CN111565552A - Porous carbon-coated CoFe alloy-SiC composite electromagnetic shielding material and preparation method thereof - Google Patents
Porous carbon-coated CoFe alloy-SiC composite electromagnetic shielding material and preparation method thereof Download PDFInfo
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- CN111565552A CN111565552A CN202010363214.0A CN202010363214A CN111565552A CN 111565552 A CN111565552 A CN 111565552A CN 202010363214 A CN202010363214 A CN 202010363214A CN 111565552 A CN111565552 A CN 111565552A
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Abstract
The invention relates to the technical field of electromagnetic shielding, and discloses a composite electromagnetic shielding material of porous carbon coated CoFe alloy-SiC, which comprises the following formula raw materials and components: biomass-based nano silicon carbide, cobalt nitrate, potassium ferricyanide and sodium citrate. The composite electromagnetic shielding material of the porous carbon coated CoFe alloy-SiC is characterized in that the Co-Fe bimetal MOFs with rich pore structures coats nano silicon carbide, the nano silicon carbide uniformly grows in an organic framework of the MOFs, CoFe nano alloy is obtained by reduction of Co and Fe iron elements through high-temperature thermal cracking, a porous carbon layer is formed on the MOFs organic framework, the porous carbon coated CoFe nano alloy modified nano SiC is obtained, the CoFe nano alloy with excellent electromagnetic performance modifies the nano SiC on the surface, the electromagnetic parameters of the SiC are improved, the electromagnetic loss performance and the impedance matching performance of the material are enhanced, the composite electromagnetic shielding material has excellent dielectric loss and magnetic loss performance, and can efficiently absorb and lose electromagnetic radiation.
Description
Technical Field
The invention relates to the technical field of electromagnetic shielding, in particular to a porous carbon coated CoFe alloy-SiC composite electromagnetic shielding material and a preparation method thereof.
Background
With the rapid development of modern electronic industry, wireless communication and digitization technology, such as broadcast television, communication navigation, power facilities, scientific research, medical high-frequency equipment and various household appliances are applied to various fields closely related to people, the equipment and products can generate electromagnetic radiation, the electromagnetic radiation not only causes mutual interference between radiation sources, but also pollutes the living space of human beings, the long-term contact with the electromagnetic radiation can affect the nervous system, reproductive system and immune system of people to induce various diseases, and the electromagnetic radiation can also affect the normal operation of precise instruments such as radar and electric energy, so the development of novel efficient electromagnetic shielding and wave-absorbing materials becomes a research hotspot.
The existing electromagnetic shielding material mainly comprises a carbon-based wave absorbing material, an iron-based wave absorbing material and a ceramic-based wave absorbing material, and can absorb and consume electromagnetic waves through resistance type loss, dielectric loss and magnetic loss, silicon carbide has proper conductivity and excellent dielectric property, is excellent in corrosion resistance and stable in chemical property, is a ceramic-based wave absorbing material widely applied, but the electromagnetic property and the electromagnetic loss property of the traditional silicon carbide electromagnetic shielding and wave absorbing material are not high, impedance matching is difficult to achieve by a single silicon carbide material, the wave absorbing property of the material is greatly reduced, and the electromagnetic parameters and the wave absorbing property of the material can be improved by compounding the material with the silicon carbide material and the material with the excellent electromagnetic property.
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a composite electromagnetic shielding material of porous carbon coated CoFe alloy-SiC and a preparation method thereof, which solve the problems that the electromagnetic loss of silicon carbide is not high and impedance matching is difficult to achieve.
(II) technical scheme
In order to achieve the purpose, the invention provides the following technical scheme: a porous carbon coated CoFe alloy-SiC composite electromagnetic shielding material comprises the following raw materials and components: the biomass-based nano silicon carbide, the cobalt nitrate, the potassium ferricyanide and the sodium citrate are mixed according to the mass ratio of 5-20:1:2-2.5: 1.6-2.
