A kind of magnetic grease and preparation method thereof

Abstract

The present invention provides a magnetic grease and a preparation method thereof, belonging to the field of magnetic material technology. Taking the total mass of the magnetic grease as 100%, the magnetic grease comprises the following components: 10-20% magnetic powder, 15-30% base carrier liquid, 10-20% surfactant, 10-50% thickener, and 1-10% additive. The magnetic powder is nanomagnetic particles modified with a hydrocarbon substance containing polar groups, the base carrier liquid is benzyl silicone oil, the surfactant is epoxy-modified silicone oil, the thickener is silica-coated micron magnetic particles modified with hydrogenated silicone oil, and the additive is vinyl silicone oil. The magnetic grease exhibits excellent magnetic properties, stability, radiation resistance, and low volatility, making it suitable for the specialized working environments of nuclear power generation. Furthermore, when encountering abnormal friction during operation, the magnetic grease can reduce component wear and tear and automatically provide feedback indicating abnormal seal conditions, allowing operators to promptly detect and troubleshoot faults.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic materials, and in particular relates to a magnetic grease and a preparation method thereof. Background Art

[0002] As a key pillar of the modern energy system, nuclear energy plays a key role in addressing global energy shortages and promoting the development of a low-carbon economy. However, its technical application still faces numerous challenges, particularly during the operation and maintenance of nuclear reactors, where efficient circulation control of the cooling medium and leakage prevention constitute dual technical bottlenecks. As the main pump of core equipment, the reliability of its sealing device is a key element in ensuring the continued stable operation of nuclear power plants. Although the existing mainstream multi-stage mechanical sealing solutions perform well under normal operating conditions, trace medium leakage still occurs during the start-up and shutdown phases of the unit, which has become a major technical problem hindering the improvement of nuclear power safety performance.

[0003] The emergence of magnetic media sealing technology has brought new hope to nuclear reactor sealing. This sealing method, based on the properties of magnetic media, demonstrates tremendous application potential in numerous high-tech and industrial fields due to its superior sealing performance, long service life, exceptional stability, and environmentally friendly characteristics. Among magnetic media sealing materials, magnetic grease is a novel composite nanomaterial. Magnetic grease is formed by coating nanometer-sized magnetic particles, uniformly dispersing them in a carrier fluid, and then thickening them with a thickening agent. Due to its extremely high viscosity, magnetic grease can withstand the erosion of liquids during sealing and exhibits high stability.

[0004] However, due to the large specific surface area and extremely high surface energy of nanomagnetic particles, they are prone to agglomeration. The base carrier fluid used has been thickened with a thickener to have a high viscosity and poor fluidity. Therefore, during the preparation process, the nanomagnetic particles are prone to uneven dispersion in the base carrier, which affects the performance of the magnetic grease. Furthermore, the high dispersion difficulty means that more nanomagnetic particles cannot be added to the magnetic grease, which limits the saturation magnetization strength of the magnetic grease and its pressure resistance when used for sealing.

[0005] Furthermore, ensuring the long-term stability and reliability of magnetic grease in the complex and harsh radiation environment surrounding nuclear reactors has become a pressing technical challenge. An ideal magnetic grease must not only exhibit excellent low volatility and radiation resistance, but also effectively absorb or shield nuclear radiation, preventing the leakage of radioactive materials and thus protecting the surrounding environment and personnel. Therefore, developing new low-volatility, radiation-resistant, and radiation-absorbing magnetic greases is crucial to improving the overall level of nuclear reactor sealing technology and is key to promoting the safe and efficient use of nuclear energy.

[0006] On the other hand, in actual use, magnetic greases have numerous components and operate in a complex environment. If they enter an abnormal operating state due to factors such as shaft eccentricity or external dust particles being drawn into the bearings and causing friction, this can directly manifest as a temperature rise in the seal area. If not promptly addressed, this can lead to rapid wear and even damage to the seal, ultimately causing leakage of the sealed medium and irreversible damage. Existing magnetic greases only isolate the sealed medium from the outside world through the magnetic field; they lack the ability to protect the seal components or generate feedback signals when temperatures exceed normal limits. Summary of the Invention

[0007] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, an embodiment of the present invention provides a magnetic grease and a preparation method thereof.

[0008] In the first aspect, an embodiment of the present invention provides a magnetic grease, which includes the following components, based on the total mass of the magnetic grease as 100%, 10-20% magnetic powder, 15-30% base carrier liquid, 10-20% surfactant, 10-50% thickener, and 1-10% additive. The magnetic powder is nanomagnetic particles modified with hydrocarbon substances with polar groups, the base carrier liquid is benzyl silicone oil, the surfactant is epoxy-modified silicone oil, the thickener is silica-coated micron magnetic particles modified with hydrogenated silicone oil, and the additive is vinyl silicone oil.

[0009] The advantages and technical effects of the magnetic grease of the embodiment of the present invention are as follows:

[0010] (1) Since phenylmethyl silicone oil is used as the base liquid, the magnetic grease of the embodiment of the present invention has the advantages of good chemical inertness, thermal stability, oxidation resistance, low vapor pressure and ignition point; in addition, compared with the magnetic grease in the prior art that uses dimethyl silicone oil as the base liquid, the magnetic grease in the embodiment of the present invention also has better low volatility and the working temperature can reach -50℃~250℃; in addition, dimethyl silicone oil is not resistant to radiation and will undergo cross-linking reaction and solidification under the action of radiation, and cannot play the role of dynamic sealing in a radiation environment. Therefore, the magnetic grease in the prior art that uses dimethyl silicone oil as the base liquid does not have radiation resistance. However, since phenylmethyl silicone oil is used as the base liquid, phenylmethyl silicone oil is resistant to radiation and will not undergo cross-linking reaction and solidification under the action of radiation. Therefore, the magnetic grease in the embodiment of the present invention has good radiation resistance and can play the role of dynamic sealing in a radiation environment.

[0011] (2) The magnetic grease in the prior art directly uses nanomagnetic particles as magnetic powder. However, the nanomagnetic particles are hydrophilic and cannot be stably dispersed in a silicone oil-based carrier liquid. They will precipitate under the influence of gravity, magnetic field, etc., while the magnetic powder in the magnetic grease of the embodiment of the present invention is nanomagnetic particles modified with hydrocarbon substances with polar groups. The magnetic powder is lipophilic and can be stably dispersed in a silicone oil-based carrier liquid.

[0012] (3) The magnetic grease of the embodiment of the present invention uses epoxy-modified silicone oil as a surfactant. The surfactant can perform secondary modification on the magnetic powder, thereby improving the compatibility between the magnetic powder and the base carrier liquid, thereby improving the stability of the magnetic grease.

[0013] (4) The magnetic grease of the embodiment of the present invention uses micron magnetic particles coated with silica modified with hydrogenated silicone oil as a thickener, which contains micron magnetic particles, thereby greatly improving the saturation magnetization intensity of the magnetic grease and greatly enhancing the pressure resistance when used for sealing.

