A silicone oil-based magnetic liquid with low volatility and radiation resistance, and its preparation method and application

Abstract

The present invention discloses a silicone oil-based magnetic liquid with low volatility and radiation resistance, and a preparation method and application thereof, and relates to the field of nuclear reactor technology. The silicone oil-based magnetic liquid includes nanomagnetic particles, a modifier, a surfactant and a base carrier liquid. The nanomagnetic particles are converted from water-soluble to oil-soluble under the action of the modifier. The surfactant is coated on the surface of the nanomagnetic particles modified by the modifier, and the base carrier liquid includes benzyl silicone oil. The silicone oil-based magnetic liquid prepared by the present invention has the advantages of chemical inertness, thermal stability, oxidation resistance, low vapor pressure and ignition point of conventional silicone oil, and also has better high temperature resistance, radiation resistance, lubrication performance and solubility performance, and an operating temperature of ‑50°C to 250°C. It is an excellent low-volatility, radiation-resistant silicone oil-based magnetic liquid.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear reactors, and in particular to a silicone oil-based magnetic liquid with low volatility and radiation resistance, and a preparation method and application thereof. Background Art

[0002] The performance of the sealing system of the nuclear reactor main pump is directly related to the safe and stable operation of the nuclear power plant. The currently widely used multi-stage mechanical sealing technology is difficult to completely avoid the problem of trace leakage when facing extreme working conditions such as shutdown and startup. The emergence of magnetic liquid sealing technology has brought new hope to nuclear reactor sealing technology. This sealing method based on the characteristics of magnetic fluid has shown great application potential in many high-tech and industrial fields with its excellent sealing effect, long service life, excellent stability and environmental protection characteristics. Combining magnetic liquid sealing with mechanical sealing technology can not only give full play to the advantages of both and form a complementary effect, but also is expected to completely solve the leakage problem of the nuclear reactor main pump and provide a more solid guarantee for the safe operation of nuclear power plants.

[0003] However, in the complex and harsh radiation environment around nuclear reactors, how to ensure the long-term stability and reliability of magnetic liquid sealing materials has become a technical problem that needs to be solved urgently. Ideal magnetic liquid sealing materials not only need to have excellent high temperature and radiation resistance, but also should be able to effectively absorb or shield nuclear radiation and prevent the leakage of radioactive materials, thereby protecting the surrounding environment and personnel safety. Therefore, the research and development of new high temperature resistant, radiation resistant, and radiation absorbing magnetic liquid materials is crucial to improving the overall level of nuclear reactor sealing technology, and is also the key to promoting the safe and efficient use of nuclear energy.

[0004] In the existing magnetic liquid preparation technology, ester and diester oils, kerosene, engine oil and water are often used as base carriers of magnetic liquids. However, these conventional base carriers usually have problems such as high volatility, high freezing point, acid and alkali resistance, poor radiation resistance, and large viscosity changes with temperature, which cannot meet the needs of some complex industrial environments. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0006] To this end, an embodiment of the present invention provides a silicone oil-based magnetic liquid with low volatility and radiation resistance, and a preparation method and application thereof.

[0007] In the first aspect, the present invention proposes a silicone oil-based magnetic liquid with low volatility and radiation resistance, comprising:

[0008] Nano magnetic particles;

[0009] A modifier, under the action of which the nano magnetic particles are transformed from water-soluble to oil-soluble;

[0010] A surfactant, wherein the surfactant is coated on the surface of the nanomagnetic particles modified by the modifier;

[0011] The base carrier liquid comprises benzyl silicone oil.

[0012] Furthermore, the mass ratio of the nanomagnetic particles to the surfactant is 1:(1-3).

[0013] Furthermore, the mass ratio of the nanomagnetic particles to the base carrier liquid is 1:(1-3).

[0014] Furthermore, the mass ratio of the modifier to the surfactant is 1:(5~20).

[0015] Furthermore, the nano magnetic particles include one or more of iron nitride, carbonyl iron, iron, ferroferric oxide, and ferrite magnetic particles.

