Manganese oxide nano-particles with anti-icing and anti-frost performance and preparation method of manganese oxide nano-particles

Abstract

The invention belongs to the technical field of anti-icing materials, and particularly relates to manganese oxide magnetic nano-particles with anti-icing and anti-frost performance and a preparation method of the manganese oxide magnetic nano-particles. The molecular formula of the manganese oxide magnetic nanoparticles provided by the invention is La < 0.3 > Ca < 0.1 > MnO < 3 >; the manganese oxide magnetic nanoparticles are modified by oleic acid and fluorosilane; the manganese oxide magnetic nano-particles modified by oleic acid and fluorosilane are in the shape of particles, and the particle size range is 200-250 nm or 250-300 nm. The manganese oxide magnetic nanoparticles provided by the invention have low Curie temperature and very small iron loss effect, and have better anti-icing and anti-frost performance.

Description

[0001] Divisional Application This application is a divisional application of a Chinese patent application with the application number CN202410969950.9, the filing date of July 18, 2024, and the invention title of "A Manganese Ferrite Magnetic Nanoparticle and Its Preparation Method and Application". Technical Field

[0002] The present invention belongs to the technical field of anti-icing materials, and specifically relates to a manganese ferrite nanoparticle with anti-icing and anti-frosting properties and a preparation method thereof. Background Art

[0003] Icing on transmission lines seriously threatens the safe operation of the power system, and China is one of the countries with the most serious wire icing disasters. Currently, the commonly used methods for preventing and controlling wire icing include mechanical methods, natural passive methods, wire surface modification methods, and thermal methods. Among them, the mechanical method can only reduce disasters to a certain extent but cannot prevent them. The natural passive method may cause line accidents such as conductor jumping due to uneven or asynchronous de-icing. The surface modification method has no effect on icing formed by glaze. Thermal de-icing is to use an additional heat source or the wire's own heat generation to prevent ice and snow from accumulating on the wire or to melt the accumulated ice and snow. Thermal de-icing includes three types. The first is to pass a transmission current higher than the normal current density on the line to obtain heat to melt the ice. The second is to use resistive ferromagnetic wires. The third is to use low Curie point anti-icing materials. When the low Curie point anti-icing material is wrapped on the surface of the wire, the de-icing principle is that when the ambient temperature drops below the Curie temperature of the material, 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 have problems such as high preparation difficulty, high preparation cost, and few materials that meet the lower Curie temperature.

[0004] The patent with the publication number CN105801099A (July 27, 2016) discloses a MnZn ferrite material with Curie point temperature sensitivity, which is prepared by means of multiple grinding and calcination of manganese oxide, zinc oxide, molybdenum disulfide powder, nano-titanium dioxide, polyethylene glycol, graphene, silica, carbonyl iron powder, cobalt oxide, and antimony trioxide, etc. However, the composition of this material is relatively complex, the preparation process requirements are high, and the lowest Curie temperature of the material is 26.8°C at room temperature. The material will generate magnetic induction heating during normal temperature power transmission, which will cause the operating burden of the transmission wire at room temperature in the long run. In addition, this material cannot meet the requirement of quickly generating heat at low icing temperatures to achieve wire de-icing.

[0005] The patent with publication number CN117551317A (February 13, 2024) discloses a polymer composite material with a low Curie point and its preparation method. In this patent, an amorphous copolymer is melted and mixed with fatty alcohols and conductive fillers to prepare a polymer composite. The anti-icing mechanism of this patent material is the electrothermal effect caused by the relatively high resistance of the material.

[0006] The patent CN112552767A (March 26, 2021) discloses a low Curie point ferromagnetic anti-icing material suitable for wires and its preparation method. Specific weight parts of iron, nickel, silicon, chromium, cerium, and praseodymium-neodymium alloy are added to a vacuum induction melting furnace, and the melt is sprayed into a cooling tower under an argon atmosphere to obtain gas atomized powder; then the gas atomized powder is blended with carbon black, added with xylene and stirred at high speed, and then fluorinated polyacrylate and antioxidant are added to prepare together. The low Curie point ferromagnetic anti-icing material prepared by this patent has a relatively complex composition and a high preparation cost.

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

[0008] The purpose of the present invention is to provide a manganese ferrite nanoparticle with anti-icing and anti-frosting properties and its preparation method, which partially solves or alleviates the above deficiencies in the existing technology. The present invention specifically adopts the following technical solutions.

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

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

[0011] As a most preferred, the morphology of the manganese ferrite magnetic nanoparticle after being modified with oleic acid and fluorosilane is granular, and the particle size is about 300nm.

[0012] Furthermore, the particle size range of the manganese ferrite magnetic nanoparticle before being modified with oleic acid and fluorosilane is 50 - 100nm.

