Method for preparing novel broadband wave-absorbing material by using ferro-nickel alloy ore heat furnace slag

Abstract

The invention discloses a method for preparing a novel broadband wave-absorbing material from ferro-nickel alloy ore heat furnace slag, and belongs to the technical field of preparation of novel wave-absorbing materials. According to the method, the ferro-nickel alloy submerged arc furnace slag with high chemical stability and a magnesium silicate solid solution as a main component is used as a raw material, chemical treatment and preliminary surface construction are performed through hydrofluoric acid, and meanwhile elements with good wave absorbing performance, such as iron, chromium, manganese and nickel, contained in the submerged arc furnace slag are released into the solution in a free-state ion form; different alkaline reagents (ammonia water, a sodium hydroxide solution, a calcium hydroxide solution or a sodium silicate solution) are selected to enrich the free-state ion elements with the good wave-absorbing performance, and the selected different alkaline reagents are used for carrying out secondary microscopic construction on the submerged arc furnace slag, so that the preparation method of the novel broadband wave-absorbing material is provided.

Description

Technical Field

[0001] The invention belongs to the technical field of wave absorbing materials, and in particular relates to a method for preparing a novel broadband wave absorbing material by utilizing nickel-iron alloy ore-fired furnace slag. Background Art

[0002] With the rapid development of the times, electromagnetic waves are widely used in various fields such as military, medicine, communication technology, aerospace, daily life, etc., but the electromagnetic wave pollution that comes with it is also becoming more and more serious. Electromagnetic wave absorbing materials can not only give weapons and equipment radar stealth performance and improve the battlefield survivability of weapons and equipment, but also absorb electromagnetic wave pollution in the surrounding environment and protect people from the harm of electromagnetic waves. They have great strategic significance and application value.

[0003] At present, the cost of electromagnetic absorbing materials is high. The price of commercially available electromagnetic absorbing coatings is as high as 200,000 yuan / ton, and they are easily oxidized and lose their absorbing properties in exposed environments. my country's nickel metallurgical enterprises accumulate a large amount of thermal slag every year. Shandong Xinhai Technology Co., Ltd. produces up to 30,000 tons of thermal slag per day in the process of producing nickel-iron alloy. This has great environmental pressure. However, the slag is rich in iron, chromium, manganese, nickel and other elements with good absorbing properties, and has the potential to develop absorbing materials. Therefore, if the nickel-iron alloy thermal slag can be effectively developed and utilized, it will have an important impact on the sustainable development of nickel metallurgical enterprises. Summary of the invention

[0004] In view of the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing a new broadband absorbing material using nickel-iron alloy slag. The present invention uses nickel-iron alloy slag with magnesium silicate solid solution as the main component produced when preparing nickel-iron alloy by pyrometallurgy under 1500-1600°C as raw material, performs chemical surface treatment with hydrofluoric acid at room temperature, and uses ammonia water, sodium hydroxide solution, calcium hydroxide solution or sodium silicate solution to construct the microscopic morphology of the surface of the chemically treated nickel-iron alloy slag to prepare a new broadband absorbing material.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] The present invention provides a method for preparing a novel broadband wave absorbing material by using nickel-iron alloy ore-fired slag, comprising the following steps:

[0007] Deionized water is added to the nickel-iron alloy slag, and the mixture is stirred evenly. A hydrofluoric acid solution is added to carry out a primary reaction, and the pH value is adjusted to be neutral or weakly alkaline with an alkaline solution. The mixture is stirred continuously, and the secondary reaction is stopped. The product after the reaction is filtered, and the precipitate is collected. The precipitate is washed with deionized water and dried to obtain a novel broadband absorbing material.

[0008] Preferably, in the above method of preparing a novel broadband absorbing material using nickel-iron alloy slag, an alkaline solution is used to adjust the pH to 7-8.

