阅读说明：本技术 一种兼具辐照屏蔽效应和隔热保温性能的稀土基气凝胶材料及其制备和应用 (Rare earth-based aerogel material with radiation shielding effect and heat insulation performance as well as preparation and application thereof ) 是由 杨帆 赵志钢 白瑞熙 于 2018-09-20 设计创作，主要内容包括：本发明提供了一种兼具辐照屏蔽效应和隔热保温性能的稀土基气凝胶材料及其制备和应用,该材料包括气凝胶基体材料和稀土基材料,所述稀土基材料与气凝胶基体材料复合,所述稀土基材料选自锆酸稀土、钛酸稀土、钨酸稀土、铈酸稀土中的一种或多种；其中,所述稀土基材料的含量为1wt％～45wt％。本发明通过稀土基材料在气凝胶中的复合有效地将辐照屏蔽性和防火隔热保温性相结合,制备的材料特别适用于核工领域中的辐射屏蔽和防火隔热保温需求。(the invention provides a rare earth-based aerogel material with radiation shielding effect and heat insulation performance as well as preparation and application thereof, the material comprises an aerogel base material and a rare earth-based material, the rare earth-based material is compounded with the aerogel base material, and the rare earth-based material is selected from one or more of zirconic acid rare earth, titanic acid rare earth, tungstic acid rare earth and ceric acid rare earth; wherein the content of the rare earth-based material is 1 wt% -45 wt%. The invention effectively combines the radiation shielding property and the fireproof heat-insulating property through the compounding of the rare earth-based material in the aerogel, and the prepared material is particularly suitable for the radiation shielding and fireproof heat-insulating requirements in the nuclear industry field.)

1. A rare earth-based aerogel material comprises an aerogel matrix material and a rare earth-based material, wherein the rare earth-based material is compounded with the aerogel matrix material and is selected from one or more of rare earth zirconate, rare earth titanate, rare earth tungstate and rare earth cerate; wherein the content of the rare earth-based material is 1 wt% -45 wt%.

2. The rare earth-based aerogel material of claim 1, wherein the bulk density of the rare earth-based aerogel material is from 70 to 180g/m³The thermal conductivity coefficient is 0.023-0.8W/(m.K), and the porosity is 85% -98%.

3. The rare earth-based aerogel material of claim 1 or 2, wherein the aerogel matrix material is an inorganic material having a nanoporous structure.

preferably, the aerogel matrix material is a mixed aerogel of one or more of silica aerogel, alumina aerogel, zirconia aerogel and titania aerogel.

4. the rare earth-based aerogel material of any of claims 1-3, wherein the rare earth elements of the rare earth zirconates, rare earth titanates, rare earth tungstates, and rare earth cerates are one or more of lanthanum, cerium, samarium, europium, gadolinium, dysprosium, holmium, erbium, ytterbium, yttrium, and scandium.

Preferably, the zirconic acid rare earth is one or more of lanthanum zirconate, samarium zirconate, gadolinium zirconate, europium zirconate and dysprosium zirconate; the rare earth titanate is one or more of lanthanum titanate, samarium titanate, gadolinium titanate, europium titanate and dysprosium titanate; the tungstic acid rare earth is one or more of lanthanum tungstate, samarium tungstate, gadolinium tungstate, europium tungstate and dysprosium tungstate; the rare earth cerate is one or more of lanthanum cerate, samarium cerate, gadolinium cerate, europium cerate and dysprosium cerate.

5. A method of preparing the rare earth-based aerogel material of any of claims 1-4, comprising the steps of:

(1) Mixing a precursor of the rare earth-based material and a precursor of the aerogel matrix material, dissolving the mixture in a solvent, and optionally completely hydrolyzing under a standing condition to obtain a mixed system; alternatively, the first and second electrodes may be,

dissolving a precursor of the rare earth-based material in a solvent, adding the precursor of the aerogel matrix, and optionally completely hydrolyzing under a standing condition to obtain a mixed system; alternatively, the first and second electrodes may be,

Dissolving a precursor of the aerogel matrix material in a solvent, optionally completely hydrolyzing under a standing condition, and then adding the rare earth-based material nano powder and optionally an auxiliary dispersing agent to obtain a mixed system;

(2) Optionally adding a network inducer into the mixed system in the step (1), standing and gelling to obtain a rare earth-based composite wet gel material;

(3) And (3) replacing the liquid in the rare earth-based composite wet gel material obtained in the step (2) with gas, and optionally carrying out heat treatment to obtain the rare earth-based aerogel material.

