Nuclear radiation-resistant magnetic particles, preparation method thereof, and nuclear radiation-resistant magnetic liquid

Abstract

The present invention relates to the field of material technology, and particularly relates to a nuclear radiation-resistant magnetic particle, a preparation method thereof, and a nuclear radiation-resistant magnetic liquid. The nuclear radiation-resistant magnetic particle comprises: a nano magnetic particle, wherein the surface of the nano magnetic particle is coated with a mesoporous silica layer, and barium sulfate is loaded on the mesoporous silica layer. In the present invention, a mesoporous silica layer is coated on the surface of the nano magnetic particle and barium sulfate is loaded by a surface in-situ synthesis method, so that the prepared magnetic particle and magnetic liquid have good nuclear radiation resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and particularly to a nuclear radiation-resistant magnetic particle, a preparation method thereof, and a nuclear radiation-resistant magnetic liquid. Background Art

[0002] Nuclear energy is one of the most important new energy sources in this era and is very important for alleviating the increasingly serious energy crisis problem; however, there are inevitable problems in the process of using nuclear energy. For example, the utilization of nuclear energy mainly relies on nuclear power. Nuclear reactors for nuclear power generation often require circulating coolants, and these coolants have characteristics such as high temperature, high pressure, and strong radiation. It is necessary to strictly limit their leakage problems, and the most critical one is the seal of the main pump of the nuclear reactor. Currently, the commonly used seal is a multi-stage mechanical seal. Although it has stable operation, strong pressure resistance, and a wide range of adaptability, leakage will occur during shutdown and startup due to uneven distribution of the oil film between the end faces.

[0003] Magnetic liquid seal is a new type of seal form, which has advantages such as tight sealing performance, immeasurable leakage rate, long service life, high reliability, and no pollution, and plays an irreplaceable and important role in many industries. Combining it with a mechanical seal can combine the respective advantages of the mechanical seal and the magnetic liquid seal to achieve zero-leakage sealing of the main pump of the nuclear reactor. Summary of the Invention

[0004] The present invention is based on the inventor's discovery and recognition of the following facts and problems: There is nuclear radiation lurking near the nuclear reactor, which will accelerate the aging of materials and cause the magnetic liquid to fail. Existing anti-nuclear radiation measures, such as plating the pipe fittings or using cement to block nuclear radiation, have unsatisfactory effects and stability.

[0005] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this reason, the embodiments of the present invention provide a nuclear radiation-resistant magnetic particle, a preparation method thereof, and a nuclear radiation-resistant magnetic liquid. By using the surface in-situ synthesis method to coat a mesoporous silica layer on the surface of the nano-magnetic particle and load barium sulfate, the prepared magnetic particle and magnetic liquid have good nuclear radiation resistance.

[0006] A nuclear radiation-resistant magnetic particle according to an embodiment of the present invention includes: a nano-magnetic particle, and the surface of the nano-magnetic particle is coated with a mesoporous silica layer, wherein the mesoporous silica layer is loaded with barium sulfate.

[0007] Advantages and technical effects brought by the nuclear radiation-resistant magnetic particles according to the embodiments of the present invention: 1. In the embodiments of the present invention, the mesoporous silica layer on the surface of the nano-magnetic particles can load a large amount of barium sulfate, effectively improving the nuclear radiation resistance of the magnetic particles of the present invention; 2. Without affecting the magnetic properties of the nano-magnetic particles, the mesoporous silica layer increases the specific surface area of the magnetic particles, increases the contact area between the modifier and the surface of the nano-magnetic particles, improves the modifiability of the nano-magnetic particles, and is conducive to improving the dispersion and stability of the subsequent magnetic liquid; 3. The nuclear radiation-resistant magnetic particles of the embodiments of the present invention have high nuclear radiation resistance, good magnetic properties and stability, and are easy to be applied in various fields.

[0008] A preparation method of a nuclear radiation-resistant magnetic particle according to an embodiment of the present invention includes the following steps:

[0009] a. Coating: Dispersing nano-magnetic particles, a pore-forming agent and an alkali in a solvent, dropping a silicon source, and performing a sol-gel reaction to obtain silica-magnetic nanoparticles;

[0010] b. Pore-forming: Removing the pore-forming agent in the silica-magnetic nanoparticles to obtain mesoporous silica-magnetic nanoparticles;

[0011] c. Loading: Dispersing the mesoporous silica-magnetic nanoparticles in a barium chloride solution for an adsorption reaction, then adding a sulfate solution, separating and washing the precipitate to obtain the nuclear radiation-resistant magnetic particles.