[0009] The nickel-iron alloy ore-fired slag is composed of MgSiO3, SiO2, MgO, all iron, ferrous iron, Al2O3, Cr2O3, CaO, MnO and Ni;

[0010] The average mass ratio of the MgSiO3, SiO2, MgO, total iron, ferrous iron, Al2O3, Cr2O3, CaO, MnO and Ni is (75-85): (45-55): (25-35): (5-10): (4-6): (2-4): (1-2): (1-2): (0.5-1): (0.03-0.06).

[0011] Preferably, the average mass ratio of MgSiO3, SiO2, MgO, total iron, ferrous iron, Al2O3, Cr2O3, CaO, MnO and Ni in the nickel-iron alloy slag is 80.42:50.74:32.17:6.61:5.45:3.01:1.66:1.02:0.83:0.046.

[0012] The basicity of the nickel-iron alloy slag is 0.5-0.7.

[0013] The formation temperature of the nickel-iron alloy slag is 1500-1600°C.

[0014] Preferably, the alkaline solution is any one of ammonia water, sodium hydroxide solution, calcium hydroxide solution or sodium silicate solution.

[0015] The mass concentration of the hydrofluoric acid solution is 10-40%;

[0016] Preferably, the mass concentration of the hydrofluoric acid solution is 40%.

[0017] The time for the first reaction of adding the hydrofluoric acid solution is 15-20 minutes, and the time for the second reaction of adding the alkaline solution is 20-30 minutes.

[0018] Beneficial effects of the present invention:

[0019] The present invention uses the nickel-iron alloy ore-fired furnace slag with high chemical stability and low cost, which is mainly composed of magnesium silicate solid solution, as a raw material, and forms MgF2 and a small amount of AlF3 micro-sized particles with higher chemical stability on the surface of the nickel-iron alloy ore-fired furnace slag through a simple hydrofluoric acid chemical treatment process, thereby increasing the surface area of ​​the particles and preliminarily constructing the microscopic morphology of the particle surface.

[0020] Furthermore, in the process of adjusting the pH value of the alkaline solution to neutral or weak alkaline, free elements with good wave absorbing properties such as iron, chromium, manganese, nickel, etc. in the solution are deposited on the surface and pores of the nickel-iron alloy slag constructed by MgF2 and a small amount of AlF3 micro-sized particles. At the same time, due to the different alkaline reagents selected (ammonia water, sodium hydroxide solution, calcium hydroxide solution or sodium silicate solution), the surface of the slag material can be further microscopically constructed and designed on the surface of the nickel-iron alloy slag, and free fluoride ions are deposited on the surface of the nickel-iron alloy slag, thereby reducing or even eliminating the environmental pollution caused by fluoride ions.

[0021] The novel broadband absorbing material prepared by the present invention has stable chemical properties, excellent absorbing performance, and the best absorbing strength is comparable to the advanced absorbing materials reported in the international academic frontier. The effective absorbing bandwidth of part of the material is greater than 5 GHz, which meets the actual industrialization needs, and the effective absorbing frequency can be designed between 3 and 18 GHz according to actual needs. The preparation method provided by the present invention has a simple process flow, low cost, and environmental protection, and can be industrialized and mass-produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 XRD patterns of the original slag and the novel broadband absorbing material samples prepared in Examples 1 to 9.

[0023] Figure 2 These are SEM images of the original slag and the novel broadband absorbing material samples prepared in Examples 1 to 9.

[0024] Figure 3 It is a two-dimensional spectrum of reflection loss and effective absorbing bandwidth of original slag and the new broadband absorbing material samples prepared in Examples 1 to 9.

[0025] Figure 4 It is a three-dimensional spectrum of reflection loss of the original slag and the new broadband absorbing material samples prepared in Examples 1 to 9; wherein, Figure 4 A is a three-dimensional spectrum of reflection loss and absorption bandwidth of the original slag; BJ correspond to the three-dimensional spectrum of reflection loss and absorption bandwidth of the absorbing materials prepared in Examples 1 to 9 respectively. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0027] As mentioned above, electromagnetic wave absorbing materials are an effective way to solve the current serious electromagnetic pollution problem. The ore-fired slag produced in the production process of my country's nickel metallurgical enterprises has the potential to develop absorbing materials. At present, there are many literatures on the research of slag recycling. There are more than 100 literatures on the use of chemical methods to modify slag. However, there are no reports on the surface chemical treatment of nickel-iron alloy ore-fired slag with magnesium silicate solid solution as the main component formed by high-temperature process.

