A method for preparing ferrite solid waste-based electromagnetic wave absorbing materials

Abstract

A method for preparing a ferrite solid waste-based electromagnetic wave absorbing material, relating to the field of electromagnetic wave absorbing materials, involves first purifying the ferrite solid waste, then surface-modifying it using a silane coupling agent KH550. Next, MoS2 nanoparticles and the surface-modified ferrite solid waste particles are ball-milled using a high-energy ball mill to obtain a composite electromagnetic wave absorber. The composite electromagnetic wave absorber is then granulated, pressed, and heat-treated to obtain a preform. Finally, the preform is processed to obtain an electromagnetic wave absorbing material of a specific shape. This invention first surface-modifies the purified ferrite solid waste particles, then composites them with molybdenum disulfide through a ball milling process. This preparation process allows for the complementary advantages of the two materials, resulting in an electromagnetic wave absorbing material with higher mechanical properties and superior electromagnetic wave absorption performance.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic wave absorbing materials, specifically to a method for preparing a ferrite solid waste-based electromagnetic wave absorbing material. Background Technology

[0002] During the manufacturing process of ferrite cores, such as grinding and cutting, a large amount of ferrite waste is generated. Currently, the main approach to addressing this waste is through recycling. Recycled ferrite materials can be used in microwave absorbing materials, allowing ferrite solid waste to be used rationally and avoiding resource and environmental damage caused by direct disposal methods.

[0003] Chinese patent application CN 111995386A discloses a method for preparing ferrite solid waste-based ceramic microwave absorbing materials. Carbon black clusters are uniformly embedded on the grain boundaries of ferrite. The interfacial dielectric relaxation caused by the active groups of carbon black on the grain boundaries is enhanced, thereby improving the performance of the composite electromagnetic absorber in the microwave band. This avoids the excessively low absorption frequency and eddy current loss after excessive modification to form a conductive network at the grain boundaries.

[0004] Chinese patent application CN 107660114A discloses a method for preparing a molybdenum disulfide / MXene layered composite microwave absorbing material. The method uses sodium molybdate dihydrate and thioacetamide as raw materials, which are mixed and dissolved in deionized water. MXene material is added, and the mixture is dispersed ultrasonically. The pH value is controlled by acetic acid. The solution is then transferred to a polytetrafluoroethylene-lined stainless steel autoclave and placed in an electrically heated constant-temperature drying oven for a certain period to obtain the molybdenum disulfide / MXene composite material solution. After washing with deionized water and drying, the molybdenum disulfide / MXene layered composite microwave absorbing material is obtained, exhibiting good microwave absorption performance in the microwave frequency range.

[0005] Based on the idea of ​​using ferrite solid waste recycling to prepare microwave absorbing materials, and combined with the microwave absorbing properties of molybdenum disulfide, this study attempts to combine the two and design a reasonable composite process to prepare microwave absorbing materials with excellent performance, hoping to apply them to the fields of electromagnetic absorption and electromagnetic shielding. Summary of the Invention

[0006] This invention proposes a method for preparing ferrite solid waste-based electromagnetic wave absorbing materials, which achieves the preparation of high-performance electromagnetic wave absorbing materials while making reasonable use of ferrite solid waste.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a ferrite solid waste-based electromagnetic wave absorbing material, comprising the following steps:

[0009] 1) Purification and treatment of ferrite solid waste:

[0010] First, the ferrite solid waste is crushed into powder particles, then deionized water is added for ultrasonic cleaning, and then separated by an external magnetic field to achieve the cleaning and removal of impurities from the ferrite solid waste. Finally, it is dried to obtain purified ferrite solid waste particles.

[0011] 2) Surface modification:

[0012] First, ferrite solid waste particles are dispersed in anhydrous ethanol. Then, silane coupling agent KH550 is added, and the surface is modified by stirring and heating. After static aging and solid-liquid separation, the product is dried to obtain surface-modified ferrite solid waste particles.

[0013] 3) Ball milling compound:

[0014] Surface-modified ferrite solid waste particles and MoS2 nanoparticles were added to a ball milling jar. Anhydrous ethanol was used as a process control agent. The jar was sealed in an argon atmosphere. Then the jar was placed in a high-energy ball mill for ball milling to obtain a composite electromagnetic wave absorber.

[0015] 4) Embryo pressing and heat treatment:

[0016] The composite electromagnetic wave absorber obtained in step 3) is granulated using polyvinyl alcohol, and then dried and pressed to obtain a green embryo; the green embryo is heat-treated to obtain a cooked embryo, and finally the cooked embryo is processed to obtain an electromagnetic wave absorbing material of a specific shape.