[0016] Furthermore, the ferrite magnetic particles include MFe2O4 and M 1-X Zn X Fe2O4, wherein M is one of Mn, Co, Ni, Cu, Cd, Pb, Sn, Ca, Sr, Ba, and Mg.

[0017] Furthermore, the modifier includes C 10 One or more of the following low molecular weight saturated fatty acids.

[0018] Furthermore, the surfactant includes epoxy-modified silicone oil.

[0019] Furthermore, the modified silicone oil includes one or more of methyl silicone oil containing epoxy groups, ethyl silicone oil containing epoxy groups, and phenyl silicone oil containing epoxy groups.

[0020] Furthermore, the benzyl silicone oil includes one or more of low benzyl silicone oil, medium benzyl silicone oil and high benzyl silicone oil.

[0021] In a second aspect, the present invention provides a method for preparing the silicone oil-based magnetic liquid provided in the first aspect, comprising the following steps:

[0022] (a) selecting high-grade pure raw materials to prepare magnetic nanoparticles, dissolving all solid raw materials into aqueous solution, removing insoluble matter by vacuum filtration, and further purifying the raw materials for preparing magnetic nanoparticles;

[0023] (b) activating the magnetic particles;

[0024] (c) Magnetic particles after modification and dispersion activation.

[0025] Furthermore, the step (a) comprises: 2+ , Fe 3+ OH - The molar ratio of Fe 3+ and Fe 2+ The compound is dissolved in deionized water, stirred evenly, and then the insoluble matter is removed by vacuum filtration to obtain a mixed iron salt solution. Ammonia water is added under the conditions of a temperature of 25-100° C. and a stirring speed of 200-500 r / min. The reaction time is 1-60 min to obtain nano magnetic particles. The nano magnetic particles are repeatedly washed with water until the conductivity σ of the eluate is ≤100 μs / cm.

[0026] Furthermore, the step (b) comprises adding the nanomagnetic particles to a ferric chloride solution with a pH of 0 to 3, and heating the solution in a water bath for 1 to 60 minutes; and washing the nanomagnetic particles until the conductivity of the eluate is σ≤10 μs / cm.

[0027] Furthermore, the step (c) comprises dispersing the activated nanomagnetic particles in a mixture of water and ethanol, adding the mixture to a mixture of a base carrier liquid, a surfactant, a modifier and a transition liquid at 20-100° C., then adding ammonia water, and stirring until the water, ethanol and the transition liquid are completely evaporated to obtain a silicone oil-based magnetic liquid.

[0028] In a third aspect, the present invention proposes the use of the silicone oil-based magnetic liquid proposed in the first aspect or the silicone oil-based magnetic liquid prepared by the method proposed in the second aspect in a nuclear reactor sealing system.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] The silicone oil-based magnetic liquid prepared by the present invention has the advantages of chemical inertness, thermal stability, oxidation resistance, low vapor pressure and ignition point of conventional silicone oil, and also has better high temperature resistance, radiation resistance, lubrication performance and solubility performance, and an operating temperature of -50°C to 250°C. It is an excellent low-volatile, radiation-resistant silicone oil-based magnetic liquid.

[0031] The present invention uses raw materials with the highest purity in the process of preparing magnetic liquid. After all solid raw materials are dissolved into aqueous solution, insoluble matter is removed by vacuum filtration and the like, and the raw materials for preparing magnetic nanoparticles are further purified, so that the magnetic liquid itself contains very little or no impurities, and its own radioactivity is reduced. The quality of the magnetic liquid is improved without affecting the magnetic properties of the magnetic nanoparticles, and a magnetic liquid with low radioactivity is obtained.

[0032] The preparation method of the silicone oil-based magnetic liquid of the present invention is simple, highly efficient, has a large magnetic saturation intensity, and simultaneously has excellent magnetic properties, stability, radiation resistance, low volatility. At the same time, it has low requirements for equipment. When applied in the sealing field related to nuclear energy, it does not react with the sealed medium and the scintillator, and has the advantages of zero leakage, long life, high reliability, environmental protection and no pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, wherein:

[0034] Figure 1 It is the preparation principle diagram of the silicone oil-based magnetic liquid of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0036] The silicone oil-based magnetic liquid with low volatility and radiation resistance of the present invention and its preparation method and application will be specifically described below.