[0028] Based on this, the present invention provides a method for preparing a new broadband absorbing material using nickel-iron alloy ore slag. The present invention uses the ore slag produced in the process of producing nickel-iron alloy by Shandong Xinhai Technology Co., Ltd. as raw material, recycles it, and prepares a broadband absorbing material by chemically treating the surface of the slag powder and reconstructing the surface micromorphology. The nickel-iron alloy ore slag used in the present invention is formed when preparing nickel-iron alloy by pyrometallurgy at 1500-1600°C. The main component is a magnesium silicate solid solution. The chemical properties are stable under strong acid and strong alkali conditions, and it is stable under strong acids such as nitric acid, sulfuric acid, and hydrochloric acid; under strong alkaline conditions, it takes more than 6 months to initially stimulate its cement activity, so the absorbing material developed from the slag will have good chemical stability. However, this has also become a technical problem for chemical surface modification of nickel-iron alloy ore slag.

[0029] The present invention first uses hydrofluoric acid as a slag surfactant and a primary surface micromorphology regulator, and further uses ammonia water, lime water, caustic soda or sodium silicate as a surface micromorphology regulator. Hydrofluoric acid reacts with the surface of the magnesium silicate solid solution to form a porous surface on the surface of the magnesium silicate, and the magnesium fluoride formed by the reaction is deposited on the new surface of the solid solution to achieve a primary micromorphology regulation. When ammonia water, lime water, caustic soda or sodium silicate are added, as the pH increases, soluble iron, chromium, manganese, nickel and other complex ions formed in the hydrogen fluoride acidic solution will gradually separate from the solution in the form of fluoride and deposit on the surface of the solid solution particles of the primary micromorphology regulation, forming a secondary micromorphology construction and a redistribution of trace absorbing elements. The present invention not only overcomes the problem that strong acids and alkalis cannot chemically treat the surface of the nickel-iron alloy ore thermal furnace slag, but also prepares a high-performance new broadband absorbing material in a relatively simple and easy way. The preparation method is low-cost and environmentally friendly, and can be industrialized and mass-produced.

[0030] In summary, the present invention has the advantages of low cost, high chemical stability, wide absorption frequency, and designability, laying a solid foundation for enterprises to develop a new path for a new material industry with deepening industry, sustainable environmental development, and high added value.

[0031] The following detailed description is for illustrative purposes only and is intended to provide further explanation of the present application, rather than to limit the scope of the present invention.

[0032] The nickel-iron alloy ore-fired slag used in the embodiment is prepared by the following method:

[0033] The nickel ore is crushed and screened to 50-150mm, and then sent to a drying kiln for drying to make the ore neither sticky nor too powdery. The prepared ore powder is put into a rotary kiln, roasted and dehydrated at a temperature of 700-900℃, and pre-reduced to form roasted sand, which is then transported to an electric furnace for reduction smelting at a high temperature of 1500-1600℃ to produce ferronickel and electric furnace slag.

[0034] The ore-melting furnace slag was crushed by using a roller press, and further ball-milled by using a ball mill. The ore-melting furnace slag was passed through a 500-mesh sieve, and the powder under the sieve was taken to obtain nickel-iron alloy ore-melting furnace slag (original slag).

[0035] It has been determined that the nickel-iron alloy ore furnace slag is mainly composed of magnesium silicate solid solution. The average mass ratios of MgSiO3, SiO2, MgO, total iron, ferrous iron, Al2O3, Cr2O3, CaO, MnO and Ni in the nickel-iron alloy ore furnace slag are 80.42:50.74:32.17:6.61:5.45:3.01:1.66:1.02:0.83:0.046.

