Manganese oxide nanoparticles with anti-icing and anti-frosting properties and methods of preparation

Abstract

The application belongs to the technical field of anti-icing materials, and particularly relates to manganese oxide magnetic nanoparticles with anti-icing and anti-frost properties and a preparation method. 0.3 Ca 0.1 MnO3; the manganese oxide magnetic nanoparticles are modified by oleic acid and fluorosilane; the manganese oxide magnetic nanoparticles modified by oleic acid and fluorosilane have a granular morphology, and a particle size range of 200-250 nm or 250-300 nm. The manganese oxide magnetic nanoparticles provided by the application have a low Curie temperature and a very small iron loss effect, and have good anti-icing and anti-frost properties.

Description

[0001] Divisional application This application is a divisional application of Chinese invention patent application CN202410969950.9, filed on July 18, 2024, entitled "A Manganese Ferrite Magnetic Nanoparticle and its Preparation Method and Application". Technical Field

[0002] This invention belongs to the field of anti-icing materials technology, specifically relating to a manganese ferrite nanoparticle with anti-icing and anti-frost properties and its preparation method. Background Technology

[0003] Icing on power transmission lines seriously threatens the operational safety of power systems. Currently, commonly used methods for preventing and controlling icing on power lines include mechanical methods, passive natural methods, wire surface modification methods, and thermal methods. Mechanical methods can only mitigate the damage to a certain extent, but cannot prevent it. Passive natural methods can cause line accidents such as conductor jumping due to uneven or asynchronous icing. Surface modification methods are ineffective against icing caused by frost. Thermal de-icing utilizes additional heat sources or the conductor's own heating to prevent ice and snow from accumulating on the conductor or to melt existing ice and snow. Thermal de-icing includes three types: the first is to pass a transmission current higher than the normal current density through the line to generate heat and melt the ice. The second is to use resistive ferromagnetic wire. The third is to use low Curie point anti-icing materials. When low Curie point anti-icing materials are applied to the surface of the conductor, the de-icing principle is that when the ambient temperature drops below the material's Curie temperature, the material generates a large magnetic induction intensity under the strong alternating magnetic field of the line, thus generating heat to achieve the anti-icing or de-icing effect. However, current low Curie point anti-icing materials are difficult to prepare, have high preparation costs, and have few materials that meet the requirements for low Curie temperatures.

[0004] Patent CN105801099A (20160727) discloses a MnZn ferrite material with Curie temperature sensitivity. This material is prepared by multiple grinding and calcination processes using manganese oxide, zinc oxide, molybdenum disulfide powder, nano-titanium dioxide, polyethylene glycol, graphene, silica, carbonyl iron powder, cobalt oxide, and guar trioxide. However, the material's composition is complex, its preparation process is demanding, and its minimum Curie temperature is only 26.8°C. At room temperature, the material generates magnetic induction heating during power transmission, which could burden the power transmission lines under long-term conditions. Furthermore, this material cannot rapidly heat up at low temperatures under icing conditions to effectively de-ic the conductors.

[0005] Patent CN117551317A (20240213) discloses a low Curie point polymer composite material and its preparation method. This patent involves melting a random copolymer and mixing it with fatty alcohols and conductive fillers to prepare a polymer composite. The mechanism by which this patented material is used for anti-icing is due to the electrothermal effect caused by the material's high resistance.

[0006] Patent CN112552767A (20210326) discloses a low Curie point ferromagnetic anti-icing material suitable for conductors and its preparation method. A specific weight proportion of iron, nickel, silicon, chromium, cerium, and praseodymium-neodymium alloy is added to a vacuum induction melting furnace. The melt is sprayed into a cooling tower under an argon atmosphere to obtain atomized powder. The atomized powder is then blended with carbon black, xylene is added and stirred at high speed, and finally fluoropolyacrylate and an antioxidant are added to prepare the material. The low Curie point ferromagnetic anti-icing material prepared by this patent has a relatively complex composition and high preparation cost.

[0007] In conclusion, it is necessary to propose new methods or strategies to prepare a material with a low Curie temperature and low preparation cost to alleviate the shortcomings of existing technologies. Summary of the Invention

[0008] The purpose of this invention is to provide manganese ferrite nanoparticles with anti-icing and anti-frost properties and their preparation method, thereby partially solving or alleviating the above-mentioned deficiencies in the prior art. The specific technical solution adopted by this invention is as follows.

