Microcrystalline amorphous soft magnetic powder and magnetic ring capable of resisting 48-hour salt spray

Abstract

The application discloses a kind of 48 hours salt fog resistant microamorphous soft magnetic powder, the microamorphous soft magnetic powder is Fe-Ni-Mo-Si-B-P-C-Cr system soft magnetic powder, its surface is successively coated with SiO2 coating and corrosion inhibitor layer, and constitutes double-layer composite coating structure.The application is directed to the amorphous powder soft magnetic characteristics, adds Ni, Mo, Cr three elements on the basis of traditional Fe-Si-B amorphous soft magnet, so that the corrosion resistance of powder itself is greatly improved, the rust prevention ability of amorphous powder is significantly improved by double-layer composite coating structure, and excellent soft magnetic performance can be maintained.

Description

Technical Field

[0001] This invention relates to the field of magnetic functional materials technology, specifically to a fine amorphous soft magnetic powder and magnetic ring that can withstand 48 hours of salt spray. Background Technology

[0002] Amorphous metals (also known as metallic glasses) exhibit excellent corrosion resistance due to their long-range disordered atomic arrangement and the absence of grain boundaries and dislocations. Traditional Fe-Si-B amorphous soft magnetic powders show high corrosion resistance in corrosive environments such as hydrochloric acid, but they still face two major challenges in practical applications: first, the presence of dangling bonds and vacancies on the surface increases surface activity and oxidation tendency; second, localized corrosion easily occurs in humid or high-temperature environments, leading to a decrease in soft magnetic properties.

[0003] To address these issues, researchers have developed various surface coating techniques, including vapor deposition methods such as atomic layer deposition (ALD), chemical vapor deposition (CVD), and physical vapor deposition (PVD), as well as liquid phase coating methods such as sol-gel and precipitation methods. While vapor deposition methods can form uniform coatings, the equipment is expensive, the process is complex and unsuitable for large-scale industrial applications, and it requires a high-temperature environment (typically >400°C). Amorphous materials are prone to crystallization at high temperatures, making it unsuitable for amorphous powders. Liquid phase coating methods, while less expensive, require precise control of reaction conditions to ensure the uniformity and density of the coating. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a fine amorphous soft magnetic powder and magnetic ring that can withstand 48 hours of salt spray. Based on the soft magnetic properties of amorphous powder, Ni, Mo, and Cr elements are added to the traditional Fe-Si-B amorphous soft magnetic powder, which greatly improves the corrosion resistance of the powder itself. The double-layer composite coating structure significantly enhances the rust prevention ability of the amorphous powder while maintaining excellent soft magnetic properties.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: a fine amorphous soft magnetic powder that can withstand 48 hours of salt spray, wherein the fine amorphous soft magnetic powder is a Fe-Ni-Mo-Si-BPC-Cr series soft magnetic powder, and its surface is sequentially coated with a SiO2 coating layer and a corrosion inhibitor layer, forming a double-layer composite coating structure.

[0006] Furthermore, the fine amorphous soft magnetic powder comprises: 0-10% Ni, 0-8% Mo, 2-8% Si, 2-6% B, 1-8% P, 0.1-1.5% C, 1.0-4.0% Cr, with the balance being Fe.

[0007] Furthermore, the SiO2 coating layer is prepared by the sol-gel method; the corrosion inhibitor layer is at least one of phosphate ester, hexamethylenetetramine, or sodium benzoate.

[0008] Furthermore, the fine amorphous soft magnetic powder is a spherical or near-spherical powder prepared by atomization.

[0009] Furthermore, the atomization method is any one of gas atomization, water atomization, or combined water-gas atomization.

[0010] Furthermore, the median particle size D50 of the fine amorphous soft magnetic powder is 1-6 μm.

[0011] On the other hand, a magnetic ring is made using the aforementioned fine amorphous soft magnetic powder.

[0012] The fine amorphous soft magnetic powder of this invention, which can withstand 48 hours of salt spray, has the following beneficial effects: 1. Based on the amorphous Fe-Si-B composition, Ni, Mo, and Cr were added. The addition of Cr facilitates the formation of a dense passivation film mainly composed of Cr2O3 / Cr(OH)3 on the surface, which essentially reduces surface activity and solves the fundamental problem of easy oxidation and corrosion of traditional amorphous powders, while providing a basic barrier against corrosion. With the presence of Cr, the addition of Mo further promotes a more Cr-rich passivation film and can inhibit the adsorption of harmful anions. The addition of Ni can significantly enhance the spontaneous passivation of the powder in corrosive media and promote the formation of a protective oxide film on the surface. The addition of these three elements not only improves the amorphous forming ability of the powder, but also provides excellent corrosion resistance.