[0013] As a most preferred, the particle size of the manganese ferrite magnetic nanoparticle before being modified with oleic acid and fluorosilane is 50nm.

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

[0015] The modification with oleic acid generates organic active groups on the surface of the oxide particles, which can better combine with other organic coatings subsequently. Further modification with fluorosilane makes the particles generate -CF groups, having certain hydrophobicity and further improving the anti-icing and anti-frost performance.

[0016] On the other hand, the present invention lies in providing a preparation method of the above-mentioned novel manganese ferrite nanomaterial.

[0017] The preparation method of the manganese ferrite magnetic nanoparticles having anti-icing and anti-frost performance, the preparation method is a hydrothermal method in a high-pressure reaction kettle, and includes the following steps: S01: Add the following parts by weight of materials to pure water and stir: 30-60 parts of lanthanum nitrate, 10-25 parts of calcium nitrate, 2-5 parts of strontium nitrate, and 30-40 parts of manganese nitrate, adjust the pH value of the reaction solution to 8-10, and further perform ultrasonic treatment; S02: Add the reaction solution of S01 to a high-pressure reaction kettle and heat it at 200-300 °C for 12-24 h; S03: Dry the product after the reaction is completed, then anneal it at 900-1000 °C for 10-15 h, and grind to obtain a crude product of manganese ferrite magnetic particles, and the particle size range of the crude product of manganese ferrite magnetic particles is 50-100 nm; S04: Add the crude product of 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 preference, add the following parts by weight of materials to pure water and stir: 30 parts of lanthanum nitrate, 10 parts of calcium nitrate, 2 parts of strontium nitrate, and 40 parts of manganese nitrate.

[0019] As a preference, add the reaction solution of S01 to a high-pressure reaction kettle and heat it at 270 °C for 24 h.

[0020] As a preference, anneal at 1000 °C for 10 h and grind to obtain a crude product of manganese ferrite magnetic particles.

[0021] Beneficial technical effects: The present invention prepares a manganese ferrite nanomaterial with a particle size of about 300 nm and in the shape of circular particles by a hydrothermal method. This nanomaterial has magnetism and is also called manganese ferrite magnetic nanoparticles. Such manganese ferrite magnetic nanoparticles have a low Curie temperature and a very small iron loss effect, and have the performance of preventing ice and frost, and can be used for the preparation of materials for preventing ice and frost on transmission wires. In addition, the maximum magnetic entropy change of the manganese ferrite magnetic nanoparticles is 1.18 J / kg K, and compared with the highest value of the magnetic entropy change published in the public data, which is 0.64 - 1.25 J / kg K, it has a better heating level.

[0022] Secondly, the prepared manganese ferrite magnetic nanoparticles of the present invention are modified with oleic acid, fluorosilane or a combination of oleic acid and fluorosilane, so that the surface of such manganese ferrite magnetic nanoparticles has active groups or shows hydrophobic characteristics, and can be better combined with other organic coatings subsequently, and is used for the preparation of anti-icing and anti-frost materials with a low Curie point.

[0023] Finally, the hydrothermal method adopted by the present invention is relatively simple in operation, has low equipment requirements, and the overall cost is controllable, and is suitable for large-scale industrial promotion. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts do not necessarily draw according to the actual scale. Obviously, the following-described drawings are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative labor.

[0025] Figure 1 SEM image of unmodified manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention (scale bar is 1 μm); Figure 2 SEM image of oleic acid-modified manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention (scale bar is 300 nm); Figure 3 Elemental composition analysis diagram of manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention; Figure 4 Control manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention (A is La 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 prepared in one embodiment of the present invention (A is La 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 diagrams of the 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 of the manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention modified by oleic acid and fluorosilane; Figure 8 Magnetic entropy change calculation results of the manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention modified by oleic acid and fluorosilane; Figure 9 Thermogravimetric test results of the manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention modified by oleic acid and fluorosilane; Figure 10 Anti-icing experiment of the manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention (A is the experimental sample, B is the control sample); Figure 11 Iron loss effect measurement results of the manganese ferrite magnetic nanoparticles prepared in one embodiment of the present invention. Detailed implementation manners

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

[0027] As used herein, "and / or" includes any and all combinations of one or more of the listed related items.

[0028] As used herein, "a plurality of" 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 stated value, more typically + / - 4% of the stated value, more typically + / - 3% of the stated value, more typically + / - 2% of the stated value, even more typically + / - 1% of the stated value, and even more typically + / - 0.5% of the stated value.

