A corrosion-resistant, purely magnetic porous foam absorbing material and its preparation method

Abstract

This invention discloses a corrosion-resistant, purely magnetic porous foam absorbing material and its preparation method, belonging to the field of electromagnetic wave absorbing material technology. The method involves hydrothermal reaction of ferric hydroxide precipitate to generate one-dimensional ferric hydroxide nanowires. Using these one-dimensional nanowires as a matrix, a porous foam material is prepared through liquid nitrogen directional freezing and vacuum drying. After calcination in an ammonia atmosphere, the corrosion-resistant, purely magnetic porous foam absorbing material is finally obtained. This invention successfully prepares a foam material with a specifically oriented porous structure by utilizing ultra-low temperature liquid nitrogen for oriented freezing followed by vacuum drying. This allows electromagnetic waves to penetrate deep into the material along these pores, converting more electromagnetic wave energy into heat energy for dissipation, thus achieving higher electromagnetic wave absorption performance. Furthermore, this invention uses an ammonia atmosphere for calcination, eliminating the need for any organic matter, ultimately obtaining a ferro-nitrogen-based purely magnetic porous foam material exhibiting stronger corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic wave absorbing materials technology, and particularly relates to a corrosion-resistant pure magnetic porous foam absorbing material and its preparation method. Background Technology

[0002] With the continuous advancement of technology, electronic information equipment has been widely used in both civilian and military fields. Because the electromagnetic waves emitted by these devices pose a potential threat to the natural environment and human health, absorbing materials capable of absorbing electromagnetic waves have been developed. However, traditional absorbing materials often possess characteristics such as light weight, large absorption bandwidth, high reflection loss, and thin matching thickness. When some electronic devices are used in complex environments, traditional absorbing materials can no longer meet the demands of these environments. Therefore, improving the environmental stability of absorbing materials has become a current research focus, leading to the development of corrosion-resistant materials. Applying these corrosion-resistant materials to electronic devices in special environments can not only effectively absorb electromagnetic waves but also extend the service life of the absorbing materials.

[0003] Chinese patent application CN202311017696.4 discloses a magnetic composite corrosion-resistant microwave absorbing material. This material has a core-shell structure, where the core is magnetic micropowder and the shell is an inorganic inner shell / organosilicon polymer outer shell. The inorganic inner shell is SiO2, and the organosilicon polymer outer shell is polymerized from 1H,1H,2H,2H-perfluorooctyltriethoxysilane (F13) and methyltrimethoxysilane (MTMS). This magnetic composite corrosion-resistant microwave absorbing material exhibits good reflection loss, a large absorption bandwidth, and excellent corrosion resistance.

[0004] In the above technical solutions, although the corrosion resistance and microwave absorption performance of the material are enhanced by constructing a magnetic core and a non-magnetic shell core-shell structure, the following problems exist: (1) The preparation process of magnetic composite core-shell materials is relatively complex; (2) Magnetic composite core-shell materials may cause local magnetic field inhomogeneity, thereby reducing the ferromagnetic properties of the material; (3) The core-shell structure cannot allow more electromagnetic waves to enter the interior of the material, thus it cannot convert more electromagnetic wave energy into heat dissipation, which will result in less electromagnetic wave loss.

[0005] Therefore, it is of great significance to prepare porous foam absorbing materials with excellent corrosion resistance and pure magnetic properties through a simple process. Summary of the Invention

[0006] The first objective of this invention is to address the shortcomings of existing technologies by proposing a method for preparing a corrosion-resistant, purely magnetic porous foam absorbing material. This method involves directional freezing with liquid nitrogen and nitriding with ammonia, and combines the material's inherent characteristics, magnetic properties, and crystal structure to obtain a corrosion-resistant electromagnetic wave absorbing material. This solves the problems of current manufacturing processes being complex, often involving composite materials, resulting in low electromagnetic wave loss, and the susceptibility to corrosion of the absorbing material.

