A method for preparing a black corundum-based TPMS endothermic ceramic by light-cured 3D printing

Abstract

The present application relates to the technical field of ceramic 3D printing, and particularly relates to a kind of black corundum-based TPMS heat-absorbing ceramic photo-curing 3D printing preparation method, comprising the following steps: (1) black metal colorant ceramic powder and alumina ceramic powder are dissolved in aqueous solution containing fatty acid salt, to obtain the black metal ceramic powder coated with alumina powder on the surface;(2) the black metal ceramic powder coated with alumina powder, alumina ceramic powder, photo-curing resin, dispersing agent and photoinitiator are mixed uniformly, to obtain composite ceramic slurry;(3) the composite ceramic slurry is used to design TPMS dot matrix structure by 3D printing, and through photo-curing 3D printing, after heat debinding and sintering, black corundum-based TPMS heat-absorbing ceramic is prepared.The above scheme uses photo-curing 3D printing technology to prepare oxide-based heat-absorbing ceramic for solar thermal power generation, which solves the technical problem that traditional forming method is difficult to prepare complex shape, high absorption rate oxide-based heat-absorbing ceramic for solar thermal power generation.

Description

Technical Field

[0001] This invention belongs to the technical field of ceramic 3D printing, and more specifically, relates to a method for photopolymerization 3D printing preparation of black corundum-based TPMS heat-absorbing ceramics. Background Technology

[0002] Two-dimensional solar thermal power generation, also known as concentrated solar power (CSP), boasts advantages such as high spectral utilization and energy conversion efficiency, and strong dispatchability. The core component of a solar thermal power plant is the solar absorber, which absorbs sunlight and converts light energy into heat energy. Therefore, solar absorbers should possess high photothermal conversion efficiency, high thermal conductivity, excellent thermal shock resistance, outstanding mechanical properties, and high-temperature stability. Currently, since solar absorbers in solar thermal power plant systems mostly operate at 800–1200℃, the materials used in these absorbers are primarily ceramics. Non-oxide ceramics, represented by silicon carbide and aluminum nitride, have advantages such as high absorption and high thermal conductivity, but suffer from weak high-temperature oxidation resistance, resulting in a shorter service life. Meanwhile, oxide ceramics, represented by alumina, exhibit excellent high-temperature mechanical properties, strong oxidation resistance, and lower manufacturing costs than non-oxide ceramics. However, because these oxide ceramics are all white, their absorption of sunlight is weak, and their thermal conductivity is low, severely limiting the application of oxide ceramics in the field of solar absorbers. Therefore, doping alumina ceramics with copper oxide, iron oxide, and chromium oxide and sintering them to obtain black corundum ceramics can significantly improve the absorption rate and thermal conductivity of pure corundum ceramics.

[0003] Furthermore, the heat absorption efficiency of solar ceramic absorbers is closely related to their structure. Compared to black corundum ceramic absorbers prepared by traditional dry pressing, the design of the biomimetic hierarchical structure channels is mainly based on the mathematical design principle of the Triply Periodic Minimal Surface (TPMS) structure. The minimal surface is a surface with the smallest area and zero average curvature under specific constraints. The lattice structure formed by the periodic arrangement of minimal surfaces in space is called the TPMS lattice structure. The pressure drop of heat flow inside the TPMS lattice structure black corundum-based absorber is lower, significantly reducing the overall photothermal conversion efficiency and thermal conductivity, while also offering advantages of being lightweight and high-strength. However, traditional ceramic forming methods are difficult to meet the forming requirements of TPMS lattice structure black corundum ceramic absorbers.

[0004] For example, in the Chinese invention patent "Integrated Corundum / SiC Ceramic Material for Solar Thermal Power Generation / Heat Storage and Its Preparation Method" (CN202010072667.8), 50-90 wt% SiC is added to alumina ceramic powder to improve the light absorption rate and thermal conductivity of corundum ceramic. While improving the light absorption rate and thermal conductivity, the high-temperature oxidation resistance of corundum ceramic is sacrificed, and the raw material and preparation costs increase significantly. In the literature "In-situ synthesis and thermal shock resistance of cordierite / silicon carbide composites used for solar absorber coating" (Solar Energy Materials and Solar Cells, 130(2014)257-263), 70-90 wt% silicon carbide is still added to alumina powder to improve the absorption rate, thermal conductivity and thermal shock resistance of corundum ceramic, which leads to a significant decrease in the oxidation resistance of corundum absorbers.