[0009] A first aspect of the present invention is to provide a novel manganese ferrite nanomaterial.

[0010] A manganese ferrite magnetic nanoparticle with anti-icing and anti-frost properties, wherein the molecular formula of the manganese ferrite magnetic nanoparticle is La. 0.3 Ca 0.1 MnO3; the manganese ferrite magnetic nanoparticles are modified with oleic acid and fluorosilane; the manganese ferrite magnetic nanoparticles modified with oleic acid and fluorosilane have a granular morphology with a particle size range of 200-250 nm or 250-300 nm.

[0011] As an optimal choice, the manganese oxidase magnetic nanoparticles modified with oleic acid and fluorosilane have a particulate morphology with a particle size of approximately 300 nm.

[0012] Furthermore, the particle size range of the manganese oxidant magnetic nanoparticles before modification with oleic acid and fluorosilane is 50-100 nm.

[0013] As an optimal choice, the manganese oxidase magnetic nanoparticles before modification with oleic acid and fluorosilane have a particle size of 50 nm.

[0014] Furthermore, the manganese ferrite magnetic nanoparticles are modified with 5%-25% oleic acid and 3%-20% fluorosilane.

[0015] Oleic acid modification generates organic active groups on the surface of oxide particles, which can better bond with other organic coatings. Further modification with fluorosilanes generates -CF groups on the particles, which have a certain degree of hydrophobicity and further improve the anti-frost performance.

[0016] Another aspect of the present invention is to provide a method for preparing the above-mentioned novel manganese ferrite nanomaterial.

[0017] The preparation method of the above-mentioned manganese ferrite magnetic nanoparticles with anti-icing and anti-frost properties is a high-pressure reactor hydrothermal method, which includes the following steps: S01: Add the following materials by weight to pure water and stir: 30-60 parts lanthanum nitrate, 10-25 parts calcium nitrate, 2-5 parts strontium nitrate and 30-40 parts manganese nitrate. Adjust the pH of the reaction solution to 8-10 and then sonicate it further. S02: Add the reaction solution described in S01 into a high-pressure reactor and heat at 200-300℃ for 12-24 hours; S03: After the reaction is completed, the product is dried and then annealed at 900-1000℃ for 10-15h. The product is then ground to obtain crude manganese ferrite magnetic particles with a particle size range of 50-100nm. S04: Add the crude manganese ferrite magnetic particles to an ethanol or methanol solution and stir. Add 5%-25% oleic acid and 3%-20% fluorosilane, stir, and heat to 60-90°C. Remove the ethanol or methanol solution, filter, and dry to obtain the manganese ferrite magnetic nanoparticles.

[0018] As a preferred option, the following materials by weight are added to pure water and stirred: 30 parts lanthanum nitrate, 10 parts calcium nitrate, 2 parts strontium nitrate, and 40 parts manganese nitrate.

[0019] As a preferred embodiment, the reaction solution of S01 is added to a high-pressure reactor and heated at 270°C for 24 hours.

[0020] As a preferred method, the product is annealed at 1000℃ for 10 hours and then ground to obtain coarse manganese ferrite magnetic particles.

[0021] Beneficial technical effects: This invention utilizes a hydrothermal method to prepare a spherical manganese ferrite nanomaterial with a particle size of approximately 300 nm. This nanomaterial is magnetic and is also known as manganese ferrite magnetic nanoparticles. These manganese ferrite magnetic nanoparticles exhibit a low Curie temperature and minimal iron loss effect, providing anti-icing and anti-frost properties, making them suitable for the preparation of anti-icing and anti-frost materials for power transmission lines. Furthermore, the highest magnetic entropy change of these manganese ferrite magnetic nanoparticles is 1.18 J / kg K, which, compared to the highest publicly reported magnetic entropy change of 0.64-1.25 J / kg K, indicates a better level of thermal conductivity.

[0022] Secondly, the present invention modifies the prepared manganese ferrite magnetic nanoparticles with oleic acid, fluorosilane, or a combination of oleic acid and fluorosilane, so that the surface of these manganese ferrite magnetic nanoparticles has active groups or exhibits hydrophobic properties, which can be better combined with other organic coatings to prepare low Curie point anti-icing and anti-frost materials.