[0007] To achieve the objectives of this invention, the invention is implemented through the following technical solutions:

[0008] A method for preparing a corrosion-resistant, purely magnetic porous foam absorbing material includes the following steps:

[0009] Step (1) Preparation of ferric hydroxide precipitate

[0010] Ferric chloride hexahydrate and sodium hydroxide were dissolved separately and then mixed. Potassium hydroxide was added, and ferric hydroxide precipitate was prepared under alkaline conditions.

[0011] Step (2) Preparation of one-dimensional iron hydroxyl oxide nanowires

[0012] One-dimensional iron hydroxide nanowires were obtained by hydrothermal reaction of ferric hydroxide precipitate.

[0013] Step (3) Preparation of porous foam material with iron hydroxyl oxide

[0014] One-dimensional iron hydroxy oxide nanowires were dissolved in deionized water, oriented and frozen using ultra-low temperature liquid nitrogen, and then vacuum dried to obtain porous iron hydroxy oxide foam material.

[0015] Step (4): Preparation of corrosion-resistant pure magnetic porous foam absorbing material

[0016] The porous foam material of iron hydroxyl oxide is calcined in an ammonia atmosphere. Under the action of reducing hydrogen and nitrogen atoms, the porous foam material of iron hydroxyl oxide undergoes a chemical reaction to generate iron tetranitrogen porous foam material, which is the corrosion-resistant pure magnetic porous foam absorbing material.

[0017] Preferably, in step (1), the weight parts of ferric chloride hexahydrate are 1-4 parts, the weight parts of sodium hydroxide are 3-12 parts, and the weight parts of potassium hydroxide are 6-10 parts.

[0018] Preferably, in step (1), the weight parts of ferric chloride hexahydrate are 1 part, the weight parts of sodium hydroxide are 3 parts, and the weight parts of potassium hydroxide are 6 parts.

[0019] Preferably, in step (1), the weight parts of ferric chloride hexahydrate are 4 parts, the weight parts of sodium hydroxide are 12 parts, and the weight parts of potassium hydroxide are 8 parts.

[0020] Preferably, the hydrothermal temperature in step (2) is 90-120℃.

[0021] Preferably, the reaction time in step (2) is 15-20 h.

[0022] Preferably, the temperature of the cryogenic liquid nitrogen in step (3) is -197°C.

[0023] Preferably, the drying time in step (3) is 12-48 hours.

[0024] Preferably, the calcination temperature in step (4) is 300-400℃.

[0025] Preferably, the calcination time in step (4) is 2-6 hours.

[0026] In this invention, cryogenic liquid nitrogen is used for directional freezing. Compared with conventional freezing methods, liquid nitrogen freezing allows for more freedom in selecting the direction of ice crystal growth, thereby achieving the purpose of directional freezing of samples. This invention also uses an ammonia atmosphere for calcination. Compared with a nitrogen atmosphere, nitrogen is less likely to decompose into nitrogen atoms, which can easily lead to uneven nitriding. However, an ammonia atmosphere can decompose into nitrogen atoms and reduced hydrogen at high temperatures. The reduced hydrogen reduces iron hydroxide, and the resulting reduced substance undergoes nitriding under the influence of surrounding nitrogen atoms, ultimately yielding a pure iron tetranitrogen phase.

[0027] The second objective of this invention is to provide a corrosion-resistant, purely magnetic, porous foam absorbing material, which is prepared using the method described above.

[0028] This invention provides a corrosion-resistant, purely magnetic porous foam absorbing material. It has the following beneficial effects:

[0029] (1) This invention uses iron hydroxyl oxide nanowires as a matrix and employs ultra-low temperature liquid nitrogen for orientation freezing to precisely control the growth direction of ice crystals. Subsequently, a porous foam material with a specific orientation arrangement was successfully prepared by vacuum drying. This material combines porous characteristics, allowing electromagnetic waves to penetrate deep into the material along these pores, converting more electromagnetic wave energy into heat energy for dissipation, which is beneficial for achieving higher electromagnetic wave absorption performance.