[0014] (5) The magnetic grease of the embodiment of the present invention uses silica-coated micron magnetic particles modified with hydrogenated silicone oil as a thickener, and vinyl silicone oil as an additive. During the use of the seal, when abnormal friction occurs, it will cause local overheating of the friction part. When the temperature exceeds the threshold, the vinyl group of the vinyl silicone oil in the magnetic grease of the embodiment of the present invention and the silicon-hydrogen bond in the hydrogenated silicone oil can spontaneously undergo a cross-linking and curing reaction to form a viscoelastic body with a buffering and shock-absorbing effect, thereby reducing the friction of parts. Its viscosity is significantly improved, and the friction torque is increased, so that the friction torque electrical signal of the motor is fed back to indicate that the seal is in an abnormal state, so that the operator can promptly discover the fault and replace the new magnetic grease, thereby realizing the intelligence of the magnetic medium seal and improving the sealing reliability.

[0015] (6) The magnetic grease of the embodiment of the present invention not only has excellent magnetic properties, stability, radiation resistance, and low volatility, but also has low equipment requirements. When used in the field of nuclear energy-related sealing, it does not react with the sealed medium, has high viscosity and extremely low volatility, and can be used in high-temperature and high-vacuum sealing conditions. Under high temperature, no thermal decomposition and volatilization of components occur, which can ensure the cleanliness requirements of the cavity. It has the advantages of zero leakage, long life, high reliability, and environmental protection.

[0016] In some embodiments, in the magnetic powder, the mass ratio of the nanomagnetic particles to the hydrocarbon substance with polar groups is (1-15):1.

[0017] In some embodiments, the hydrocarbon substance with a polar group is selected from at least one of oleic acid, linoleic acid, linolenic acid, stearic acid and palmitic acid.

[0018] In some embodiments, the surfactant is selected from at least one of methyl silicone oil containing epoxy groups, ethyl silicone oil containing epoxy groups, and phenyl silicone oil containing epoxy groups.

[0019] In some embodiments, in the thickening agent, the mass ratio of the hydrogen-containing silicone oil, the silicon dioxide, and the micron magnetic particles is (5-10):1:(15-30).

[0020] In some embodiments, the material of the nano magnetic particles is selected from at least one of magnetite, ferric oxide, iron nitride, iron carbonyl, iron, MFe2O4, and M 1-X Zn X Fe2O4, where M is Mn, Co, Ni, Cu, Cd, Pb, Sn, Ca, Sr, Ba, or Mg, 0 < x ≤ 1; and / or, the material of the micron magnetic particles is selected from at least one of magnetite, ferric oxide, iron nitride, and iron carbonyl.

[0021] In a second aspect, an embodiment of the present invention provides a method for preparing a magnetic grease, including the following steps:

[0022] S1. Mix the magnetic powder with water to obtain a magnetic powder suspension; then mix the magnetic powder suspension with an organic hydrocarbon solvent to obtain a volatile solvent-based magnetic liquid.

[0023] S2. Mix the volatile solvent-based magnetic liquid with the surfactant and the base carrier liquid, add ammonia water for modification treatment during stirring, and then perform evaporation treatment to obtain a silicone oil-based magnetic liquid.

[0024] S3. Mix the silicone oil-based magnetic liquid with the thickening agent and the additive to obtain the magnetic grease described in the first aspect.

[0025] The advantages and technical effects brought by the method for preparing the magnetic grease according to the embodiment of the present invention are as follows:

[0026] (1) In step S1, the nano magnetic particles modified with a hydrocarbon substance with a polar group are used as the magnetic powder, and the magnetic powder can be stably dispersed in the silicone oil-based carrier liquid; in addition, preparing the volatile solvent-based magnetic liquid first in step S1 can also make the magnetic powder in a uniformly dispersed state, so that the magnetic powder can be stably dispersed in the silicone oil-based carrier liquid, and then the volatile medium is evaporated in step S2 to obtain a uniformly and stably dispersed silicone oil-based magnetic liquid.

[0027] (2) The role of ammonia water in step S2 is to promote the hydrolysis and ring opening of the surfactant, perform secondary modification on the magnetic powder, and improve the compatibility between the magnetic powder and the base carrier liquid, thereby improving the stability of the magnetic grease.

[0028] (3) In step S3, the silicone oil-based magnetic liquid is mixed with a thickener and an additive. The thickener can thicken the flowing base carrier liquid into a non-flowing solid to semi-solid base carrier fat, thereby obtaining the magnetic grease described in the first aspect.

[0029] In some embodiments, in step S1, the preparation method of the magnetic powder is as follows: dispersing the nanomagnetic particles in water to obtain a nanomagnetic particle dispersion, adding ammonia water to the nanomagnetic particle dispersion to adjust the pH to 9-10 to obtain a nanomagnetic particle suspension; then adding the hydrocarbon substance with polar groups to the nanomagnetic particle suspension, performing a modification treatment under stirring, and then performing a magnetic precipitation treatment, and then washing the material obtained after the magnetic precipitation treatment with water until it is neutral to obtain the magnetic powder;

[0030] And / or, the organic hydrocarbon solvent is at least one selected from kerosene, petroleum gas, gasoline, paraffin oil, benzene and toluene.

[0031] In some embodiments, in step S2, the mass ratio of the magnetic powder contained in the volatile solvent-based magnetic liquid to the surfactant and the base carrier liquid is 1:(0.5-1.5):(0.5-2.5).

[0032] In some embodiments, in step S3, the thickener is prepared as follows:

[0033] (1) adding the micron magnetic particles to a mixture of water and anhydrous ethanol and performing ultrasonic dispersion to form a suspension;

[0034] (2) The suspension is heated while being stirred, and then a mixture of ammonia water and alcohol is slowly poured into the suspension being stirred, and stirring is continued. Then, a mixture of ethyl orthosilicate and alcohol is slowly poured into the suspension. After the addition is completed, the mixture is capped and stirred to obtain a turbid liquid;

[0035] (3) subjecting the turbid liquid to magnetic precipitation until the upper liquid is clear, discarding the supernatant, and repeatedly washing the precipitate until the pH value of the supernatant reaches 7 to 8. Discarding the supernatant to obtain washed magnetic particles;

[0036] (4) drying and crushing the cleaned magnetic particles to obtain silica-coated micron magnetic particles;

[0037] (5) The silica-coated micron magnetic particles are transferred into a three-necked flask equipped with a stirrer and a reflux condenser, and acetone is added at the same time. The hydrogenated silicone oil is slowly added dropwise into the three-necked flask through a constant pressure dropping funnel, and the reaction is carried out at room temperature. The reaction product is transferred to a rotary evaporator and subjected to rotary evaporation under heating to obtain a hydrogenated silicone oil-modified substance. The hydrogenated silicone oil-modified substance is then dried and pulverized to obtain the thickener;

[0038] And / or, the mass ratio of the thickener, the additive, and the magnetic powder contained in the silicone oil-based magnetic liquid is (0.2-3):(0.2-3):1. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 3 is a comparison diagram of the magnetic grease prepared in an embodiment of the present invention and the magnetic grease after cross-linking and curing; wherein, a is the magnetic grease prepared in an embodiment of the present invention, and b is the magnetic grease after cross-linking and curing. DETAILED DESCRIPTION

[0040] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0041] In the first aspect, an embodiment of the present invention provides a magnetic grease. Taking the total mass of the magnetic grease as 100%, the magnetic grease includes the following components: 10-20% magnetic powder, 15-30% base carrier liquid, 10-20% surfactant, 10-50% thickener, and 1-10% additive. The magnetic powder is nanomagnetic particles modified with hydrocarbon substances with polar groups, the base carrier liquid is benzyl silicone oil, the surfactant is epoxy-modified silicone oil, the thickener is silica-coated micron magnetic particles modified with hydrogenated silicone oil, and the additive is vinyl silicone oil.

