High-performance porous alumina ceramics with low-temperature rapid sintering and its preparation method

Abstract

The present invention discloses a high-performance porous alumina ceramic with low-temperature rapid sintering and a preparation method thereof. The raw materials for preparing the alumina ceramic include the following components by mass percentage: 55-65% of nano-alumina powder, 20-30% of low-melting-point multi-component composite salt, 8-12% of polymer pore-forming agent, and 3-5% of intelligent response type self-propagating initiator; the polymer pore-forming agent includes poly-N-isopropylacrylamide, polyacrylic acid, and azobenzene-modified polyvinyl alcohol; the intelligent response type self-propagating initiator is a core-shell structure composite material of PNVCL-coated Al / Ni; the porous alumina ceramic is made by low-temperature sintering using the above-mentioned raw materials. The porous alumina ceramic has a high porosity and a rich pore structure, and has excellent mechanical properties, thermal conductivity, and mass transfer properties, and at the same time has the characteristics of low-temperature rapid sintering.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and particularly relates to a high-performance porous alumina ceramic with low-temperature rapid sintering and a preparation method thereof. Background Art

[0002] Porous ceramics are a new type of ceramic material, which have uniformly distributed pores, a very large specific surface area, unique physical surface characteristics, selective permeability to liquid and gas media, and the ability to absorb energy (such as sound waves) or have damping characteristics, and have a relatively high porosity and a small bulk density; at the same time, due to the excellent properties of ceramic materials themselves, such as high temperature resistance, wear resistance, corrosion resistance, high strength, high hardness, and high elastic modulus, this green material of porous ceramics can be widely used in many aspects such as gas or liquid filtration, purification and separation, chemical catalytic carriers, sound absorption and shock absorption, advanced thermal insulation materials, biological implant materials, special wall materials, and sensor materials.

[0003] Among many porous ceramic materials, porous alumina ceramics have excellent characteristics such as cheap raw materials, good material strength, low manufacturing cost, low thermal conductivity, and anti-aging. Porous alumina ceramics refer to ceramic materials with alumina as the aggregate, and a large number of mutually connected or closed pores are formed inside through the processes of material forming and high-temperature sintering.

[0004] The existing porous alumina ceramics have a relatively low porosity, a single pore structure, unsatisfactory comprehensive performance, and a relatively high sintering temperature during the preparation process. Summary of the Invention

[0005] To solve the above technical problems, the purpose of the present invention is to provide a high-performance porous alumina ceramic with low-temperature rapid sintering and a preparation method thereof. The porous alumina ceramic has a relatively high porosity and a rich pore structure, and has excellent mechanical properties, thermal conductivity, and mass transfer properties, and at the same time has the characteristics of low-temperature rapid sintering.

[0006] To achieve the above technical purposes and reach the above technical effects, the present invention is realized through the following technical solutions:

[0007] A high-performance porous alumina ceramic with low-temperature rapid sintering, the preparation raw materials of which include the following components by mass percentage: 55-65% of nano-alumina powder, 20-30% of low-melting-point multi-component composite salts, 8-12% of polymer pore-forming agents, and 3-5% of intelligent-responsive self-propagating initiators; the intelligent-responsive self-propagating initiator is a core-shell structure composite material of PNVCL-coated Al / Ni; the polymer pore-forming agents include poly(N-isopropylacrylamide), polyacrylic acid, and azobenzene-modified polyvinyl alcohol; the porous alumina ceramic is made by low-temperature sintering using the above preparation raw materials.

[0008] Furthermore, the particle size of the nano-aluminum oxide powder is 20-50 nm.

[0009] Furthermore, the low melting point multi-component composite salt is Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 -CsCl composite salt.

[0010] Furthermore, the preparation method of the PNVCL-coated Al / Ni core-shell structure composite material is as follows: adding vinylcaprolactam monomer, crosslinking agent and initiator into the Al / Ni alloy powder dispersion liquid, and carrying out a polymerization reaction at a certain temperature to obtain the PNVCL-coated Al / Ni core-shell structure composite material.

[0011] Furthermore, the preparation raw materials of the high-performance porous alumina ceramic further include 2-4% of a multifunctional additive, and the multifunctional additive includes graphene oxide, boron nitride nanotubes and yttrium-stabilized nano-ZrO 2 .

[0012] Furthermore, the sintering temperature of the high-performance porous alumina ceramic is 900-1100 °C.