[0012] Advantages and technical effects brought by the preparation method of the nuclear radiation-resistant magnetic particles according to the embodiments of the present invention: 1. The preparation method of the embodiments of the present invention uses a surface in-situ synthesis method to coat a mesoporous silica layer on the surface of nano-magnetic particles, and then loads barium sulfate on the mesoporous silica layer by a co-precipitation method. Due to the high porosity of the mesoporous silica layer, the loading amount of barium sulfate is greatly increased, effectively improving the nuclear radiation resistance of the magnetic particles of the present invention; 2. Coating a mesoporous silica shell layer on the surface of nano-magnetic particles increases the specific surface area of the particles without affecting the magnetic properties of the magnetic nanoparticles, increases the contact area between the modifier and the surface of the nano-magnetic particles, improves the modifiability of the nano-magnetic particles, and is conducive to improving the dispersion and stability of the subsequent magnetic liquid; 3. The nuclear radiation-resistant magnetic particles of the embodiments of the present invention have a simple preparation method, high efficiency, good magnetic saturation intensity, good magnetic properties and stability, and at the same time have low requirements for equipment and are easy to be applied in various fields.

[0013] The preparation method of nuclear radiation-resistant magnetic particles according to an embodiment of the present invention, wherein the nano magnetic particles are selected from at least one of Fe3O4, γ-Fe2O3 or CoFe2O4, and the nano magnetic particles are prepared by a coprecipitation method.

[0014] The preparation method of nuclear radiation-resistant magnetic particles according to an embodiment of the present invention, in step a, the silicon source is selected from at least one of tetraethyl orthosilicate, sodium silicate, and polysiloxane. Calculated by silicon element, the weight ratio of the silicon source to the magnetic nanoparticles is (1-6):1; and / or, the base is selected from at least one of ammonia water or tetramethoxyammonium hydroxide.

[0015] The preparation method of nuclear radiation-resistant magnetic particles according to an embodiment of the present invention, the pore-forming agent is selected from at least one of cetyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and cetyltrimethylammonium chloride, and the weight ratio of the pore-forming agent to the magnetic nanoparticles is (0.5-2):1.

[0016] The preparation method of nuclear radiation-resistant magnetic particles according to an embodiment of the present invention, in step a, the stirring speed of the sol-gel reaction is 200-1000 r / min; the solvent includes an ethanol aqueous solution, wherein the mass ratio of ethanol to water is (1-5):1.

[0017] The preparation method of nuclear radiation-resistant magnetic particles according to an embodiment of the present invention, the method for removing the pore-forming agent in step b includes: dispersing the silica-magnetic nanoparticles in an ethanol solution of ammonium nitrate and refluxing at 70-90 °C for 1-4 h; or, calcining the silica-magnetic nanoparticles at 300-400 °C for 2-5 h.

[0018] The preparation method of a modified nuclear radiation-resistant magnetic particle according to an embodiment of the present invention, dispersing the nuclear radiation-resistant magnetic particle described above or the nuclear radiation-resistant magnetic particle prepared by the method described above in a mixed solution of a surfactant and ammonia water, heating and stirring, separating the solid particles after cooling, and washing and drying to obtain a modified nuclear radiation-resistant magnetic particle, wherein the surfactant is selected from a silane coupling agent or a fatty acid with a carbon chain length ≥ 16.

[0019] The advantages and technical effects brought by the preparation method of the modified nuclear radiation-resistant magnetic particle according to an embodiment of the present invention: modifying the nuclear radiation-resistant magnetic particle with a surfactant and ammonia water, reducing the surface tension of the nuclear radiation-resistant magnetic particle, improving the dispersibility and compatibility of the nuclear radiation-resistant magnetic particle in the magnetic liquid, thereby enhancing the nuclear radiation resistance and stability of the magnetic liquid.

[0020] A nuclear radiation-resistant magnetic liquid according to an embodiment of the present invention includes a base carrier liquid and the modified nuclear radiation-resistant magnetic particle described above.