[0013] 2. A sol-gel coating method is used to construct a thin and dense SiO2 insulating layer on the surface of the Cr2O3 passivation layer inherent in the powder, providing a second rust-proof barrier. An impregnation method is employed, immersing the powder in an organic corrosion inhibitor solution. The flexibility of the organic material allows it to embed into the gaps between the SiO2 crystal nuclei on the powder surface, forming a continuous and complete corrosion-resistant film. These two methods, together with the alloy's own passivation film, provide the powder with absolute rust-proof properties. Furthermore, the "low-temperature sol-gel method + solution impregnation" preparation method constructs a dense double-layer protective layer while avoiding amorphous crystallization caused by high temperatures. This process is simple, inexpensive, and overcomes the industrialization challenges of expensive equipment and complex processes associated with vapor deposition methods.

[0014] 3. The amorphous soft magnetic powder prepared by the method of the present invention has excellent corrosion resistance and can withstand 48 hours of salt spray without rusting. Attached Figure Description

[0015] Figure 1This is a SEM image of the surface microstructure of the Fe-Ni-Mo-Si-BPC-Cr amorphous soft magnetic powder prepared in Example 1.

[0016] Figure 2 The image shows the morphology of Fe-Ni-Mo-Si-BPC-Cr amorphous soft magnetic powder prepared in Example 1, without coating, after a 12-hour salt spray test.

[0017] Figure 3 The image shows the powder morphology of Fe-Ni-Mo-Si-BPC-Cr amorphous soft magnetic powder prepared in Example 1 after double-layer coating and 48 hours of salt spray test.

[0018] Figure 4 This is a powder morphology image of the Fe-Si-BC soft magnetic powder prepared in Comparative Example 1 after a 48-hour salt spray test.

[0019] Figure 5 This is a schematic diagram of the structure of the fine amorphous soft magnetic powder in this invention.

[0020] Figure label: 10 fine amorphous soft magnetic powder, 1 soft magnetic powder, 2 SiO2 coating layer, 3 corrosion inhibitor layer. Detailed Implementation

[0021] The technical solutions in 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see the appendix Figure 1-5 As shown, this invention provides a fine amorphous soft magnetic powder 10 that can withstand 48 hours of salt spray. The fine amorphous soft magnetic powder 10 comprises a Fe-Ni-Mo-Si-BPC-Cr based soft magnetic powder 1 in the middle, with a SiO2 coating layer 2 and a corrosion inhibitor layer 3 sequentially coated on its surface, forming a double-layer composite coating structure. The fine amorphous soft magnetic powder 10 of this invention, capable of withstanding 48 hours of salt spray, is suitable for manufacturing high-frequency inductors, transformer cores, electromagnetic shielding materials, 3D-printed magnetic components, corrosion-resistant sensors, etc.

[0023] This invention utilizes Fe-Ni-Mo-Si-BPC-Cr soft magnetic powder 1, which exhibits lower losses and superior soft magnetic properties compared to other soft magnetic powders. The added Ni, Mo, and Cr elements not only enhance amorphous formation ability to maintain soft magnetic properties but also spontaneously form a passivation film to improve the powder's rust prevention capabilities. Furthermore, a double-layer composite coating is achieved through a low-temperature sol-gel method combined with solution impregnation, offering advantages such as simple operation, good stability, and high film uniformity. The coated Fe-Ni-Mo-Si-BPC-Cr magnetic powder exhibits superior rust prevention performance and excellent overall soft magnetic properties.

[0024] The fine amorphous soft magnetic powder 10 comprises: 0-10% Ni, 0-8% Mo, 2-8% Si, 2-6% B, 1-8% P, 0.1-1.5% C, 1.0-4.0% Cr, with the balance being Fe. Among these, Si, B, P, and C provide the powder with extremely high amorphous forming ability, enabling the powder to achieve an amorphous structure under atomization conditions. The addition of Cr facilitates the formation of a dense passivation film on the surface, primarily composed of Cr₂O₃ / Cr(OH)₃, providing a basic barrier against corrosion. A certain amount of Cr addition also enhances the amorphous forming ability; however, excessively high Cr content will affect both the amorphous forming ability and magnetic properties. Therefore, the mass percentage of Cr is 1.0-4.0%. Furthermore, with the presence of Cr, the addition of Mo further enriches the passivation film with Cr and inhibits the adsorption of harmful anions. Meanwhile, Mo has a large atomic radius, and its addition increases the disorder of the alloy, making the mixing enthalpy more negative, thereby improving the amorphous forming ability. Appropriate addition of Mo has a significant effect on improving rust prevention and amorphous forming ability, but excessive addition may cause segregation, which will reduce corrosion resistance and deteriorate magnetic properties. Therefore, the mass percentage content of Mo is 0-8%. On the other hand, the addition of Ni can significantly enhance the spontaneous passivation of powder in corrosive media, promote the formation of a protective oxide film on the surface, and improve passivation ability. However, excessive addition may destroy the Fe-Si solid solution and affect the amorphous forming ability. Therefore, the mass percentage content of Ni is 0-10%.