[0013] The present invention also provides a preparation method of a high-performance porous alumina ceramic with low-temperature and rapid sintering, comprising the following steps:

[0014] (1) Mixing the preparation raw materials evenly according to the mass percentage;

[0015] (2) Forming the mixture obtained in step (1) through a forming process to form a green body, and under the protection of an inert gas, using a laser ignition technique to initiate a self-propagating exothermic reaction at a temperature of 200-250 °C, and sintering at 900-1100 °C;

[0016] (3) After sintering, cooling to obtain the high-performance porous alumina ceramic.

[0017] Furthermore, the nano-aluminum oxide powder in the preparation raw materials is pre-treated by high-temperature surface activation.

[0018] Furthermore, the preparation method of the core-shell structured composite material of PNVCL-coated Al / Ni in the preparation raw materials is as follows: disperse the Al / Ni alloy powder in deionized water, add an appropriate amount of PVP as a dispersant, and ultrasonically disperse it evenly to obtain a dispersion; then add vinylcaprolactam monomer, crosslinking agent MBA, and initiator MPS to the dispersion and stir evenly; transfer the mixture into a reactor, introduce nitrogen to remove oxygen, heat up to 60-70 °C, and carry out a polymerization reaction for 4-6 h under nitrogen protection; after the reaction, centrifuge, wash, and dry the product to obtain the core-shell structured composite material of PNVCL-coated Al / Ni.

[0019] Furthermore, the low-melting-point multi-component composite salt in the preparation raw materials is pre-dehydrated under vacuum and then refined by ball milling.

[0020] The beneficial effects of the present invention are as follows:

[0021] (1) The present invention uses an intelligent responsive self-propagating initiator. The PNVCL shell layer provides a thermal trigger mechanism. At a lower initiation temperature, the PNVCL shell layer depolymerizes, exposing the Al / Ni core and initiating a self-propagating exothermic reaction to provide sufficient heat for sintering; thus, the alumina ceramic of the present invention does not require a high sintering temperature and can initiate an exothermic reaction and achieve sintering only at 200-250 °C.

[0022] (2) The present invention uses a Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 -CsCl composite salt, whose melting point is as low as about 400 °C, can provide a low-temperature liquid phase environment to promote the rapid transport of the main material. Under the synergistic action of multiple ions, a complex pore network structure is formed, optimizing the specific surface area and mass transfer performance of the material; the carbonate therein can also decompose to generate CO 2 , further increasing the porosity;

[0023] (3) The present invention adopts a polymer pore-forming agent composite system. Among them, poly(N-isopropylacrylamide) provides temperature responsiveness and undergoes a phase change during heating to form a macroporous structure; polyacrylic acid is sensitive to pH, and precise control of the microporous structure is achieved through the regulation of the local pH value; azobenzene-modified polyvinyl alcohol can undergo a configurational change under the illumination generated during sintering to produce a dynamic pore structure. The three polymers act synergistically to achieve a multi-scale, multi-morphology, and adjustable pore structure, further optimizing the specific surface area and mass transfer performance of the material.

[0024] (4) The present invention also adds a multifunctional additive. Among them, the lamellar structure of graphene oxide can enhance heat conduction and mechanical properties, and can also be used as a pore-forming template; boron nitride nanotubes provide thermal stability and dielectric properties, and form unique tubular pores; yttrium-stabilized nano-ZrO 2 can promote phase strengthening and toughening at high temperatures, and endow the ceramic material with optical functions at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 SEM image of the alumina ceramic of Example 3 of the present invention;

[0026] Figure 2 SEM image of the alumina ceramic of Comparative Example 1;

[0027] Figure 3 SEM image of the alumina ceramic of Comparative Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0028] The technical solutions in the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0029] The present invention provides a high-performance porous alumina ceramic with low-temperature and rapid sintering. The preparation raw materials include the following components by mass percentage: 55-65% of nano-alumina powder, 20-30% of low-melting-point multi-component composite salt, 8-12% of polymer pore-forming agent, and 3-5% of intelligent response-type self-propagating initiator; the low-melting-point multi-component composite salt is Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 -CsCl composite salt, and the molar ratio is Li 2 CO 3 : Na 2 CO 3 : K 2 CO 3:CsCl = (40 - 50) : (20 - 35) : (15 - 20) : (5 - 15); The intelligent response type self - propagating initiator is a core - shell structure composite material of PNVCL coated Al / Ni; The polymer pore - forming agent is a composite system, which includes poly(N - isopropylacrylamide), polyacrylic acid and azobenzene - modified polyvinyl alcohol, and their mass ratio is: poly(N - isopropylacrylamide) : polyacrylic acid : azobenzene - modified polyvinyl alcohol = (1.5 - 2.5) : (1 - 1.5) : 1; This porous alumina ceramic is made by low - temperature sintering using the above - mentioned raw materials.