[0042] Since phenylmethyl silicone oil is used as the base carrier liquid, the magnetic grease of the embodiment of the present invention has the advantages of good chemical inertness, thermal stability, oxidation resistance, low vapor pressure and flash point; in addition, compared with the magnetic grease in the prior art that uses dimethyl silicone oil as the base carrier liquid, the magnetic grease in the embodiment of the present invention also has better low volatility, and the operating temperature can reach -50°C to 250°C; in addition, dimethyl silicone oil is not resistant to radiation, and will undergo a cross-linking reaction and solidification under the action of radiation, and cannot play a dynamic sealing role in a radiation environment. Therefore, the magnetic grease in the prior art that uses dimethyl silicone oil as the base carrier liquid does not have radiation resistance. Since phenylmethyl silicone oil is used as the base carrier liquid, phenylmethyl silicone oil is resistant to radiation and will not undergo a cross-linking reaction and solidification under the action of radiation. Therefore, the magnetic grease in the embodiment of the present invention has good radiation resistance and can play a dynamic sealing role in a radiation environment.

[0043] The magnetic grease in the prior art directly uses nanomagnetic particles as magnetic powder. However, the nanomagnetic particles are hydrophilic and cannot be stably dispersed in a silicone oil-based carrier liquid. They will precipitate under the influence of gravity, magnetic field, etc., while the magnetic powder in the magnetic grease of the embodiment of the present invention is nanomagnetic particles modified with hydrocarbon substances with polar groups. The magnetic powder is lipophilic and can be stably dispersed in a silicone oil-based carrier liquid.

[0044] The magnetic grease of the embodiment of the present invention uses epoxy-modified silicone oil as a surfactant. The surfactant can perform secondary modification on the magnetic powder, thereby improving the compatibility between the magnetic powder and the base carrier liquid, thereby improving the stability of the magnetic grease.

[0045] The magnetic grease of the embodiment of the present invention uses hydrogenated silicone oil-modified silica-coated micron magnetic particles as a thickener, which contains micron magnetic particles, thereby greatly improving the saturation magnetization intensity of the magnetic grease and greatly enhancing the pressure resistance when used for sealing.

[0046] The magnetic grease of the embodiment of the present invention uses silica-coated micron magnetic particles modified with hydrogen-containing silicone oil as a thickener, and vinyl silicone oil as an additive. During the use of the seal, when abnormal friction occurs, it will cause local overheating of the friction part. When the temperature exceeds the threshold, the vinyl group of the vinyl silicone oil in the magnetic grease of the embodiment of the present invention and the silicon-hydrogen bond in the hydrogen-containing silicone oil can spontaneously undergo a cross-linking and curing reaction to form a viscoelastic body with a buffering and shock-absorbing effect, thereby reducing the friction of parts. Its viscosity is significantly improved, and the friction torque is increased, so that the friction torque electrical signal of the motor is used to feedback that the seal is in an abnormal state, so that the operator can promptly detect the fault and replace the new magnetic grease, thereby realizing the intelligence of the magnetic medium seal and improving the sealing reliability.

[0047] The magnetic grease of the present invention not only exhibits excellent magnetic properties, stability, radiation resistance, and low volatility, but also has low equipment requirements. When used in nuclear energy-related sealing applications, it exhibits no reaction with the sealed medium, high viscosity, and extremely low volatility, making it suitable for high-temperature and high-vacuum sealing conditions. Thermal decomposition and volatilization of components are prevented at high temperatures, ensuring cleanliness requirements within the cavity. It offers advantages such as zero leakage, long life, high reliability, and environmental friendliness.

[0048] Based on the total mass of the magnetic grease being 100%, the content of the magnetic powder is 10-20%, for example, 10%, 12%, 14%, 16%, 18%, 20%, etc. When the content of the magnetic powder is too low, it is not conducive to improving the saturation magnetization intensity of the magnetic grease. When the content of the magnetic powder is too high, it is not conducive to improving the uniformity and stability of the magnetic grease.

[0049] Based on the total mass of the magnetic grease being 100%, the content of the base carrier liquid is 15-30%, for example, 15%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, etc. If the content of the base carrier liquid is too low, uniform dispersion of the magnetic powder is not achieved. If the content of the base carrier liquid is too high, the content of the magnetic powder may be too low, which is not conducive to increasing the saturation magnetization of the magnetic grease.

[0050] The base carrier fluid used in the embodiments of the present invention is a phenylmethyl silicone oil containing phenyl groups in the siloxane chain. Due to the introduction of aromatic groups with a large conjugated structure, phenylmethyl silicone oil has better high-temperature resistance, radiation resistance, and solubility than conventional dimethyl silicone oil. It has an operating temperature range of -50°C to 250°C and is an excellent low-volatility, radiation-resistant base carrier fluid. In some embodiments, the phenylmethyl silicone oil is at least one of low-, medium-, and high-benzyl silicone oils.

[0051] Based on the total mass of the magnetic grease as 100%, the content of the surfactant is 10-20%, for example, 10%, 12%, 14%, 16%, 18%, 20%, etc. When the content of the surfactant is too low, it is not conducive to improving the compatibility between the magnetic powder and the base carrier liquid, thereby not conducive to improving the stability of the magnetic grease. When the content of the surfactant is too high, the improvement of the aforementioned effects is not significant, and it is not conducive to reducing costs and increasing efficiency.

[0052] Based on the total mass of the magnetic grease as 100%, the thickener content is 10-50%, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc. If the thickener content is too low, it is not conducive to increasing the saturation magnetization strength of the magnetic grease and is not conducive to reducing component friction when the magnetic grease encounters abnormal friction during operation. If the thickener content is too high, it is not conducive to improving the uniformity of the magnetic grease.

[0053] Based on the total mass of the magnetic grease as 100%, the additive content is 1-10%, for example, 1%, 2%, 4%, 6%, 8%, 10%, etc. If the additive content is too low, the magnetic grease will not be able to reduce component wear when encountering abnormal friction during operation. If the additive content is too high, the contents of other components will be too low, which will not be conducive to improving the overall performance of the magnetic grease.