[0037] The silicone oil-based magnetic liquid with low volatility and radiation resistance of the present invention includes nano-magnetic particles, modifiers, surfactants and base carriers. The magnetic liquid is composed of nano-scale magnetic particles highly dispersed in the base carrier. This special colloidal liquid has both the fluidity of a liquid and the magnetic properties of a solid.

[0038] The preparation principle of the silicone oil-based magnetic liquid of the present invention is as Figure 1 shown.

[0039] In some embodiments, the nano-magnetic particles include one or more of iron nitride, iron carbonyl, iron, magnetite, and ferrite magnetic particles. The ferrite magnetic particles include MFe2O4 and M 1-X Zn X Fe2O4, where 0 < x < 1, and M is one of Mn, Co, Ni, Cu, Cd, Pb, Sn, Ca, Sr, Ba, Mg.

[0040] In some embodiments, the base carrier is phenylmethyl silicone oil, and the phenylmethyl silicone oil includes one or more of low phenylmethyl silicone oil, medium phenylmethyl silicone oil, and high phenylmethyl silicone oil. Among them, the phenyl molar fraction in the low phenylmethyl silicone oil is 5% - 10%, the phenyl molar fraction in the medium phenylmethyl silicone oil is 25%, and the phenyl molar fraction in the high phenylmethyl silicone oil is 45%.

[0041] The silicone oil-based carrier liquid is a benzyl silicone oil containing phenyl groups on the siloxane chain. Due to the introduction of aromatic groups with large conjugated structures, benzyl silicone oil has better high temperature resistance, radiation resistance, lubrication and solubility than ordinary dimethyl silicone oil. The working temperature is -50℃~250℃, and it has strong adaptability. It is an excellent low-volatile, radiation-resistant carrier liquid.

[0042] In some embodiments, the mass ratio of the nanomagnetic particles to the base carrier liquid is 1:(1-3). The mass ratio of the nanomagnetic particles to the base carrier liquid is within a suitable range so that the magnetic liquid has good fluidity and a high saturation magnetization; when the content of the base carrier liquid is too low, the viscosity of the magnetic liquid will increase greatly due to the increase in the content of the magnetic particles, and it may even be unable to flow, which will lead to an increase in the starting torque in dynamic sealing applications, and the excessive proportion of magnetic particles will also lead to a decrease in the stability of the magnetic liquid; when the content of the base carrier liquid is too high, since the sealing pressure resistance of the magnetic liquid is related to the saturation magnetization of the magnetic liquid, and the saturation magnetization of the magnetic liquid is related to the proportion of magnetic particles in the magnetic liquid, when the content of the base carrier liquid is high, the proportion of magnetic powder is small, the saturation magnetization of the magnetic liquid is small, the sealing pressure resistance is small, and the use requirements cannot be met.

[0043] In some embodiments, the modifier comprises C 10 One or more of the following small molecular weight saturated fatty acids, for example, n-octanoic acid, n-decanoic acid, etc. Under the action of the modifier, the nano magnetic particles are changed from being water-soluble to being oil-soluble.

[0044] In some embodiments, the mass ratio of the modifier to the surfactant is 1:(5-20). The mass ratio of the modifier to the surfactant is within a suitable range to stabilize the properties of the magnetic liquid, and even if it is placed in a magnetic field for a long time, the base carrier liquid will not precipitate; when the content of the surfactant is too low or too high, the base carrier liquid will precipitate under the magnetic field, causing the magnetic liquid to fail, thereby causing the seal to fail.

[0045] The surfactant is coated on the surface of the nanomagnetic particles modified by the modifier to ensure that the magnetic particles will not agglomerate under the action of gravity, inter-particle magnetic force or van der Waals force, and each nanoparticle surface needs to be provided with sufficient repulsive force by the coated surfactant. In some embodiments, the surfactant includes epoxy-modified silicone oil. The modified silicone oil includes one or more of methyl silicone oil containing epoxy groups, ethyl silicone oil containing epoxy groups, and phenyl silicone oil containing epoxy groups.