[0023] Finally, the hydrothermal method used in this invention is relatively simple to operate, requires low-end equipment, and has controllable overall costs, making it suitable for large-scale industrial application. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0025] Figure 1 This is a SEM image (scale bar is 1 μm) of unmodified manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention. Figure 2 This is a SEM image (scale bar 300 nm) of oleic acid-modified manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention. Figure 3 The elemental composition analysis diagram of manganese ferrite magnetic nanoparticles prepared according to one embodiment of the present invention is shown. Figure 4 The control manganese ferrite magnetic nanoparticles (A is La) prepared in one embodiment of the present invention are shown below. 0.67 Ca 0.33 MnO3, B is La 0.7 Ca 0.25 Sr 0.05 MnO3, C is La0.6 Ca 0.35 Sr 0.15 MnO3); Figure 5 The control manganese ferrite magnetic nanoparticles (A is La) prepared in one embodiment of the present invention are shown below. 0.67 Ca 0.33 MnO3, B is La 0.6 Ca 0.35 Sr 0.15 MnO3, C is La 0.1 Ca 0.1 MnO3); Figure 6 EDS images of manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention modified by different means (A is OA modification, B is OA+FAS modification). Figure 7 Curie temperature test results for manganese ferrite magnetic nanoparticles modified with oleic acid and fluorosilane prepared in one embodiment of the present invention. Figure 8 The magnetic entropy change calculation results of manganese ferrite magnetic nanoparticles modified with oleic acid and fluorosilane prepared in one embodiment of the present invention are shown below. Figure 9 Thermogravimetric analysis results of manganese ferrite magnetic nanoparticles modified with oleic acid and fluorosilane prepared according to one embodiment of the present invention; Figure 10 Anti-frost test of manganese ferrite magnetic nanoparticles prepared according to one embodiment of the present invention (A is the experimental sample, B is the control sample); Figure 11 The iron loss effect measurement results of manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention are shown. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] In this document, "and / or" includes any and all combinations of one or more of the listed related items.

[0028] In this article, "multiple" means two or more, that is, it includes two, three, four, five, etc.

[0029] As used in this specification, the term "about" typically means + / -5% of the value, more typically + / -4% of the value, more typically + / -3% of the value, more typically + / -2% of the value, even more typically + / -1% of the value, and even more typically + / -0.5% of the value.

[0030] In this specification, certain embodiments may be disclosed in a range-bound format. It should be understood that this "range-bound" description is merely for convenience and brevity and should not be construed as a rigid limitation on the disclosed range. Therefore, the description of a range should be considered as having specifically disclosed all possible subranges and the individual numerical values ​​within those ranges. For example, a description of the range 1-6 should be considered as having specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the individual numbers within those ranges, such as 1, 2, 3, 4, 5, and 6. This rule applies regardless of the breadth of the range.

[0031] Example 1 This embodiment provides an example of a method for preparing manganese ferrite magnetic nanoparticles.

[0032] Preparation method: S01: Add the following parts by weight of materials to pure water and stir for 1 hour: 30 parts of lanthanum nitrate, 10 parts of calcium nitrate, 2 parts of strontium nitrate and 40 parts of manganese nitrate. Adjust the pH of the reaction solution to 9 and then sonicate for 1 hour. S02: Add the reaction solution of S01 into a high-pressure reactor and heat at 270°C for 24 hours; S03: The product after the reaction is completed is dried, then annealed at 1000℃ for 10h, and ground to obtain crude manganese ferrite magnetic particles; S04: Add the crude manganese ferrite magnetic particles prepared in S03 to an ethanol or methanol solution and stir. Then add 5%-25% oleic acid (OA) and 3%-20% fluorosilane (FAS), stir and heat to 60-90℃, remove the ethanol or methanol, filter and dry to finally obtain the manganese ferrite magnetic nanoparticles.

[0033] The manganese ferrite magnetic nanoparticles prepared in this embodiment have the molecular formula La. 0.3 Ca 0.1 The crude MnO3 has a particle size of approximately 50 nm. After modification, the particle size is approximately 300 nm, and the overall morphology is that of small particles. See Figure 1 and Figure 2 The surface total spectrum of the component analysis is shown below. Figure 3 .