[0021] Advantages and technical effects brought by the nuclear radiation-resistant magnetic liquid according to the embodiments of the present invention: 1. By using modified nuclear radiation-resistant magnetic particles, the dispersion effect of the nuclear radiation-resistant magnetic particles in the base carrier liquid is improved, thereby enhancing the nuclear radiation resistance and stability of the nuclear radiation-resistant magnetic liquid; 2. The mesoporous silica shell layer in the modified nuclear radiation-resistant magnetic particles increases the specific surface area of the particles, improves the barium sulfate loading amount, increases the contact area between the modifier and the surface of the nano-magnetic particles, is easy to modify, and is beneficial to improving the dispersion degree and stability of the nuclear radiation-resistant magnetic liquid without affecting the magnetic properties of the magnetic nanoparticles; 3. The nuclear radiation-resistant magnetic liquid of the embodiments of the present invention has a simple preparation method, high efficiency, good magnetic saturation intensity, and has good magnetic properties and stable properties. At the same time, it has low requirements for equipment and is easy to be applied in various fields.

[0022] For the nuclear radiation-resistant magnetic liquid according to the embodiments of the present invention, the particle size of the modified nuclear radiation-resistant magnetic particles is 15 - 30 nm; the base carrier liquid is selected from kerosene, mineral oil, vegetable oil, machine oil, esters or water. Specific embodiments

[0023] The embodiments of the present invention are described in detail below. The embodiments are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0024] A nuclear radiation-resistant magnetic particle according to an embodiment of the present invention includes: a nano-magnetic particle, and the surface of the nano-magnetic particle is coated with a mesoporous silica layer, wherein barium sulfate is loaded on the mesoporous silica layer.

[0025] Advantages and technical effects brought by the nuclear radiation-resistant magnetic particle according to the embodiments of the present invention: 1. In the embodiments of the present invention, a large amount of barium sulfate can be loaded on the mesoporous silica layer on the surface of the nano-magnetic particle, effectively improving the nuclear radiation resistance of the magnetic particle of the present invention; 2. The mesoporous silica layer increases the specific surface area of the magnetic particle without affecting the magnetic properties of the nano-magnetic particle, increases the contact area between the modifier and the surface of the nano-magnetic particle, improves the modifiability of the nano-magnetic particle, and is beneficial to improving the dispersion degree and stability of the subsequent prepared magnetic liquid; 3. The nuclear radiation-resistant magnetic particle of the embodiments of the present invention has high nuclear radiation resistance and has good magnetic properties and stable properties, and is easy to be applied in various fields.

[0026] A preparation method of a nuclear radiation-resistant magnetic particle according to an embodiment of the present invention includes the following steps:

[0027] a. Coating: Dispersing the nano-magnetic particle, the pore-forming agent and the base in a solvent, dropping the silicon source, and performing a sol-gel reaction to obtain a silica-magnetic nano-particle;

[0028] b. Pore formation: Removing the pore-forming agent from the silica-magnetic nanoparticles to obtain mesoporous silica-magnetic nanoparticles;

[0029] c. Loading: Dispersing the mesoporous silica-magnetic nanoparticles in a barium chloride solution for an adsorption reaction, then adding a sulfate solution, separating and washing the precipitate to obtain the nuclear radiation-resistant magnetic particles.

[0030] Advantages and technical effects brought by the preparation method of the nuclear radiation-resistant magnetic particles according to the embodiments of the present invention: 1. The preparation method of the embodiments of the present invention uses the surface in-situ synthesis method to coat a mesoporous silica layer on the surface of the nano-magnetic particles, and then loads barium sulfate on the mesoporous silica layer by the coprecipitation method. Since the porosity of the mesoporous silica layer is relatively high, the loading amount of barium sulfate is greatly increased, effectively improving the nuclear radiation resistance of the magnetic particles of the present invention; 2. Coating a mesoporous silica shell layer on the surface of the nano-magnetic particles increases the specific surface area of the particles while not affecting the magnetic properties of the nano-magnetic particles, increases the contact area between the modifier and the surface of the nano-magnetic particles, improves the modifiability of the nano-magnetic particles, and is beneficial to improving the dispersion and stability of the magnetic liquid prepared subsequently; 3. The nuclear radiation-resistant magnetic particles of the embodiments of the present invention have a simple preparation method, high efficiency, good magnetic saturation intensity, and have good magnetic and stable properties. At the same time, the requirements for equipment are relatively low, and it is easy to realize applications in various fields.

[0031] According to the preparation method of the nuclear radiation-resistant magnetic particles of the embodiments of the present invention, the nano-magnetic particles are selected from at least one of Fe3O4, γ-Fe2O3 or CoFe2O4, and the nano-magnetic particles are prepared by the coprecipitation method.