[0030] Among them, the particle size of the nano - alumina powder is 20 - 50 nm.

[0031] The preparation method of the core - shell structure composite material of PNVCL coated Al / Ni is: adding vinylcaprolactam monomer, cross - linker and initiator into the Al / Ni alloy powder dispersion liquid, and carrying out a polymerization reaction at a certain temperature to obtain the core - shell structure composite material of PNVCL coated Al / Ni.

[0032] In order to further improve the performance of this porous alumina ceramic, the raw materials for preparing the high - performance porous alumina ceramic also include 2 - 4% of a multifunctional additive. The multifunctional additive includes graphene oxide, boron nitride nanotubes and yttrium - stabilized nano - ZrO 2 , and their mass ratio is: graphene oxide : boron nitride nanotubes : yttrium - stabilized nano - ZrO 2 = 1 : (1.5 - 2.5) : (1.5 - 2.5).

[0033] The sintering temperature of this high - performance porous alumina ceramic is 900 - 1100 °C.

[0034] The preparation method of this high - performance porous alumina ceramic with low - temperature and rapid sintering includes the following steps:

[0035] (1) Raw material preparation and pretreatment:

[0036] ① Carry out high - temperature surface activation treatment on the nano - alumina powder. The main purpose is to remove surface impurities to increase porosity. The treatment process is: heat treatment at 700 - 800 °C, keep warm for 1 - 4 h, and the heating rate is 5 - 15 °C / min.

[0037] ② Mix Li 2 CO 3 , Na 2 CO 3 , K 2 CO 3After being mixed with CsCl in proportion, it is dehydrated under vacuum and refined by ball milling to form an anhydrous salt and homogenize the composite salt particles. The specific treatment process is as follows: the vacuum degree is 0.085 - 0.095 MPa, the temperature is 70 - 80 °C, and the vacuum dehydration time is 3 - 6 h. Then, dry ball milling is used for ball milling refinement. Among them, the mass ratio of the multi-component composite salt: large grinding balls: small grinding balls is 1:3:2, the ball milling speed is 40 - 80 rpm, and the ball milling time is 12 - 18 h.

[0038] ③ Preparation of intelligent response type self-propagating initiator:

[0039] a) Mechanical alloying treatment of Al / Ni nano-composite powder

[0040] The purpose of mechanical alloying treatment of Al / Ni nano-composite powder is to form a uniformly dispersed Al / Ni composite powder.

[0041] The treatment equipment uses a ball milling equipment, specifically a planetary ball mill. The ball milling medium is alumina balls. The ball-to-material ratio is 10:1 - 30:1. The ball milling speed is 200 - 500 rpm. The ball milling time is 5 h - 8 h. This treatment is carried out in an inert atmosphere such as argon to avoid oxidation. The ball milling method uses an intermittent ball milling method.

[0042] b) Preparation of core-shell structure composite material with PNVCL coated on Al / Ni by in-situ polymerization method

[0043] Disperse the Al / Ni alloy powder in deionized water, add an appropriate amount of PVP (such as polyvinylpyrrolidone) as a dispersant, and disperse it evenly by ultrasonic wave. Then add vinylcaprolactam monomer (NVCL), crosslinking agent MBA (such as N,N'-methylenebisacrylamide) and initiator MPS (such as ammonium persulfate) to the dispersion and stir evenly. Transfer the mixed solution into a reactor, purge with nitrogen to remove oxygen, heat up to 60 - 70 °C, and carry out a polymerization reaction for 4 - 6 h under nitrogen protection. After the reaction, centrifuge, wash, and dry the product to obtain a core-shell structure composite material with PNVCL coated on Al / Ni.

[0044] (2) Use ultrasonic-assisted high-shear mixing technology to mix the preparation raw materials evenly according to the mass percentage to achieve nano-scale dispersion of each component.

[0045] (3) Form the mixture obtained in step (2) into a green body through a forming process. Under the protection of an inert gas, use laser ignition technology to initiate a self-propagating exothermic reaction at a temperature of 200 - 250 °C, and carry out sintering at 900 - 1100 °C. The duration of the self-propagating exothermic reaction is 10 - 30 seconds.

[0046] (4) After sintering, cool down programmatically to control grain growth and obtain high-performance porous alumina ceramics.