6. the method of claim 5, comprising the steps of:

(1) Mixing a precursor of the rare earth-based material and a precursor of the aerogel matrix material, dissolving the mixture in a solvent, and optionally completely hydrolyzing under a standing condition to obtain a mixed system; alternatively, the first and second electrodes may be,

Dissolving a precursor of the rare earth-based material in a solvent, adding the precursor of the aerogel matrix, and optionally completely hydrolyzing under a standing condition to obtain a mixed system;

(2) Optionally adding a network inducer into the mixed system in the step (1), standing and gelling to obtain a rare earth-based composite wet gel material;

(3) and (3) replacing the liquid in the rare earth-based composite wet gel material obtained in the step (2) with gas, and carrying out heat treatment to obtain the rare earth-based aerogel material.

7. The production method according to claim 5 or 6, comprising the steps of:

(1) dissolving a precursor of the aerogel matrix material in a solvent, optionally completely hydrolyzing under a standing condition, and then adding the rare earth-based material nano powder and optionally an auxiliary dispersing agent to obtain a mixed system;

(2) optionally adding a network inducer into the mixed system in the step (1), standing and gelling to obtain a rare earth-based composite wet gel material;

(3) and (3) replacing the liquid in the rare earth-based composite wet gel material obtained in the step (2) with gas to obtain the rare earth-based aerogel material.

8. The production method according to any one of claims 5 to 7, wherein in the step (1), the precursor of the rare earth-based material includes one or more of a soluble rare earth salt and a soluble compound of zirconium, titanium, tungsten or cerium.

Preferably, the precursor of the rare earth-based material comprises a soluble rare earth salt and one or more of a soluble zirconium salt, a soluble titanium salt, a soluble tungsten salt or a soluble cerium salt.

Preferably, in step (1), the precursor of the aerogel matrix material is selected from one or more of a silicon source (such as ethyl orthosilicate, tetramethoxysilane or sodium silicate), an aluminum source (such as an organic aluminum alkoxide: aluminum isopropoxide or aluminum sec-butoxide, an inorganic aluminum salt: aluminum nitrate or aluminum chloride), a zirconium source (such as an organic zirconium alkoxide: zirconium n-butoxide or zirconium n-propoxide, an inorganic zirconium salt: zirconium oxynitrate or zirconium oxychloride), a titanium source (such as an organic titanium salt: tetrabutyl titanate or tetraisopropyl titanate, an inorganic titanium compound: titanium tetrachloride or a titanate salt).

Preferably, in step (2), the standing time is 12 to 72 hours, for example 24 or 36 hours.

preferably, in step (2), the network inducing agent is selected from propylene oxide and/or an alkaline solution. The alkali solution is selected from an aqueous ammonia solution.

9. The production method according to any one of claims 5 to 8, step (3) comprising:

(3a) After the gel is formed, replacing liquid in the gel by using a supercritical carbon dioxide drying method to obtain a product; alternatively, the first and second electrodes may be,

after the gel is formed, immersing the gel in an aging solvent for aging, and optionally performing surface hydrophobic modification on the aged gel by using a hydrophobic modifier; selecting a solvent with small surface tension to wash the gel, exchanging the aging solvent, and drying at normal pressure to obtain a product;

(3b) Optionally, the product of the step (3a) is subjected to heat treatment at 500-800 ℃ for 3-8 hours to obtain the rare earth-based aerogel material.

Preferably, in step (3a), the aging solvent is selected from ethanol.

preferably, the aging time is 24 to 96 hours, for example 48 hours. Preferably, the temperature of the aging is 50 to 75 ℃, e.g. 60 ℃.