[0025] The SiO2 coating layer 2 is prepared by the sol-gel method; the corrosion inhibitor layer 3 is at least one of phosphate ester, hexamethylenetetramine or sodium benzoate.

[0026] The fine amorphous soft magnetic powder 10 is a spherical or near-spherical powder prepared by atomization. The atomization method is any one of gas atomization, water atomization, or water-gas combined atomization.

[0027] The median particle size D50 of the micro-fine amorphous soft magnetic powder 10 is 1-6 μm. Generally, the larger the particle size of the micro-fine amorphous soft magnetic powder 10, the higher the corresponding loss; while the smaller the particle size, the lower the loss. This type of micro-fine amorphous powder is more suitable for applications above MHz.

[0028] The present invention also includes a magnetic ring made from the aforementioned fine amorphous soft magnetic powder.

[0029] The double-layer coating process of the micro-fine amorphous soft magnetic powder 10 includes the following steps: S1: Surface coupling treatment is performed on amorphous soft magnetic powder 1; S2: Add the coupled amorphous soft magnetic powder 1 to a tetraethyl orthosilicate solution to form a SiO2 coating layer 2 through a sol-gel reaction; mix tetraethyl orthosilicate with an alcohol solvent, add the amorphous soft magnetic powder to the mixed solution, stir and react at a certain temperature for a period of time, and then filter out the amorphous soft magnetic powder using a filter cloth to obtain SiO2-coated amorphous soft magnetic powder; using the sol-gel coating method, a thin and dense SiO2 insulating layer is constructed on the surface of the amorphous soft magnetic powder 1, thereby providing a second rust-proof barrier.

[0030] S3: The corrosion inhibitor is first prepared into a corrosion inhibitor solution in an alcohol solvent. The amorphous soft magnetic powder 1 with SiO2 coating layer 2 is then immersed in the corrosion inhibitor solution for vacuum impregnation treatment to form corrosion inhibitor layer 3. By using the impregnation method, the powder is immersed in the corrosion inhibitor solution, which allows the corrosion inhibitor to be fully adsorbed on the powder surface, forming a continuous and complete corrosion-resistant film, thereby providing the powder with absolute rust prevention properties.

[0031] S4: The amorphous magnetic powder is placed in a dryer and dried thoroughly to remove excess solvent from the surface, resulting in fine amorphous soft magnetic powder 10 with a double layer of SiO2-corrosion inhibitor coating.

[0032] In step S1, the coupling agent used in the coupling treatment is at least one of organochromium coupling agent, organosilicon coupling agent, or titanate coupling agent, and the concentration of the coupling agent solution is 0.1-1%. The solvent used in the coupling treatment is an alcohol solvent. The coupling agent, utilizing its unique structure, can couple the magnetic powder-SiO2 interface, thereby increasing the adhesion strength of the SiO2 coating layer. Only a small amount of coupling agent is needed to obtain a good coupling effect; to avoid diluting the soft magnetic properties, the amount of coupling agent used is usually no more than 1%.

[0033] In step S2, the concentration of the tetraethyl orthosilicate solution is 0.1-3%, the reaction temperature is 20-120℃, and the reaction time is 1-8 hours. A lower concentration of tetraethyl orthosilicate reacting at a suitable temperature can form uniform and fine SiO2 crystal nuclei on the powder surface. Controlling the appropriate reaction time is also to avoid deterioration of magnetic properties caused by an excessively thick coating layer.

[0034] In step S3, the corrosion inhibitor is at least one of phosphate ester, hexamethylenetetramine, or sodium benzoate, the concentration of the corrosion inhibitor solution is 1-20%, and the immersion time is 5-60 minutes. These corrosion inhibitors are mainly adsorption-type, which can stably adsorb onto the surface of the powder and form a dense protective film, hindering the migration and diffusion of corrosive media to the powder surface, thereby inhibiting or delaying corrosion. Filtering out the powder after immersion is to prevent the corrosion inhibitor layer from becoming too thick and affecting the soft magnetic properties.