[0030] In this specification, certain embodiments may be disclosed in a format that is within a certain range. It should be understood that this description of "within a certain range" is merely for convenience and brevity and should not be construed as a rigid limitation on the disclosed range. Therefore, the description of the range should be considered to have specifically disclosed all possible sub-ranges and the individual numerical values within that range. For example, the description of the range 1 - 6 should be considered to have specifically disclosed sub-ranges 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., as well as the individual numbers within that range, such as 1, 2, 3, 4, 5, and 6. The above rules apply regardless of the breadth of the range.

[0031] Example 1 This example 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 h: 30 parts of lanthanum nitrate, 10 parts of calcium nitrate, 2 parts of strontium nitrate, and 40 parts of manganese nitrate. Adjust the pH value of the reaction solution to 9, and then ultrasonicate for 1 h; S02: Add the reaction solution of S01 to a high-pressure reactor and heat at 270 °C for 24 h; S03: Dry the product after the reaction is completed, then anneal at 1000 °C for 10 h, and grind to obtain the crude manganese ferrite magnetic particles; S04: Add the crude manganese ferrite magnetic particles prepared in S03 to an ethanol or methanol solution and stir. Further add 5% - 25% oleic acid (OA) and 3% - 20% fluorosilane (FAS), stir and heat at 60 - 90 °C, remove the ethanol or methanol, filter and dry to finally obtain the manganese ferrite magnetic nanoparticles.

[0033] The molecular formula of the manganese ferrite magnetic nanoparticles prepared in this example is La 0.3 Ca 0.1 MnO3. The particle size of the crude product is about 50 nm, and after modification, the particle size is about 300 nm. The overall morphology is small particle-like. See Figure 1 and Figure 2 , and the surface total spectrum of the composition analysis can be seen in Figure 3 .

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

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

[0036] Table 1 Nanoparticles Prepared with Different Material Ratios (2) Based on the method of Example 1, by adjusting the material composition and performing annealing operations with different parameters, rod-like structures and granular structures can be obtained.

[0037] (3) Based on the La 0.3 Ca 0.1 MnO3 nanoparticles prepared in Example 1, different methods are selected for modification, including selecting oleic acid (OA) and oleic acid (OA) plus fluorosilane (FAS) for modification, as shown in Figure 6 . After modification by the two methods, nanoparticles with a particle size of about 300 nm and an overall morphology of small granular shapes can be obtained.

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

[0039] 3.1 Curie Temperature Test Method steps: Use the SQUID-VSM magnetic measurement system of Quantum Design Company in the United States. This system is based on quantum superconducting interference device detection technology. By applying a direct current or alternating current magnetic field to the magnetic material, the curves of the direct current (alternating current) magnetization intensity of the sample to be measured changing with temperature (magnetic field strength) are obtained, that is, the measurement of the MH and MT curves. The M-T curve is linearly fitted, and the temperature point with the largest slope is the Curie temperature point. The specific steps are as follows.

[0040] (1) Weigh the mass of 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 direct current or alternating current magnetic field to the magnetic powder, the curve of the direct current (alternating current) magnetization intensity of the sample to be measured changing with temperature (magnetic field strength) is obtained, that is, the measurement of the M-T curve. A linear fit is performed on the M-T curve, and the temperature point with the largest slope is the Curie temperature point.

[0045] Results: The Curie temperature of the La 0.3 Ca 0.1 MnO3 nanoparticles modified by oleic acid and fluorosilane is about 264.50 K, reaching the low temperature state (about -8.65 °C). It meets the Curie point temperature requirement of about 0 °C, as shown in Figure 7 .

[0046] According to the above M-T curve test results, the magnetic entropy change at different temperatures can be calculated through the formula referenced in the public materials to evaluate its heating efficiency, as follows Figure 8 shown. The highest magnetic entropy change near the Curie temperature of the material prepared in the present invention is 1.18 J / kg K. Compared with the highest magnetic entropy change value of 0.64 - 1.25 J / kg K published in the public materials, it has a better heating level. The cited public material is Observation of the magnetic entropy change in Zndoped MnFe2O4common ceramic: Be cool being environmental friendly.

[0047] 3.2 Thermogravimetric test Method steps: Detect using a thermogravimetric analyzer (TGA). Under programmed temperature control (from 0 °C to 1200 °C, heating for 1 hour), measure the relationship between the mass of the magnetic powder and temperature (or time), and measure the endothermic and exothermic processes during the measurement.

[0048] Results: The La 0.3 Ca 0.1 MnO3 nanoparticles modified by oleic acid and fluorosilane are subjected to thermogravimetric test, as Figure 9 shown, showing that the mass can be kept stable in the temperature range of 800 - 900 °C.

[0049] Example 4 This example provides a test on the anti-icing and anti-frosting performance of the modified manganese ferrite magnetic nanoparticles prepared in Example 1.