[0005] For example, the Chinese invention patent "A heat dissipation design method based on the combination of variable density topology optimization and TPMS lattice" (CN202310188252.0) discloses a heat dissipation design method based on the combination of variable density topology optimization and TPMS lattice, which completes the heat dissipation optimization design combining topology optimization and triple periodic minimal surface, which can effectively improve the thermal conductivity and heat dissipation performance of the structure. The literature "ZAQureshi, SABAOmari, E. Elnajjar, et al. Using triply periodic minimal surfaces (TPMS)-based metal foams structures as skeleton for metal-foam-PCM composites for thermal energy storage and energy management applications" (International Communications in Heat and Mas Transfer, 2021, 124, 105265) proposes that TPMS structure can effectively improve the thermal conductivity absorption rate of solar thermal power generation receivers.

[0006] However, the aforementioned patents and documents only involved thermal simulations and have not actually produced TPMS structured ceramic receivers for solar thermal power generation. Summary of the Invention

[0007] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a photopolymerization 3D printing method for preparing black corundum-based TPMS heat-absorbing ceramics. The method involves coating black metallic colorant ceramic powder and alumina ceramic powder with fatty acid salts to form two types of ceramic powders with hydrophobic C-chains on their surfaces. Furthermore, alumina powder is successfully coated onto the surface of the black metallic ceramic powder using van der Waals forces, significantly reducing the light absorption rate and refractive index of the black colorant ceramic powder. The method then utilizes photopolymerization to form a TPMS black corundum absorber with excellent surface quality and high precision, further improving the heat absorption efficiency and photothermal conversion efficiency of solar absorbers.

[0008] To achieve the above objectives, according to a first aspect of the present invention, a method for photopolymerization 3D printing of black corundum-based TPMS endothermic ceramics is provided, comprising the following steps:

[0009] (1) Dissolve the ferrous metal colorant ceramic powder and the alumina ceramic powder in an aqueous solution containing fatty acid salts to obtain a ferrous metal ceramic powder with alumina powder coating on the surface.

[0010] (2) The black metal ceramic powder coated with alumina powder, alumina ceramic powder, photocurable resin, dispersant and photoinitiator are mixed evenly to obtain a composite ceramic slurry;

[0011] (3) The composite ceramic slurry is designed with 3D printing to create a TPMS lattice structure, and after photopolymerization 3D printing, thermal degreasing and sintering, a black corundum-based TPMS heat-absorbing ceramic is obtained.

[0012] As a preferred embodiment of the present invention, in step (1);

[0013] The ferrous metal colorant ceramic powder is one of copper oxide ceramic powder, manganese oxide ceramic powder, and titanium oxide ceramic powder; the average particle size of the ferrous metal colorant ceramic powder is 1.0 to 2.0 μm.

[0014] The alumina ceramic powder has an average particle size of 0.1–0.5 μm;

[0015] The amount of alumina ceramic powder used is 10-20 wt% of the amount of ferrous metal colorant ceramic powder used.

[0016] As a preferred embodiment of the present invention, in step (1);

[0017] The fatty acid salt is one of sodium oleate, sodium stearate, potassium oleate, and potassium stearate;

[0018] The amount of the fatty acid salt is 2-4 wt% of the amount of the ferrous metal colorant ceramic powder.

[0019] As a preferred embodiment of the present invention, in step (2);

[0020] The mass ratio of the ferrous metal ceramic powder coated with alumina powder to the alumina ceramic powder is 2:8 to 4:6.

[0021] As a preferred embodiment of the present invention, in step (2);

[0022] The photocurable resin is a mixture of monofunctional photocurable monomers, difunctional photocurable monomers and polyfunctional photocurable monomers; and the difunctional photocurable monomer accounts for 50% of the volume fraction of the photocurable resin, and the volume ratio of the monofunctional photocurable monomer to the polyfunctional photocurable monomer is 4:(16~1).

[0023] The monofunctional photocurable monomer is one of acrylamide morpholine, isobornyl acrylate, o-phenylphenoxyethyl acrylate, and cyclotrimethylolpropane methyl acetal acrylate.

[0024] The bifunctional photocurable monomer is one of 1,6-hexanediol acrylate, tricyclodecanediethanol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, and propoxylated neopentyl glycol acrylate.