[0030] (2) This invention uses ammonia as a reducing atmosphere to calcine hydroxyl iron oxide porous foam material at 300-400℃ without adding any organic matter, ultimately obtaining iron tetranitrogen pure magnetic porous foam material. This pure magnetic material is free of impurities, can effectively absorb and attenuate electromagnetic waves, and exhibits stronger corrosion resistance compared with conventional carbonyl iron powder materials, thus realizing the effective application of this microwave absorbing material in complex environments. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the preparation method steps of the present invention.

[0032] Figure 2 This is a surface morphology image of porous iron hydroxyl oxide foam material obtained by liquid nitrogen freezing under an optical microscope.

[0033] Figure 3 This is a surface morphology image of porous iron hydroxyl oxide foam material obtained by freeze drying under an optical microscope.

[0034] Figure 4 This is an electron microscope image of the microstructure of the corrosion-resistant pure magnetic porous foam material in Example 1 at 800x magnification.

[0035] Figure 5 This is an electron microscope image of the microstructure of the corrosion-resistant pure magnetic porous foam material in Example 1, magnified at 3200x. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solutions of this invention, the invention will be described in detail below with reference to the embodiments and illustrations. These embodiments are only used to explain the invention and do not constitute a limitation on the scope of protection of the invention.

[0037] The raw materials used in the following examples were all obtained through conventional commercial channels.

[0038] like Figure 1 As shown, this invention provides a method for preparing a corrosion-resistant, purely magnetic porous foam absorbing material, comprising the following steps:

[0039] Step (1) Preparation of one-dimensional iron hydroxyoxide nanowires

[0040] 1-4 parts by weight of ferric chloride hexahydrate and 3-12 parts by weight of sodium hydroxide were dissolved and mixed, and then 6-10 parts by weight of potassium hydroxide were added to prepare ferric hydroxide precipitate under alkaline environment. The ferric hydroxide precipitate was placed in an oven at 90-120℃ for hydrothermal reaction for 15-20 hours to obtain one-dimensional ferric hydroxide nanowires.

[0041] Step (2) Preparation of porous foam material with iron hydroxyl oxide

[0042] One-dimensional iron hydroxy oxide nanowires were dissolved in deionized water, oriented and frozen using ultra-low temperature liquid nitrogen (-197℃), and then vacuum dried for 12-48 hours to obtain porous iron hydroxy oxide foam material.

[0043] Step (3) Preparation of corrosion-resistant pure magnetic porous foam absorbing material

[0044] The porous foam material of hydroxyl iron oxide is calcined in an ammonia atmosphere at 300-400℃ for 2-6 hours. Under the action of reducing hydrogen and nitrogen atoms, the porous foam material of hydroxyl iron oxide undergoes a chemical reaction to generate iron tetranitrogen porous foam material, thus obtaining the corrosion-resistant pure magnetic porous foam absorbing material.

[0045] In the above preparation process, the amount of each raw material, reaction time, and reaction temperature can be selected according to actual needs. For example, in some embodiments, the weight parts of ferric chloride hexahydrate are 1-4 parts, specifically selected from 1 part, 2 parts, 3 parts, and 4 parts; the weight parts of sodium hydroxide are 3-12 parts, specifically selected from 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, and 12 parts; the weight parts of potassium hydroxide are 6-10 parts, specifically selected from 6 parts, 7 parts, 8 parts, 9 parts, and 10 parts; and the oven temperature is 90-120℃, specifically selected from 90℃, 95℃, 100℃, and 105℃. ℃, 110℃, 115℃, 120℃; hydrothermal reaction time is 15-20h, specifically selected from 15h, 16h, 17h, 18h, 19h, 20h; vacuum drying time is 12-48h, specifically selected from 12h, 24h, 36h, 48h; calcination temperature in ammonia atmosphere is 300-400℃, specifically selected from 300℃, 320℃, 340℃, 360℃, 380℃, 400℃; calcination time is 2-6h, specifically selected from 2h, 3h, 4h, 5h, 6h; in addition to the values ​​listed above, any value within the range is acceptable and is not limited here.

[0046] The present invention will be further described below with reference to specific embodiments.