[0017] As a preferred technical solution of the preparation method of the present invention, the preparation method includes:

[0018] In step 1), add 3-5 times the mass of deionized water to the powder particles and ultrasonically clean for 1-2 hours. Then, separate the powder particles using an external magnetic field. Repeat this magnetic separation purification process 3-5 times. After magnetic separation purification, dry the product at 60-80℃ for 5-10 hours.

[0019] In step 2), the mass ratio of ferrite solid waste particles to anhydrous ethanol is 1:10-20, and the mass ratio of ferrite solid waste particles to silane coupling agent KH550 is 1-3:1. After adding silane coupling agent KH550, the mixture is stirred at 300-800 rpm while being heated to 50-70°C for 1-3 hours. After the reaction is complete, the mixture is allowed to stand and age for 12-24 hours. After solid-liquid separation, the product is dried at 60-80°C for 5-10 hours.

[0020] In step 3), the mass ratio of surface-modified ferrite solid waste particles to MoS2 nanoparticles is 10–12:1, and the amount of anhydrous ethanol added is 20–25% of the total mass of the powder. The material-to-ball ratio in the ball mill is 7–10:1, and the ball milling time is 12–36 hours.

[0021] In step 4), the obtained composite electromagnetic wave absorber is granulated using 5% polyvinyl alcohol and dried at 60–80°C for 1–3 hours. The pressure is 0.5–10 MPa / cm. 2 The pressure is pressed into a mold to obtain a green blank; the green blank is placed in a heat treatment furnace, heated to 600-800℃ and held for 5-8 hours; it is cooled to room temperature with the furnace to obtain a cooked blank; finally, the cooked blank is processed to obtain an electromagnetic wave absorbing material of a specific shape.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. This invention combines surface-modified ferrite solid waste particles with molybdenum disulfide, thereby achieving the preparation of high-performance electromagnetic wave absorbing materials while making reasonable use of ferrite solid waste.

[0024] 2. This invention first modifies the surface of purified ferrite solid waste particles, and then combines them with molybdenum disulfide through a ball milling process. This preparation process allows for the complementary advantages of the two materials, resulting in an electromagnetic wave absorbing material with higher mechanical properties and excellent electromagnetic wave absorption performance.

[0025] 3. The ferrite solid waste-based electromagnetic wave absorbing material prepared by this invention exhibits excellent electromagnetic wave absorption performance. Reflection loss (RL) tests with a matching thickness of 2 mm revealed that the RL values ​​exceeded -26 dB in the 10 MHz to 1 GHz frequency band and exceeded -48 dB in the 10 to 300 MHz frequency band. At a frequency of 10 MHz, the RL reached a minimum value of -85.48 dB. Detailed Implementation

[0026] The preferred embodiments of the present invention will be described in detail below so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0027] Example 1

[0028] A method for preparing a ferrite solid waste-based electromagnetic wave absorbing material, comprising the following steps:

[0029] 1) Purification and treatment of ferrite solid waste:

[0030] First, the ferrite solid waste is crushed and sieved through a 100-mesh sieve, retaining the residual powder particles. Then, five times the weight of the powder particles are added to deionized water for ultrasonic cleaning for 2 hours, followed by separation using an external magnetic field to remove dust, debris, and other impurities from the ferrite solid waste. This magnetic separation purification process is repeated five times. Finally, the product is dried at 80°C for 5 hours to obtain purified ferrite solid waste particles.

[0031] 2) Surface modification:

[0032] First, anhydrous ethanol was added to the ferrite solid waste particles and ultrasonically dispersed; the mass ratio of ferrite solid waste particles to anhydrous ethanol was 1:15; then, silane coupling agent KH550 was added, and the mixture was stirred at 500 rpm while being heated to 60°C for 3 hours; the mass ratio of ferrite solid waste particles to silane coupling agent KH550 was 3:1; after the reaction was completed, the mixture was allowed to stand for 24 hours, and after solid-liquid separation, the product was dried at 80°C for 5 hours to obtain surface-modified ferrite solid waste particles.

[0033] 3) Ball milling compound:

[0034] The powder material was ball-milled and composited using a high-energy ball mill. Surface-modified ferrite solid waste particles and MoS2 nanoparticles were added to the ball mill jar at a mass ratio of 10:1. Anhydrous ethanol was used as a process control agent, added at 25% of the total powder mass. The ball-to-particle ratio was controlled at 7:1. The jar was sealed under an argon atmosphere, and then the jar was placed in the high-energy ball mill for ball milling for 30 hours to obtain the composite electromagnetic wave absorber.