Preferably, in step (3a), the hydrophobic modifier is selected from trimethylchlorosilane. The solvent with low surface tension is selected from n-hexane.

preferably, in the step (3b), the heat treatment may be performed using a box furnace or a vacuum tube furnace, for example.

10. use of the rare earth-based aerogel material of any of claims 1-4 in the nuclear industry field; in particular to radiation shielding and fireproof heat insulation for a nuclear reactor loop system.

Technical Field

The invention belongs to the technical field of nano porous heat insulation materials and preparation thereof, and particularly relates to a rare earth-based aerogel material with radiation shielding effect and heat insulation performance, and a preparation method and application thereof.

Background

generally, a radiation shielding layer and a heat insulation layer are required to be arranged in a nuclear reactor loop system (including a loop system, a secondary loop system and the like), wherein the radiation shielding layer is used for preventing radioactive rays from damaging people, and the heat insulation layer is used for reducing heat loss and improving energy utilization rate.

The main materials selected in the conventional radiation shielding layer are lead (Pb), boron-10 (Pb)¹⁰B) And cadmium (Cd), wherein,¹⁰b and Cd are mainly used in nuclear reactor control rods and shields. In recent years, research has proposed that rare earth elements are introduced into the radiation shielding layer to replace the conventional materials, and the absorption cross sections of thermal neutrons (n, γ) based on most rare earth elements are very large, wherein the absorption cross sections of thermal neutrons (n, γ) of samarium (Sm), europium (Eu) and gadolinium (Gd) are 5600, 4300 and 4600010 respectively^-28·m²All above the boron-10: (¹⁰B，3800 10^-28·m²) And cadmium (Cd, 245010)^-28·m²) Etc.; in addition, the traditional lead (Pb) shielding material has a weak absorption region for the radiation with the energy of 40-88 keV, and the rare earth elements can make up the weak absorption region for Pb.

The existing nuclear power station mainly adopts glass wool fiber heat-insulating materials; the third generation nuclear power station mainly adopts metal reflection type heat insulation materials and nuclear grade glass wool fibers, has single function, and can cause the problem of performance deterioration due to irreversible change of the materials under the long-time action of high temperature and high energy rays. In recent years, inorganic aerogel is proposed as the material of the heat insulation and preservation layer, the inorganic aerogel is a material with a nano-scale porous structure formed by mutually aggregating nano particles, the high porosity of the inorganic aerogel reduces the heat conduction of a solid phase material, the nano-porous structure inhibits the convection heat transfer of gas in the material, and the multiple pore walls reduce the radiation heat transfer; therefore, it has been reported that the heat-insulating effect is achieved by applying the heat-insulating material to a heat-insulating layer of a nuclear reactor. However, the flame retardant performance is poor and the function is single.

disclosure of Invention

The invention aims to provide a novel rare earth-based aerogel material which can effectively shield radiation of a nuclear reactor loop system and reduce heat loss, has radiation shielding effect, thermal insulation performance and excellent flame retardance and fire resistance, and a preparation method and application thereof. The rare earth-based aerogel material is obtained by introducing zirconic acid rare earth, titanic acid rare earth, tungstic acid rare earth and ceric acid rare earth into an aerogel matrix material. The prepared composite material can be used for replacing the existing radiation shielding layer and heat insulation layer in a nuclear reactor loop system, and has the advantages of radiation shielding effect, heat insulation and heat preservation performance and excellent flame-retardant and fire-resistant performance. Specifically, the heat insulation performance is improved compared with that of an aerogel matrix material, and the heat conductivity coefficient is only 0.023-0.8W/(m.K); compared with aerogel matrix materials, the material has the advantages that the new performance of shielding (n, gamma) radiation is improved, the blocking efficiency of neutrons and gamma rays is improved by 3-10 times, and meanwhile, the radiation-resistant service life is prolonged from 3000 years to 300000 years; in addition, the composite material also has good fire resistance, can reach A-level flame retardant level (GB 8624-2012), and is far better than aerogel matrix materials.