[0047] Example 1

[0048] A method for preparing a corrosion-resistant, purely magnetic porous foam absorbing material includes the following steps:

[0049] Step 1: Preparation of ferric hydroxide precipitate

[0050] Dissolve 1 part ferric chloride hexahydrate and 3 parts sodium hydroxide in deionized water and mix them to form ferric hydroxide precipitate. Then add 6 parts potassium hydroxide to create an alkaline environment.

[0051] Step 2: Preparation of one-dimensional iron hydroxyoxide nanowires

[0052] After stirring the mixed solution containing ferric hydroxide precipitate obtained in step one, it was placed in a 120℃ oven for 18 hours of hydrothermal treatment to obtain one-dimensional ferric hydroxide nanowire materials.

[0053] Step 3: Preparation of porous foam structure with iron hydroxyl oxide

[0054] The one-dimensional nanowire material prepared in step two was mixed with deionized water at a ratio of 1:2 and poured into a constant container. The mixture was then freeze-dried using liquid nitrogen at -197°C. The frozen sample was then vacuum-dried for 12 hours. The purpose of the drying was to allow the ice crystals to evaporate and create a porous structure, ultimately producing a porous foam material of iron hydroxyl oxide. Figure 2 This is a surface morphology image of the porous iron hydroxyl oxide foam material obtained by liquid nitrogen freezing in this embodiment, as shown under an optical microscope.

[0055] Step 4: Preparation of Iron-Nitrogen Corrosion-Resistant Pure Magnetic Porous Foam Material

[0056] The hydroxyl iron oxide porous foam material prepared in step three is placed in a tube furnace and subjected to nitriding with 95% pure ammonia at 300°C for 6 hours. The purpose is to obtain a corrosion-resistant iron tetranitrogen compound, and finally obtain a corrosion-resistant pure magnetic porous foam material.

[0057] Figure 4 and 5 This is a microstructure diagram of this embodiment, wherein... Figure 4 This is an electron microscope image at 800x magnification. Figure 5 This is an electron microscope image at 3200x magnification.

[0058] Example 2

[0059] A method for preparing a corrosion-resistant, purely magnetic porous foam absorbing material includes the following steps:

[0060] Step 1: Preparation of ferric hydroxide precipitate

[0061] Dissolve 2 parts of ferric chloride hexahydrate and 6 parts of sodium hydroxide in deionized water and mix them together to form ferric hydroxide precipitate. Then add 7 parts of potassium hydroxide to create an alkaline environment.

[0062] Step 2: Preparation of one-dimensional iron hydroxyoxide nanowires

[0063] After stirring the mixed solution containing ferric hydroxide precipitate obtained in step one, it was placed in a 120℃ oven for 18 hours of hydrothermal treatment to obtain one-dimensional ferric hydroxide nanowire materials.

[0064] Step 3: Preparation of porous foam structure with iron hydroxyl oxide

[0065] The one-dimensional nanowire material prepared in step two was mixed with deionized water at a ratio of 1:2, poured into a constant container, and freeze-dried using liquid nitrogen at -197°C. The frozen sample was then vacuum-dried for 16 hours to finally obtain porous foam material of iron hydroxyl oxide.

[0066] Step 4: Preparation of Iron-Nitrogen Corrosion-Resistant Pure Magnetic Porous Foam Material

[0067] The hydroxyl iron oxide porous foam material prepared in step three is placed in a tube furnace and nitrided at 320°C for 5 hours with 95% pure ammonia gas to finally obtain a corrosion-resistant pure magnetic porous foam material.

[0068] In this embodiment, the remaining parameters are the same as in Embodiment 1.

[0069] Example 3

[0070] A method for preparing a corrosion-resistant, purely magnetic porous foam absorbing material includes the following steps:

[0071] Step 1: Preparation of ferric hydroxide precipitate

[0072] Dissolve 4 parts of ferric chloride hexahydrate and 12 parts of sodium hydroxide in deionized water and mix them together to form ferric hydroxide precipitate. Then add 10 parts of potassium hydroxide to create an alkaline environment.