Preferably, the preparation method of the composite electromagnetic shielding material of the porous carbon coated CoFe alloy-SiC comprises the following steps:
(1) washing waste corn straws, putting the washed waste corn straws into a planetary ball mill, ball-milling the waste corn straws into fine powder at the revolution speed of 340-250 rpm and the rotation speed of 170-250rpm, adding ethanol solvent, cobalt nitrate and tetraethoxysilane into a reaction bottle, uniformly stirring, adding aqueous solution of oxalic acid, uniformly stirring for 20-30h, fully drying the ball-milled biomass fine powder, pouring the dried biomass fine powder into the solution, ultrasonically dispersing the mixture uniformly, adding hexamethylenetetramine, uniformly stirring until the mixture is gelatinous, fully drying the gelatinous product to remove the solvent, putting the solid mixed product into an atmosphere resistance furnace, heating to 500-550 ℃ at the heating rate of 5-10 ℃/min in the argon atmosphere, carrying out heat preservation treatment for 30-60min, heating to 950-1050 ℃, carrying out heat preservation treatment for 30-60min, adjusting the heating rate to 2-4 ℃, heating to 1300-.
(2) Adding a distilled water solvent and biomass-based nano-silicon carbide into a reaction bottle, adding cobalt nitrate and sodium citrate after uniformly dispersing by ultrasound, slowly dropwise adding a potassium ferricyanide aqueous solution after uniformly stirring, reacting for 15-25h with uniform stirring, standing and aging for 10-20h, centrifugally separating the solution to remove the solvent, washing a solid product by using distilled water and ethanol, and fully drying to prepare the Co-Fe bimetal MOFs coated nano-silicon carbide.
(3) Placing Co-Fe bimetal MOFs coated nano silicon carbide in an atmosphere resistance furnace, heating to 680-750 ℃ at the heating rate of 2-5 ℃/min in the mixed gas atmosphere of hydrogen and argon, and carrying out heat preservation and calcination for 1-1.5h to prepare the composite electromagnetic shielding material of the porous carbon coated CoFe alloy-SiC.
Preferably, the atmosphere resistance furnace comprises an atmosphere chamber, a vent pipe fixedly connected inside the atmosphere chamber, vent holes arranged on the surface of the vent pipe, a base fixedly connected below the inside of the atmosphere chamber, and a calcining crucible arranged above the base.
Preferably, the mass ratio of the cobalt nitrate, the ethyl orthosilicate, the oxalic acid, the biomass fine powder and the hexamethylenetetramine in the step (1) is 2-3:100:7-9:70-120: 4-5.
Preferably, the volume ratio of the hydrogen to the argon in the step (3) is 8-15: 85-92.
(III) advantageous technical effects
Compared with the prior art, the invention has the following beneficial technical effects:
the composite electromagnetic shielding material of porous carbon coated CoFe alloy-SiC is prepared by taking biomass straws as a carbon source and adopting a sol-gel method to obtain nano SiO2As a silicon source, the prepared biomass nano SiC caters to the green chemical concept and the green sustainableThe development is continued, under the action of sodium citrate, cobalt nitrate and potassium ferricyanide generate Co-Fe bimetal MOFs coated nano silicon carbide with rich pore structures, the nano silicon carbide uniformly grows in an organic framework of the MOFs, then CoFe and Fe iron elements are reduced through high-temperature thermal cracking to obtain CoFe nano alloy, the MOFs organic framework forms a porous carbon layer, the porous carbon coated CoFe nano alloy modified nano SiC is obtained, the CoFe nano alloy with excellent electromagnetic performance modifies the nano SiC on the surface, the electromagnetic parameter of the SiC can be obviously improved, the electromagnetic loss performance of the material is enhanced, carriers are promoted to form stronger macroscopic current through coating of the porous carbon layer with excellent conductivity, the electromagnetic energy is converted into heat energy to be diffused and removed, the excellent impedance matching performance is shown, and the electromagnetic shielding composite material of the porous carbon coated CoFe alloy-SiC has excellent dielectric loss and magnetic loss performance, electromagnetic radiation can be absorbed and lost efficiently.