[0025] The polyfunctional photocurable monomer is one of ethoxytrimethylolpropane triacrylate, dipentaerythritol hexaacrylate, ethoxytripentaerythritol tetraacrylate, and pentaerythritol triacrylate.

[0026] As a preferred embodiment of the present invention, in step (2);

[0027] The dispersant is a polymer copolymer, and the dispersant is one of BYK111, BYK163, and BYK180; the amount of the dispersant is 2 to 4 wt% of the total amount of the black metal ceramic powder coated with alumina powder and the alumina ceramic powder.

[0028] The photoinitiator is one of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone (184), and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; the amount of the photoinitiator is 1 to 5 wt% of the amount of the photocurable resin.

[0029] As a preferred embodiment of the present invention, in step (3);

[0030] The exposure power of the photopolymer 3D printing is 5-10 W / cm. 2 The single-layer exposure time is 2–4 s, and the printing layer thickness is 20–40 μm;

[0031] The degreasing temperature is increased from 25℃ to 600℃ at a rate of 0.1 to 0.2℃ / min, and the temperature is maintained at 200℃, 340℃, 420℃, 500℃ and 550℃ for 30-120 minutes respectively.

[0032] The sintering temperature is 1550–1650℃, and the holding time is 60–180 min.

[0033] According to another aspect of the present invention, a black corundum-based TPMS heat-absorbing ceramic is prepared based on the preparation method described in the first aspect of the present invention.

[0034] According to another aspect of the present invention, the black corundum-based TPMS heat-absorbing ceramic described in another aspect of the present invention is used as a heat-absorbing material in a solar thermal power generation system.

[0035] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0036] (1) The present invention uses photopolymerization 3D printing technology to prepare black fused alumina-based TPMS lattice structure ceramics for solar thermal power generation systems. Compared with black fused alumina ceramics prepared by traditional methods such as dry pressing and gel casting, the thermal conductivity and photothermal efficiency of TPMS lattice structure black fused alumina ceramics are further increased, which can improve the light utilization rate of solar thermal power plants by 20-50%.

[0037] (2) This invention utilizes fatty acid salt modification to coat alumina ceramic powder on the surface of a type of black metal colorant ceramic powder with high refractive index and absorptivity. This can suppress the absorption and scattering of ultraviolet light by copper oxide powder during photopolymerization 3D printing, and significantly improve the curing thickness and forming accuracy of ceramic slurry.

[0038] (3) The black corundum ceramic prepared by the present invention has the advantages of excellent high-temperature oxidation resistance and low raw material and preparation cost compared with non-oxide-based heat-absorbing ceramics represented by silicon carbide; compared with pure black corundum heat-absorbing ceramics, it has the advantages of high absorption rate, high thermal conductivity and high photothermal conversion efficiency. Attached Figure Description

[0039] Figure 1 The refractive index and absorptivity at 405 nm for black metallic ceramic powder or a mixture of black metallic ceramic powder with a surface coated alumina powder in the embodiments and comparative examples of the present invention.

[0040] Figure 2 These are graphs showing the photocuring properties of ceramic slurries in embodiments and comparative examples of the present invention; wherein, Figure 2 In this context, 'a' represents the cured thickness data of the ceramic slurry. Figure 2 In the figure, b represents the over-curing width data of the ceramic slurry;

[0041] Figure 3 The diagram shows the mechanical and thermal properties of black corundum ceramics in the embodiments and comparative examples of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0043] This invention provides a method for photopolymerization 3D printing of black corundum-based TPMS heat-absorbing ceramics, comprising the following steps:

[0044] Step 1: Dissolve the ferrous metal colorant ceramic powder and alumina ceramic powder in an aqueous solution containing fatty acid salts to obtain ferrous metal ceramic powder with alumina powder coating on the surface;

[0045] Step 2: Mix the ferrous metal ceramic powder coated with alumina powder, alumina ceramic powder, photocurable resin, dispersant and photoinitiator to obtain alumina / ferrous metal composite ceramic slurry;

[0046] Step 3: The composite ceramic slurry is used to form a TPMS lattice structure by photopolymerization 3D printing. After thermal debinding and sintering, black corundum-based TPMS heat-absorbing ceramic is obtained.