[0073] Step 2: Preparation of one-dimensional iron hydroxyoxide nanowires

[0074] After stirring the mixed solution containing ferric hydroxide precipitate obtained in step one, it was placed in a 120℃ oven for 18 hours of hydrothermal treatment to obtain one-dimensional ferric hydroxide nanowire materials.

[0075] Step 3: Preparation of porous foam structure with iron hydroxyl oxide

[0076] The one-dimensional nanowire material prepared in step two was mixed with deionized water at a ratio of 1:2, poured into a constant container, and freeze-dried using liquid nitrogen at -197°C. The frozen sample was then vacuum-dried for 24 hours to finally obtain porous foam material of iron hydroxyl oxide.

[0077] Step 4: Preparation of Iron-Nitrogen Corrosion-Resistant Pure Magnetic Porous Foam Material

[0078] The porous hydroxyl iron oxide material prepared in step three is placed in a tube furnace and nitrided at 400°C for 2 hours with 95% pure ammonia gas to finally obtain a corrosion-resistant pure magnetic porous foam material.

[0079] In this embodiment, the remaining parameters are the same as in Embodiment 1.

[0080] Combining Examples 1, 2, and 3, this invention employs a corrosion-resistant, purely magnetic porous foam absorbing material. Using iron hydroxyl oxide nanowires as the matrix, and utilizing ultra-low temperature liquid nitrogen orientation freezing to control the ice crystal growth direction, an oriented porous structure is obtained. This porous structure allows electromagnetic waves to penetrate deep into the material along these pores, converting more electromagnetic wave energy into heat energy for dissipation, thus achieving higher electromagnetic wave absorption performance. Furthermore, in this invention, calcination under an ammonia atmosphere yields a single-phase, purely magnetic iron tetranitrogen compound, further enhancing the corrosion resistance of the porous foam absorbing material.

[0081] Comparative Example 1: Hydrogen was used as the reducing atmosphere.

[0082] This comparative example prepared a pure magnetic iron oxide porous foam absorbing material, including the following steps:

[0083] Step 1: Preparation of ferric hydroxide precipitate

[0084] Dissolve 1 part ferric chloride hexahydrate and 3 parts sodium hydroxide in deionized water and mix them to form ferric hydroxide precipitate. Then add 6 parts potassium hydroxide to create an alkaline environment.

[0085] Step 2: Preparation of one-dimensional iron hydroxyoxide nanowires

[0086] After stirring the mixed solution containing ferric hydroxide precipitate obtained in step one, it was placed in a 120℃ oven for 18 hours of hydrothermal treatment to obtain one-dimensional ferric hydroxide nanowire materials.

[0087] Step 3: Preparation of porous foam structure with iron hydroxyl oxide

[0088] The one-dimensional nanowire material prepared in step two was mixed with deionized water at a ratio of 1:2 and poured into a constant container. The mixture was then freeze-dried using liquid nitrogen at -197°C. The frozen sample was then vacuum-dried for 12 hours. The purpose of the drying was to allow the ice crystals to evaporate and create a porous structure, ultimately producing a porous foam material of iron hydroxyl oxide.

[0089] Step 4: Preparation of pure magnetic porous foam material of iron(III) oxide

[0090] The hydroxyl iron oxide porous foam material prepared in step three is placed in a tube furnace and reduced with hydrogen at 300°C for 5 hours to obtain pure magnetic porous foam material of iron oxide.

[0091] Comparative Example 2: Hydrogen was used as the reducing atmosphere.

[0092] This comparative example prepared a porous foam absorbing material of pure magnetic iron and iron(III) oxide, including the following steps:

[0093] Step 1: Preparation of ferric hydroxide precipitate

[0094] Dissolve 1 part ferric chloride hexahydrate and 3 parts sodium hydroxide in deionized water and mix them to form ferric hydroxide precipitate. Then add 6 parts potassium hydroxide to create an alkaline environment.

[0095] Step 2: Preparation of one-dimensional iron hydroxyoxide nanowires

[0096] After stirring the mixed solution containing ferric hydroxide precipitate obtained in step one, it was placed in a 120℃ oven for 18 hours of hydrothermal treatment to obtain one-dimensional ferric hydroxide nanowire materials.