Drawings
FIG. 1 is a schematic front view of an atmosphere chamber;
FIG. 2 is an enlarged schematic view of a vent;
FIG. 3 is a schematic vent adjustment view;
FIG. 4 is a TEM image of a Co-Fe bimetallic MOFs coated nano-sized silicon carbide;
FIG. 5 is a powder X-ray diffraction method of a composite electromagnetic shielding material of a porous carbon-coated CoFe alloy-SiC.
1. An atmosphere chamber; 2. a breather pipe; 3. a vent hole; 4. a base; 5. the crucible is calcined.
Detailed Description
To achieve the above object, the present invention provides the following embodiments and examples: a porous carbon coated CoFe alloy-SiC composite electromagnetic shielding material comprises the following raw materials and components: the biomass-based nano silicon carbide, the cobalt nitrate, the potassium ferricyanide and the sodium citrate are mixed according to the mass ratio of 5-20:1:2-2.5: 1.6-2.
The preparation method of the composite electromagnetic shielding material of the porous carbon-coated CoFe alloy-SiC comprises the following steps:
(1) washing waste corn straws, putting the washed waste corn straws into a planetary ball mill, ball-milling the waste corn straws into fine powder at the revolution speed of 340-250 rpm and the rotation speed of 170-250rpm, adding ethanol solvent, cobalt nitrate and tetraethoxysilane into a reaction bottle, uniformly stirring, adding aqueous solution of oxalic acid, uniformly stirring for 20-30h, fully drying the well-ball-milled biomass fine powder, pouring the well-ball-milled biomass fine powder into the solution, ultrasonically dispersing the mixture uniformly, adding hexamethylenetetramine, wherein the mass ratio of the cobalt nitrate to the tetraethoxysilane to the oxalic acid to the biomass fine powder to the hexamethylenetetramine is 2-3:100:7-9:70-120:4-5, uniformly stirring until gel is formed, fully drying the gel product to remove the solvent, putting the solid mixed product into an atmosphere resistance furnace, wherein the atmosphere resistance furnace comprises an atmosphere chamber, and the inside of the atmosphere resistance furnace is fixedly connected with a vent pipe, The surface of the vent pipe is provided with a vent hole, the lower part of the inner part of the atmosphere chamber is fixedly connected with a base, a calcining crucible is arranged above the base, the heating rate is 5-10 ℃/min, the temperature is increased to 500-.
(2) Adding a distilled water solvent and biomass-based nano-silicon carbide into a reaction bottle, adding cobalt nitrate and sodium citrate after uniformly dispersing by ultrasound, slowly dropwise adding a potassium ferricyanide aqueous solution after uniformly stirring, reacting for 15-25h with uniform stirring, standing and aging for 10-20h, centrifugally separating the solution to remove the solvent, washing a solid product by using distilled water and ethanol, and fully drying to prepare the Co-Fe bimetal MOFs coated nano-silicon carbide.
(3) Placing Co-Fe bimetal MOFs coated nano silicon carbide in an atmosphere resistance furnace, heating to 680-fold-750 ℃ at the heating rate of 2-5 ℃/min in the atmosphere of mixed gas of hydrogen and argon with the volume ratio of 8-15:85-92, and carrying out heat preservation and calcination for 1-1.5h to prepare the porous carbon coated CoFe alloy-SiC composite electromagnetic shielding material.