[0034] Example 2 This embodiment provides a control preparation example based on Example 1.

[0035] (1) Based on the method of Example 1, by adjusting the material composition, without annealing, only rod-shaped structures can be obtained.

[0036] Table 1. Nanoparticles prepared with different material ratios (2) Based on the method of Example 1, rod-shaped structure and granular structure are obtained by adjusting the material composition and performing annealing operations with different parameters.

[0037] (3) La prepared in Example 1 0.3 Ca 0.1 Based on MnO3 nanoparticles, different modification methods were selected, including modification with oleic acid (OA) and oleic acid (OA) with fluorosilane (FAS), see [link to relevant documentation]. Figure 6 After modification using both methods, nanoparticles with a particle size of approximately 300 nm and an overall morphology of small particles can be obtained.

[0038] Example 3 This embodiment provides performance verification of the modified manganese ferrite magnetic nanoparticles prepared in Example 1.

[0039] 3.1 Curie Temperature Test Methodology and Procedure: The SQUID-VSM magnetic measurement system from Quantum Design, USA, is used. This system is based on quantum superconducting interferometry (QFID) detection technology. By applying a DC or AC magnetic field to the magnetic material, the DC (AC) magnetization intensity of the sample as a function of temperature (field strength) is obtained, i.e., the MH and MT curves are measured. The MT curve is fitted with a straight line, and the temperature point with the steepest slope is the Curie temperature. The specific steps are as follows.

[0040] (1) Weigh the magnetic powder.

[0041] (2) Load the magnetic powder sample into the instrument sample rod and place the sample rod into the sample chamber.

[0042] (3) Clean the cavity with helium (the program defaults to cleaning three times), and then evacuate.

[0043] (4) Set the temperature (100K-400K) and magnetic field (1.5 T), and determine the sample position by scanning the "signal-position" curve of the sample.

[0044] (5) By applying a DC or AC magnetic field to the magnetic powder, the curve of the DC (AC) magnetization intensity of the sample under test as a function of temperature (field strength) is obtained, i.e., the measurement of the MT curve. The MT curve is fitted with a straight line, and the temperature point with the largest slope is the Curie temperature point.

[0045] Results: La modified with oleic acid and fluorosilane 0.3 Ca 0.1 The Curie temperature of MnO3 nanoparticles is approximately 264.50 K, reaching a low-temperature state (around -8.65 °C). This meets the Curie point temperature requirement of around 0 °C. (See...) Figure 7 .

[0046] Based on the above MT curve test results, the heating efficiency can be evaluated by calculating the magnetic entropy change at different temperatures using formulas referenced in publicly available information, as follows: Figure 8 As shown, the material prepared by this invention exhibits a maximum magnetic entropy change of 1.18 J / kg K near the Curie temperature. Compared to the highest magnetic entropy change values ​​of 0.64-1.25 J / kg K published in other sources, this material demonstrates a better heating level. The cited publication is "Observation of the magnetic entropy change in Zndoped MnFe2O4 common ceramic: Be cool being environmentally friendly."

[0047] 3.2 Thermogravimetric Test Methods and Procedures: Thermogravimetric analysis (TGA) was used for testing. Under programmed temperature control (0℃ to 1200℃, heating for 1 hour), the mass change of the magnetic powder with temperature (or time) was measured, and the endothermic and exothermic processes were also measured.

[0048] Results: La modified with oleic acid and fluorosilane 0.3 Ca 0.1 MnO3 nanoparticles underwent thermogravimetric testing, such as Figure 9 As shown, the quality remains stable within a temperature range of 800-900℃.

[0049] Example 4 This embodiment provides an ice- and frost-resistant performance test of the modified manganese ferrite magnetic nanoparticles prepared in Example 1.

[0050] Method and Procedure: Using a semiconductor refrigeration platform LTD1-350, the sample was placed on the platform for a frosting experiment at -8°C. The La-modified sample prepared in Example 1, modified with oleic acid and fluorosilane, was used... 0.3 Ca 0.1MnO3 nanoparticles were mixed with alcohol and coated onto the surface of a superhydrophobic porous sample. The sample was then placed on a magnet with a magnetic field of 2600 GS (a relatively weak magnetic field). The dark areas represent the oxide porous sample coated with magnetic particles, while the white areas represent the uncoated oxide sample.