[0032] Preferably, the preparation method of the nano-magnetic particles includes: dropping concentrated ammonia water into a metal ion solution under heating and stirring conditions for a coprecipitation reaction, magnetic sedimentation and washing to obtain nano-magnetic particles; wherein, the metal ion solution contains at least one of ferric ions, ferrous ions or cobalt ions. Preferably, the preparation method of the nuclear radiation-resistant magnetic particles of the embodiments of the present invention further includes the preparation of nano-magnetic particles.

[0033] Preparation method of nuclear radiation-resistant magnetic particles according to an embodiment of the present invention. In step a, the silicon source is selected from at least one of tetraethyl orthosilicate, sodium silicate, and polysiloxane. Calculated by silicon element, the weight ratio of the silicon source to the magnetic nanoparticles is (1-6):1; and / or, the base is selected from at least one of ammonia water or tetramethoxyammonium hydroxide. The preparation method of the nuclear radiation-resistant magnetic particles according to the embodiment of the present invention preferably disperses the silicon source reagent in an ethanol solution and then drops it, which can make the silicon source reagent fully dispersed in the solution. And adding an alkaline substance such as ammonia water or tetramethoxyammonium hydroxide can promote the sol-gel reaction. In the embodiment of the present invention, the dosage of the silicon source is preferably selected. If the addition amount is too much, it will affect the magnetic properties of the magnetic particles. If the addition amount is too little, the loading amount of the radiation-proof substance barium sulfate will be insufficient and effective radiation-proof ability cannot be provided.

[0034] Preparation method of nuclear radiation-resistant magnetic particles according to an embodiment of the present invention. In step a, the stirring speed of the sol-gel reaction is 200-1000 r / min; the solvent is an ethanol aqueous solution, wherein the mass ratio of ethanol to water is (1-5):1. The preparation method of the nuclear radiation-resistant magnetic particles according to the embodiment of the present invention preferably selects the stirring speed of the sol-gel reaction, which can make the silicon source reagent and the nano magnetic particle principle fully contact, and the surface of the original particle is coated with silica.

[0035] Preparation method of nuclear radiation-resistant magnetic particles according to an embodiment of the present invention. The pore-forming agent is selected from at least one of cetyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and cetyltrimethylammonium chloride. The weight ratio of the pore-forming agent to the magnetic nanoparticles is (0.5-2):1. In the embodiment of the present invention, the pore-forming agent and the dosage of the pore-forming agent are preferably selected. If the dosage of the pore-forming agent is too little, the barium sulfate loading will be insufficient and the radiation-proof ability will be insufficient; if too much pore-forming agent is added, the silica coating will not be successful.

[0036] Preparation method of nuclear radiation-resistant magnetic particles according to an embodiment of the present invention. The method for removing the pore-forming agent in step b includes: dispersing the silica-magnetic nanoparticles in an ethanol solution of ammonium nitrate and refluxing at 70-90 °C for 1-4 h; or calcining the silica-magnetic nanoparticles at 300-400 °C for 2-5 h. The embodiment of the present invention preferably selects the method for removing the pore-forming agent according to the properties of the nano magnetic particles. Fe3O4 nano magnetic particles are easily oxidized to Fe2O3 at high temperatures. It is preferred to use the method of low-temperature heating and reflux to remove the pore-forming agent; γ-Fe2O3 has stable properties and the pore-forming agent can be removed by calcination.

[0037] In step c of the embodiment of the present invention, magnetic separation is preferably used to separate the precipitate, which can reduce metal loss.

[0038] A preparation method of modified nuclear radiation resistant magnetic particles according to an embodiment of the present invention is to disperse the above-mentioned nuclear radiation resistant magnetic particles or the nuclear radiation resistant magnetic particles prepared by the above-mentioned method in a mixed solution of a surfactant and ammonia water, heat and stir, separate the solid particles after cooling, and wash and dry to obtain the modified nuclear radiation resistant magnetic particles, wherein the surfactant is selected from a silane coupling agent or a fatty acid with a carbon chain length ≥ 16.

[0039] The preparation method of the modified nuclear radiation resistant magnetic particles according to an embodiment of the present invention: the nuclear radiation resistant magnetic particles are modified by a surfactant and ammonia water, improving the dispersibility and compatibility of the nuclear radiation resistant magnetic particles in the magnetic liquid base carrier liquid, thereby enhancing the nuclear radiation resistance and stability of the magnetic liquid.

[0040] In the preparation method of the modified nuclear radiation resistant magnetic particles according to an embodiment of the present invention, preferably, the modification is carried out at 70 - 80 °C for a reaction time of 1 - 2 h; preferably, the mass ratio of the surfactant to ammonia water is 1:(1 - 2), and the ammonia water concentration is 5 - 30 wt%.