[0047] In some embodiments, step one includes:

[0048] One of the following ceramic powders, such as copper oxide, manganese oxide, and titanium oxide, and alumina ceramic powder, are dissolved in an aqueous solution containing fatty acid salts and uniformly mixed at 50–90°C. For example, copper oxide and alumina ceramic powders are dissolved in an aqueous solution containing fatty acid salts and magnetically stirred at 50–80°C, 400–600 rpm for 1–4 hours. The alumina and copper oxide ceramic powders dissolved in the fatty acid salt aqueous solution are then added to an aqueous solvent in a certain proportion and magnetically stirred at 50–100°C, 400–600 rpm for 0.5–1.0 hours to prepare copper oxide powder with an alumina ceramic powder coating.

[0049] In some embodiments, in step one, the average particle size of the alumina ceramic powder is between 0.1 and 1.0 μm; the average particle size of the ferrous metal colorant ceramic powder is between 1.0 and 2.0 μm. Furthermore, the amount of alumina ceramic powder used is 10 to 20 wt% of the amount of ferrous metal colorant ceramic powder used.

[0050] In some embodiments, in step one, the fatty acid salt is one of sodium oleate, sodium stearate, potassium oleate, or potassium stearate. The amount of fatty acid salt used is 2-4 wt% of the amount of the ferrous metal colorant ceramic powder.

[0051] In some embodiments, in step one, the black metal ceramic powder with surface-coated alumina powder prepared based on any of the above embodiments has a light absorption rate of less than 60% at wavelengths of 365 nm and 410 nm, and a refractive index of less than 2.0.

[0052] In some embodiments, after step one, the method of the present invention further includes:

[0053] The copper oxide ceramic powder coated with alumina ceramic powder is repeatedly washed and dried to remove sodium or potassium ions adhering to the powder surface. For example, the copper oxide ceramic powder coated with alumina ceramic powder is washed alternately with alcohol and water, centrifuged, dried, ground, and sieved; the number of times of washing with distilled water and alcohol is alternated is 3 to 5, and the centrifugation speed is 5000 to 10000 rpm.

[0054] In some embodiments, in step two, the mass ratio of ferrometallic powder coated with alumina powder to alumina ceramic powder is 2:8 to 4:6. The amounts of other photocurable resins, dispersants, and photoinitiators are the same as those described in the same field.

[0055] In some embodiments, in step two, the photocurable resin is a mixture of monofunctional, difunctional, and polyfunctional photocurable monomers, and the volume ratio of the monofunctional, difunctional, and polyfunctional photocurable monomers is 1:5:4 to 4:5:1. The polyfunctional photocurable monomer referred to in this invention is a photocurable monomer with a light energy greater than or equal to 3, as known in the art.

[0056] The difunctional photocurable monomer accounts for 50% of the volume fraction of the photocurable resin, and the volume ratio of the monofunctional photocurable monomer to the polyfunctional photocurable monomer is 4:(16-1).

[0057] Among them, the monofunctional photocurable monomer is one of acrylamide morpholine (ACMO), isobornyl acrylate (IBOA), o-phenylphenoxyethyl acrylate (TMCHA), and cyclotrimethylolpropane methyl acetal acrylate (CTFA).

[0058] The bifunctional monomer is one of 1,6-hexanediol acrylate (HDDA), tricyclodecanediethanol diacrylate (DCPDA), tripropylene glycol diacrylate (TPGDA), dipropylene glycol diacrylate (DPGDA), and neopentyl glycol acrylate (NPG2PODA).

[0059] Among them, the polyfunctional monomer is one of trimethylolpropane triacrylate (TMP3EOTA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PPTTA), and pentaerythritol triacrylate (PETA).

[0060] In some embodiments, in step two, the dispersant is one of the polymer copolymer dispersants BYK111, BYK163, and BYK180; the amount of dispersant is 2 to 4 wt% of the total amount of ceramic powder, that is, the amount of dispersant is 2 to 4 wt% of the total amount of black metal ceramic powder and alumina ceramic powder coated with alumina powder.

[0061] In some embodiments, in step two, the photoinitiator is one of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), 1-hydroxycyclohexylphenyl methyl ketone (184), or phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819), and the amount of dispersant added is 2-4 wt%; the amount of photoinitiator used is 1-5 wt% of the amount of photocurable resin.

[0062] In some embodiments, after step two, the alumina / copper oxide composite ceramic slurry is further transferred to a ball mill for high-speed ball milling, and finally a uniformly dispersed alumina / copper oxide composite slurry is obtained; the ball milling speed is 300 to 600 rpm, and the ball-to-material ratio is 1:1 to 3:1.