The following technical solutions are disclosed herein:

A rare earth-based aerogel material comprises an aerogel matrix material and a rare earth-based material, wherein the rare earth-based material is compounded with the aerogel matrix material and is selected from one or more of rare earth zirconate, rare earth titanate, rare earth tungstate and rare earth cerate; wherein the content of the rare earth-based material is 1 wt% -45 wt%.

The composite material is a skeleton structure of the rare earth-based aerogel material formed by mixing the rare earth-based material and the aerogel matrix material in a nanoscale.

Wherein the bulk density of the rare earth-based aerogel material is 70-180 g/m³The thermal conductivity coefficient is 0.023-0.8W/(m.K), and the porosity is 85% -98%.

wherein the aerogel matrix material is an inorganic material having a nanoporous structure.

Wherein, the aerogel matrix material can be one or more of silica aerogel, alumina aerogel, zirconia aerogel, titania aerogel and the like mixed aerogel according to different use temperatures and environments.

Wherein, the rare earth elements in the zirconic acid rare earth, the titanic acid rare earth, the tungstic acid rare earth and the ceric acid rare earth are one or more of lanthanum, cerium, samarium, europium, gadolinium, dysprosium, holmium, erbium, ytterbium, yttrium and scandium.

Wherein the zirconic acid rare earth is one or more of lanthanum zirconate, samarium zirconate, gadolinium zirconate, europium zirconate, dysprosium zirconate and the like; the rare earth titanate is one or more of lanthanum titanate, samarium titanate, gadolinium titanate, europium titanate, dysprosium titanate and the like; the tungstic acid rare earth is one or more of lanthanum tungstate, samarium tungstate, gadolinium tungstate, europium tungstate, dysprosium tungstate and the like; the rare earth cerate is one or more of lanthanum cerate, samarium cerate, gadolinium cerate, europium cerate, dysprosium cerate and the like.

The following technical scheme is also provided:

a preparation method of the rare earth-based aerogel material comprises the following steps:

(1) Mixing a precursor of the rare earth-based material and a precursor of the aerogel matrix material, dissolving the mixture in a solvent, and optionally completely hydrolyzing under a standing condition to obtain a mixed system; alternatively, the first and second electrodes may be,

Dissolving a precursor of the rare earth-based material in a solvent, adding the precursor of the aerogel matrix, and optionally completely hydrolyzing under a standing condition to obtain a mixed system; alternatively, the first and second electrodes may be,

Dissolving a precursor of the aerogel matrix material in a solvent, optionally completely hydrolyzing under a standing condition, and then adding the rare earth-based material nano powder and optionally an auxiliary dispersing agent to obtain a mixed system;

(2) Optionally adding a network inducer into the mixed system in the step (1), standing and gelling to obtain a rare earth-based composite wet gel material;

(3) And (3) replacing the liquid in the rare earth-based composite wet gel material obtained in the step (2) with gas, and optionally carrying out heat treatment to obtain the rare earth-based aerogel material.

According to an embodiment of the present invention, the method for preparing the rare earth based aerogel material comprises the following steps:

(1) mixing a precursor of the rare earth-based material and a precursor of the aerogel matrix material, dissolving the mixture in a solvent, and optionally completely hydrolyzing under a standing condition to obtain a mixed system; alternatively, the first and second electrodes may be,

dissolving a precursor of the rare earth-based material in a solvent, adding the precursor of the aerogel matrix, and optionally completely hydrolyzing under a standing condition to obtain a mixed system;

(2) Optionally adding a network inducer into the mixed system in the step (1), standing and gelling to obtain a rare earth-based composite wet gel material;

(3) and (3) replacing the liquid in the rare earth-based composite wet gel material obtained in the step (2) with gas, and carrying out heat treatment to obtain the rare earth-based aerogel material.

According to an embodiment of the present invention, the method for preparing the rare earth based aerogel material comprises the following steps:

(1) dissolving a precursor of the aerogel matrix material in a solvent, optionally completely hydrolyzing under a standing condition, and then adding the rare earth-based material nano powder and optionally an auxiliary dispersing agent to obtain a mixed system;

(2) Optionally adding a network inducer into the mixed system in the step (1), standing and gelling to obtain a rare earth-based composite wet gel material;

(3) and (3) replacing the liquid in the rare earth-based composite wet gel material obtained in the step (2) with gas to obtain the rare earth-based aerogel material.