[0041] Preferably, the silane coupling agent is selected from at least one of methacryloxypropyltriethoxysilane (KH570), dodecyltrioxysilane (DTEOS), or octadecyltrioxysilane (OTMOS); the fatty acid with a carbon chain length ≥ 16 is selected from at least one of oleic acid, stearic acid, or palmitic acid, preferably oleic acid.

[0042] A nuclear radiation resistant magnetic liquid according to an embodiment of the present invention includes a base carrier liquid and the above-mentioned modified nuclear radiation resistant magnetic particles.

[0043] The nuclear radiation resistant magnetic liquid of the embodiment of the present invention uses modified nuclear radiation resistant magnetic particles to improve the dispersion effect of the nuclear radiation resistant magnetic particles in the base carrier liquid, thereby enhancing the nuclear radiation resistance and stability of the nuclear radiation resistant magnetic liquid; the mesoporous silica shell layer in the modified nuclear radiation resistant magnetic particles increases the specific surface area of the particles, improves the barium sulfate loading amount, increases the contact area between the modifier and the surface of the nano magnetic particles, is easy to modify, and is beneficial to improving the dispersion degree and stability of the nuclear radiation resistant magnetic liquid without affecting the magnetic properties of the magnetic nanoparticles; the nuclear radiation resistant magnetic liquid of the embodiment of the present invention has a simple preparation method, high efficiency, good magnetic saturation intensity, and has good magnetic and stable properties, and at the same time has low requirements for equipment and is easy to be applied in various fields.

[0044] The nuclear radiation-resistant magnetic fluid according to an embodiment of the present invention, wherein the particle size of the modified nuclear radiation-resistant magnetic particles is 15 - 30 nm; the base carrier liquid is selected from kerosene, mineral oil, vegetable oil, machine oil, esters or water, preferably dioctyl phthalate. In the nuclear radiation-resistant magnetic fluid according to the embodiment of the present invention, the particle size of the modified nuclear radiation-resistant magnetic particles is optimized to ensure that the nuclear radiation-resistant magnetic fluid has both magnetic properties and nuclear radiation resistance. If the particle size is too large, the particles will not be stably dispersed in the base carrier liquid and a magnetic fluid cannot be formed; if the particle size is too small, the saturation magnetization intensity is very low, reducing the magnetic properties.

[0045] Furthermore, the preparation method of the nuclear radiation-resistant magnetic fluid includes: grinding or ultrasonically dispersing the modified nuclear radiation-resistant magnetic particles in the base carrier liquid.

[0046] The present invention will be described in detail below with reference to embodiments.

[0047] Example 1

[0048] Preparation of Fe3O4 nuclear radiation-resistant magnetic particles

[0049] a. Preparation of nano magnetic particles: Weigh 11 g of FeCl3·6H2O and 9.7 g of FeCl2·4H2O, dissolve them in 513 mL of deionized water, stir at 45 °C in a water bath for 10 min to make it uniform; weigh 17 g of concentrated ammonia water, drop it into the mixed salt solution, keep heating and stirring for 40 min, and it can be observed that the mixed solution quickly turns from yellow to black, magnetically precipitate, and wash repeatedly with deionized water to obtain black Fe3O4 nano magnetic particles;

[0050] b. Coating: Add 1 g of Fe3O4 nano magnetic particles, 70 mL of water, 280 mL of ethanol, and 1 g of cetyltrimethylammonium bromide (CTAB) into a 500 mL three-necked flask, stir under ultrasonic for 30 min; then add 10 mL of ammonia water, dissolve 4.5 mL of tetraethyl orthosilicate (TEOS) in 20 mL of ethanol, slowly drop it and stir for 4 h to obtain Fe3O4@SiO2 magnetic particles;

[0051] c. Pore formation: After vacuum drying the magnetically separated Fe3O4@SiO2 magnetic particles, disperse them in 200 mL of an ethanol solution of ammonium nitrate with a concentration of 10 mg / L, reflux at 80 °C for 1 h, repeat twice to remove the pore-forming agent CTAB, and obtain Fe3O4@mSiO2 magnetic particles with a mesoporous structure;

[0052] d. Load: Weigh 5 g of BaCl₂·2H₂O and dissolve it in 300 mL of deionized water to obtain a barium salt solution with a concentration of 0.07 moL / L. Then disperse the obtained Fe₃O₄@mSiO₂ magnetic particles into the barium salt solution and stir for 4 h. Separately, weigh 3 g of Na₂SO₄ and dissolve it in 100 mL of water to obtain a sodium sulfate solution. Drop the sodium sulfate solution into the mixed solution of magnetic nanoparticles and barium salt to obtain Fe₃O₄@mSiO₂ magnetic particles loaded with BaSO₄, that is, Fe₃O₄ nuclear radiation-resistant magnetic particles.