[0035] The beneficial technical effects of the micro-fine amorphous soft magnetic powder 10 of the present invention will be explained below through several examples and comparative examples. Example 1

[0036] This example provides a fine amorphous soft magnetic powder that can withstand 48 hours of salt spray. The fine amorphous soft magnetic powder is a Fe-Ni-Mo-Si-BPC-Cr based soft magnetic powder, with a SiO2 coating layer and a corrosion inhibitor layer sequentially coated on its surface, forming a double-layer composite coating structure. The fine amorphous soft magnetic powder comprises 4.2% Ni, 2.5% Mo, 1.5% Si, 2% B, 4% P, 1.4% C, 3.5% Cr, with the balance being Fe. The fine amorphous soft magnetic powder is a spherical powder prepared by a water-air combined atomization method, which is dried and sieved to obtain a powder with a particle size of D50 = 2.5 μm. The double-layer coating process of the fine amorphous soft magnetic powder includes the following steps: S1: Prepare a 0.6% silane coupling agent-ethanol solution and perform surface coupling treatment on the amorphous soft magnetic powder; S2: The coupled amorphous soft magnetic powder is added to a 1.2% tetraethyl orthosilicate-ethanol solution and stirred at 60°C for 6 hours to form a SiO2 coating layer using a sol-gel reaction; the amorphous soft magnetic powder is filtered out using a filter cloth to obtain SiO2-coated amorphous soft magnetic powder. S3: Prepare a 10% sodium benzoate-ethanol solution, immerse the amorphous soft magnetic powder with SiO2 coating in the sodium benzoate-ethanol solution for vacuum impregnation, filter out the powder after immersion for 5 minutes to form a corrosion inhibitor layer, and obtain amorphous soft magnetic powder with SiO2-corrosion inhibitor double coating. S4: The amorphous magnetic powder was thoroughly dried in a dryer to remove excess solvent from the surface, resulting in a fine amorphous soft magnetic powder with a SiO2-corrosion inhibitor double-layer coating. SEM images of its microscopic surface morphology are attached. Figure 1 As shown, its 48-hour salt spray diagram is attached. Figure 3 As shown. Example 2

[0037] This example provides a fine amorphous soft magnetic powder that can withstand 48 hours of salt spray. The fine amorphous soft magnetic powder is a Fe-Ni-Mo-Si-BPC-Cr based soft magnetic powder, with a SiO2 coating layer and a corrosion inhibitor layer sequentially coated on its surface, forming a double-layer composite coating structure. The fine amorphous soft magnetic powder comprises 4.2% Ni, 2.5% Mo, 1.5% Si, 2% B, 4% P, 1.4% C, 3.5% Cr, with the balance being Fe. The fine amorphous soft magnetic powder is a spherical powder prepared by a water-air combined atomization method, which is dried and sieved to obtain a powder with a particle size of D50 = 2.5 μm. The double-layer coating process of the fine amorphous soft magnetic powder includes the following steps: S1: Prepare a 0.6% silane coupling agent-ethanol solution and perform surface coupling treatment on the amorphous soft magnetic powder; S2: The coupled amorphous soft magnetic powder is added to a 2% tetraethyl orthosilicate-ethanol solution and stirred at 60°C for 6 hours to form a SiO2 coating layer using a sol-gel reaction; the amorphous soft magnetic powder is filtered out using a filter cloth to obtain SiO2-coated amorphous soft magnetic powder. S3: Prepare a 5% sodium benzoate-ethanol solution, immerse the amorphous soft magnetic powder with SiO2 coating in the sodium benzoate-ethanol solution for vacuum impregnation, filter out the powder after 10 minutes to form a corrosion inhibitor layer, and obtain amorphous soft magnetic powder with SiO2-corrosion inhibitor double coating. S4: The amorphous magnetic powder is placed in a dryer and dried thoroughly to remove excess solvent from the surface, resulting in fine amorphous soft magnetic powder with a double layer of SiO2-corrosion inhibitor coating. Example 3