[0036] Example 1: Preparation of a novel broadband absorbing material

[0037] Weigh 2g of nickel-iron alloy slag, put it in a plastic beaker, add 20ml of deionized water, stir evenly, add 0.5ml of hydrofluoric acid (mass concentration 40%) for a primary reaction for 20min, adjust the pH value to weak alkalinity (pH=8.0) with ammonia water (mass concentration 25%), continue stirring for 30min for a secondary reaction, filter the reaction product, wash the precipitate with deionized water, and dry to obtain a new broadband absorbing material.

[0038] Example 2: Preparation of a novel broadband absorbing material

[0039] Weigh 2g of nickel-iron alloy slag, put it in a plastic beaker, add 20ml of deionized water, stir evenly, add 5.5ml of hydrofluoric acid (mass concentration 40%) for a primary reaction for 20min, adjust the pH value to weak alkalinity (pH=8.0) with ammonia water (mass concentration 25%), continue stirring for 30min for a secondary reaction, filter the reaction product, wash the precipitate with deionized water, and dry to obtain a new broadband absorbing material.

[0040] Example 3: Preparation of a novel broadband absorbing material

[0041] Weigh 2g of nickel-iron alloy ore furnace slag, put it in a plastic beaker, add 20ml of deionized water, stir evenly, add 10ml of hydrofluoric acid (mass concentration 40%) for a primary reaction for 20min, adjust the pH value to weak alkalinity (pH=8.0) with ammonia water (mass concentration 25%), continue stirring for 30min for a secondary reaction, filter the reaction product, wash the precipitate with deionized water, and dry to obtain a new broadband absorbing material.

[0042] Example 4: Preparation of a novel broadband absorbing material

[0043] Weigh 2 g of nickel-iron alloy slag, put it in a plastic beaker, add 20 ml of deionized water, stir evenly, add 0.5 ml of hydrofluoric acid (mass concentration 40%) for a primary reaction for 20 min, adjust the pH value to neutral (pH = 7.0) with sodium hydroxide solution (mass concentration 20%), continue stirring for 30 min for a secondary reaction, filter the reaction product, wash the precipitate with deionized water, and dry to obtain a new broadband absorbing material.

[0044] Example 5: Preparation of a novel broadband absorbing material

[0045] Weigh 2 g of nickel-iron alloy slag, put it in a plastic beaker, add 20 ml of deionized water, stir evenly, add 10 ml of hydrofluoric acid (mass concentration 40%) for a primary reaction for 20 min, adjust the pH value to neutral (pH = 7.0) with sodium hydroxide solution (mass concentration 20%), continue stirring for 30 min for a secondary reaction, filter the reaction product, wash the precipitate with deionized water, and dry to obtain a new broadband absorbing material.

[0046] Example 6: Preparation of a novel broadband absorbing material

[0047] Weigh 2g of nickel-iron alloy ore furnace slag, put it in a plastic beaker, add 20ml of deionized water, stir evenly, add 0.5ml of hydrofluoric acid (mass concentration 40%) for a primary reaction for 20min, adjust the pH value to weak alkalinity (pH=8.0) with saturated calcium hydroxide solution, continue stirring for 30min for a secondary reaction, filter the reaction product, wash the precipitate with deionized water, and dry to obtain a new broadband absorbing material.

[0048] Example 7: Preparation of a novel broadband absorbing material

[0049] Weigh 2g of nickel-iron alloy ore furnace slag, put it in a plastic beaker, add 20ml of deionized water, stir evenly, add 10ml of hydrofluoric acid (mass concentration 40%) for a primary reaction for 20min, adjust the pH value to weak alkalinity (pH=8.0) with saturated calcium hydroxide solution, continue stirring for 30min for a secondary reaction, filter the reaction product, wash the precipitate with deionized water, and dry to obtain a new broadband absorbing material.

[0050] Example 8: Preparation of a novel broadband absorbing material

[0051] Weigh 2g of nickel-iron alloy slag, put it in a plastic beaker, add 20ml of deionized water, stir evenly, add 0.5ml of hydrofluoric acid (mass concentration 40%) to react once for 20min, adjust the pH value to neutral (pH=7.0) with sodium silicate solution (mass concentration 20%), continue stirring for 30min for secondary reaction, filter the reaction product, wash the precipitate with deionized water, and dry to obtain a new broadband absorbing material.