[0097] Step 3: Preparation of porous foam structure with iron hydroxyl oxide

[0098] The one-dimensional nanowire material prepared in step two was mixed with deionized water at a ratio of 1:2 and poured into a constant container. The mixture was then freeze-dried using liquid nitrogen at -197°C. The frozen sample was then vacuum-dried for 12 hours. The purpose of the drying was to allow the ice crystals to evaporate and create a porous structure, ultimately producing a porous foam material of iron hydroxyl oxide.

[0099] Step 4: Preparation of pure magnetic porous foam materials made of iron and iron(III) oxide

[0100] The hydroxyl iron oxide porous foam material prepared in step three was placed in a tube furnace and reduced with hydrogen at 300°C for 6 hours to obtain pure magnetic porous foam material of iron and iron oxide.

[0101] Comparative Example 3: Reducing atmosphere using hydrogen and nitrogen

[0102] This comparative example prepared a pure magnetic iron porous foam absorbing material, including the following steps:

[0103] Step 1: Preparation of ferric hydroxide precipitate

[0104] Dissolve 1 part ferric chloride hexahydrate and 3 parts sodium hydroxide in deionized water and mix them to form ferric hydroxide precipitate. Then add 6 parts potassium hydroxide to create an alkaline environment.

[0105] Step 2: Preparation of one-dimensional iron hydroxyoxide nanowires

[0106] After stirring the mixed solution containing ferric hydroxide precipitate obtained in step one, it was placed in a 120℃ oven for 18 hours of hydrothermal treatment to obtain one-dimensional ferric hydroxide nanowire materials.

[0107] Step 3: Preparation of porous foam structure with iron hydroxyl oxide

[0108] The one-dimensional nanowire material prepared in step two was mixed with deionized water at a ratio of 1:2 and poured into a constant container. The mixture was then freeze-dried using liquid nitrogen at -197°C. The frozen sample was then vacuum-dried for 12 hours. The purpose of the drying was to allow the ice crystals to evaporate and create a porous structure, ultimately producing a porous foam material of iron hydroxyl oxide.

[0109] Step 4: Preparation of pure magnetic porous foam materials made of iron and iron tetranitrogen

[0110] The hydroxyl iron oxide porous foam material prepared in step three is placed in a tube furnace and calcined at 300°C with hydrogen and nitrogen for 8 hours to obtain pure magnetic porous foam materials of iron and iron tetranitrogen.

[0111] Comparative Example 4: Preparation of porous foam material of iron hydroxyl oxide using conventional freezing method

[0112] Step 1: Preparation of ferric hydroxide precipitate

[0113] Dissolve 1 part ferric chloride hexahydrate and 3 parts sodium hydroxide in deionized water and mix them to form ferric hydroxide precipitate. Then add 6 parts potassium hydroxide to create an alkaline environment.

[0114] Step 2: Preparation of one-dimensional iron hydroxyoxide nanowires

[0115] After stirring the mixed solution containing ferric hydroxide precipitate obtained in step one, it was placed in a 120℃ oven for 18 hours of hydrothermal treatment to obtain one-dimensional ferric hydroxide nanowire materials.

[0116] Step 3: Preparation of porous foam structure with iron hydroxyl oxide

[0117] The one-dimensional nanowire material prepared in step two was mixed with deionized water at a ratio of 1:2 and poured into a constant container. The mixture was then freeze-dried using a freeze dryer for 12 hours. The purpose of the freeze drying was to allow the ice crystals to evaporate and create a porous structure, ultimately producing a porous foam material of iron hydroxyl oxide.

[0118] The macroscopic morphology of the porous hydroxyl oxide foam material prepared in this comparative example is as follows: Figure 3 As shown.

[0119] contrast Figure 2 and Figure 3 It can be found that after the sample is subjected to directional freezing with ultra-low temperature liquid nitrogen, the growth direction of ice crystals can be precisely controlled, thereby obtaining a more controllable directional porous structure with a specific orientation arrangement than that obtained by freeze dryer.