[0054] In some embodiments, the mass ratio of the nanomagnetic particles to the hydrocarbon material with polar groups in the magnetic powder is (1-15):1, for example, 1:1, 3:1, 5:1, 7:1, 9:1, 11:1, 13:1, 15:1, etc. If this mass ratio is too low, it is not conducive to increasing the proportion of nanomagnetic particles in the magnetic grease, thereby hindering the improvement of the saturation magnetization intensity of the magnetic grease. If this mass ratio is too high, it is not conducive to improving the lipophilicity of the magnetic powder, thereby hindering the improvement of the dispersion uniformity of the magnetic powder.

[0055] In some embodiments, the hydrocarbon substance with polar groups is selected from at least one of oleic acid, linoleic acid, linolenic acid, stearic acid, and palmitic acid. The above substances can increase the lipophilicity of the magnetic powder, thereby improving the dispersion uniformity of the magnetic powder.

[0056] In some embodiments, the surfactant is selected from at least one of methyl silicone oil containing epoxy groups, ethyl silicone oil containing epoxy groups, and phenyl silicone oil containing epoxy groups. These surfactants help improve the compatibility between the magnetic powder and the base carrier liquid, thereby improving the stability of the magnetic grease.

[0057] In some embodiments, the mass ratio of the hydrogenated silicone oil, silica, and micronized magnetic particles in the thickener is (5-10):1:(15-30), for example, 5:1:15, 5:1:20, 5:1:25, 5:1:30, 8:1:15, 8:1:20, 8:1:30, 10:1:15, 10:1:20, 10:1:30, etc. The silica protective layer can increase the number of active sites on the surface of the micronized magnetic particles, enhancing their ability to be modified; it can also prevent air oxidation. Within this mass ratio of the three substances, the thickener exhibits good lipophilicity and thickening properties, while also increasing the saturation magnetization of the magnetic grease. Furthermore, the silica protective layer protects the micronized magnetic particles by coating them.

[0058] The thickener contains micron magnetic particles instead of nano magnetic particles because the saturation magnetization intensity of micron magnetic particles is greater. The obtained magnetic grease has a higher saturation magnetization intensity and stronger sealing and pressure resistance.

[0059] In some embodiments, the material of the nanomagnetic particles is selected from ferroferric oxide, ferric oxide, iron nitride, carbonyl iron, iron, MFe2O4 and M 1-X Zn X At least one of Fe2O4, wherein M is Mn, Co, Ni, Cu, Cd, Pb, Sn, Ca, Sr, Ba or Mg, <x≤1。

[0060] In some embodiments, the material of the micron magnetic particles is selected from at least one of ferroferric oxide, ferrous oxide, iron nitride, and carbonyl iron.

[0061] In a second aspect, an embodiment of the present invention provides a method for preparing a magnetic lipid, comprising the following steps:

[0062] S1. The magnetic powder is mixed with water to obtain a magnetic powder suspension; the magnetic powder suspension is then mixed with an organic hydrocarbon solvent to obtain a volatile solvent-based magnetic liquid;

[0063] S2. The volatile solvent-based magnetic liquid is mixed with the surfactant and the base carrier liquid, and ammonia is added during the stirring process for modification, and then evaporated to obtain a silicone oil-based magnetic liquid;

[0064] S3. Mix the silicone oil-based magnetic liquid with the thickener and the additive to obtain the magnetic grease described in the first aspect.

[0065] In step S1, nanomagnetic particles modified with hydrocarbon substances with polar groups are used as magnetic powder, and the magnetic powder can be stably dispersed in a silicone oil-based carrier liquid; in addition, the volatile solvent-based magnetic liquid is first prepared in step S1, which can also make the magnetic powder in a uniformly dispersed state; then, in step S2, the volatile medium is evaporated to obtain a uniformly and stably dispersed silicone oil-based magnetic liquid. The role of ammonia water in step S2 is to promote the hydrolysis and ring opening of the surfactant, so as to achieve secondary modification of the magnetic powder, improve the compatibility of the magnetic powder with the base carrier liquid, and thus improve the stability of the magnetic grease. In step S3, the silicone oil-based magnetic liquid is mixed with a thickener and an additive. The thickener can thicken the flowing base carrier liquid into a non-flowing solid to semi-solid base carrier grease to obtain the magnetic grease described in the first aspect.

[0066] In some embodiments, in step S1, the magnetic powder is prepared as follows: the nanomagnetic particles are dispersed in water to obtain a nanomagnetic particle dispersion; aqueous ammonia is added to the nanomagnetic particle dispersion to adjust the pH to 9-10 to obtain a nanomagnetic particle suspension; the hydrocarbon substance with polar groups is then added to the nanomagnetic particle suspension, the suspension is modified under stirring, and then subjected to magnetic precipitation. The resulting suspension is then washed with water until neutral to obtain the magnetic powder. Modifying the nanomagnetic particles with a hydrocarbon substance with polar groups can increase the lipophilicity of the magnetic powder, thereby improving the uniformity of its dispersion. The addition of aqueous ammonia in this step adjusts the pH of the nanomagnetic particle dispersion to 9-10, allowing the hydrocarbon substance with polar groups to better modify the nanomagnetic particles. Optionally, in step S1, the modification temperature is 20-100°C, the stirring speed is 200-500 rpm, and the reaction time is 120-300 min.

[0067] In some embodiments, in step S1, the organic hydrocarbon solvent is selected from at least one of kerosene, petroleum gas, gasoline, paraffin oil, benzene, and toluene. All of these organic hydrocarbon solvents are volatile solvents. Preparing a volatile solvent-based magnetic liquid in step S1 allows the magnetic powder to be uniformly dispersed. Then, in step S2, the volatile solvent is replaced with the base carrier liquid of the present invention, allowing the magnetic powder to be uniformly dispersed in the base carrier liquid.

[0068] In some embodiments, in step S2, the mass ratio of the magnetic powder, the surfactant, and the base carrier liquid in the volatile solvent-based magnetic liquid is 1:(0.5-1.5):(0.5-2.5), for example, 1:0.5:0.5, 1:1:1, 1:1.5:1.5, 1:0.5:1, 1:0.5:1.5, 1:0.5:2.5, 1:1:0.5, 1:1:1.5, 1:1:2, 1:1:2.5, 1:1:0.5, 1:1.5:0.5, 1:1.5:2, 1:1.5:2.5, etc. When the mass ratio of the above three substances is within this range, the magnetic grease can achieve good saturation magnetization, uniformity, and stability.

[0069] In some embodiments, in step S2, the modification temperature is 20-100° C., the stirring speed is 200-500 rpm, and the reaction time is 120-300 min.