[0063] In some embodiments, in step three, the alumina / copper oxide composite slurry obtained in step two is used as raw material to form an alumina / copper oxide ceramic green body using a photopolymerization 3D printer. The printer exposure power is 5–10 W / cm². 2 The single-layer exposure time is 2–4 s, and the printing layer thickness is 20–40 μm.

[0064] In some embodiments, in step three, the alumina / copper oxide ceramic green body is thermally degreased and sintered to finally obtain black corundum heat-absorbing ceramic for solar thermal power generation. The degreasing temperature is increased from 25°C to 600°C at a heating rate of 0.1–0.2°C / min, and held at 200°C, 340°C, 420°C, 500°C, and 550°C for 30–120 min each. The sintering temperature is 1550–1650°C, and the holding time is 60–180 min.

[0065] The black fused alumina ceramic prepared by the present invention is applied to a solar thermal power generation system. Compared with black fused alumina ceramics prepared by traditional methods such as dry pressing and gel casting, the thermal conductivity and photothermal efficiency of the TPMS lattice structure black fused alumina ceramic are further increased, which can improve the light utilization rate of the solar thermal power plant by 20-50%.

[0066] The following will provide some specific embodiments, and the characteristics of the obtained two-dimensional porous oxides will be described in detail with reference to the accompanying drawings.

[0067] Example 1:

[0068] A method for preparing a black corundum-based TPMS endothermic ceramic is as follows:

[0069] 1) Dissolve 100g of copper oxide (d50:0.5μm) and 20g of alumina ceramic powder (d50:0.5μm) in an aqueous solution containing 3g of sodium oleate, and stir magnetically at 400rpm for 2h at 60℃ to complete the surface modification of copper oxide and alumina ceramic powder and obtain copper oxide powder with alumina ceramic powder coating on the surface.

[0070] 2) The copper oxide ceramic powder coated with alumina ceramic powder was washed with alcohol and water alternately, centrifuged 5 times at 6000 rpm, dried, ground and sieved.

[0071] 3) The copper oxide powder and alumina ceramic powder coated with the above-mentioned alumina ceramic powder were prepared into a composite ceramic powder at a mass ratio of 2:8. IBOA, HDDA, and PPTTA were prepared into a photocurable resin premix at a volume ratio of 2:5:3. The composite ceramic powder and the photocurable resin premix were prepared into an alumina / copper oxide ceramic slurry suspension at a volume ratio of 5:5. 2 wt% of dispersant BYK111 and 3 wt% of TPO photoinitiator were added to the ceramic powder. The slurry was transferred to a ball mill and ball-milled at 400 rpm with a ball-to-powder ratio of 1:1, ultimately obtaining a uniformly dispersed alumina / copper oxide composite slurry.

[0072] 4) Using the above-mentioned alumina / copper oxide composite slurry as raw material, a TPMS lattice structured alumina / copper oxide ceramic green body was obtained by photopolymerization 3D printing. The printer exposure power was 5W / cm. 2The single-layer exposure time was 2s, and the printed layer thickness was 20μm. After thermal degreasing and sintering, black corundum heat-absorbing ceramics for solar thermal power generation were finally obtained. The degreasing temperature was increased from 25℃ to 600℃ at a heating rate of 0.2℃ / min, and the holding time was 120min at 200℃, 340℃, 420℃, 500℃ and 550℃ respectively. The sintering temperature was 1600℃ and the holding time was 180min.

[0073] Example 2:

[0074] A method for preparing a black corundum-based TPMS endothermic ceramic is as follows:

[0075] 1) Dissolve 100g of manganese oxide (d50:0.5μm) and 10g of alumina ceramic powder (d50:0.5μm) in an aqueous solution containing 2g of potassium fatty acid, and stir magnetically at 400rpm for 2h at 60℃ to complete the surface modification of manganese oxide and alumina ceramic powder, and obtain manganese oxide powder with alumina ceramic powder coated on the surface.

[0076] 2) The manganese oxide ceramic powder coated with alumina ceramic powder was washed alternately with alcohol and water, centrifuged 5 times at 6000 rpm, dried, ground and sieved.