[0035] 4) Embryo pressing and heat treatment:

[0036] The composite electromagnetic wave absorber obtained in step 3) was granulated using 5% polyvinyl alcohol, dried at 80°C for 3 hours, and then subjected to a pressure of 5 MPa / cm. 2 The pressure is pressed into shape in the mold to obtain a green blank; the green blank is placed in a heat treatment furnace, heated to 800°C, and held for 5 hours; it is cooled to room temperature with the furnace to obtain a cooked blank; finally, the cooked blank is processed to obtain an electromagnetic wave absorbing material of a specific shape.

[0037] Example 1 shows that the electromagnetic wave absorbing material prepared in the 10MHz to 1GHz frequency range, with a 2mm thickness, exhibits a reflection loss (RL) test. The results indicate that the RL values ​​exceed -26dB in the 10MHz to 1GHz frequency band and exceed -48dB in the 10 to 300MHz frequency band. At a frequency of 10MHz, the RL reaches a minimum value of -85.48dB.

[0038] Example 2

[0039] A method for preparing a ferrite solid waste-based electromagnetic wave absorbing material, comprising the following steps:

[0040] 1) Purification and treatment of ferrite solid waste:

[0041] First, the ferrite solid waste is crushed and sieved through a 100-mesh sieve, retaining the residual powder particles. Then, five times the weight of the powder particles are added to deionized water for ultrasonic cleaning for 2 hours, followed by separation using an external magnetic field to remove dust, debris, and other impurities from the ferrite solid waste. This magnetic separation purification process is repeated five times. Finally, the product is dried at 80°C for 5 hours to obtain purified ferrite solid waste particles.

[0042] 2) Surface modification:

[0043] First, anhydrous ethanol was added to the ferrite solid waste particles and ultrasonically dispersed; the mass ratio of ferrite solid waste particles to anhydrous ethanol was 1:20. Then, silane coupling agent KH550 was added, and the mixture was stirred at 500 rpm while being heated to 70°C for 1.5 hours; the mass ratio of ferrite solid waste particles to silane coupling agent KH550 was 2:1. After the reaction was completed, the mixture was allowed to stand for 24 hours, and after solid-liquid separation, the product was dried at 70°C for 8 hours to obtain surface-modified ferrite solid waste particles.

[0044] 3) Ball milling compound:

[0045] The powder material was ball-milled and composited using a high-energy ball mill. Surface-modified ferrite solid waste particles and MoS2 nanoparticles were added to the ball mill jar at a mass ratio of 10:1. Anhydrous ethanol was used as a process control agent, added at 25% of the total powder mass. The ball-to-powder ratio was controlled at 7:1. The jar was sealed under an argon atmosphere, and then the jar was placed in the high-energy ball mill for ball milling for 36 hours to obtain the composite electromagnetic wave absorber.

[0046] 4) Embryo pressing and heat treatment:

[0047] The composite electromagnetic wave absorber obtained in step 3) was granulated using 5% polyvinyl alcohol, dried at 70°C for 2.5 hours, and then subjected to a pressure of 5 MPa / cm. 2 The pressure is pressed into shape in the mold to obtain a green blank; the green blank is placed in a heat treatment furnace, heated to 800°C, and held for 5 hours; it is cooled to room temperature with the furnace to obtain a cooked blank; finally, the cooked blank is processed to obtain an electromagnetic wave absorbing material of a specific shape.

[0048] Example 2 shows that the electromagnetic wave absorbing material prepared in the 10MHz to 1GHz frequency range, with a 2mm thickness, exhibits a reflection loss (RL) test. The results indicate that the RL values ​​exceed -26dB in the 10MHz to 1GHz frequency band and exceed -48dB in the 10 to 300MHz frequency band. At a frequency of 10MHz, the RL reaches a minimum value of -76.23dB.

[0049] Example 3

[0050] A method for preparing a ferrite solid waste-based electromagnetic wave absorbing material, comprising the following steps:

[0051] 1) Purification and treatment of ferrite solid waste:

[0052] First, the ferrite solid waste is crushed and sieved through a 100-mesh sieve, retaining the residual powder particles. Then, five times the weight of the powder particles are added to deionized water for ultrasonic cleaning for 2 hours, followed by separation using an external magnetic field to remove dust, debris, and other impurities from the ferrite solid waste. This magnetic separation purification process is repeated five times. Finally, the product is dried at 80°C for 5 hours to obtain purified ferrite solid waste particles.

[0053] 2) Surface modification:

[0054] First, anhydrous ethanol was added to the ferrite solid waste particles and ultrasonically dispersed; the mass ratio of ferrite solid waste particles to anhydrous ethanol was 1:10. Then, silane coupling agent KH550 was added, and the mixture was stirred at 500 rpm while being heated to 55°C for 2.5 hours; the mass ratio of ferrite solid waste particles to silane coupling agent KH550 was 1.5:1. After the reaction was completed, the mixture was allowed to stand for 24 hours, and after solid-liquid separation, the product was dried at 75°C for 6 hours to obtain surface-modified ferrite solid waste particles.