[0052] Example 9: Preparation of a novel broadband absorbing material

[0053] Weigh 2 g of nickel-iron alloy slag, put it in a plastic beaker, add 20 ml of deionized water, stir evenly, add 10 ml of hydrofluoric acid (mass concentration 40%) for a primary reaction for 20 min, adjust the pH value to neutral (pH = 7.0) with sodium silicate solution (mass concentration 20%), continue stirring for 30 min for a secondary reaction, filter the reaction product, wash the precipitate with deionized water, and dry to obtain a new broadband absorbing material.

[0054] Comparative Example 1: Preparation of a new broadband absorbing material

[0055] The difference between Comparative Example 1 and Example 2 is that the nickel-iron alloy slag is not treated with hydrofluoric acid, and the specific preparation method is as follows:

[0056] Weigh 2g of nickel-iron alloy ore furnace slag, put it in a plastic beaker, add 20ml of deionized water, stir evenly, add ammonia water (mass concentration 25%) equal to that in Example 2, continue stirring for 30min, and stop the reaction. Filter the product after the reaction, wash the precipitate with deionized water, and dry it to obtain a new broadband absorbing material.

[0057] Comparative Example 2: Preparation of a new broadband absorbing material

[0058] The difference between Comparative Example 1 and Example 2 is that the nickel-iron alloy slag is not treated with an alkaline solution. The specific preparation method is as follows:

[0059] Weigh 2g of nickel-iron alloy ore furnace slag, put it in a plastic beaker, add 20ml of deionized water, stir evenly, add 5.5ml of hydrofluoric acid (mass concentration 40%) to react for 20min, stop the reaction, filter the product after the reaction, wash the precipitate with deionized water, and dry it to obtain a new broadband absorbing material.

[0060] Test Example 1: XRD pattern analysis

[0061] The original slag (nickel-iron alloy ore thermal furnace slag) and the novel broadband absorbing materials prepared in Examples 1 to 9 were subjected to XRD data analysis. The XRD analysis results are as follows: Figure 1 As shown, the main component of Example 1 is the same as the main crystalline phase of slag, MgSiO3, while in Examples 2 and 3, due to the increase in HF, the main chemical component of the sample surface is converted to MgF2; in Examples 4 and 5, due to the influence of NaOH, the main chemical component of the sample surface is converted to Na2SiF6; in Examples 6 and 7, due to the influence of Ca(OH)2, the main chemical component of the sample surface is converted to MgF2 and CaF2; in Example 8, the main chemical component of the sample surface is still MgSiO3, and in Example 9, the main chemical component of the sample surface is converted to MgF2. This shows that the present invention can achieve effective regulation of the chemical composition of the slag surface through a simple hydrofluoric acid slag surface chemical treatment process and adjustment with different alkaline reagents, laying a good foundation for the functional design of the later absorbing material. At the same time, the amorphous silica and a small amount of absorbing elements (doping) produced by the sol-gel method during the alkaline adjustment process cannot be displayed in the XRD main crystalline phase.

[0062] Test Example 2: SEM images and surface area and pore volume analysis

[0063] The original slag and the new broadband absorbing materials prepared in Examples 1 to 9 were subjected to SEM analysis of the crystal structure. From the SEM images of Examples 1 to 3, it can be seen that as the amount of hydrofluoric acid added increases, the surface morphology of the slag is gradually reconstructed by MgF2 and silicon dioxide to form a porous surface structure; from the SEM images of Examples 4 and 5, it can be seen that the slag surface is covered with Na2SiF6 to form a porous interface; from the SEM images of Examples 6 and 7, it can be seen that a secondary flower-shaped porous interface covered successively by MgF2 and CaF2 is formed on the slag surface; from the SEM images of Examples 8 and 9, it can be seen that when the amount of hydrofluoric acid added is small, an interface with a MgSiO3 structure is formed on the slag surface, and when the amount of hydrofluoric acid added is high, an interface with MgF2 as the main crystalline phase is formed. Figure 2 It can be clearly seen from the SEM images that multiple constructions of the slag surface and design of the slag surface morphology can be achieved through simple hydrofluoric acid chemical treatment and subsequent different types of alkali treatment processes.