[0070] In some embodiments, in step S3, the thickener is prepared as follows:

[0071] (1) adding the micron magnetic particles to a mixture of water and anhydrous ethanol and performing ultrasonic dispersion to form a suspension;

[0072] (2) The suspension is heated while being stirred, and then a mixture of ammonia water and alcohol is slowly poured into the suspension being stirred, and stirring is continued. Then, a mixture of ethyl orthosilicate and alcohol is slowly poured into the suspension. After the addition is completed, the mixture is capped and stirred to obtain a turbid liquid;

[0073] (3) subjecting the turbid liquid to magnetic precipitation until the upper liquid is clear, discarding the supernatant, and repeatedly washing the precipitate until the pH value of the supernatant reaches 7 to 8. Discarding the supernatant to obtain washed magnetic particles;

[0074] (4) drying and crushing the cleaned magnetic particles to obtain silica-coated micron magnetic particles;

[0075] (5) The silica-coated micron magnetic particles are transferred into a three-necked flask equipped with a stirrer and a reflux condenser, and acetone is added at the same time. The hydrogenated silicone oil is slowly added dropwise into the three-necked flask through a constant pressure dropping funnel, and the reaction is carried out at room temperature. The reaction product is transferred into a rotary evaporator and subjected to rotary evaporation under heating conditions to obtain a substance modified with hydrogenated silicone oil. The hydrogenated silicone oil modified substance is then dried and pulverized to obtain the thickener.

[0076] In some embodiments, in step S3, the mass ratio of the thickener, the additive and the magnetic powder contained in the silicone oil-based magnetic liquid is (0.2-3): (0.2-3): 1, for example, 0.2:0.2:1, 0.5:0.5:1, 1:1:1, 1.5:1.5:1, 2:2:1, 2.5:2.5:1, 3:3:1, 0.2:0.5:1, 0.2:1:1, 0.2:1.5:1, 0.2:2:1, 0.2 :2.5:1, 0.2:3:1, 1:0.2:1, 1:0.5:1, 1:1.5:1, 1:2:1, 1:2.5:1, 1:3:1, 1.5:0.2:1, 1.5:1:1, 1.5:1.5:1, 1.5:2:1, 1.5:2.5:1, 1.5:3:1, 2:0.2:1, 2:1:1, 2:2:1, 2:3:1, 3:0.2:1, 3:1:1, 3:2:1, 3:3:1, etc. When the mass ratio of the above three substances is within this range, it is helpful for the magnetic grease to have a good saturation magnetization and give full play to the role of reducing component friction when encountering abnormal friction during operation.

[0077] The present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0078] The raw materials used in the following examples are all high-grade pure raw materials.

[0079] Example 1: Preparation of Fe3O4 silicon-based magnetic grease

[0080] 1. Dissolve 32g of ferric chloride in 600mL of deionized water, stir evenly, and heat in a water bath to 45°C. Weigh 20g of ferrous chloride tetrahydrate and add it to the ferric chloride solution. Stir at 400rpm for 5min to obtain a mixed salt solution.

[0081] 100 mL of concentrated aqueous ammonia (precipitant) was added to the mixed salt solution to adjust its pH to 9-10, and the solution was heated in a water bath and stirred for 45 minutes to obtain a nanomagnetic particle suspension.

[0082] 2. Take 5mL of oleic acid (a hydrocarbon substance with polar groups) and add it to the nanomagnetic particle suspension. Raise the water bath temperature to 80℃ and stir at 400rpm for 1 hour. Then cool it and use a magnet to precipitate it. Then wash the material obtained after magnetic precipitation with pure water five times until it is neutral to obtain Fe3O4 magnetic powder.

[0083] 3. Then, add 600 mL of ultrapure water to the Fe3O4 magnetic powder prepared above and sonicate for 30 minutes to obtain a Fe3O4 magnetic powder suspension. The Fe3O4 magnetic powder suspension is then placed in an 80°C water bath and stirred at 400 rpm. Add 30 mL of kerosene (an organic hydrocarbon solvent) and continue heating in the water bath with stirring for 1 hour. The suspension is then transferred to a magnet and the supernatant removed to obtain a kerosene-based magnetic liquid.

[0084] 4. Add 24g of epoxy-terminated benzyl silicone oil (surfactant) and 40mL of benzyl silicone oil (base carrier liquid) to the kerosene-based magnetic liquid, then continue to place it in a water bath, start stirring at 400rpm, add 5mL of ammonia water, keep heating in the water bath and continue stirring for 2h to obtain silicone oil-based magnetic liquid.

[0085] 5. Prepare the thickener. First, take 60g of Fe3O4 magnetic powder with a particle size of 2μm and add it to a mixture of 100mL deionized water, 300mL and anhydrous ethanol to form a suspension, and ultrasonically disperse it for 30min; heat the suspension to 60℃ and stir it with a stirrer at 400rpm for 10min, then measure 20mL of ammonia water and 20mL of alcohol, mix them and slowly pour them into the stirring suspension, continue stirring for 5min, then measure 10mL of ethyl orthosilicate and 10mL of alcohol, mix them thoroughly, and then slowly pour them into the above suspension. After the addition is complete, cover and stir for 3h to obtain a turbid liquid containing magnetic particles; use The turbid solution containing the magnetic particles was precipitated by a magnet until the upper liquid layer became clear. The supernatant was discarded and washed with sufficient deionized water. This washing step was repeated until the pH value of the supernatant reached 7-8. The washed magnetic particles were dried in a 60°C drying oven for 48 hours. The dried magnetic particles were then crushed into powder using a grinder to obtain micron magnetic particles with a particle size of 2 μm and a silica protective layer covering the entire surface. The above sample was transferred to a three-necked flask equipped with a stirrer and a reflux condenser. Acetone (as a solvent) was added and hydrogenated polysiloxane (also known as hydrogenated silicone oil) was slowly added dropwise to the three-necked flask via a constant pressure dropping funnel. The reaction was carried out at room temperature for 4 hours. The product was then transferred to a rotary evaporator and evaporated at 65°C to remove the solvent and small molecular compounds. The product was then dried in a 40°C forced air drying oven. The bulk sample was crushed using a high-speed rotary grinder to obtain hydrogenated silicone oil-modified silica-coated micron magnetic particles, i.e., a thickener.

[0086] 6. Raise the water bath temperature to 90°C, add 60g of the thickener prepared in step 5 and 12g of vinyl silicone oil (additive) to the silicone oil-based magnetic liquid, keep heating in the water bath and continue stirring for 2h to finally obtain silicone-based magnetic grease.

[0087] Based on 100% total mass, the magnetic grease comprises the following components: 16% magnetic powder, 20% base liquid, 16% surfactant, 40% thickener, and 8% additives. The mass ratio of the magnetic powder to the polar hydrocarbon is 8:1. The mass ratio of the thickener to hydrogenated silicone oil, silica, and micronized magnetic particles is 20:3:60.

[0088] The saturation magnetization intensity of the magnetic grease obtained above is 75 emu / g, and it has excellent high and low temperature resistance. The working temperature can reach -50℃ to 250℃, and it has excellent radiation resistance. The particles are evenly distributed, without agglomeration or sedimentation. The volatility loss of the magnetic grease within 80 hours at 90℃ is less than 1%, which makes it capable of working in the special working environment of nuclear power generation. It is a silicone-based magnetic grease with low volatility and radiation resistance.