Example 1
(1) Washing waste corn straws, putting the washed waste corn straws into a planetary ball mill, ball-milling the waste corn straws into fine powder at the revolution speed of 340rpm and the rotation speed of 170rpm, adding ethanol solvent, cobalt nitrate and tetraethoxysilane into a reaction bottle, adding aqueous solution of oxalic acid after uniformly stirring, uniformly stirring for 20 hours, fully drying the well ball-milled biomass fine powder, pouring the well ball-milled biomass fine powder into the solution, adding hexamethylenetetramine after uniformly dispersing by ultrasound, wherein the mass ratio of the cobalt nitrate to the tetraethoxysilane to the oxalic acid to the biomass fine powder to the hexamethylenetetramine is 2:100:7:70:4, uniformly stirring until the mixture is in a gel state, fully drying the gel product to remove the solvent, putting the solid mixed product into an atmosphere resistance furnace, wherein the atmosphere resistance furnace comprises an atmosphere chamber, the inside of the atmosphere chamber is fixedly connected with a base, the surface of a vent pipe is arranged, and the lower part of the inside, And arranging a calcining crucible above the base, heating to 500 ℃ at a heating rate of 5 ℃/min in an argon atmosphere, carrying out heat preservation treatment for 30min, heating to 950 ℃ again, carrying out heat preservation treatment for 30min, adjusting the heating rate to 2 ℃, heating to 1300 ℃, carrying out heat preservation treatment for 6h, reducing the calcining temperature to 600 ℃, introducing air, carrying out heat preservation and calcining for 2h, dipping the calcined product in hydrofluoric acid to remove silicon dioxide, washing and drying to prepare the biomass-based nano silicon carbide.
(2) Adding a distilled water solvent and biomass-based nano-silicon carbide into a reaction bottle, adding cobalt nitrate and sodium citrate after ultrasonic dispersion is uniform, stirring uniformly, slowly dropwise adding a potassium ferricyanide aqueous solution, controlling the mass ratio of the biomass-based nano-silicon carbide to the cobalt nitrate to the potassium ferricyanide to the sodium citrate to be 5:1:2:1.6, stirring at a constant speed for reaction for 15 hours, standing and aging for 10 hours, centrifugally separating the solution to remove the solvent, washing the solid product by using distilled water and ethanol, and fully drying to prepare the Co-Fe bimetallic MOFs-coated nano-silicon carbide.
(3) Placing Co-Fe bimetal MOFs coated nano silicon carbide in an atmosphere resistance furnace, heating to 680 ℃ at the heating rate of 2 ℃/min in the atmosphere of mixed gas of hydrogen and argon with the volume ratio of 8:92, and carrying out heat preservation and calcination for 1h to prepare the porous carbon coated CoFe alloy-SiC composite electromagnetic shielding material 1.
Example 2
(1) Washing waste corn straws, putting the washed waste corn straws into a planetary ball mill, ball-milling the waste corn straws into fine powder at the revolution speed of 500rpm and the rotation speed of 250rpm, adding ethanol solvent, cobalt nitrate and tetraethoxysilane into a reaction bottle, adding aqueous solution of oxalic acid after uniformly stirring, uniformly stirring for 20 hours, fully drying the well-ball-milled biomass fine powder, pouring the well-ball-milled biomass fine powder into the solution, adding hexamethylenetetramine after uniformly dispersing by ultrasound, wherein the mass ratio of the cobalt nitrate to the tetraethoxysilane to the oxalic acid to the hexamethylenetetramine is 2.2:100:7.5:80:4.3, uniformly stirring until the mixture forms a gel, fully drying the gel product to remove the solvent, putting the solid mixed product into an atmosphere resistance furnace, wherein the atmosphere resistance furnace comprises an atmosphere chamber, an air vent pipe is fixedly connected inside the atmosphere chamber, the surface of the air vent pipe is provided with an air vent hole, a base is fixedly connected below the, And arranging a calcining crucible above the base, heating to 500 ℃ at a heating rate of 10 ℃/min in an argon atmosphere, carrying out heat preservation treatment for 60min, then heating to 1000 ℃, carrying out heat preservation treatment for 50min, adjusting the heating rate to 4 ℃, heating to 1350 ℃, carrying out heat preservation treatment for 6h, reducing the calcining temperature to 700 ℃, introducing air, carrying out heat preservation and calcining for 3h, soaking the calcined product in hydrofluoric acid to remove silicon dioxide, washing and drying to prepare the biomass-based nano silicon carbide.