[0053] Preparation of Fe₃O₄ Nuclear Radiation-Resistant Magnetic Liquid

[0054] (1) Modification: Weigh 1.0 g of oleic acid, 4 g of water, and 1.5 g of concentrated ammonia water (mass concentration 28%). After stirring evenly, add Fe₃O₄ nuclear radiation-resistant magnetic particles, and disperse again to obtain a black suspension. Heat the suspension in a water bath to 80 °C and keep it for 60 min. After it cools to room temperature, magnetically separate the black solid, wash it with water until the pH is 7, wash it three times with ethanol, and dry it in vacuum at 60 °C for 12 h to obtain modified Fe₃O₄ nuclear radiation-resistant magnetic particles.

[0055] (2) Solution preparation: Grind the modified Fe₃O₄ nuclear radiation-resistant magnetic particles in a mortar, add dioctyl phthalate, continue to grind until uniform, and then ultrasonicate for 2.5 h to obtain Fe₃O₄ nuclear radiation-resistant magnetic liquid.

[0056] Example 2

[0057] Preparation of γ-Fe₂O₃ Nuclear Radiation-Resistant Magnetic Particles

[0058] a. Preparation of nano magnetic particles: Weigh 11 g of FeCl₃·6H₂O and 9.7 g of FeCl₂·4H₂O, dissolve them in 513 mL of deionized water, stir at 45 °C in a water bath for 10 min to make it uniform. Weigh 17 g of concentrated ammonia water and drop it into the mixed salt solution, keep heating and stirring for 40 min, and it can be observed that the mixed solution quickly changes from yellow to black. Magnetically precipitate and wash repeatedly with deionized water, and dry at 100 °C for 12 h to obtain γ-Fe₂O₃ nano magnetic particles.

[0059] b. Coating: Add 1 g of γ-Fe₂O₃ nano magnetic particles, 70 mL of water, 280 mL of ethanol, and 1 g of cetyltrimethylammonium bromide (CTAB) into a 500 mL three-necked flask, stir under ultrasonic for 30 min. Then add 10 mL of ammonia water, dissolve 4.5 mL of tetraethyl orthosilicate (TEOS) in 20 mL of ethanol and slowly drop it while stirring for 4 h to prepare γ-Fe₂O₃@SiO₂ magnetic particles.

[0060] c. Pore formation: After vacuum drying the magnetically separated γ-Fe2O3@SiO2 magnetic particles, they were calcined in a muffle furnace at 350 °C for 3 h to remove the pore-forming agent CTAB, obtaining γ-Fe2O3@mSiO2 magnetic particles with a mesoporous structure.

[0061] d. Loading: Weigh 5 g of BaCl2·2H2O and dissolve it in 300 mL of deionized water to obtain a barium salt solution with a concentration of 0.07 moL / L. Then disperse the obtained γ-Fe2O3@mSiO2 magnetic particles into the barium salt solution and stir for 4 h. Separately, dissolve 3 g of Na2SO4 in 100 mL of water to obtain a sodium sulfate solution. Drop the sodium sulfate solution into the mixed solution of magnetic nanoparticles and barium salt to obtain γ-Fe2O3@mSiO2 magnetic particles loaded with BaSO4, that is, γ-Fe2O3 nuclear radiation-resistant magnetic particles.

[0062] Preparation of γ-Fe2O3 Nuclear Radiation-Resistant Magnetic Liquid

[0063] (1) Modification: Weigh 1.0 g of oleic acid, 4 g of water, and 1.5 g of concentrated ammonia water (mass concentration 28%). After stirring evenly, add γ-Fe2O3 nuclear radiation-resistant magnetic particles, and obtain a black suspension after redispersing. Heat the suspension in a water bath to 80 °C and keep it for 60 min. After it cools to room temperature, magnetically separate the black solid, wash it with water until the pH is 7, wash it three times with ethanol, and vacuum dry it at 60 °C for 12 h to obtain modified γ-Fe2O3 nuclear radiation-resistant magnetic particles.