[0038] This example provides a fine amorphous soft magnetic powder that can withstand 48 hours of salt spray. The fine amorphous soft magnetic powder is a Fe-Ni-Mo-Si-BPC-Cr based soft magnetic powder, with a SiO2 coating layer and a corrosion inhibitor layer sequentially coated on its surface, forming a double-layer composite coating structure. The fine amorphous soft magnetic powder comprises 4.2% Ni, 2.5% Mo, 1.5% Si, 2% B, 4% P, 1.4% C, 3.5% Cr, with the balance being Fe. The fine amorphous soft magnetic powder is a spherical powder prepared by a water-air combined atomization method, which is dried and sieved to obtain a powder with a particle size of D50 = 5 μm. The double-layer coating process of the fine amorphous soft magnetic powder includes the following steps: S1: Prepare a 0.6% silane coupling agent-ethanol solution and perform surface coupling treatment on the amorphous soft magnetic powder; S2: The coupled amorphous soft magnetic powder is added to a 1.2% tetraethyl orthosilicate-ethanol solution and stirred at 60°C for 6 hours to form a SiO2 coating layer using a sol-gel reaction; the amorphous soft magnetic powder is filtered out using a filter cloth to obtain SiO2-coated amorphous soft magnetic powder. S3: Prepare a 10% hexamethylenetetramine-ethanol solution, immerse the amorphous soft magnetic powder with SiO2 coating in the hexamethylenetetramine-ethanol solution for vacuum impregnation, filter out the powder after immersion for 60 minutes to form a corrosion inhibitor layer, and obtain amorphous soft magnetic powder with SiO2-corrosion inhibitor double coating. S4: The amorphous magnetic powder is placed in a dryer and dried thoroughly to remove excess solvent from the surface, resulting in fine amorphous soft magnetic powder with a double layer of SiO2-corrosion inhibitor coating.

[0039] Comparative Example 1 This example provides an amorphous soft magnetic powder, which is an Fe-Si-BC based soft magnetic powder with a phosphate layer coated on its surface. The phosphate layer contains 5.3% Si, 2.0% B, 0.5% C, and the balance is Fe. The fine amorphous soft magnetic powder is a spherical powder prepared by a water-air combined atomization method. After drying, it is sieved to obtain an amorphous powder with a particle size of D50 = 3 μm. The coating process of this amorphous soft magnetic powder includes the following steps: the amorphous soft magnetic powder is added to a 0.5% phosphate-ethanol solution for coating treatment, and after thorough stirring, it is dried to obtain phosphated amorphous soft magnetic powder.

[0040] Comparative Example 2 This example provides an amorphous soft magnetic powder, Fe-Si-BC amorphous powder prepared by water-air co-atomization, wherein the Si content is 3.5%, the B content is 2.5%, and the C content is 0.5%, and its surface is coated with a phosphate layer. After drying, it is sieved to obtain powder with a particle size of D50=3μm. The coating process of the fine amorphous soft magnetic powder includes the following steps: the amorphous soft magnetic powder is added to a 0.5% phosphate-ethanol solution for coating treatment, and after thorough stirring, it is dried to obtain phosphated amorphous soft magnetic powder.

[0041] Comparative Example 3 This example provides an amorphous soft magnetic powder. Fe-Si-BC amorphous soft magnetic powder is prepared by water-air combined atomization, wherein the Si content is 3.5%, the B content is 2.5%, and the C content is 0.5%. After drying, the powder is sieved to obtain an amorphous soft magnetic powder with a particle size of D50=5μm. The powder is then impregnated with a 10% hexamethylenetetramine corrosion inhibitor for 30 minutes. After impregnation, the powder is filtered out using a filter cloth to obtain amorphous soft magnetic powder with a single layer of corrosion inhibitor coating.

[0042] Comparative Example 4 This example provides an amorphous soft magnetic powder. Fe-Si-BC amorphous soft magnetic powder was prepared using a water-air co-atomization method, wherein the Si content was 3.5%, the B content was 2.5%, and the C content was 0.5%. After drying, the powder was sieved to obtain an amorphous soft magnetic powder with a particle size of D50 = 5 μm. A 0.1% silane coupling agent-ethanol solution was prepared, and the amorphous soft magnetic powder was added to the coupling agent solution for coupling treatment for 1 hour to obtain coupled amorphous magnetic powder. A 2% tetraethyl orthosilicate-ethanol solution was prepared, and the coupled amorphous magnetic powder was added to the tetraethyl orthosilicate solution. The mixture was stirred and reacted at 60°C for 3 hours to form a SiO2 coating layer through a sol-gel reaction. After the reaction was completed, the powder was filtered out using a filter cloth to obtain a single-layer SiO2-coated amorphous soft magnetic powder.