(2) Adding a distilled water solvent and biomass-based nano-silicon carbide into a reaction bottle, adding cobalt nitrate and sodium citrate after uniform ultrasonic dispersion, slowly dropwise adding an aqueous solution of potassium ferricyanide after uniform stirring, controlling the mass ratio of the biomass-based nano-silicon carbide to the cobalt nitrate to the potassium ferricyanide to the sodium citrate to be 10:1:2.2:1.7, uniformly stirring for reaction for 25 hours, standing and aging for 10 hours, centrifugally separating the solution to remove the solvent, washing the solid product by using distilled water and ethanol, and fully drying to prepare the Co-Fe bimetallic MOFs-coated nano-silicon carbide.
(3) Placing Co-Fe bimetal MOFs coated nano silicon carbide in an atmosphere resistance furnace, heating to 750 ℃ at the heating rate of 5 ℃/min in the atmosphere of mixed gas of hydrogen and argon with the product ratio of 10:90, and carrying out heat preservation and calcination for 1.5h to prepare the composite electromagnetic shielding material 2 of the porous carbon coated CoFe alloy-SiC.
Example 3
(1) Washing waste corn straws, putting the washed waste corn straws into a planetary ball mill, ball-milling the waste corn straws into fine powder at the revolution speed of 400rpm and the rotation speed of 200rpm, adding ethanol solvent, cobalt nitrate and tetraethoxysilane into a reaction bottle, adding aqueous solution of oxalic acid after uniformly stirring, uniformly stirring for 25 hours, fully drying the well-ball-milled biomass fine powder, pouring the well-ball-milled biomass fine powder into the solution, adding hexamethylenetetramine after uniformly dispersing by ultrasound, wherein the mass ratio of the cobalt nitrate to the tetraethoxysilane to the oxalic acid to the biomass fine powder to the hexamethylenetetramine is 2.5:100:8:100:4.5, uniformly stirring until the mixture forms a gel, fully drying the gel product to remove the solvent, putting a solid mixed product into an atmosphere resistance furnace, wherein the atmosphere resistance furnace comprises an atmosphere chamber, a vent pipe is fixedly connected inside the atmosphere chamber, the surface of the vent pipe is provided with vent holes, and a base is fixedly connected, And arranging a calcining crucible above the base, heating to 520 ℃ at a heating rate of 8 ℃/min in an argon atmosphere, carrying out heat preservation treatment for 45min, then heating to 1000 ℃, carrying out heat preservation treatment for 45min, regulating the heating rate to 3 ℃, heating to 1320 ℃, carrying out heat preservation treatment for 6.5h, reducing the calcining temperature to 650 ℃, introducing air, carrying out heat preservation and calcining for 2.5h, soaking the calcined product in hydrofluoric acid to remove silicon dioxide, washing and drying to prepare the biomass-based nano silicon carbide.
(2) Adding a distilled water solvent and biomass-based nano-silicon carbide into a reaction bottle, adding cobalt nitrate and sodium citrate after uniform ultrasonic dispersion, slowly dropwise adding a potassium ferricyanide aqueous solution after uniform stirring, controlling the mass ratio of the biomass-based nano-silicon carbide to the cobalt nitrate to the potassium ferricyanide to the sodium citrate to be 12:1:2.2:1.8, uniformly stirring for reaction for 20 hours, standing and aging for 15 hours, centrifugally separating the solution to remove the solvent, washing a solid product by using distilled water and ethanol, and fully drying to prepare the Co-Fe bimetallic MOFs coated nano-silicon carbide.
(3) Placing Co-Fe bimetal MOFs coated nano silicon carbide in an atmosphere resistance furnace, heating to 720 ℃ at the heating rate of 3 ℃/min in the atmosphere of mixed gas of hydrogen and argon with the volume ratio of 12:88, and carrying out heat preservation and calcination for 1.2h to prepare the composite electromagnetic shielding material 3 of the porous carbon coated CoFe alloy-SiC.
