating the process 1 to 8 times to obtain a molded body coated with the second component; (e) performing a high-temperature sintering treatment on the molded body coated with the second component to obtain the porous ceramic; the high-temperature sintering treatment is performed with a holding time of 1 to 4 hours and a holding temperature of 1000 to 1300°C.

5. The method for preparing the porous ceramic according to claim 4, wherein: In step (a), the mass ratio of the skeleton material, the pore-forming agent, and the foaming agent is (6-7.5): (0.8-2.5): 0.06; Alternatively, in step (b), the mass ratio of the framework material to the pore-forming agent is (6-9):(3-5.5).

6. The method for preparing porous ceramics according to claim 4, wherein: In the first component, the pore-forming agent includes any one or both of a porous structure pore-forming agent and a non-porous structure pore-forming agent; In the second component, the pore-forming agent includes any one or both of a porous structure pore-forming agent and a non-porous structure pore-forming agent.

7. The method for preparing porous ceramics according to claim 4, wherein: In the first component, the mass ratio of the skeleton material, pore-forming agent, curing agent, sintering aid, binder, foaming agent, and foam stabilizer is (650-800):(80-250):(80-130):(0-130):(50-70):(4-8):(1-3); Alternatively, in the first component, the mass ratio of the skeleton material, pore-forming agent, curing agent, sintering aid, binder, foaming agent, and foam stabilizer is (650-800):(80-130):(80-130):(0-130):(50-70):(4-8):(1-3); Alternatively, in the second component, the mass ratio of the skeleton material, pore-forming agent, curing agent, sintering aid and binder is (20-30):(10-20):(2-8):(0-8):(1-6).

8. The method for preparing a porous ceramic according to any one of claims 4 to 7, characterized in that: In step (c), the curing includes sealed curing and non-sealed curing; The sealing and curing stage lasts for 30 to 60 hours at a temperature of 15 to 30°C; The duration of the non-sealing curing stage is 30 to 60 hours, and the temperature is 15 to 30°C.

9. The method for preparing a porous ceramic according to any one of claims 4 to 7, characterized in that: In step (c), the foaming time is 1 to 3 hours and the temperature is 15 to 30° C.; Stirring is performed during the foaming process, and the stirring speed is 700 to 900 rpm.

10. The method for preparing a porous ceramic according to any one of claims 4 to 5, 7 to 9, characterized in that: The skeleton material includes one, two or more of steel slag, blast furnace slag, fly ash, red mud, tailings, alumina, zirconium oxide, titanium oxide, silicon oxide, silicon carbide, boron carbide, silicon nitride, aluminum nitride, mullite, zircon, and cordierite; The porous structure pore-forming agent includes one, two or more of diatomaceous earth, expanded vermiculite, expanded perlite, kaolin, bentonite and quartz; The non-porous structure pore-forming agent includes one, two or more of calcium carbonate, calcite, dolomite, carbon powder, coal powder, corn starch, wheat starch and potato starch; The curing agent includes one or both of gypsum and cement; The sintering aid includes one, two or more of waste glass, sodium feldspar and potassium feldspar; The binder includes one, two or more of polyvinyl alcohol, xanthan gum, polypropylene alcohol and sodium carboxymethyl cellulose; The foaming agent includes one, two or three of sodium lauryl sulfate, sodium dodecylbenzene sulfonate and soap; The foam stabilizer includes one, two or more of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, acrylamide, polyvinyl alcohol, cellulose and starch.

Images