[0050] Method steps: Use a semiconductor refrigeration platform LTD1-350 to conduct a frosting experiment at -8 °C with the sample placed on the semiconductor refrigeration platform. The La 0.3 Ca 0.1MnO3 nanoparticles and alcohol are mixed and coated on the surface of the super-hydrophobic pore structure sample. The sample is placed on a magnet with a magnetic field of 2600GS (smaller magnetic field). The dark part is the oxidized pore sample coated with magnetic particles, and the white part is the uncoated oxidized sample.

[0051] Figure 10 It can be seen that as time goes by, it can be found that the dark part can resist delayed frost formation, further improving the frosting effect of the super-hydrophobic pore structure. It is proved that the magnetic particles prepared by the present invention can effectively prevent frost. In contrast, the blank substrate sample has been completely frosted in 5 minutes, while the super-hydrophobic pore structure coated with magnetic particles can delay to 30 minutes.

[0052] It can be understood that the super-hydrophobic pore structure sample in this embodiment can be prepared according to any feasible method in the public information.

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

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

[0055] (1) Weigh the mass of 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 it.

[0058] (4) Set the temperature (100K-400K) and magnetic field (1.5 T), and determine the sample position by scanning the sample's "signal-position" curve.

[0059] (5) By applying a DC or AC magnetic field to the magnetic powder, the DC (AC) magnetization intensity of the sample to be tested is measured as a function of temperature (field strength), that is, the MH curve. For the MH curve at each temperature, the value of H is calculated when M=0. The larger the absolute value of H, the greater the coercive force, which is more likely to cause heating under the alternating magnetic field of power transmission at room temperature, and then lead to iron loss. Similarly, the smaller the value of H or the closer the curves are to 0, the smaller the coercive force is, the better the paramagnetism is, and the less heat is generated under the alternating magnetic field at room temperature.

[0060] Results: La modified with oleic acid and fluorosilane 0.3 Ca 0.1The coercivity of MnO3 nanoparticles is 0.4 Oe at each temperature of 260K, 270K, 280K, 290K and 300K, and the remanence is also very small and close to 0. It is determined to be a soft magnetic material, which will not cause hysteresis loss and heating effect during power transmission, and can be used for anti-icing or anti-frost of power transmission wires. See Figure 11 .

[0061] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the present invention and the claims. All of these fall within the protection scope of the present invention.

Claims

1. A manganese oxide magnetic nanoparticle with anti-icing and anti-frost properties, characterized in that: The molecular formula of the manganese oxide magnetic nanoparticles is La 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 are granular in shape with a particle size range of 200-250nm or 250-300nm.

2. The manganese oxide magnetic nanoparticles according to claim 1, characterized in that: The particle size of the manganese oxide magnetic nanoparticles before modification with oleic acid and fluorosilane is in the range of 50-100 nm.

3. The manganese oxide magnetic nanoparticles according to claim 1, characterized in that: The manganese oxide magnetic nanoparticles are modified with 5%-25% oleic acid and 3%-20% fluorosilane.

4. The method for preparing manganese oxide magnetic nanoparticles according to any one of claims 1 to 3, characterized in that: The preparation method is a high-pressure reactor hydrothermal method, comprising the following steps: S01: Add the following materials in parts by weight into pure water and stir: 30-60 parts of lanthanum nitrate, 10-25 parts of calcium nitrate, 2-5 parts of strontium nitrate and 30-40 parts of manganese nitrate, adjust the pH value of the reaction solution to 8-10, and further perform ultrasound; S02: adding the reaction solution of S01 into a high pressure reactor and heating at 200-300° C. for 12-24 hours; S03: drying the product after the reaction, annealing it at 900-1000° C. for 10-15 hours, and grinding it to obtain a crude manganese oxide magnetic particle product, wherein the particle size of the crude manganese oxide magnetic particle product is in the range of 50-100 nm; S04: adding the crude manganese oxide magnetic particles to an ethanol or methanol solution and stirring, adding 5%-25% oleic acid and 3%-20% fluorosilane and stirring and heating to 60-90°C, removing the ethanol or methanol solution, filtering and drying to obtain the manganese oxide magnetic nanoparticles.

5. The preparation method according to claim 4, characterized in that: The following materials in parts by weight were added into pure water and stirred: 30 parts of lanthanum nitrate, 10 parts of calcium nitrate, 2 parts of strontium nitrate and 40 parts of manganese nitrate.

6. The preparation method according to claim 4, characterized in that: The reaction solution of S01 was added into a high pressure reactor and heated at 270° C. for 24 h.

7. The preparation method according to claim 4, characterized in that: The mixture was annealed at 1000°C for 10 hours and ground to obtain crude manganese oxide magnetic particles.

Images