[0064] (2) Solution preparation: Grind the modified γ-Fe2O3 nuclear radiation-resistant magnetic particles in a mortar, add dioctyl phthalate, continue to grind until uniform, and then ultrasonicate for 2.5 h to obtain γ-Fe2O3 nuclear radiation-resistant magnetic liquid.

[0065] Example 3

[0066] Preparation of CoFe2O4 Nuclear Radiation-Resistant Magnetic Particles

[0067] a. Preparation of nano magnetic particles: Weigh 9.7 g of CoCl2·6H2O and 9.7 g of FeCl2·4H2O, dissolve them in 513 mL of deionized water, stir at 45 °C in a water bath for 10 min to make them uniform. Weigh 17 g of concentrated ammonia water and drop it into the mixed salt solution, keep heating and stirring for 40 min. After the reaction is completed, magnetically separate the magnetic particles and repeatedly wash them with deionized water until the conductivity σ of the washing liquid ≤ 100 μs / cm to obtain CoFe2O4 nano magnetic particles.

[0068] b. Coating: Add 1 g of CoFe₂O₄ magnetic nanoparticles, 70 mL of water, 280 mL of ethanol, and 1 g of cetyltrimethylammonium bromide (CTAB) into a 500 mL three-necked flask, and stir under ultrasonic for 30 min. Then add 10 mL of ammonia water, and slowly add 4.5 mL of tetraethyl orthosilicate (TEOS) dissolved in 20 mL of ethanol while stirring for 4 h to obtain CoFe₂O₄@SiO₂ magnetic particles.

[0069] c. Pore formation: After vacuum drying the magnetically separated CoFe₂O₄@SiO₂ magnetic particles, disperse them in 200 mL of an ethanol solution of ammonium nitrate with a concentration of 10 mg / L, reflux at 80 °C for 1 h, repeat twice to remove the pore-forming agent CTAB, and obtain CoFe₂O₄@mSiO₂ magnetic particles with a mesoporous structure.

[0070] d. Loading: Weigh 5 g of BaCl₂·2H₂O and dissolve it in 300 mL of deionized water to obtain a barium salt solution with a concentration of 0.07 moL / L. Then disperse the obtained CoFe₂O₄@mSiO₂ magnetic particles into the barium salt solution and stir for 4 h. Separately, weigh 3 g of Na₂SO₄ and dissolve it in 100 mL of water to obtain a sodium sulfate solution. Add the sodium sulfate solution dropwise to the mixed solution of magnetic nanoparticles and barium salt to obtain CoFe₂O₄@mSiO₂ magnetic particles loaded with BaSO₄, that is, CoFe₂O₄ nuclear radiation-resistant magnetic particles.

[0071] Preparation of CoFe₂O₄ Nuclear Radiation-Resistant Magnetic Liquid

[0072] (1) Modification: Weigh 1.0 g of oleic acid, 4 g of water, and 1.5 g of concentrated ammonia water (mass concentration 28%), stir evenly, add CoFe₂O₄ nuclear radiation-resistant magnetic particles, and obtain a black suspension after redispersion. Heat the suspension in a water bath to 80 °C and keep it for 60 min. After cooling to room temperature, magnetically separate the black solid, wash it with water until the pH is 7, wash it three times with ethanol, and vacuum dry at 60 °C for 12 h to obtain modified CoFe₂O₄ nuclear radiation-resistant magnetic particles.

[0073] (2) Solution preparation: Grind the modified CoFe₂O₄ nuclear radiation-resistant magnetic particles in a mortar, add dioctyl phthalate, continue to grind until uniform, and then ultrasonicate for 2.5 h to obtain CoFe₂O₄ nuclear radiation-resistant magnetic liquid.

[0074] Comparative Example 1

[0075] The preparation method is the same as that of Example 1, except that the Fe₃O₄ magnetic nanoparticles prepared in step a of Example 1 are used instead of the Fe₃O₄ nuclear radiation-resistant magnetic particles prepared in step d to prepare the magnetic liquid.

[0076] Comparative Example 2

[0077] The preparation method was the same as that of Example 1, except that in step b, no pore-forming agent was added, step c was cancelled, and no pore-forming treatment was performed on the outer silica layer.

[0078] Comparative Example 3

[0079] The preparation method was the same as that of Example 1, except that step d was cancelled and barium sulfate was not loaded in the silica layer.

[0080] The nuclear radiation resistance tests were carried out on the nuclear radiation resistant magnetic particles and magnetic liquids prepared in the above examples and comparative examples:

[0081] (1) The irradiation dose rate of the sample was 5 kGy / h, and the total irradiation dose was 2×10 3 kGy;

[0082] (2) Irradiation environment: normal temperature and pressure, aerobic environment.