[0046] In some embodiments, the mass ratio of the nanomagnetic particles to the surfactant is 1:(1-3). The mass ratio of the nanomagnetic particles to the surfactant is within a suitable range so that the obtained magnetic liquid has stable properties, and the base carrier liquid will not precipitate even if it is placed in a magnetic field for a long time; when the content of the surfactant is too high or too low, the base carrier liquid will precipitate under the magnetic field, causing the magnetic liquid to fail, thereby causing the seal to fail.

[0047] The method for preparing the silicone oil-based magnetic liquid of the present invention comprises the following steps:

[0048] (a) selecting high-grade pure raw materials to prepare magnetic nanoparticles, dissolving all solid raw materials into aqueous solution, removing insoluble matter by vacuum filtration, and further purifying the raw materials for preparing magnetic nanoparticles;

[0049] (b) activating the magnetic particles;

[0050] (c) Magnetic particles after modification and dispersion activation.

[0051] In some embodiments, step (a) comprises pressing Fe 2+ , Fe 3+ OH - The molar ratio of Fe 3+ and Fe 2+ The compound is dissolved in deionized water, stirred evenly to obtain a mixed iron salt solution, and then ammonia water is added. Under the conditions of temperature of 25-100° C. and stirring speed of 200-500 r / min, the reaction time is 1-60 min to obtain nano magnetic particles; the nano magnetic particles are repeatedly washed with water until the conductivity σ of the eluate is ≤100 μs / cm.

[0052] In some embodiments, step (b) comprises adding the nanomagnetic particles to a ferric chloride solution with a pH of 0 to 3, and heating the solution in a water bath for 1 to 60 minutes; and washing the nanomagnetic particles until the conductivity of the eluate is σ≤10 μs / cm.

[0053] In some embodiments, the step (c) comprises dispersing the activated nanomagnetic particles in a mixture of water and ethanol, adding the mixture to a base carrier liquid, a surfactant, a modifier and a transition liquid at 20-100° C., and then adding ammonia water, stirring at a stirring speed of 200-500 r / min and a reaction time of 120-300 min until the water, ethanol and transition liquid are completely evaporated to obtain a silicone oil-based magnetic liquid.

[0054] The present invention first synthesizes magnetic nanoparticles by coprecipitation with the highest purity material, then partially modifies the surface of the particles to change them from water-soluble to oil-soluble, then modifies the particles by using epoxy-modified silicone oil as a surfactant, and finally disperses the modified magnetic particles into a silicone oil-based carrier liquid to obtain the silicone oil-based magnetic liquid.

[0055] The silicone oil-based magnetic liquid of the present invention has the advantages of simple preparation method, high efficiency, large magnetic saturation intensity, excellent magnetic performance, stability, radiation resistance, low volatility, low equipment requirements, no reaction with the sealed medium and scintillator when used in the sealing field related to nuclear energy, zero leakage, long life, high reliability, environmental protection and no pollution, etc., and is suitable for application in the sealing system of nuclear reactors.

[0056] The present invention uses raw materials with the highest purity in the process of preparing the magnetic liquid, so that the magnetic liquid itself contains very little or no impurities, reduces its own radioactivity, improves the quality of the magnetic liquid without affecting the magnetic properties of the magnetic nanoparticles, and obtains a magnetic liquid with low radioactivity.

[0057] The present invention is described below in conjunction with specific examples. The test materials and reagents used in the following examples, unless otherwise specified, can be obtained from commercial sources. If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0058] Example 1

[0059] Preparation of Fe3O4 silicone oil-based magnetic liquid:

[0060] Weigh 16.2g of FeCl3 and 10g of FeCl2·4H2O, dissolve them in 300mL of deionized water, place them in a water bath at 40°C, control the stirring speed to 400r / min, stir for 10min to make them uniform, then remove the insoluble matter from the dissolved mixed iron salt solution by vacuum filtration to obtain a pure mixed iron salt solution, then place it in a 40°C water bath again and start stirring; weigh 50mL of concentrated ammonia water (25wt%), add it to the mixed salt solution, and it can be observed that the mixed solution quickly changes from yellow to black. Keep heating and stirring for 45min. After the reaction is completed, magnetic particles are separated by magnetism and repeatedly washed with deionized water until the conductivity σ of the eluate is ≤100μs / cm.