[0064] Further, the specific surface area and pore volume of the original slag and the novel broadband absorbing materials prepared in Examples 1 to 9 were measured by nitrogen adsorption and desorption experiment (77K) using a specific surface and pore size analyzer (model: Micromeritics ASAP 2460 3.01). The data were summarized and analyzed, and the test results are shown in Table 1:

[0065] Table 1 Specific surface area and pore volume of samples

[0066]

[0067] Through the specific surface area and pore volume of the slag and the new broadband absorbing material samples prepared in Examples 1 to 9, it can be seen that the original slag belongs to a conventional powder material with an extremely small surface area and almost no pores; after the slag surface is redesigned and micro-constructed through hydrofluoric acid surface chemical treatment and alkali treatment process, the slag surface area and pore volume have undergone significant changes, especially the specific surface area is larger than the specific surface area of ​​general nanomaterials.

[0068] Test Example 3: Wave Absorption Performance Test

[0069] (1) Performance test of new broadband absorbing materials

[0070] The original slag and the novel broadband absorbing materials prepared in Examples 1 to 9 were taken respectively, and the absorbing materials and paraffin were mixed at a mass ratio of 1:1. After being evenly mixed, they were put into a coaxial mold and pressed into a ring sample with an inner diameter of 3.04 mm, an outer diameter of 7.00 mm, and a thickness of 2.0 mm under the same pressure. A vector network analyzer (HP-8722ES) was used to measure the minimum reflection loss value and the maximum effective bandwidth of the absorbing wave of each sample in the coating thickness range of 1 to 10 mm and the electromagnetic wave frequency range of 2 to 18 GHz. The two-dimensional spectrum of the detection results is as follows: Figure 3 As shown, the three-dimensional map of the detection results is as follows Figure 4 shown.

[0071] pass Figure 3 and Figure 4 It can be seen that the minimum RL value of the original slag is -13.57dB, and the corresponding coating thickness is 10.00mm. In the electromagnetic wave frequency range of 2 to 18GHz, the maximum effective absorption bandwidth of the sample is 0.8GHz, and the corresponding coating thickness is 6.78mm.

[0072] The minimum RL value of the sample in Example 1 is -67.68 dB, and the corresponding coating thickness is 7.92 mm. In the electromagnetic wave frequency range of 2 to 18 GHz, the maximum effective absorption bandwidth of the sample is 5.89 GHz, and the corresponding coating thickness is 6.79 mm.

[0073] The minimum RL value of the sample in Example 2 is -58.6dB, and the corresponding coating thickness is 4.07mm. In the electromagnetic wave frequency range of 2 to 18GHz, the maximum effective absorption bandwidth of the sample is 7.4GHz, and the corresponding coating thickness is 9.83mm.

[0074] The minimum RL value of the sample in Example 3 is -57.58 dB, and the corresponding coating thickness is 2.05 mm. In the electromagnetic wave frequency range of 2 to 18 GHz, the maximum effective absorption bandwidth of the sample is 7.03 GHz, and the corresponding coating thickness is 7.45 mm.

[0075] The minimum RL value of the sample of Example 4 is -43.7dB, and the corresponding coating thickness is 7.14mm. In the electromagnetic wave frequency range of 2 to 18GHz, the maximum effective absorption bandwidth of the sample is 2.47GHz, and the corresponding coating thickness is 6.78mm.

[0076] The minimum RL value of the sample in Example 5 is -35.94 dB, and the corresponding coating thickness is 6.15 mm. In the electromagnetic wave frequency range of 2 to 18 GHz, the maximum effective absorption bandwidth of the sample is 1.75 GHz, and the corresponding coating thickness is 6.58 mm.