[0043] Testing: Salt spray tests were conducted on the Fe-Ni-Mo-Si-BPC-Cr amorphous soft magnetic powders prepared in Examples 1-3 and the Fe-Si-BC amorphous soft magnetic powders prepared in Comparative Examples 1-3 for 6 hours, 12 hours, 24 hours, and 48 hours. The soft magnetic properties (effective permeability) of the magnetic rings were also tested after pressing and molding.

[0044] Table 1. Performance Comparison of Amorphous Soft Magnetic Powder and Pressed Magnetic Rings Prepared in the Examples and Comparative Examples

[0045] Based on the performance test results shown in Table 1 and the appendix Figure 1-4 Comparative analysis leads to the following conclusions: The amorphous soft magnetic powder 1 with specific components (Fe-Ni-Mo-Si-BPC-Cr) of this invention, combined with a SiO2-corrosion inhibitor double-layer coating structure, endows the fine amorphous soft magnetic powder 10 with excellent long-term rust prevention capabilities. Specifically: 1. Example 1: The uncoated powder, due to the inherent corrosion resistance of its alloy (derived from the addition of Ni, Mo, and Cr), can withstand 12 hours of salt spray (with attached...). Figure 2 However, it rusts within 24 hours. The same powder with the same composition, after being coated with a double layer according to this invention, exhibits a significant improvement in rust resistance and can fully withstand 48 hours of salt spray (…). Figure 3 This proves that long-term rust prevention cannot be achieved by the alloy itself or a single coating layer alone; it must rely on the synergistic effect of the corrosion-resistant alloy itself and the dense double-layer coating.

[0046] 2. The rust prevention time of all comparative examples (single-layer phosphating, single-layer corrosion inhibitor, and single-layer SiO2) did not exceed 24 hours. Among them, Comparative Example 3 (single corrosion inhibitor layer) only lasted for 6 hours, and Comparative Example 4 (single SiO2 layer), although it lasted for 12 hours, could not withstand longer corrosion tests, proving that the single-layer barrier has defects. In contrast, the double-layer structure of the present invention (SiO2 layer + corrosion inhibitor layer) provides more complete and durable protection.

[0047] 3. Examples 1-3 differed in parameters such as the type of corrosion inhibitor (sodium benzoate / hexamethylenetetramine), concentration (5% / 10%), and particle size (D50=2.5 / 5μm), but the powders obtained could all pass the 48-hour salt spray test, indicating the reliability and universality of the preparation method.

[0048] 4. The effective magnetic permeability (15.8-18.1) of the double-layer coated magnetic rings (Examples 1-3) is at the same level as that of the single-layer coated magnetic rings (16.2-18.5) in the comparative example, indicating that the coating process significantly improves the rust prevention performance without causing substantial damage to the core soft magnetic properties of the magnetic ring.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fine amorphous soft magnetic powder resistant to 48 hours of salt spray, characterized in that: The fine amorphous soft magnetic powder is a Fe-Ni-Mo-Si-BPC-Cr series soft magnetic powder, and its surface is sequentially coated with a SiO2 coating layer and a corrosion inhibitor layer, forming a double-layer composite coating structure.

2. The fine amorphous soft magnetic powder capable of withstanding 48 hours of salt spray according to claim 1, characterized in that: The fine amorphous soft magnetic powder comprises: 0-10% Ni, 0-8% Mo, 2-8% Si, 2-6% B, 1-8% P, 0.1-1.5% C, 1.0-4.0% Cr, with the balance being Fe.

3. The fine amorphous soft magnetic powder capable of withstanding 48 hours of salt spray according to claim 1, characterized in that: The SiO2 coating layer is prepared by the sol-gel method; the corrosion inhibitor layer is at least one of phosphate ester, hexamethylenetetramine or sodium benzoate.

4. The fine amorphous soft magnetic powder capable of withstanding 48 hours of salt spray according to claim 1, characterized in that: The fine amorphous soft magnetic powder is a spherical or near-spherical powder prepared by atomization.

5. The fine amorphous soft magnetic powder capable of withstanding 48 hours of salt spray according to claim 4, characterized in that: The atomization method can be any one of gas atomization, water atomization, or combined water-gas atomization.

6. The fine amorphous soft magnetic powder capable of withstanding 48 hours of salt spray according to claim 5, characterized in that: The median particle size D50 of the fine amorphous soft magnetic powder is 1-6 μm.

7. A magnetic ring, characterized in that, It is prepared using the fine amorphous soft magnetic powder described in any one of claims 1-6.

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