[0089] When abnormal friction occurs during the use of the magnetic grease during sealing, it will cause local overheating of the friction part. When the temperature exceeds the threshold, the magnetic grease can spontaneously undergo a cross-linking and curing reaction to form a viscoelastic body with a buffering and shock-absorbing effect, reducing the friction of parts. Its viscosity is significantly improved, and the friction torque is increased. The friction torque electrical signal of the motor is used to feedback that the seal is in an abnormal state, so that the operator can detect the fault in time and replace the new magnetic grease, realizing the intelligentization of magnetic medium sealing and improving the sealing reliability. The comparison diagram of the magnetic grease (a) of Example 1 and the cross-linked and cured magnetic grease (b) is as follows: Figure 1 shown.

[0090] Example 2: Preparation of Iron Nitride-Based Silicon-Based Magnetic Grease

[0091] 1. Weigh 16.2g of FeCl3 and 10g of FeCl2·4H2O and dissolve them in 300mL of deionized water. Stir at 400rpm in a water bath at 40°C for 10 minutes to homogenize the mixture to obtain a mixed salt solution. Weigh 50mL of concentrated aqueous ammonia and add it to the mixed salt solution. Observe that the mixed solution quickly turns from yellow to black. Maintain heating and stirring for 45 minutes. After the reaction is complete, magnetic particles are separated and repeatedly washed with deionized water until the supernatant is neutral. Then, air dry the mixture at 100°C for 8 hours to obtain iron oxide particles.

[0092] The iron oxide particles were placed in a tube furnace, and pure ammonia was introduced with a gas flow rate of 50 mL / min. The temperature was raised to 500°C at a heating rate of 10°C / min. After being kept warm for 3 hours, the temperature was naturally cooled to room temperature. The surface was passivated with a 1% O2 / N2 mixed gas at room temperature to obtain a stable iron nitride product.

[0093] The stabilized iron nitride product was mixed with water and added to a ball mill. High-energy ball milling was performed for 5 hours to obtain a dispersion of iron nitride nanomagnetic particles. The dispersion was stirred in an 80°C water bath, and the pH of the dispersion was adjusted to 10 with an appropriate amount of ammonia water to obtain a suspension of nanomagnetic particles.

[0094] 2. Take another 5mL of oleic acid and add it to the iron nitride nanomagnetic particle suspension, place it in an 80°C water bath, stir at 400rpm for 1h, then cool it, use a magnet to perform magnetic precipitation, and then wash the material obtained after magnetic precipitation with pure water five times until neutral to obtain iron nitride magnetic powder.

[0095] 3. Then, add 300 mL of ultrapure water to the prepared iron nitride magnetic powder and sonicate for 30 minutes to obtain an iron nitride magnetic powder suspension. The iron nitride magnetic powder suspension is then placed in an 80°C water bath and stirred at 400 rpm. 30 mL of kerosene is added and the water bath is heated and stirred for 1 hour. The suspension is then transferred to a magnet and the supernatant removed to obtain a kerosene-based magnetic liquid.

[0096] 4. Add 12 g of epoxy-terminated benzyl silicone oil and 20 mL of benzyl silicone oil to the kerosene-based magnetic liquid, then continue to place it in a water bath, start stirring at 400 rpm, add 5 mL of ammonia water, keep heating in the water bath and continue stirring for 2 hours to obtain a silicone oil-based magnetic liquid.

[0097] 5. Prepare the thickener. First, take 60g of Fe3O4 magnetic powder with a particle size of 2μm and add it to a mixture of 100mL deionized water, 300mL and anhydrous ethanol to form a suspension, and ultrasonically disperse it for 30min; heat the suspension to 60℃ and stir it with a stirrer at 400rpm for 10min, then measure 20mL of ammonia water and 20mL of alcohol, mix them and slowly pour them into the stirring suspension, continue stirring for 5min, then measure 10mL of ethyl orthosilicate and 10mL of alcohol, mix them thoroughly, and then slowly pour them into the above suspension. After the addition is complete, cover and stir for 3h to obtain a turbid suspension containing magnetic particles. liquid; using a magnet to precipitate the turbid liquid containing magnetic particles until the upper liquid is clear, pouring off the supernatant, adding sufficient deionized water for washing, and repeating the washing step until the pH value of the supernatant reaches 7-8; placing the washed magnetic particles in a drying oven at 60°C for 48 hours, and then crushing the dried magnetic particles into powder using a grinder to obtain micron magnetic particles with a powder particle size of 2 μm and the entire surface of which is covered with a silica protective layer; the above sample is transferred to a three-necked flask equipped with a stirrer and a reflux condenser, and acetone (as a solvent) is added at the same time. Hydrogen-containing polysiloxane is slowly added dropwise to the three-necked flask through a constant pressure dropping funnel, and the reaction is carried out at room temperature for 4 hours. The product is transferred to a rotary evaporator and rotary evaporated at 65°C to remove the solvent and small molecular compounds in the product, and then placed in a 40°C forced air drying oven for drying. The block sample is crushed by a high-speed rotary grinder to obtain hydrogen silicone oil-modified silica-coated micron magnetic particles, i.e., a thickener.

[0098] 6. Raise the water bath temperature to 90°C, add 30g of the thickener prepared in step 5 and 6g of vinyl silicone oil to the silicone oil-based magnetic liquid, keep heating in the water bath and continue stirring for 2h to finally obtain silicone-based magnetic grease.

[0099] Based on 100% total mass, the magnetic grease comprises the following components: 16% magnetic powder, 20% base carrier liquid, 16% surfactant, 40% thickener, and 8% additives. The mass ratio of the magnetic powder to the polar hydrocarbon is 8:1. The mass ratio of the thickener to hydrogenated silicone oil, silica, and micronized magnetic particles is 15:3:45.

[0100] The resulting magnetic grease has a saturation magnetization of 76 emu / g and exhibits excellent high and low temperature resistance, with an operating temperature range of -50°C to 250°C. It also exhibits excellent radiation resistance, with uniform particle distribution, no agglomeration, and no sedimentation. The volatile loss of this magnetic grease within 80 hours at 90°C is less than 1%, making it suitable for the specialized working environments of nuclear power generation. This low-volatility, radiation-resistant silicone-based magnetic grease is also known. During sealing, abnormal friction can cause localized overheating of the frictional portion. When the temperature exceeds a threshold, the grease spontaneously undergoes a cross-linking and curing reaction, forming a viscoelastic body with cushioning and shock-absorbing properties, reducing component wear. This significantly increases viscosity and friction torque, significantly boosting the motor's friction torque signal to signal abnormal seal conditions. This allows operators to promptly detect faults and replace the grease, achieving intelligent magnetic media sealing and improving seal reliability.

[0101] Example 3: Preparation of CoFe2O4 silicon-based magnetic grease

[0102] 1. Dissolve 32g of ferric chloride in 600mL of deionized water, stir evenly, and heat in a water bath to 45°C. Weigh 24g of cobalt chloride hexahydrate and add it to the ferric chloride solution. Stir at 400rpm for 5min to obtain a mixed salt solution.