[0047] The present invention will be further described in detail below through specific embodiments.

[0048] The preparation method of the intelligent response type self-propagating initiator used in the following examples and comparative examples is as follows:

[0049] Disperse the Al / Ni alloy powder in deionized water, add an appropriate amount of PVP as a dispersant, and ultrasonically disperse it evenly; then add vinylcaprolactam monomer (NVCL), crosslinking agent MBA (N,N'-methylenebisacrylamide), and initiator MPS (ammonium persulfate) to the dispersion and stir evenly. Among them, the mass ratio of the Al / Ni alloy powder, vinylcaprolactam monomer, crosslinking agent MBA, and initiator MPS is 1:4:0.04:0.02; transfer the mixed solution into a reactor, introduce nitrogen to remove oxygen, heat up to 65 °C, and carry out a polymerization reaction for 5 h under nitrogen protection. After the reaction is completed, centrifuge, wash, and dry the product to obtain a core-shell structure composite material of PNVCL-coated Al / Ni.

[0050] Example 1

[0051] A high-performance porous alumina ceramic with low-temperature rapid sintering, the preparation raw materials of which include the following components by mass percentage: 55% of nano-alumina powder, 28% of low-melting-point multi-component composite salt, 10% of polymer pore-forming agent, 3% of intelligent response type self-propagating initiator, and 4% of multifunctional additive; the particle size of the nano-alumina powder is 30 nm; the low-melting-point multi-component composite salt is Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 -CsCl composite salt, and the molar ratio is Li 2 CO 3 :Na 2 CO 3 :K 2 CO 3 :CsCl = 40:30:20:10; the intelligent response type self-propagating initiator is a core-shell structure composite material of PNVCL-coated Al / Ni; the polymer pore-forming agent is a composite system, which includes poly(N-isopropylacrylamide), polyacrylic acid, and azobenzene-modified polyvinyl alcohol; the mass ratio of poly(N-isopropylacrylamide), polyacrylic acid, and azobenzene-modified polyvinyl alcohol is 2:1:1; the multifunctional additive is a compound of graphene oxide, boron nitride nanotubes, and yttrium-stabilized nano-ZrO 2 ; the mass ratio of graphene oxide, boron nitride nanotubes, and yttrium-stabilized nano-ZrO 2 is 1:2:2.

[0052] The preparation method of the high-performance porous alumina ceramic with low-temperature rapid sintering is as follows:

[0053] (1) Using ultrasonic-assisted high-shear mixing technology, mix the nano-alumina powder after high-temperature surface activation treatment, the low-melting-point multi-component composite salt after vacuum dehydration and ball milling refinement, the polymer pore-forming agent, the intelligent-responsive self-propagating initiator, and the multifunctional additive evenly according to the mass percentage;

[0054] (2) Form the mixture obtained in step (1) into a green body through a forming process. Under the protection of inert gas, use laser ignition technology to initiate a self-propagating exothermic reaction at a temperature of 200 °C, and sinter at 900 °C;

[0055] (3) After sintering, cool down programmatically to control grain growth and obtain the high-performance porous alumina ceramic.

[0056] Example 2

[0057] A high-performance porous alumina ceramic with low-temperature rapid sintering, the preparation raw materials of which include the following components according to the mass percentage: 60% nano-alumina powder, 25% low-melting-point multi-component composite salt, 8% polymer pore-forming agent, 5% intelligent-responsive self-propagating initiator, and 2% multifunctional additive; the particle size of the nano-alumina powder is 30 nm; the low-melting-point multi-component composite salt is Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 -CsCl composite salt, and its compounding ratio is the same as that in Example 1; the intelligent-responsive self-propagating initiator is a core-shell structure composite material of PNVCL-coated Al / Ni; the polymer pore-forming agent is a composite system, which includes poly(N-isopropylacrylamide), polyacrylic acid, and azobenzene-modified polyvinyl alcohol, and its compounding ratio is the same as that in Example 1; the multifunctional additive is a compound of graphene oxide, boron nitride nanotubes, and yttrium-stabilized nano-ZrO 2 and its compounding ratio is the same as that in Example 1.

[0058] The preparation method of the high-performance porous alumina ceramic with low-temperature rapid sintering in this Example 2 is the same as that in Example 1.