[0077] 3) The manganese oxide powder and alumina ceramic powder coated with the above-mentioned alumina ceramic powder were prepared into a composite ceramic powder at a mass ratio of 3:7. ACMO, HDDA, and DPHA were prepared into a photocurable resin premix at a volume ratio of 1:5:4. The composite ceramic powder and the photocurable resin premix were prepared into an alumina / manganese oxide ceramic slurry suspension at a volume ratio of 5:5. 2 wt% of dispersant BYK180 and 3 wt% of photocurable resin premix 819 photoinitiator were added. The slurry was transferred to a ball mill and ball-milled at 400 rpm with a ball-to-powder ratio of 1:1, ultimately obtaining a uniformly dispersed alumina / manganese oxide composite slurry.

[0078] 4) Using the above-mentioned alumina / manganese oxide composite slurry as raw material, a TPMS lattice structured alumina / manganese oxide ceramic green body was obtained by photopolymerization 3D printing. The printer exposure power was 10 W / cm². 2 The single-layer exposure time was 2s, and the printed layer thickness was 25μm. After thermal degreasing and sintering, black corundum heat-absorbing ceramics for solar thermal power generation were finally obtained. The degreasing temperature was increased from 25℃ to 600℃ at a heating rate of 0.2℃ / min, and the temperature was maintained at 200℃, 340℃, 420℃, 500℃ and 550℃ for 120min. The sintering temperature was 1600℃ and the holding time was 180min.

[0079] Example 3:

[0080] 1) Dissolve 100g of iron oxide (d50:0.5μm) and 15g of alumina ceramic powder (d50:0.5μm) in an aqueous solution containing 3g of sodium fatty acid, and stir magnetically at 400rpm for 2h at 60℃ to complete the surface modification of iron oxide and alumina ceramic powder and obtain iron oxide powder with alumina ceramic powder coating on the surface.

[0081] 2) Wash the iron oxide ceramic powder coated with alumina ceramic powder alternately with alcohol and water, centrifuge at 6000 rpm 5 times, dry, grind and sieve.

[0082] 3) The iron oxide powder and alumina ceramic powder coated with the above-mentioned alumina ceramic powder were prepared into a composite ceramic powder at a mass ratio of 4:6. CTFA, NPGDA, and PPTTA were prepared into a photocurable resin premix at a volume ratio of 4:5:1. The composite ceramic powder and the photocurable resin premix were prepared into an alumina / iron oxide ceramic slurry suspension at a volume ratio of 5:5. 3 wt% of dispersant BYK163 and 2 wt% of photocurable resin premix 184 photoinitiator were added. The slurry was transferred to a ball mill and ball-milled at 400 rpm with a ball-to-powder ratio of 1:1 to obtain a uniformly dispersed alumina / iron oxide composite slurry.

[0083] 4) Using the above-mentioned alumina / copper oxide composite slurry as raw material, a TPMS lattice structured alumina / iron oxide ceramic green body was obtained by photopolymerization 3D printing. The printer exposure power was 5W / cm². 2 The single-layer exposure time was 4s, and the printed layer thickness was 20μm. After thermal degreasing and sintering, black corundum heat-absorbing ceramics for solar thermal power generation were finally obtained. The degreasing temperature was increased from 25℃ to 600℃ at a heating rate of 0.2℃ / min, and the holding time was 120min at 200℃, 340℃, 420℃, 500℃ and 550℃ respectively. The sintering temperature was 1600℃ and the holding time was 180min.

[0084] Comparative Example 1:

[0085] 1) A photocurable resin premix was prepared by mixing CTFA, NPGDA, and PPTTA at a volume ratio of 4:5:1. An alumina / copper oxide ceramic slurry suspension was prepared by mixing alumina ceramic powder and the photocurable resin premix at a volume ratio of 5:5. 3 wt% of dispersant BYK163 (based on the total mass of the ceramic powder) and 2 wt% of photoinitiator 184 (based on the mass of the photocurable resin premix) were added. The slurry was then transferred to a ball mill and ball-milled at 400 rpm with a ball-to-powder ratio of 1:1, ultimately obtaining a uniformly dispersed alumina composite slurry.