According to an embodiment of the present invention, in step (1), the precursor of the rare earth-based material includes, for example, a soluble rare earth salt, and one or more of soluble compounds of zirconium, titanium, tungsten, or cerium; illustratively, the precursor of the rare earth-based material includes a soluble rare earth salt, and one or more of a soluble zirconium salt, a soluble titanium salt, a soluble tungsten salt, or a soluble cerium salt.

the term "soluble" as used herein means having the property of being soluble in the solvent used.

The soluble rare earth salt may be, for example, a soluble rare earth nitrate, chloride, or sulfate, such as one or more of lanthanum nitrate, lanthanum chloride, europium nitrate, gadolinium nitrate, and the like.

wherein, the soluble zirconium salt can be one or more of zirconium nitrate, zirconyl chloride and the like; the soluble titanium salt may be, for example, titanium sulfate; the soluble tungsten salt may be, for example, one or more of tungsten chloride, ammonium tungstate, and the like; the soluble cerium salt may be, for example, one or more of cerium nitrate, cerium chloride, and the like.

According to an embodiment of the present invention, in the step (1), the rare earth-based material nanopowder may be one or more of a zirconic acid rare earth nanopowder, a titanic acid rare earth nanopowder, a tungstic acid rare earth nanopowder or a ceric acid rare earth nanopowder, for example.

Wherein, the definition of the zirconic acid rare earth, the titanic acid rare earth, the tungstic acid rare earth or the ceric acid rare earth is as described above.

wherein the particle size of the rare earth-based material nano powder is 10-500 nm.

According to an embodiment of the present invention, in step (1), the dispersion aid additive is, for example, hexametaphosphate, polyacrylamide, alginic acid, or the like.

According to an embodiment of the present invention, in the step (1), the precursor of the aerogel base material is selected from one or more of a silicon source (e.g., ethyl orthosilicate, tetramethoxysilane, sodium silicate, etc.), an aluminum source (e.g., an organic aluminum alkoxide: aluminum isopropoxide, aluminum sec-butoxide, etc., an inorganic aluminum salt: aluminum nitrate, aluminum chloride, etc.), a zirconium source (e.g., an organic zirconium alkoxide: zirconium n-butoxide, zirconium n-propoxide, etc., an inorganic zirconium salt: zirconium oxynitrate, zirconium oxychloride, etc.), a titanium source (e.g., an organic titanium salt: tetrabutyl titanate, tetraisopropyl titanate, etc., an inorganic titanium compound: titanium tetrachloride, titanates, etc.).

according to an embodiment of the present invention, in the step (1), the solvent is at least one selected from water and alcohol organic solvents, such as a mixed solution of ethanol and water, a mixed solution of propanol and water, and the like. When a mixed solution of water and an alcohol organic solvent is used, the molar ratio of water to the alcohol organic solvent in the mixed solution is 8:2 to 6, for example, 8:3 to 5.

according to an embodiment of the invention, in the step (1), the molar ratio of the precursor of the aerogel matrix to the solvent is 1:2 to 1: 15.

according to the embodiment of the invention, in the step (1), the amounts of the precursor of the rare earth-based material and the aerogel matrix are calculated by the mass ratio of the rare earth-based material to the aerogel matrix material in the aerogel product (the content of the rare earth-based material is 1 wt% to 45 wt%).

according to an embodiment of the invention, the dissolution of step (1) in the solvent is carried out under continuous stirring.

wherein, the stirring can be performed under the condition of magnetic stirring or mechanical stirring, for example; the stirring time is not particularly limited, and it is sufficient to completely dissolve each precursor in the mixed solution.

Further, an inorganic acid may be added under continuous stirring. The inorganic acid is selected from concentrated hydrochloric acid or at least one of concentrated nitric acid and concentrated sulfuric acid. The amount of the inorganic acid is preferably such that each precursor is completely dissolved.