[0103] 100 mL of concentrated ammonia water was added to the mixed salt solution to adjust the pH to 9-10, and the solution was heated in a water bath and stirred for 45 minutes to obtain a nanomagnetic particle suspension.

[0104] 2. Take 5mL of oleic acid and add it to the nanomagnetic particle suspension. Raise the water bath temperature to 80°C, stir at 400rpm for 1h, then cool and use a magnet for magnetic precipitation. Then, wash the material obtained after magnetic precipitation with pure water five times until neutral. Then, add 600mL of ultrapure water and sonicate for 30min to obtain a magnetic powder suspension. After the reaction is complete, magnetically separate the magnetic particles and repeatedly wash them with deionized water until the eluate is neutral to obtain CoFe2O4 magnetic powder.

[0105] 3. Then, add 600 mL of ultrapure water to the CoFe2O4 magnetic powder prepared above and sonicate for 30 minutes to obtain a CoFe2O4 magnetic powder suspension. The CoFe2O4 magnetic powder suspension is placed in an 80°C water bath and stirred at 400 rpm. Add 30 mL of kerosene and continue heating in the water bath with stirring for 1 hour. The suspension is then transferred to a magnet and the supernatant removed to obtain a kerosene-based magnetic liquid.

[0106] 4. Add 24 g of end-epoxy modified silicone oil and 40 mL of benzyl silicone oil to the kerosene-based magnetic liquid, then continue to place it in a water bath, start stirring at 400 rpm, add 5 mL of ammonia water, keep heating in the water bath and continue stirring for 2 hours to obtain a silicone oil-based magnetic liquid.

[0107] 5. Prepare the thickener. First, take 60g of Fe3O4 magnetic powder with a particle size of 2μm and add it to a mixture of 100mL deionized water, 300mL and anhydrous ethanol to form a suspension, and ultrasonically disperse it for 30min; heat the suspension to 60℃ and stir it with a stirrer at 400rpm for 10min, then measure 20mL of ammonia water and 20mL of alcohol, mix them and slowly pour them into the stirring suspension, continue stirring for 5min, then measure 10mL of ethyl orthosilicate and 10mL of alcohol, mix them thoroughly, and then slowly pour them into the above suspension. After the addition is complete, cover and stir for 3h to obtain a turbid suspension containing magnetic particles. liquid; using a magnet to precipitate the turbid liquid containing magnetic particles until the upper liquid is clear, pouring off the supernatant, adding sufficient deionized water for washing, and repeating the washing step until the pH value of the supernatant reaches 7-8; placing the washed magnetic particles in a drying oven at 60°C for 48 hours, and then crushing the dried magnetic particles into powder using a grinder to obtain micron magnetic particles with a powder particle size of 2 μm and the entire surface of which is covered with a silica protective layer; the above sample is transferred to a three-necked flask equipped with a stirrer and a reflux condenser, and acetone (as a solvent) is added at the same time. Hydrogen-containing polysiloxane is slowly added dropwise to the three-necked flask through a constant pressure dropping funnel, and the reaction is carried out at room temperature for 4 hours. The product is transferred to a rotary evaporator and rotary evaporated at 65°C to remove the solvent and small molecular compounds in the product, and then placed in a 40°C forced air drying oven for drying. The block sample is crushed by a high-speed rotary grinder to obtain hydrogen silicone oil-modified silica-coated micron magnetic particles, i.e., a thickener.

[0108] 6. Raise the water bath temperature to 90°C, add 60g of the thickener prepared in step 5 and 12g of vinyl silicone oil to the silicone oil-based magnetic liquid, keep heating in the water bath and continue stirring for 2h to finally obtain silicone-based magnetic grease.

[0109] Based on 100% total mass, the magnetic grease comprises the following components: 16% magnetic powder, 20% base liquid, 16% surfactant, 40% thickener, and 8% additives. The mass ratio of the magnetic powder to the polar hydrocarbon is 8:1. The mass ratio of the thickener to hydrogenated silicone oil, silica, and micronized magnetic particles is 20:3:60.

[0110] The saturation magnetization intensity of the magnetic grease obtained above is 73 emu / g, and it has excellent high and low temperature resistance. The working temperature can reach -50℃ to 250℃, and it has excellent radiation resistance. The particles are evenly distributed, without agglomeration or sedimentation. The volatility loss of the magnetic grease within 80 hours at 90℃ is less than 1%, which makes it capable of working in the special working environment of nuclear power generation. It is a silicone-based magnetic grease with low volatility and radiation resistance.

[0111] When abnormal friction occurs during the use of the magnetic grease during sealing, it will cause local overheating of the friction part. When the temperature exceeds the threshold, the magnetic grease can spontaneously undergo a cross-linking and curing reaction to form a viscoelastic body with buffering and shock-absorbing effects, reducing the collision and wear of parts. Its viscosity is significantly improved, and the friction torque is increased. The friction torque electrical signal of the motor is used to feedback that the seal is in an abnormal state, so that the operator can detect the fault in time and replace the new magnetic grease, realizing the intelligence of magnetic medium sealing and improving sealing reliability.

[0112] Example 4

[0113] The preparation method of Example 4 is the same as that of Example 1, except that the mass of the phenylmethyl silicone oil-based carrier liquid is 75 mL, the amount of the thickener is 96 g, and the amount of the additive is 24 g. The magnetic grease obtained in this scheme is composed of the following components based on the total mass of the magnetic grease as 100%: 10% magnetic powder, 30% base carrier liquid, 10% surfactant, 40% thickener, and 10% additive. In the magnetic powder, the mass ratio of nanomagnetic particles to hydrocarbon substances with polar groups is 8:1. In the thickener, the mass ratio of hydrogenated silicone oil, silicon dioxide, and micron magnetic particles is 20:3:60.

[0114] The saturation magnetization intensity of the magnetic grease obtained above is 68 emu / g, and it has excellent high and low temperature resistance. The working temperature can reach -50℃ to 250℃, and it has excellent radiation resistance. The particles are evenly distributed, without agglomeration or sedimentation. The volatility loss of the magnetic grease within 80 hours at 90℃ is less than 1%, which makes it capable of working in the special working environment of nuclear power generation. It is a silicone-based magnetic grease with low volatility and radiation resistance.

[0115] When abnormal friction occurs during the use of the magnetic grease during sealing, it will cause local overheating of the friction part. When the temperature exceeds the threshold, the magnetic grease can spontaneously undergo a cross-linking and curing reaction to form a viscoelastic body with buffering and shock-absorbing effects, reducing the collision and wear of parts. Its viscosity is significantly improved, and the friction torque is increased. The friction torque electrical signal of the motor is used to feedback that the seal is in an abnormal state, so that the operator can detect the fault in time and replace the new magnetic grease, realizing the intelligence of magnetic medium sealing and improving sealing reliability.