Example 4
(1) Washing waste corn straws, putting the washed waste corn straws into a planetary ball mill, ball-milling the waste corn straws into fine powder at the revolution speed of 440rpm and the rotation speed of 220rpm, adding ethanol solvent, cobalt nitrate and tetraethoxysilane into a reaction bottle, adding aqueous solution of oxalic acid after uniformly stirring, uniformly stirring for 30 hours, fully drying the well-ball-milled biomass fine powder, pouring the well-ball-milled biomass fine powder into the solution, adding hexamethylenetetramine after uniformly dispersing by ultrasound, wherein the mass ratio of the cobalt nitrate to the tetraethoxysilane to the oxalic acid to the biomass fine powder to the hexamethylenetetramine is 2.7:100:8:110:4.8, uniformly stirring until the mixture forms a gel, fully drying the gel product to remove the solvent, putting a solid mixed product into an atmosphere resistance furnace, wherein the atmosphere resistance furnace comprises an atmosphere chamber, a vent pipe is fixedly connected inside the atmosphere chamber, the surface of the vent pipe is provided with vent holes, and a base is fixedly connected, And arranging a calcining crucible above the base, heating to 550 ℃ at a heating rate of 10 ℃/min in an argon atmosphere, carrying out heat preservation treatment for 30min, heating to 1050 ℃, carrying out heat preservation treatment for 45min, adjusting the heating rate to 4 ℃, heating to 1320 ℃, carrying out heat preservation treatment for 6.5h, reducing the calcining temperature to 650 ℃, introducing air, carrying out heat preservation and calcining for 2.5h, soaking the calcined product in hydrofluoric acid to remove silicon dioxide, washing and drying to prepare the biomass-based nano silicon carbide.
(2) Adding a distilled water solvent and biomass-based nano-silicon carbide into a reaction bottle, adding cobalt nitrate and sodium citrate after uniform ultrasonic dispersion, slowly dropwise adding an aqueous solution of potassium ferricyanide after uniform stirring, controlling the mass ratio of the biomass-based nano-silicon carbide to the cobalt nitrate to the potassium ferricyanide to the sodium citrate to be 18:1:2.4:1.9, uniformly stirring for reaction for 25 hours, standing and aging for 15 hours, centrifugally separating the solution to remove the solvent, washing the solid product by using distilled water and ethanol, and fully drying to prepare the Co-Fe bimetallic MOFs-coated nano-silicon carbide.
(3) Placing Co-Fe bimetal MOFs coated nano silicon carbide in an atmosphere resistance furnace, heating to 720 ℃ at the heating rate of 5 ℃/min in the atmosphere of hydrogen and argon mixed gas with the volume ratio of 14:86, and carrying out heat preservation and calcination for 1h to prepare the composite electromagnetic shielding material 4 of the porous carbon coated CoFe alloy-SiC.
Example 5
(1) Washing waste corn straws, putting the washed waste corn straws into a planetary ball mill, ball-milling the waste corn straws into fine powder at the revolution speed of 500rpm and the rotation speed of 250rpm, adding ethanol solvent, cobalt nitrate and tetraethoxysilane into a reaction bottle, adding aqueous solution of oxalic acid after uniformly stirring, uniformly stirring for 30 hours, fully drying the well ball-milled biomass fine powder, pouring the well ball-milled biomass fine powder into the solution, adding hexamethylenetetramine after uniformly dispersing by ultrasound, wherein the mass ratio of the cobalt nitrate to the tetraethoxysilane to the oxalic acid to the biomass fine powder to the hexamethylenetetramine is 3:100:9:120:5, uniformly stirring until the mixture is in a gel state, fully drying the gel product to remove the solvent, putting the solid mixed product into an atmosphere resistance furnace, wherein the atmosphere resistance furnace comprises an atmosphere chamber, the inside of the atmosphere chamber is fixedly connected with a base, the surface of a vent pipe is arranged, and the lower part of the inside, And arranging a calcining crucible above the base, heating to 550 ℃ at a heating rate of 10 ℃/min in an argon atmosphere, carrying out heat preservation treatment for 60min, heating to 1050 ℃, carrying out heat preservation treatment for 60min, adjusting the heating rate to 4 ℃, heating to 1350 ℃, carrying out heat preservation treatment for 7h, cooling the calcining temperature to 700 ℃, introducing air, carrying out heat preservation and calcining for 3h, soaking the calcined product in hydrofluoric acid to remove silicon dioxide, washing and drying to prepare the biomass-based nano silicon carbide.