[0083] The test results are shown in Table 1.

[0084] Table 1

[0085]

[0086] It can be seen from Examples 1-3 and Comparative Example 1 that the nuclear radiation resistant magnetic particles prepared in the examples of the present invention have good silica coating, regular particle size, and excellent nuclear radiation resistance; the nuclear radiation resistant magnetic liquid prepared from the nuclear radiation resistant magnetic particles has high nuclear radiation resistance. After irradiation, the particles are still evenly distributed, the solution properties are stable, there is no agglomeration or sedimentation, and the use performance is excellent.

[0087] Comparing Example 1 and Comparative Example 2, it can be seen that the mesoporous silica coating formed by adding a pore-forming agent in the examples of the present invention not only increases the loading amount of barium sulfate, but also helps the modified nuclear radiation resistant magnetic particles to be better dispersed in the base carrier liquid, improving the nuclear radiation resistance of the magnetic liquid. After irradiation, the magnetic liquid still has good stability.

[0088] Comparing Example 1 and Comparative Example 3, it can be seen that loading barium sulfate on the magnetic particles can endow the magnetic particles with excellent nuclear radiation resistance, so that the irradiated magnetic particles can still maintain a stable solution state.

[0089] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0090] In the present invention, terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0091] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A nuclear radiation-resistant magnetic fluid, characterized in that, It consists of a base carrier liquid and modified nuclear radiation-resistant magnetic particles. The preparation method of the modified nuclear radiation-resistant magnetic particles includes: dispersing the nuclear radiation-resistant magnetic particles in a mixed solution of a surfactant and ammonia water, heating to 70-80°C, with a reaction time of 1-2 h, stirring, separating the solid particles after cooling, and washing and drying to obtain the modified nuclear radiation-resistant magnetic particles. Among them, the surfactant is selected from a silane coupling agent or a fatty acid with a carbon chain length ≥16. The mass ratio of the surfactant to ammonia water is 1:(1-2), and the concentration of ammonia water is 5-30 wt%; the preparation method of the nuclear radiation-resistant magnetic particles is: a. Coating: Dispersing the nano magnetic particles, pore-forming agent and base in a solvent, dropping a silicon source, and performing a sol-gel reaction to obtain silica-magnetic nano particles; b. Pore formation: Removing the pore-forming agent in the silica-magnetic nano particles to obtain mesoporous silica-magnetic nano particles; c. Loading: Dispersing the mesoporous silica-magnetic nano particles in a barium chloride solution for an adsorption reaction, then adding a sodium sulfate solution, separating and washing the precipitate to obtain the nuclear radiation-resistant magnetic particles.

2. The nuclear radiation resistant magnetic fluid according to claim 1, wherein The nano magnetic particles are selected from at least one of Fe3O4, γ-Fe2O3 or CoFe2O4, and the nano magnetic particles are prepared by a coprecipitation method.

3. The nuclear radiation resistant magnetic fluid according to claim 1, characterized in that, In the step a, the silicon source is selected from at least one of tetraethyl orthosilicate, sodium silicate, and polysiloxane. Calculated by silicon element, the weight ratio of the silicon source to the magnetic nano particles is (1~6):1; and / or, the base is selected from at least one of ammonia water or tetramethoxyammonium hydroxide.

4. The nuclear radiation resistant magnetic fluid according to claim 1, wherein The pore-forming agent is selected from at least one of cetyltrimethylammonium bromide, octadecyltrimethylammonium chloride, and cetyltrimethylammonium chloride. The weight ratio of the pore-forming agent to the magnetic nano particles is (0.5~2):

1.

5. The nuclear radiation resistant magnetic fluid according to claim 1, wherein In the step a, the stirring speed of the sol-gel reaction is 200-1000 r / min; the solvent includes an ethanol aqueous solution, where the mass ratio of ethanol to water is (1-5):

1.

6. The nuclear radiation resistant magnetic fluid according to claim 1, wherein The method for removing the pore-forming agent in the step b includes: dispersing the silica-magnetic nano particles in an ethanol solution of ammonium nitrate and refluxing at 70-90°C for 1-4 h; or calcining the silica-magnetic nano particles at 300-400°C for 2-5 h.

7. The nuclear radiation resistant magnetic fluid according to claim 1, characterized in that, The particle size of the modified nuclear radiation-resistant magnetic particles is 15-30 nm; the base carrier liquid is selected from vegetable oil, machine oil, esters or water.

Images