[0086] 2) Using the above-mentioned alumina composite slurry as raw material, a TPMS lattice structure alumina ceramic green body was obtained by forming using a photopolymerization 3D printer. The printer exposure power was 5 W / cm². 2 The single-layer exposure time was 4s, and the printed layer thickness was 20μm. After thermal degreasing and sintering, black corundum heat-absorbing ceramics for solar thermal power generation were finally obtained. The degreasing temperature was increased from 25℃ to 600℃ at a heating rate of 0.2℃ / min, and the holding time was 120min at 200℃, 340℃, 420℃, 500℃ and 550℃ respectively. The sintering temperature was 1600℃ and the holding time was 180min.

[0087] Comparative Example 2:

[0088] 1) Mix 100g of copper oxide (d50:0.5μm) and 20g of alumina ceramic powder (d50:0.5μm) separately to obtain a mixed ceramic powder containing copper oxide powder and alumina ceramic powder.

[0089] 2) The above-mentioned mixed ceramic powder of alumina and copper oxide and alumina ceramic powder were prepared into a composite ceramic powder at a mass ratio of 4:6. CTFA, NPGDA, and PPTTA were prepared into a photocurable resin premix at a volume ratio of 4:5:1. The composite ceramic powder and the photocurable resin premix were prepared into an alumina / copper oxide ceramic slurry suspension at a volume ratio of 5:5. 3 wt% of dispersant BYK163 (by mass of ceramic powder) and 2 wt% of photoinitiator 184 (by mass of photocurable resin premix) were added. The above slurry was transferred to a ball mill and ball-milled at 400 rpm with a ball-to-powder ratio of 1:1, finally obtaining a uniformly dispersed alumina / copper oxide composite slurry.

[0090] 4) Using the above-mentioned alumina / copper oxide composite slurry as raw material, a TPMS lattice structured alumina / copper oxide ceramic green body was obtained by photopolymerization 3D printing. The printer exposure power was 5W / cm. 2 The single-layer exposure time was 4s, and the printed layer thickness was 20μm. After thermal degreasing and sintering, black corundum heat-absorbing ceramics for solar thermal power generation were finally obtained. The degreasing temperature was increased from 25℃ to 600℃ at a heating rate of 0.2℃ / min, and the holding time was 120min at 200℃, 340℃, 420℃, 500℃ and 550℃ respectively. The sintering temperature was 1600℃ and the holding time was 180min.

[0091] The following tests were conducted based on the above embodiments and comparative examples:

[0092] Tests were conducted using a digital Abbe refractometer and a UV-Vis spectrometer, such as... Figure 1The figures show the refractive index and absorptivity of the black metallic ceramic powder coated with alumina powder in Examples 1-3, and the mixture of black metallic ceramic powder in Comparative Example 2, at a wavelength of 405 nm. The results indicate that the method of coating alumina powder onto black metallic ceramic powder using the method of the present invention can effectively reduce its refractive index and absorptivity, which is beneficial for photopolymerization 3D printing.

[0093] The cured thickness and over-cured width of the cured single layer of the composite ceramic slurry in Examples 1-3 and Comparative Example 2 under the same exposure time were measured using an optical microscope. Figure 2 The image shows the photocuring properties of the ceramic slurries from Examples 1-3 and Comparative Example 2. Figure 2 As can be seen from a, coating the surface of ferrous metal ceramic powder with alumina ceramic powder can significantly improve the curing thickness and forming accuracy of composite ceramic slurry.

[0094] Through three-point bending strength test, thermal conductivity analyzer test, and ultraviolet-visible absorption spectroscopy analysis, such as Figure 3 The figures shown are the mechanical and thermal properties of the black corundum ceramics in Examples 1-3 and Comparative Example 1. The results indicate that by introducing black metallic ceramic powder coated with alumina powder into the alumina ceramic slurry, the thermal conductivity and light absorption rate of the photopolymerized 3D printed black corundum ceramic can be significantly improved, while slightly reducing its mechanical properties, thus giving it promising prospects for solar thermal power generation applications.

[0095] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for the preparation of a black fused corundum-based TPMS heat absorption ceramic for solar thermal power generation by photocuring 3D printing, characterized by, The method comprises the following steps: (1) dissolving black metal colorant ceramic powder and alumina ceramic powder in an aqueous solution containing a fatty acid salt to obtain black metal ceramic powder coated with alumina powder; the black metal ceramic powder coated with alumina powder has an absorption rate of less than 60% and a refractive index of less than 2.0 at wavelengths of 365 nm and 410 nm; the black metal colorant ceramic powder is one of copper oxide ceramic powder, manganese oxide ceramic powder and titanium oxide ceramic powder; the fatty acid salt is one of sodium oleate, sodium stearate, potassium oleate and potassium stearate; (2) uniformly mixing the black metal ceramic powder coated with alumina powder, alumina ceramic powder, photocuring resin, dispersant and photoinitiator to obtain a composite ceramic slurry; (3) using 3D printing to design a TPMS dot array structure with the composite ceramic slurry, and through photocuring 3D printing, heat debinding and sintering, a black corundum-based TPMS heat-absorbing ceramic is prepared.