(2) Adding a distilled water solvent and biomass-based nano-silicon carbide into a reaction bottle, adding cobalt nitrate and sodium citrate after ultrasonic dispersion is uniform, stirring uniformly, slowly dropwise adding a potassium ferricyanide aqueous solution, controlling the mass ratio of the biomass-based nano-silicon carbide to the cobalt nitrate to the potassium ferricyanide to the sodium citrate to be 20:1:2.5:2, stirring at a constant speed for reaction for 25 hours, standing and aging for 20 hours, centrifugally separating the solution to remove the solvent, washing the solid product by using distilled water and ethanol, and fully drying to prepare the Co-Fe bimetallic MOFs-coated nano-silicon carbide.
(3) Placing Co-Fe bimetal MOFs coated nano silicon carbide in an atmosphere resistance furnace, heating to 750 ℃ at the heating rate of 5 ℃/min in the atmosphere of mixed gas of hydrogen and argon with the product ratio of 15:85, and carrying out heat preservation and calcination for 1.5h to prepare the composite electromagnetic shielding material 5 of the porous carbon coated CoFe alloy-SiC.
The composite electromagnetic shielding material of the porous carbon coated CoFe alloy-SiC in the embodiments 1-5 and the liquid paraffin are respectively mixed, poured into a mold and pressed into an annular sample with the thickness of 2mm, and the wave absorption performance and the electromagnetic shielding performance are tested by using an R & S rod and Schwarz ZNB vector network analyzer, wherein the test standard is GB/T32596-2016.
To sum up, the composite electromagnetic shielding material of the porous carbon coated CoFe alloy-SiC is prepared by using biomass straws as a carbon source and adopting a sol-gel method to obtain the nano SiO2The preparation method is used as a silicon source to prepare biomass nano SiC, meets the green chemical concept and the green sustainable development, under the action of sodium citrate, cobalt nitrate and potassium ferricyanide generate Co-Fe bimetal MOFs coated nano silicon carbide with rich pore structures, the nano silicon carbide uniformly grows in an organic framework of the MOFs, then CoFe nano alloy is obtained by reducing Co and Fe elements through high-temperature thermal cracking, a porous carbon layer is formed on the MOFs organic framework, the porous carbon coated CoFe nano alloy modified nano SiC is obtained, the CoFe nano alloy modified nano SiC with excellent electromagnetic performance is on the surface, the electromagnetic parameters of the SiC can be obviously improved, the electromagnetic loss performance of the material is enhanced, and the carrier is promoted to form stronger macroscopic current through the coating of the porous carbon layer with excellent conductivity, the electromagnetic energy is favorably converted into heat energy to be diffused and removed, and the excellent impedance matching performance is shown, the composite electromagnetic shielding material of the porous carbon-coated CoFe alloy-SiC has excellent dielectric loss and magnetic loss performance, and can efficiently absorb and lose electromagnetic radiation.
Claims (5)
1. A porous carbon coated CoFe alloy-SiC composite electromagnetic shielding material comprises the following raw materials and components, and is characterized in that: the biomass-based nano silicon carbide, the cobalt nitrate, the potassium ferricyanide and the sodium citrate are mixed according to the mass ratio of 5-20:1:2-2.5: 1.6-2.