[0055] 3) Ball milling compound:

[0056] The powder material was ball-milled and composited using a high-energy ball mill. Surface-modified ferrite solid waste particles and MoS2 nanoparticles were added to the ball mill jar at a mass ratio of 12:1. Anhydrous ethanol was used as a process control agent, added at 25% of the total powder mass. The ball-to-particle ratio was controlled at 7:1. The jar was sealed under an argon atmosphere, and then the jar was placed in the high-energy ball mill for ball milling for 36 hours to obtain the composite electromagnetic wave absorber.

[0057] 4) Embryo pressing and heat treatment:

[0058] The composite electromagnetic wave absorber obtained in step 3) was granulated using 5% polyvinyl alcohol, dried at 75°C for 2 hours, and then subjected to a pressure of 5 MPa / cm. 2 The pressure is pressed into shape in the mold to obtain a green blank; the green blank is placed in a heat treatment furnace, heated to 800°C, and held for 5 hours; it is cooled to room temperature with the furnace to obtain a cooked blank; finally, the cooked blank is processed to obtain an electromagnetic wave absorbing material of a specific shape.

[0059] Example 3 shows that the electromagnetic wave absorbing material prepared in the 10MHz to 1GHz frequency range, with a 2mm thickness, exhibits a reflection loss (RL) test. The results indicate that the RL values ​​exceed -26dB in the 10MHz to 1GHz frequency band and exceed -48dB in the 10 to 300MHz frequency band. At a frequency of 10MHz, the RL reaches a minimum value of -80.98dB.

[0060] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a ferrite solid waste-based electromagnetic wave absorbing material, characterized in that, The steps are as follows: 1) Purification and treatment of ferrite solid waste: First, the ferrite solid waste is crushed into powder particles, then deionized water is added for ultrasonic cleaning, and then separated by an external magnetic field to achieve the cleaning and removal of impurities from the ferrite solid waste. Finally, it is dried to obtain purified ferrite solid waste particles. After magnetic separation purification, the product is dried at 60-80℃ for 5-10 hours. 2) Surface modification: First, ferrite solid waste particles are dispersed in anhydrous ethanol. Then, silane coupling agent KH550 is added, and the surface is modified by stirring and heating. After static aging and solid-liquid separation, the product is dried to obtain surface-modified ferrite solid waste particles. The mass ratio of ferrite solid waste granules to anhydrous ethanol is 1:10-20, and the mass ratio of ferrite solid waste granules to silane coupling agent KH550 is 1-3:

1. After adding silane coupling agent KH550, the mixture is stirred at 300-800 rpm while being heated to 50-70°C for 1-3 hours. After the reaction is completed, the mixture is allowed to stand and age for 12-24 hours. After solid-liquid separation, the product is dried at 60-80°C for 5-10 hours. 3) Ball milling compound: Surface-modified ferrite solid waste particles and MoS2 nanoparticles were added to a ball milling jar. Anhydrous ethanol was used as a process control agent. The jar was sealed in an argon atmosphere. Then the jar was placed in a high-energy ball mill for ball milling to obtain a composite electromagnetic wave absorber. The mass ratio of surface-modified ferrite solid waste particles to MoS2 nanoparticles is 10–12:1, and the amount of anhydrous ethanol added is 20–25% of the total mass of the powder. The ball-to-material ratio in the ball mill jar is 7–10:1, and the milling time is 12–36 hours. 4) Embryo pressing and heat treatment: The composite electromagnetic wave absorber obtained in step 3) was granulated using polyvinyl alcohol, and then dried at 0.5–10 MPa / cm. 2 The pressure is pressed into a mold to obtain a green blank; the green blank is placed in a heat treatment furnace, heated to 600-800℃ and held for 5-8 hours; it is cooled to room temperature with the furnace to obtain a cooked blank; finally, the cooked blank is processed to obtain an electromagnetic wave absorbing material of a specific shape.

2. The preparation method according to claim 1, characterized in that, In step 1), add 3 to 5 times the mass of deionized water to the powder particles and ultrasonically clean for 1 to 2 hours. Then, separate the powder particles by applying an external magnetic field. Repeat this magnetic separation and purification process 3 to 5 times.

3. The preparation method according to claim 1, characterized in that, In step 4), the obtained composite electromagnetic wave absorber is granulated using 5% polyvinyl alcohol and dried at 60-80°C for 1-3 hours.