[0061] The magnetic particles obtained above were placed in a 1.0 mol / L ferric chloride solution, heated in a 50°C water bath for 30 min, and then washed with ethanol until the conductivity of the eluate was σ≤10 μs / cm, thereby obtaining activated magnetic particles.

[0062] 12 g of the activated magnetic particles were dispersed in a mixed solution of water and ethanol (volume ratio of ethanol: water = 1:1), and stirred in a water bath at 80°C; 12 g of epoxyphenyl silicone oil and 20 g of phenylmethyl silicone oil were dissolved in 50 mL of n-heptane, and 1.5 mL of n-octanoic acid was added. After stirring evenly, it was completely added to the magnetic powder dispersion, and 5 mL of ammonia water was added. After stirring for 300 minutes, the silicone oil-based magnetic liquid was obtained.

[0063] The magnetic liquid obtained above has a saturation magnetization intensity of 18.75emu / g, has excellent high and low temperature resistance, radiation resistance, lubrication performance, uniform particle distribution, no agglomeration, no sedimentation, and is capable of working in the special working environment in the field of nuclear power generation. It is a silicone oil-based magnetic liquid with low volatility and radiation resistance.

[0064] Example 2

[0065] Preparation of iron nitride-based silicone oil-based magnetic liquid:

[0066] Weigh 16.2g of FeCl3 and 10g of FeCl2·4H2O, dissolve them in 300mL of deionized water, place them in a water bath at 40°C, control the stirring speed to 400r / min, stir for 10min to make them uniform, then remove the insoluble matter from the dissolved mixed iron salt solution by vacuum filtration to obtain a pure mixed iron salt solution, then place it in a 40°C water bath again and start stirring; weigh 50mL of concentrated ammonia water (25wt%), add it to the mixed salt solution, and it can be observed that the mixed solution quickly changes from yellow to black. Keep heating and stirring for 45min. After the reaction is completed, magnetic particles are separated by magnetism and repeatedly washed with deionized water until the conductivity σ of the eluate is ≤100μs / cm.

[0067] The magnetic particles obtained above were placed in a 1.0 mol / L ferric chloride solution, heated in a 50°C water bath for 30 min, and then washed with ethanol until the conductivity of the eluate σ ≤ 10 μs / cm, and then dried in air. After drying at 100°C for 8 h, activated iron oxide particles were obtained.

[0068] The iron oxide particles were placed in a tubular furnace, pure ammonia was introduced, the gas flow rate was controlled at 50 mL / min, the temperature was raised to 500°C at a heating rate of 10°C / min, and after being kept warm for 3 hours, the temperature was naturally cooled to room temperature, and the surface was passivated with 1% O2 / N2 mixed gas at room temperature to stabilize the obtained iron nitride product.

[0069] After mixing 12g of the stabilized iron nitride product with a mixed solution of water and ethanol (volume ratio of ethanol: water = 1:1), the mixture was added to a ball mill and subjected to high-energy ball milling for 5h to obtain a dispersion of iron nitride magnetic particles. The dispersion was stirred in a water bath at 80°C, 12g of epoxyphenyl silicone oil and 20g of phenylmethyl silicone oil were dissolved in 50mL of n-heptane, and 1.5mL of n-octanoic acid was added. After stirring evenly, the mixture was completely added to the magnetic powder dispersion, and 5mL of ammonia water was added. After stirring for 300min, the silicone oil-based magnetic liquid was obtained.

[0070] The magnetic liquid obtained above has a saturation magnetization intensity of 20.36emu / g, has excellent high and low temperature resistance, radiation resistance, lubrication performance, uniform particle distribution, no agglomeration, no sedimentation, and is capable of working in the special working environment in the field of nuclear power generation. It is a silicone oil-based magnetic liquid with low volatility and radiation resistance.