[0059] Example 3

[0060] A high-performance porous alumina ceramic with low-temperature and rapid sintering, and the preparation raw materials thereof include the following components according to mass percentage: 65% of nano-alumina powder, 20% of low-melting-point multi-component composite salt, 9% of polymer pore-forming agent, 4% of intelligent response-type self-propagating initiator, and 2% of multifunctional additive; the particle size of the nano-alumina powder is 30 nm; the low-melting-point multi-component composite salt is Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 -CsCl composite salt, and its compounding ratio is the same as that in Example 1; the intelligent response-type self-propagating initiator is a core-shell structure composite material of PNVCL-coated Al / Ni; the polymer pore-forming agent is a composite system, which includes poly-N-isopropylacrylamide, polyacrylic acid, and azobenzene-modified polyvinyl alcohol, and its compounding ratio is the same as that in Example 1; the multifunctional additive is a compound of graphene oxide, boron nitride nanotube, and yttrium-stabilized nano-ZrO 2 , and its compounding ratio is the same as that in Example 1.

[0061] The preparation method of the high-performance porous alumina ceramic with low-temperature and rapid sintering in this Example 3 is the same as that in Example 1.

[0062] Figure 1 This is the SEM image of the alumina ceramic in Example 3 of the present invention; from Figure 1 it can be seen that the alumina ceramic in this Example 3 is sintered relatively densely and has a rich pore structure.

[0063] Comparative Example 1

[0064] For the porous alumina ceramic in Comparative Example 1, the preparation raw materials thereof include the following components according to mass percentage: 65% of nano-alumina powder, 20% of low-melting-point multi-component composite salt, 9% of polymer pore-forming agent, and 6% of multifunctional additive; the particle size of the nano-alumina powder is 30 nm; the low-melting-point multi-component composite salt is Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 -CsCl composite salt, and its compounding ratio is the same as that in Example 1; the multifunctional additive is a compound of graphene oxide, boron nitride nanotube, and yttrium-stabilized nano-ZrO 2 , and its compounding ratio is the same as that in Example 1; the polymer pore-forming agent is a composite system, which includes poly-N-isopropylacrylamide, polyacrylic acid, and azobenzene-modified polyvinyl alcohol, and its compounding ratio is the same as that in Example 1.

[0065] The preparation method of the porous alumina ceramic in this Comparative Example 1 is as follows:

[0066] (1) The nano-aluminum oxide powder treated by high-temperature surface activation, the low-melting-point multi-component composite salt treated by vacuum dehydration and ball milling refinement, the polymer pore former, and the multifunctional additive are uniformly mixed by using an ultrasonic-assisted high-shear mixing technique according to the mass percentage;

[0067] (2) The mixture obtained in step (1) is formed and sintered to obtain a porous alumina ceramic; wherein, the sintering temperature is 1350 °C and the sintering time is 3 h.

[0068] The sintering temperature of the alumina ceramic in Comparative Example 1 is relatively high; the SEM image of the alumina ceramic is as Figure 2 shown, and it can be seen from Figure 2 that the sintering degree of the alumina ceramic in Comparative Example 1 is insufficient and the sintering is not dense.

[0069] Comparative Example 2

[0070] For the porous alumina ceramic in Comparative Example 2, its preparation raw materials include the following components according to the mass percentage: 65% nano-aluminum oxide powder, 20% low-melting-point multi-component composite salt, 9% polymer pore former, 4% intelligent response type self-propagating initiator, and 2% multifunctional additive; the low-melting-point multi-component composite salt is Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 -CsCl composite salt; the multifunctional additive is a composite of graphene oxide, boron nitride nanotubes and yttrium-stabilized nano-ZrO 2 ; wherein, the particle size of the nano-aluminum oxide powder is 30 nm; the polymer pore former is poly-N-isopropylacrylamide.

[0071] The preparation method of the porous alumina ceramic in Comparative Example 2 is as follows:

[0072] (1) The nano-aluminum oxide powder treated by high-temperature surface activation, the low-melting-point multi-component composite salt treated by vacuum dehydration and ball milling refinement, the polymer pore former, and the multifunctional additive are uniformly mixed by using an ultrasonic-assisted high-shear mixing technique according to the mass percentage;

[0073] (2) The mixture obtained in step (1) is formed by a forming process to form a green body, and the green body is under inert gas protection, and a self-propagating exothermic reaction is initiated at a temperature of 200 °C by using a laser ignition technique and sintered at 900 °C;

[0074] (3) After the sintering is completed, the temperature is decreased programatically to obtain a high-performance porous alumina ceramic.

[0075] Figure 3 is the SEM image of the alumina ceramic in Comparative Example 2; fromFigure 3 It can be seen that the alumina ceramic of Comparative Example 2 has a low porosity and a relatively single pore structure.