According to an embodiment of the invention, in step (2), the standing time is 12 to 72 hours, for example 24 or 36 hours.

According to an embodiment of the present invention, in step (2), the network inducing agent is selected from propylene oxide and/or an alkali solution. The alkali solution is selected from an aqueous ammonia solution. The alkaline solution is added to adjust the pH to promote the polymerization of the sol particles in amounts conventional in the art. The propylene oxide is added to promote gel formation.

according to an embodiment of the present invention, step (3) includes, for example:

(3a) After the gel is formed, replacing liquid in the gel by using a supercritical carbon dioxide drying method to obtain a product; alternatively, the first and second electrodes may be,

After the gel is formed, immersing the gel in an aging solvent for aging, and optionally performing surface hydrophobic modification on the aged gel by using a hydrophobic modifier; selecting a solvent with small surface tension to wash the gel, exchanging the aging solvent, and drying at normal pressure to obtain a product;

(3b) Optionally, the product of the step (3a) is subjected to heat treatment at 500-800 ℃ for 3-8 hours to obtain the rare earth-based aerogel material.

According to an embodiment of the invention, in step (3a), the aging solvent is selected from ethanol. The aging time is 24 to 96 hours, for example 48 hours. The temperature of the aging is 40-90 deg.C, such as 60 deg.C.

According to an embodiment of the present invention, in the step (3a), the hydrophobic modifier is selected from trimethylchlorosilane. The solvent with low surface tension is selected from n-hexane.

According to an embodiment of the present invention, in the step (3b), the heat treatment may be performed using, for example, a box furnace or a vacuum tube furnace.

also provided herein are uses of the above-described rare earth-based aerogel materials in the field of nuclear medicine; in particular to radiation shielding and fireproof heat insulation for a nuclear reactor loop system.

The invention has the beneficial effects that:

The invention provides a novel rare earth-based aerogel material which can effectively shield radiation of a nuclear reactor loop system and reduce heat loss and has radiation shielding effect and heat insulation performance, and a preparation method and application thereof. The rare earth-based aerogel material is prepared by introducing a rare earth-based material in the preparation process of the aerogel; the zirconic acid rare earth material has the advantages of high melting point, low thermal conductivity, high chemical stability, high irradiation stability and the like, and is widely applied to the aspect of high-temperature thermal barrier coatings; the rare earth titanate material has the advantages of high neutron absorption rate, no swelling and the like; the tungstic acid rare earth material is a typical negative thermal expansion material, wherein the shielding capacity of metal element tungsten to gamma rays is far higher than that of lead; the cerium acid rare earth has higher thermal expansion coefficient, low thermal conductivity and low specific heat, and can keep stable crystal phase for a long time at high temperature. The zirconic acid rare earth, the titanic acid rare earth, the tungstic acid rare earth and the ceric acid rare earth with special performance are compounded with the aerogel matrix material, so that the composite aerogel not only has more excellent radiation shielding effect and heat insulation performance compared with the aerogel matrix material, but also has better fire resistance. For example, compared with an aerogel matrix material, the heat preservation performance of the rare earth-based aerogel material is improved, and the thermal conductivity is only 0.023-0.8W/(m.K)); compared with aerogel matrix materials, the material has the advantages that the new performance of shielding (n, gamma) radiation is improved, the blocking efficiency of neutrons and gamma rays is improved by 3-10 times, and meanwhile, the radiation-resistant service life is prolonged from 3000 years to 300000 years; moreover, the fire resistance of the aerogel can reach the A-grade flame retardant level and is far better than that of an aerogel matrix material.

drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 shows a rare earth-based aerogel material (powder form) prepared according to the present invention.

Detailed Description

the invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, it should be understood that various changes or modifications can be made by those skilled in the art after reading the description of the present invention, and such equivalents also fall within the scope of the invention.

the method is a conventional method unless otherwise specified. The starting materials are commercially available from the open literature unless otherwise specified.

the process flow of the invention is shown in figure 1, and is a new preparation process of the rare earth-based aerogel material with radiation shielding performance and fireproof, heat-insulating and heat-preserving performance, and the preparation process is suitable for the following examples 1-4.