[0071] Example 3

[0072] Preparation of CoFe2O4 silicone oil-based magnetic liquid:

[0073] Weigh 9.7 g of CoCl2·6H2O and 9.7 g of FeCl2·4H2O, dissolve them in 513 mL of deionized water, stir them in a water bath at 40°C for 10 min to make them uniform, then remove the insoluble matter from the dissolved mixed iron salt solution by vacuum filtration to obtain a pure mixed iron salt solution, which is then placed in a 40°C water bath again and stirred; weigh 25 mL of concentrated ammonia water (25wt%), add it dropwise to the mixed salt solution, keep heating and stirring for 60 min, and after the reaction is completed, magnetically separate the magnetic particles and repeatedly wash them with deionized water until the conductivity σ of the eluate is ≤100μs / cm.

[0074] The magnetic particles obtained above were placed in a 1.0 mol / L ferric chloride solution, heated in a 50°C water bath for 30 min, and then washed with ethanol until the conductivity of the eluate σ ≤ 10 μs / cm. They were then placed in a vacuum drying oven at 65°C and dried for 8 h to obtain activated magnetic particles.

[0075] 6 g of activated magnetic particles were dispersed in a mixed solution of water and ethanol (volume ratio of ethanol: water = 1:1), and stirred in a water bath at 80°C; 6 g of epoxyphenyl silicone oil and 10 g of phenylmethyl silicone oil were dissolved in 50 mL of n-heptane, and 0.5 mL of n-octanoic acid was added. After stirring evenly, it was completely added to the magnetic powder dispersion, and 2.5 mL of ammonia water was added. After stirring for 300 minutes, the silicone oil-based magnetic liquid was obtained.

[0076] The magnetic liquid obtained above has a saturation magnetization intensity of 15.63emu / g, has excellent high and low temperature resistance, radiation resistance, lubrication performance, uniform particle distribution, no agglomeration, no sedimentation, and is capable of working in the special working environment in the field of nuclear power generation. It is a silicone oil-based magnetic liquid with low volatility and radiation resistance.

[0077] Example 4

[0078] The difference from Example 1 is that epoxymethyl silicone oil is used as the surfactant.

[0079] Example 5

[0080] The difference from Example 1 is that ethylene oxide silicone oil is used as the surfactant.

[0081] Example 6

[0082] The difference from Example 1 is that n-decanoic acid is used as the modifier.

[0083] Comparative Example 1

[0084] The difference from Example 1 is that oleic acid (C 18 unsaturated fatty acids). The black viscous liquid obtained in this example will directly undergo stratification after standing, resulting in the failure of the preparation of the magnetic liquid.

[0085] Comparative Example 2

[0086] The difference from Example 2 is that no surfactant is added during the preparation process. In this example, the preparation is unsuccessful due to the lack of surfactant, and the magnetic liquid cannot be obtained.

[0087] Comparative Example 3

[0088] The difference from Example 3 is that no modifier is added during the preparation process. The magnetic liquid obtained in this example precipitates the base carrier liquid after being left to stand for about half an hour under the magnetic field, and a stable magnetic liquid cannot be obtained.

[0089] Comparative Example 4

[0090] The difference from Example 1 is that 12 g of the activated magnetic particles are dispersed in a mixed solution of water and ethanol (volume ratio of ethanol: water = 1:1), and stirred in a water bath at 80°C; 12 g of epoxyphenyl silicone oil and 20 g of methylphenyl silicone oil are dissolved in 50 mL of n-heptane, and 1.5 mL of n-octanoic acid is added. After stirring evenly, it is completely added to the magnetic powder dispersion, and stirring is continued for 300 minutes to obtain a black viscous liquid. The liquid is placed on a magnet, and stratification occurs after 12 hours, resulting in failure in the preparation of the magnetic liquid.

[0091] Test example

[0092] The saturation magnetic intensity test was performed on the magnetic liquids prepared in Examples 1 to 6, and the test results are shown in Table 1 below.

[0093] The saturation magnetic intensity test method is as follows: the obtained magnetic liquid is subjected to a saturation magnetic intensity test using a vibrating sample magnetometer.