2. The method according to claim 1, wherein the method is a photocuring 3D printing method for preparing a black fused-corn-based TPMS heat-absorbing ceramic for solar thermal power generation. In step (1); the average particle size of the black metal colorant ceramic powder is 1.0-2.0 μm; the average particle size of the alumina ceramic powder is 0.1-0.5 μm; the amount of the alumina ceramic powder is 10-20 wt% of the amount of the black metal colorant ceramic powder.

3. The method according to claim 1, wherein the method is a photocuring 3D printing method for preparing a black fused-corn-based TPMS heat-absorbing ceramic for solar thermal power generation. In step (1); the amount of the fatty acid salt is 2-4 wt% of the amount of the black metal colorant ceramic powder.

4. The method according to claim 1, wherein the method is a photocuring 3D printing method for preparing a black fused-corn-cob-based TPMS heat-absorbing ceramic for solar thermal power generation. In step (2); the mass ratio of the black metal ceramic powder coated with alumina powder to the alumina ceramic powder is 2:8-4:

6.

5. The method according to claim 1, wherein the method is a photocuring 3D printing method for preparing a black fused-corn-based TPMS heat-absorbing ceramic for solar thermal power generation. In step (2); the photocuring resin is a mixture of mono-functional photocuring monomer, bi-functional photocuring monomer and multi-functional photocuring monomer; the volume fraction of the bi-functional photocuring monomer in the photocuring resin is 50%, and the volume ratio of the mono-functional photocuring monomer to the multi-functional photocuring monomer is 4:(16-1); the mono-functional photocuring monomer is one of acryloyl morpholine, isobornyl acrylate, o-phenylphenoxyethyl acrylate and cyclo-trihydroxymethylpropane formal acrylate; the bi-functional photocuring monomer is one of 1,6-hexanediol acrylate, tricyclodecane dimethanol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate and propoxylated neopentyl glycol acrylate; the multi-functional photocuring monomer is one of ethoxylated trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, ethoxylated pentaerythritol tetraacrylate and pentaerythritol triacrylate.

6. The method according to claim 1, wherein the method is a photocuring 3D printing method for preparing a black fused-corn-cob-based TPMS heat-absorbing ceramic for solar thermal power generation. In step (2); the dispersant is one of high-molecular copolymer dispersants BYK111, BYK163 and BYK180; the amount of the dispersant is 2-4 wt% of the total amount of the black metal ceramic powder coated with alumina powder and the alumina ceramic powder; The photoinitiator is one of phenyl bis (2, 4, 6-trimethyl benzoyl) phosphine oxide, 1-hydroxycyclohexyl phenyl ketone, 2, 4, 6-trimethyl benzoyl-diphenyl phosphine oxide; the amount of the photoinitiator is 1 ~ 5 wt% of the amount of the photocuring resin.

7. The method according to claim 1, wherein the method is a photocuring 3D printing method for preparing a black fused-corn-cob-based TPMS heat-absorbing ceramic for solar thermal power generation. In step (3); The exposure power of the light-cured 3D printing is 5-10 w / cm 2 The single-layer exposure time is 2-4 s, and the printing layer thickness is 20-40 μm; The temperature of the debinding is from 25 ℃ to 600 ℃, the heating rate is 0.1 ~ 0.2 ℃ / min, and the temperature is kept at 200 ℃, 340 ℃, 420 ℃, 500 ℃ and 550 ℃ for 30-120 min respectively; The sintering temperature is 1550 ~ 1650 ℃, and the holding time is 60 ~ 180 min.

8. The black corundum-based TPMS heat-absorbing ceramic for solar thermal power generation prepared by the preparation method of any one of claims 1-7.

9. The application of the black corundum-based TPMS heat-absorbing ceramic for solar thermal power generation of claim 8 as a heat-absorbing material in a solar thermal power generation system.

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