[0116] Example 5

[0117] The preparation method of Example 5 is the same as that of Example 1, except that the mass of the phenylmethyl silicone oil-based carrier liquid is 35 mL, the amount of the thickener is 24 g, and the amount of the additive is 12 g. The magnetic grease obtained in this scheme is composed of the following components, based on the total mass of the magnetic grease as 100%, the magnetic grease is composed of the following components: 20% magnetic powder, 30% base carrier liquid, 20% surfactant, 20% thickener, and 10% additive. In the magnetic powder, the mass ratio of nanomagnetic particles to hydrocarbon substances with polar groups is 8:1. In the thickener, the mass ratio of hydrogenated silicone oil, silicon dioxide, and micron magnetic particles is 20:3:60.

[0118] The saturation magnetization intensity of the magnetic grease obtained above is 54 emu / g, and it has excellent high and low temperature resistance. The working temperature can reach -50℃ to 250℃, and it has excellent radiation resistance. The particles are evenly distributed, without agglomeration or sedimentation. The volatility loss of the magnetic grease within 80 hours at 90℃ is less than 1%, which makes it capable of working in the special working environment of nuclear power generation. It is a silicone-based magnetic grease with low volatility and radiation resistance.

[0119] When abnormal friction occurs during the use of the magnetic grease during sealing, it will cause local overheating of the friction part. When the temperature exceeds the threshold, the magnetic grease can spontaneously undergo a cross-linking and curing reaction to form a viscoelastic body with buffering and shock-absorbing effects, reducing the collision and wear of parts. Its viscosity is significantly improved, and the friction torque is increased. The friction torque electrical signal of the motor is used to feedback that the seal is in an abnormal state, so that the operator can detect the fault in time and replace the new magnetic grease, realizing the intelligence of magnetic medium sealing and improving sealing reliability.

[0120] In the present invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean 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 do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification, as well as features of different embodiments or examples, unless they are mutually inconsistent.

[0121] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A magnetic grease, characterized in that Taking the total mass of the magnetic grease as 100%, the magnetic grease includes the following components: 10-20% magnetic powder, 15-30% base carrier liquid, 10-20% surfactant, 20-50% thickener, and 1-10% additive. The magnetic powder is nanomagnetic particles modified with hydrocarbon substances with polar groups, the base carrier liquid is benzyl silicone oil, the surfactant is epoxy-modified silicone oil, and the thickener is silica-coated micron magnetic particles modified with hydrogen-containing silicone oil. In the thickener, the mass ratio of the hydrogen-containing silicone oil, the silica, and the micron magnetic particles is (5-10):1:(15-30); the additive is vinyl silicone oil.

2. The magnetic grease according to claim 1, characterized in that In the magnetic powder, the mass ratio of the nanomagnetic particles to the hydrocarbon substance with polar groups is (1-15):

1.

3. The magnetic grease according to claim 1, characterized in that The hydrocarbon substance with polar groups is selected from at least one of oleic acid, linoleic acid, linolenic acid, stearic acid and palmitic acid.

4. The magnetic grease according to claim 1, characterized in that The surfactant is selected from at least one of methyl silicone oil containing epoxy groups, ethyl silicone oil containing epoxy groups, and phenyl silicone oil containing epoxy groups.

5. The magnetic grease according to claim 1, characterized in that The material of the nano magnetic particles is selected from at least one of iron tetroxide, iron oxide, iron nitride, iron carbonyl, iron, MFe2O4 and M 1-X Zn X Fe2O4, where M is Mn, Co, Ni, Cu, Cd, Pb, Sn, Ca, Sr, Ba or Mg, and 0 < x ≤ 1; and / or, the material of the micron magnetic particles is selected from at least one of iron tetroxide, iron oxide, iron nitride and iron carbonyl.

6. The method for preparing magnetic lipoprotein according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. The magnetic powder is mixed with water to obtain a magnetic powder suspension; the magnetic powder suspension is then mixed with an organic hydrocarbon solvent to obtain a volatile solvent-based magnetic liquid; S2. The volatile solvent-based magnetic liquid is mixed with the surfactant and the base carrier liquid, and ammonia is added during the stirring process for modification, and then evaporated to obtain a silicone oil-based magnetic liquid; S3. Mixing the silicone oil-based magnetic liquid with the thickener and the additive to obtain the magnetic grease.

7. The method for preparing magnetic grease according to claim 6, wherein: In step S1, the preparation method of the magnetic powder is as follows: dispersing the nanomagnetic particles in water to obtain a nanomagnetic particle dispersion, adding ammonia water to the nanomagnetic particle dispersion to adjust the pH to 9-10 to obtain a nanomagnetic particle suspension; then adding the hydrocarbon substance with polar groups to the nanomagnetic particle suspension, performing a modification treatment under stirring, and then performing a magnetic precipitation treatment. The material obtained after the magnetic precipitation treatment is washed with water until it is neutral to obtain the magnetic powder.

8. The method for preparing magnetic grease according to claim 6, wherein: In step S1, the organic hydrocarbon solvent is selected from at least one of kerosene, petroleum gas, gasoline, paraffin oil, benzene, and toluene.

9. The method for preparing magnetic grease according to claim 6, wherein: In step S2, the mass ratio of the magnetic powder contained in the volatile solvent-based magnetic liquid to the surfactant and the base carrier liquid is 1:(0.5-1.5):(0.5-2.5).

10. The method for preparing magnetic grease according to claim 6, wherein: In step S3, the preparation method of the thickener is as follows: (1) adding the micron magnetic particles to a mixture of water and anhydrous ethanol and performing ultrasonic dispersion to form a suspension; (2) The suspension is heated while being stirred, and then a mixture of ammonia water and alcohol is slowly poured into the suspension being stirred, and stirring is continued. Then, a mixture of ethyl orthosilicate and alcohol is slowly poured into the suspension. After the addition is completed, the mixture is capped and stirred to obtain a turbid liquid; (3) subjecting the turbid liquid to magnetic precipitation until the upper liquid is clear, discarding the supernatant, and repeatedly washing the precipitate until the pH value of the supernatant reaches 7 to 8. Discarding the supernatant to obtain washed magnetic particles; (4) drying and crushing the cleaned magnetic particles to obtain silica-coated micron magnetic particles; (5) The silica-coated micron magnetic particles are transferred into a three-necked flask equipped with a stirrer and a reflux condenser, and acetone is added at the same time. The hydrogenated silicone oil is slowly added dropwise into the three-necked flask through a constant pressure dropping funnel, and the reaction is carried out at room temperature. The reaction product is transferred into a rotary evaporator and subjected to rotary evaporation under heating conditions to obtain a substance modified with hydrogenated silicone oil. The hydrogenated silicone oil modified substance is then dried and pulverized to obtain the thickener.

11. The method for preparing magnetic grease according to claim 6, wherein: In step S3, the mass ratio of the thickener, the additive, and the magnetic powder contained in the silicone oil-based magnetic liquid is (0.2-3):(0.2-3):1.

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