2. The composite electromagnetic shielding material of porous carbon coated CoFe alloy-SiC according to claim 1, wherein: the preparation method of the porous carbon-coated CoFe alloy-SiC composite electromagnetic shielding material comprises the following steps:
(1) washing waste corn straws, putting the washed waste corn straws into a planetary ball mill, ball-milling the waste corn straws into fine powder at the revolution speed of 340-250 rpm and the rotation speed of 170-250rpm, adding aqueous solution of cobalt nitrate, ethyl orthosilicate and oxalic acid into an ethanol solvent, stirring at a constant speed for 20-30h, fully drying the ball-milled biomass fine powder, pouring the dried biomass fine powder into the solution, ultrasonically dispersing the biomass fine powder uniformly, adding hexamethylenetetramine, stirring until the mixture is gelatinous, drying the gelatinous product to remove the solvent, putting the solid mixed product into an atmosphere resistance furnace, heating to 500-550 ℃ at the heating rate of 5-10 ℃/min in the argon atmosphere, carrying out heat preservation treatment for 30-60min, heating to 950-1050 ℃, carrying out heat preservation treatment for 30-60min, adjusting the heating rate to 2-4 ℃, heating to 1300-1350 ℃ and carrying out heat preservation treatment for 6-7h, reducing the calcination temperature to 600-700 ℃, introducing air, carrying out heat preservation calcination for 2-3h, soaking the calcined product in hydrofluoric acid to remove silicon dioxide, washing and drying to prepare the biomass-based nano silicon carbide;
(2) adding biomass-based nano silicon carbide into a distilled aqueous solvent, adding cobalt nitrate and sodium citrate after ultrasonic dispersion is uniform, slowly dropwise adding a potassium ferricyanide aqueous solution, reacting for 15-25h, standing and aging for 10-20h, centrifugally separating, washing and drying to prepare Co-Fe bimetallic MOFs coated nano silicon carbide;
(3) placing Co-Fe bimetal MOFs coated nano silicon carbide in an atmosphere resistance furnace, heating to 680-750 ℃ at the heating rate of 2-5 ℃/min in the mixed gas atmosphere of hydrogen and argon, and carrying out heat preservation and calcination for 1-1.5h to prepare the composite electromagnetic shielding material of the porous carbon coated CoFe alloy-SiC.
3. The composite electromagnetic shielding material of porous carbon coated CoFe alloy-SiC according to claim 2, wherein: the atmosphere resistance furnace comprises an atmosphere chamber, a vent pipe fixedly connected inside the atmosphere chamber, vent holes arranged on the surface of the vent pipe, a base fixedly connected below the inside of the atmosphere chamber, and a calcining crucible arranged above the base.
4. The composite electromagnetic shielding material of porous carbon coated CoFe alloy-SiC according to claim 2, wherein: the mass ratio of the cobalt nitrate, the ethyl orthosilicate, the oxalic acid, the biomass fine powder and the hexamethylenetetramine in the step (1) is 2-3:100:7-9:70-120: 4-5.
5. The composite electromagnetic shielding material of porous carbon coated CoFe alloy-SiC according to claim 2, wherein: the volume ratio of the hydrogen to the argon in the step (3) is 8-15: 85-92.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112743098A (en) * | 2020-12-23 | 2021-05-04 | 南昌航空大学 | Preparation method of nitrogen-doped porous carbon-coated hollow cobalt-nickel alloy composite wave-absorbing material |
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2020
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112743098A (en) * | 2020-12-23 | 2021-05-04 | 南昌航空大学 | Preparation method of nitrogen-doped porous carbon-coated hollow cobalt-nickel alloy composite wave-absorbing material |
| CN112743098B (en) * | 2020-12-23 | 2022-07-01 | 南昌航空大学 | Preparation method of nitrogen-doped porous carbon-coated hollow cobalt-nickel alloy composite wave-absorbing material |
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