[0077] The minimum RL value of the sample of Example 6 is -43.87dB, and the corresponding coating thickness is 6.01mm. In the electromagnetic wave frequency range of 2 to 18GHz, the maximum effective absorption bandwidth of the sample is 3.74GHz, and the corresponding coating thickness is 7.7mm.

[0078] The minimum RL value of the sample of Example 7 is -35.67dB, and the corresponding coating thickness is 5.41mm. In the electromagnetic wave frequency range of 2 to 18GHz, the maximum effective absorption bandwidth of the sample is 2.95GHz, and the corresponding coating thickness is 5.71mm.

[0079] The minimum RL value of the sample of Example 8 is -53.08 dB, and the corresponding coating thickness is 3.55 mm. In the electromagnetic wave frequency range of 2 to 18 GHz, the maximum effective absorption bandwidth of the sample is 6.77 GHz, and the corresponding coating thickness is 7.3 mm.

[0080] The minimum RL value of the sample of Example 9 is -43.84dB, and the corresponding coating thickness is 8.68mm. In the electromagnetic wave frequency range of 2 to 18GHz, the maximum effective absorption bandwidth of the sample is 6.61GHz, and the corresponding coating thickness is 7.57mm.

[0081] By testing the minimum reflection loss and the maximum effective wave absorption bandwidth, it can be seen that the original slag has basically no wave absorption performance. After the slag has undergone hydrofluoric acid surface chemical treatment and alkali treatment process, it has shown excellent wave absorption performance. Examples 4, 5, and 7 are only to show that the wave absorption performance can be adjusted by adjusting the amount of hydrofluoric acid. When only considering the minimum reflection loss, it can be seen that the electromagnetic wave absorption performance of the wave absorbing material prepared in Example 1 is the best. When looking at the maximum effective wave absorption bandwidth, the effective wave absorption bandwidth of the wave absorbing material prepared in Example 2 is the widest, and the wave absorption performance is better. In general, the optimal wave absorption strength of the wave absorbing materials prepared in Examples 1-9 is comparable to the advanced wave absorbing materials reported in the international academic frontier; some wave absorption bandwidths are greater than 5 GHz, which has met the actual industrialization needs; and the effective wave absorption frequency can be designed between 3 and 18 GHz according to actual needs.

[0082] (2) Test on the influence of the preparation process of the present invention on the performance of the absorbing material

[0083] Compared with the reflection loss value, the maximum effective absorption bandwidth is a more convincing indicator of the absorption performance. Therefore, the absorption material prepared in Example 2 was selected based on comprehensive considerations to test the effect of the preparation process on the performance of the absorption material.

[0084] In Examples 1, 2, and 3, three hydrofluoric acid dosages were used, and then ammonia water was used to adjust the pH value to a weak alkaline state, in order to illustrate that the absorbing performance of the material can be adjusted with the change of the hydrofluoric acid dosage. Examples 4, 5; 6, 7; 8, and 9 are used to demonstrate that the absorbing material performance design can be achieved by adjusting the pH value with different bases at two extreme hydrofluoric acid dosages.

[0085] Take the absorbing materials prepared in Example 2 and Comparative Examples 1 and 2 respectively. The absorbing materials and paraffin were mixed in a mass ratio of 1:1 respectively, and after being evenly mixed, they were placed in a coaxial mold and pressed into a ring sample with an inner diameter of 3.04 mm, an outer diameter of 7.00 mm, and a thickness of 2.0 mm under the same pressure. The ring sample prepared by the absorbing material of Example 2 was numbered as Experimental Group 1, the ring sample prepared by the absorbing material of Comparative Example 1 was numbered as Experimental Group 2, and the ring sample prepared by the absorbing material of Comparative Example 2 was numbered as Experimental Group 3. The ring sample prepared by the original slag was used as a control. The minimum reflection loss value and the maximum effective bandwidth of the absorbing wave were measured for each sample in the range of 1 to 10 mm in coating thickness and 2 to 18 GHz in electromagnetic wave frequency using a vector network analyzer (HP-8722ES). The measurement results are shown in Table 2.