[0094] Table 1:

[0095]

[0096] According to Table 1, the silicone oil-based magnetic liquids prepared in Examples 1 to 6 have excellent high and low temperature resistance, radiation resistance, lubrication performance, uniform particle distribution, no agglomeration, no sedimentation, and are novel silicone oil-based magnetic liquids that can cope with the special working environment in the field of nuclear power generation; Comparative Examples 1 to 4 cannot obtain stable magnetic liquids.

[0097] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction 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 may be for different embodiments or examples. 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, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0098] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0099] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A silicone oil-based magnetic liquid with low volatility and radiation resistance, characterized in that: include: Nanomagnetic particles; Modifier, the nano magnetic particles are transformed from water-soluble to oil-soluble under the action of the modifier, and the modifier includes C 10 One or more of the following low molecular weight saturated fatty acids; A surfactant, wherein the surfactant is coated on the surface of the nanomagnetic particles modified by the modifier, the surfactant comprises epoxy-modified silicone oil, the mass ratio of the modifier to the surfactant is 1:(5-20), and the mass ratio of the nanomagnetic particles to the surfactant is 1:(1-3); The base carrier liquid comprises benzyl silicone oil, and the mass ratio of the nano magnetic particles to the base carrier liquid is 1:(1-3).

2. The silicone oil-based magnetic liquid according to claim 1, characterized in that: The nano magnetic particles include one or more of iron nitride, carbonyl iron, iron, ferroferric oxide, and ferrite magnetic particles.

3. The silicone oil-based magnetic liquid according to claim 2, characterized in that: The ferrite magnetic particles include MFe2O4 and M 1-X Zn X Fe2O4, wherein M is one of Mn, Co, Ni, Cu, Cd, Pb, Sn, Ca, Sr, Ba, and Mg.

4. The silicone oil-based magnetic liquid according to claim 1, characterized in that: The epoxy-modified silicone oil includes one or more of methyl silicone oil containing epoxy groups, ethyl silicone oil containing epoxy groups, and phenyl silicone oil containing epoxy groups; And / or, the benzyl silicone oil includes one or more of low benzyl silicone oil, medium benzyl silicone oil and high benzyl silicone oil.

5. A method for preparing a silicone oil-based magnetic liquid, characterized in that: The method for preparing the silicone oil-based magnetic liquid according to any one of claims 1 to 4 comprises the following steps: (a) selecting high-grade pure raw materials to prepare magnetic nanoparticles, dissolving all solid raw materials into aqueous solution, removing insoluble matter by vacuum filtration, and further purifying the raw materials for preparing magnetic nanoparticles; (b) activating the magnetic particles; (c) Magnetic particles after modification and dispersion activation.

6. The method according to claim 5, characterized in that The step (a) comprises: 2+ , Fe 3+ OH - The molar ratio of Fe 3+ and Fe 2+ The compound is dissolved in deionized water, stirred evenly, and then the insoluble matter is removed by vacuum filtration to obtain a mixed iron salt solution. Ammonia water is added under the conditions of a temperature of 25-100° C. and a stirring speed of 200-500 r / min. The reaction time is 1-60 min to obtain nano magnetic particles. The nano magnetic particles are repeatedly washed with water until the conductivity σ of the eluate is ≤100 μs / cm.

7. The method according to claim 5, characterized in that The step (b) comprises adding the nanomagnetic particles to a ferric chloride solution with a pH of 0 to 3, and heating the solution in a water bath for 1 to 60 minutes; and washing the nanomagnetic particles until the conductivity of the eluate is σ≤10 μs / cm.

8. The method according to claim 5, characterized in that The step (c) comprises dispersing the activated nano magnetic particles in a mixture of water and ethanol, adding the mixture to a mixture of a base carrier liquid, a surfactant, a modifier and a transition liquid at 20-100° C., adding ammonia water, and stirring until the water, ethanol and the transition liquid are completely volatilized to obtain a silicone oil-based magnetic liquid.

9. Use of the silicone oil-based magnetic liquid according to any one of claims 1 to 4 or the silicone oil-based magnetic liquid prepared by the method according to any one of claims 5 to 8 in a nuclear reactor sealing system.

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