[0076] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced by the present invention.

[0077] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-performance porous alumina ceramic sintered at low temperature and rapidly, characterized in that: The raw materials for preparation thereof include the following components in terms of mass percentage: 55-65% of nano-alumina powder, 20-30% of low-melting-point multi-component composite salt, 8-12% of polymer pore-forming agent and 3-5% of intelligent response type self-propagating initiator; the intelligent response type self-propagating initiator is a shell-core structure composite material of PNVCL coated Al / Ni; the polymer pore-forming agent includes poly-N-isopropylacrylamide, polyacrylic acid and azobenzene-modified polyvinyl alcohol; the mass ratio of poly-N-isopropylacrylamide, polyacrylic acid and azobenzene-modified polyvinyl alcohol is (1.5-2.5): (1-1.5): 1; the porous alumina ceramic is prepared by low-temperature sintering using the raw materials for preparation, and includes the following steps: (1) Mix the raw materials uniformly according to the mass percentage; (2) subjecting the mixture obtained in step (1) to a molding process to form a green body, inducing a self-propagating exothermic reaction of the green body at a temperature of 200-250° C. by laser ignition technology under the protection of an inert gas, and sintering the green body at a temperature of 900-1100° C.; (3) After sintering, the temperature is lowered to obtain high-performance porous alumina ceramics.

2. The high-performance porous alumina ceramic sintered at low temperature and rapidly according to claim 1, characterized in that: The particle size of the nano alumina powder is 20-50 nm.

3. The low-temperature fast-sintering high-performance porous alumina ceramic according to claim 1, characterized in that: The low melting point multi-component composite salt is Li2CO3-Na2CO3-K2CO3-CsCl composite salt.

4. The low-temperature fast-sintering high-performance porous alumina ceramic according to claim 1, characterized in that: The preparation method of the PNVCL coated Al / Ni shell-core structure composite material is as follows: vinyl caprolactam monomer, crosslinking agent and initiator are added to Al / Ni alloy powder dispersion, and polymerization reaction is carried out at a certain temperature to obtain the PNVCL coated Al / Ni shell-core structure composite material.

5. The low-temperature fast-sintering high-performance porous alumina ceramic according to claim 1, characterized in that: The preparation raw materials also include 2-4% of multifunctional additives, and the multifunctional additives include graphene oxide, boron nitrogen nanotubes and yttrium-stabilized nano ZrO2.

6. The low-temperature fast-sintering high-performance porous alumina ceramic according to claim 1, characterized in that: Its sintering temperature is 900-1100℃.

7. A method for preparing a low-temperature fast-sintering high-performance porous alumina ceramic according to any one of claims 1 to 6, characterized in that: The steps include: (1) Mix the raw materials uniformly according to the mass percentage; (2) subjecting the mixture obtained in step (1) to a molding process to form a green body, inducing a self-propagating exothermic reaction of the green body at a temperature of 200-250° C. by laser ignition technology under the protection of an inert gas, and sintering the green body at a temperature of 900-1100° C.; (3) After sintering, the temperature is lowered to obtain high-performance porous alumina ceramics.

8. The method for preparing the low-temperature fast-sintering high-performance porous alumina ceramic according to claim 7, characterized in that: The nano-alumina powder in the preparation raw material is preliminarily subjected to high-temperature surface activation treatment.

9. The method for preparing a high-performance porous alumina ceramic by low-temperature rapid sintering according to claim 7, characterized in that: The preparation method of the PNVCL coated Al / Ni shell-core structure composite material in the raw material is as follows: Al / Ni alloy powder is dispersed in deionized water, an appropriate amount of PVP is added as a dispersant, and ultrasonic dispersion is performed uniformly to obtain a dispersion; vinyl caprolactam monomer, crosslinking agent MBA and initiator MPS are added to the dispersion and stirred uniformly; the mixed solution is transferred into a reactor, nitrogen is introduced for deoxygenation, the temperature is raised to 60~70°C, and polymerization reaction is carried out under nitrogen protection for 4~6 hours; after the reaction, the product is centrifuged, washed, and dried to obtain the PNVCL coated Al / Ni shell-core structure composite material.

10. The method for preparing the low-temperature fast-sintering high-performance porous alumina ceramic according to claim 7, characterized in that: The low melting point multi-component composite salt in the preparation raw material is preliminarily subjected to vacuum dehydration and then subjected to ball milling for refinement.

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