[0086] Table 2: Composite absorbing material performance test data table

[0087] sample Minimum reflection loss value (dB) Maximum effective absorption bandwidth (GHz) Experimental Group 1 -58.60dB 7.40GHz Experimental Group 2 -14.20dB 0.92GHz Experimental Group 3 -34.10dB 1.68GHz Comparison -13.57dB 0.8GHz

[0088] The test results show that the absorbing material prepared by treating the original slag with hydrofluoric acid and alkaline solution has better absorbing performance. The preparation method provided by the present invention has a simple and easy process flow and low cost, which lays a solid foundation for enterprises to develop a new way of industry deepening, environmental sustainable development and high value-added new material industry.

[0089] In summary, the present invention discloses a nickel-iron alloy ore thermal furnace slag with high chemical stability whose main component is magnesium silicate solid solution as raw material, chemical treatment and preliminary surface construction are carried out by hydrofluoric acid, and elements with good wave absorbing performance such as iron, chromium, manganese, nickel, etc. contained in the solid solution slag are released into the solution in the form of free ions, and the above-mentioned free ion elements with good wave absorbing performance are enriched by selecting different alkaline reagents (ammonia water, sodium hydroxide solution, calcium hydroxide solution or sodium silicate solution), and porous silicon dioxide or sodium magnesium ferrite microcrystals or porous calcium hexafluorosilicate are deposited on the surface of the nickel-iron alloy ore thermal furnace slag according to the selected alkaline reagents to secondary microstructure the slag surface morphology and design the wave absorbing performance, thereby providing a preparation method of a new broadband wave absorbing material.

[0090] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, replacement, improvement or introduction of other materials based on this technology, etc., within the spirit and principle of the present application, shall be included in the protection scope of the present application.

Claims

1. A method for preparing a novel broadband wave absorbing material using nickel-iron alloy ore-fired slag, characterized in that: The steps include: Deionized water is added to the nickel-iron alloy slag, and the mixture is stirred evenly. A hydrofluoric acid solution is added to carry out a primary reaction, and the pH value is adjusted to be neutral or weakly alkaline with an alkaline solution. The mixture is stirred continuously, and the secondary reaction is stopped. The product after the reaction is filtered, and the precipitate is collected. The precipitate is washed with deionized water and dried to obtain a novel broadband absorbing material.

2. The method according to claim 1, characterized in that The alkaline solution is used to adjust the pH to 7-8.

3. The method according to claim 1, characterized in that The nickel-iron alloy ore-fired slag is composed of MgSiO3, SiO2, MgO, all iron, ferrous iron, Al2O3, Cr2O3, CaO, MnO and Ni; The average mass ratio of the MgSiO3, SiO2, MgO, total iron, ferrous iron, Al2O3, Cr2O3, CaO, MnO and Ni is (75-85): (45-55): (25-35): (5-10): (4-6): (2-4): (1-2): (1-2): (0.5-1): (0.03-0.06).

4. The method according to claim 3, characterized in that The average mass ratio of MgSiO3, SiO2, MgO, total iron, ferrous iron, Al2O3, Cr2O3, CaO, MnO and Ni in the nickel-iron alloy slag is 80.42:50.74:32.17:6.61:5.45:3.01:1.66:1.02:0.83:0.

046.

5. The method according to claim 1, characterized in that The basicity of the nickel-iron alloy slag is 0.5-0.

7.

6. The method according to claim 1, characterized in that The formation temperature of the nickel-iron alloy slag is 1500-1600°C.

7. The method according to claim 1, characterized in that The alkaline solution is any one of ammonia water, sodium hydroxide solution, calcium hydroxide solution or sodium silicate solution.

8. The method according to claim 1, characterized in that The mass concentration of the hydrofluoric acid solution is 10-40%.

9. The method according to claim 1, characterized in that: The time for the first reaction of adding the hydrofluoric acid solution is 15-20 minutes, and the time for the second reaction of adding the alkaline solution is 20-30 minutes.

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