[0120] The purely magnetic porous foam absorbing materials provided in Examples 1, 2, and 3 were measured using a vector network analyzer. The test results are shown in Table 1 below.

[0121] Table 1 Performance test results of pure magnetic porous foam absorbing materials

[0122]

[0123] As shown in the table above, the corrosion-resistant pure magnetic porous foam absorbing material provided by this invention has excellent electromagnetic wave absorption characteristics.

[0124] The pure magnetic porous foam absorbing materials provided in Examples 1, 2, and 3 were tested using an electrochemical workstation and compared with a control group (compared to commercially available carbonyl iron powder with a particle size of 1-2 μm and a purity of 99.99%). The test results are shown in Table 2 below.

[0125] Table 2. Corrosion Resistance Test Results of Pure Magnetic Porous Foam Absorbing Materials

[0126]

[0127]

[0128] As shown in the table above, the corrosion potential of the iron-nitrogen corrosion-resistant pure magnetic porous foam absorbing material obtained by this invention is closer to a positive value, and it exhibits better corrosion resistance than other pure magnetic porous foam materials and carbonyl iron powder materials.

[0129] The above embodiments illustrate the basic principles, main features, and advantages of the present invention. Furthermore, the present invention is merely illustrative of technical aspects and not intended to limit the scope of protection of the invention. Any improvements made based on the above embodiments are within the scope of protection of the present invention.

Claims

1. A method for preparing a corrosion-resistant, purely magnetic porous foam absorbing material, characterized in that, The preparation method includes the following steps: Step (1) Preparation of ferric hydroxide precipitate Ferric chloride hexahydrate and sodium hydroxide were dissolved separately and then mixed. Potassium hydroxide was added, and ferric hydroxide precipitate was prepared under alkaline conditions. Step (2) Preparation of one-dimensional iron hydroxyl oxide nanowires One-dimensional iron hydroxide nanowires were obtained by hydrothermal reaction of ferric hydroxide precipitate. Step (3) Preparation of porous foam material with iron hydroxyl oxide One-dimensional iron hydroxy oxide nanowires were dissolved in deionized water, oriented and frozen using ultra-low temperature liquid nitrogen, and then vacuum dried to obtain porous iron hydroxy oxide foam material. Step (4): Preparation of corrosion-resistant pure magnetic porous foam absorbing material Ferric hydroxyl oxide porous foam material was calcined in an ammonia atmosphere to obtain ferronitrogen porous foam material, namely the corrosion-resistant pure magnetic porous foam absorbing material.

2. The method for preparing the corrosion-resistant pure magnetic porous foam absorbing material according to claim 1, characterized in that, In step (1), the weight parts of ferric chloride hexahydrate are 1-4 parts, the weight parts of sodium hydroxide are 3-12 parts, and the weight parts of potassium hydroxide are 6-10 parts.

3. The method for preparing the corrosion-resistant pure magnetic porous foam absorbing material according to claim 1, characterized in that, In step (2), the hydrothermal temperature is 90-120℃.

4. The method for preparing the corrosion-resistant pure magnetic porous foam absorbing material according to claim 3, characterized in that, The reaction time in step (2) is 15-20 hours.

5. The method for preparing the corrosion-resistant pure magnetic porous foam absorbing material according to claim 1, characterized in that, In step (3), the temperature of the cryogenic liquid nitrogen is -197℃.

6. The method for preparing the corrosion-resistant pure magnetic porous foam absorbing material according to claim 5, characterized in that, The drying time in step (3) is 12-48 hours.

7. The method for preparing the corrosion-resistant pure magnetic porous foam absorbing material according to claim 1, characterized in that, The calcination temperature in step (4) is 300-400℃.

8. The method for preparing the corrosion-resistant pure magnetic porous foam absorbing material according to claim 7, characterized in that, The calcination time in step (4) is 2-6 hours.

9. A corrosion-resistant, purely magnetic, porous foam absorbing material, prepared by the method described in any one of claims 1-8.

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