[0051] Figure 10 As can be seen, over time, the darker areas exhibit resistance to delayed frosting, further enhancing the frosting effect of the superhydrophobic porous structure. This demonstrates that the magnetic particles prepared in this invention are effective at preventing frost. In contrast, the blank substrate sample was completely frosted after 5 minutes, while the superhydrophobic porous structure coated with magnetic particles could delay frost formation for up to 30 minutes.

[0052] It is understood that the superhydrophobic porous structure sample in this embodiment can be prepared according to any feasible method disclosed in the public information.

[0053] Example 5 This embodiment provides an iron loss test of the modified manganese ferrite magnetic nanoparticles prepared in Example 1.

[0054] Method and Procedure: The SQUID-VSM magnetic measurement system from Quantum Design, USA, was used. The specific steps are as follows.

[0055] (1) Weigh the magnetic powder.

[0056] (2) Load the sample into the sample rod and place the sample rod into the sample cavity.

[0057] (3) Clean the cavity with helium (the program defaults to cleaning three times), and then evacuate.

[0058] (4) Set the temperature (100K-400K) and magnetic field (1.5 T), and determine the sample position by scanning the "signal-position" curve of the sample.

[0059] (5) By applying a DC or AC magnetic field to the magnetic powder, the DC (AC) magnetization intensity of the sample under test as a function of temperature (field strength) is obtained, i.e., the MH curve is measured. For the MH curves at various temperatures, the value of H when M=0 is calculated. The larger the absolute value of H, the greater the coercivity, which is more likely to cause heating under the alternating magnetic field of power transmission at room temperature, thus leading to iron loss. Similarly, the smaller the value of H or the closer the curve is to 0, the smaller the coercivity, the better the paramagnetism, and the less heating under the alternating magnetic field at room temperature.

[0060] Results: La modified with oleic acid and fluorosilane 0.3 Ca 0.1MnO3 nanoparticles exhibit a coercivity of 0.4 Oe at various temperatures (260 K, 270 K, 280 K, 290 K, and 300 K), and their remanence is also very small, close to zero. This confirms that they are soft magnetic materials, causing no hysteresis loss or heating effect during power transmission, and can be used for anti-icing or anti-frost applications in power transmission lines. (See...) Figure 11 .

[0061] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for preparing manganese ferrite magnetic nanoparticles, characterized in that, The preparation method is a high-pressure reactor hydrothermal method, including the following steps: S01: Add the following materials by weight to pure water and stir: 30-60 parts lanthanum nitrate, 10-25 parts calcium nitrate, 2-5 parts strontium nitrate and 30-40 parts manganese nitrate. Adjust the pH of the reaction solution to 8-10 and then sonicate it further. S02: Add the reaction solution described in S01 into a high-pressure reactor and heat at 200-300℃ for 12-24 hours; S03: After the reaction is completed, the product is dried and then annealed at 900-1000℃ for 10-15h. The product is then ground to obtain crude manganese ferrite magnetic particles with a particle size range of 50-100nm. S04: The crude manganese ferrite magnetic particles are added to an ethanol or methanol solution and stirred. 5%-25% oleic acid and 3%-20% fluorosilane are added, stirred, and heated to 60-90°C. The ethanol or methanol solution is removed, and the mixture is filtered and dried to obtain the manganese ferrite magnetic nanoparticles. The molecular formula of the manganese ferrite magnetic nanoparticles is La. 0.3 Ca 0.1 MnO3.

2. The preparation method according to claim 1, characterized in that, Add the following ingredients by weight to pure water and stir: 30 parts lanthanum nitrate, 10 parts calcium nitrate, 2 parts strontium nitrate, and 40 parts manganese nitrate.

3. The preparation method according to claim 1, characterized in that, The reaction solution of S01 was added to a high-pressure reactor and heated at 270°C for 24 hours.

4. The preparation method according to claim 1, characterized in that, Annealing at 1000℃ for 10 hours and grinding yielded coarse manganese ferrite magnetic particles.

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