CN117886624A - Broadband wave-absorbing material for 25-1300 ℃ and preparation method thereof - Google Patents
Broadband wave-absorbing material for 25-1300 ℃ and preparation method thereof Download PDFInfo
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Abstract
The invention disclosesA broadband wave-absorbing material for 25-1300 ℃ and a preparation method thereof relate to the technical field of wave-absorbing materials. The wave absorbing material comprises a material with a three-dimensional structure formed by interconnecting silicon carbide nanowires; the surface of the silicon carbide nanowire is coated with Al 4 SiC 4 Ternary compounds. The invention is made of Al 4 SiC 4 Coating SiC with NWs Electromagnetic parameters and conductivity of the material are improved, the conductivity loss of the material is improved, and meanwhile, a special structural network of the material increases an electromagnetic wave transmission path, so that the wave absorbing performance of the material is improved.
Description
Technical Field
The invention relates to the technical field of wave-absorbing materials, in particular to a broadband wave-absorbing material for 25-1300 ℃ and a preparation method thereof.
Background
The wave absorbing material dissipates the incident electromagnetic wave energy in a Joule heat mode, so that the stealth purpose is achieved. Meanwhile, people are devoted to developing stealth materials with light weight, small thickness, high strength, low cost, strong wave absorption and wide range. Porous silicon carbide structures have open porosity, low density, low thermal conductivity, high temperature resistance, and excellent chemical inertness, and are attractive for applications such as thermal insulators, filters, catalyst supports, and absorbers. If the microstructure and the dielectric constant of the material can be regulated, the material has excellent wave absorbing performance, and has very good application prospect.
Replica template technology is one of the most common methods for fabricating porous silicon carbide. The porous template is immersed in the pre-ceramic slurry, and then dried and pyrolyzed. The template is extracted by combustion or decomposition during pyrolysis, leaving a three-dimensional open-cell structure template that mimics the original template. Polymeric sponges such as Melamine Foam (MF) have the advantages of high permeability, light weight, superelasticity, and low cost, and are often selected as templates.
Silicon carbide (Al) 4 SiC 4 ) As a promising high temperature ceramic and additive, attention has been paid to its low density, high melting point and high oxidation resistance. However, synthesized in Al 4 SiC 4 High temperatures and long reaction times are often required, which limits Al 4 SiC 4 Synthesis and application of (3). The use of sintering additives can be reducedSintering temperature. In recent years, yttrium silicon carbide (Y 3 Si 2 C 2 ) Is successfully used as a sintering additive for silicon carbide and is predicted to be a very promising inter-phase material for SiC composites.
The prior art discloses a composite electromagnetic wave-absorbing foam prepared from ZIF-67/melamine, which is prepared from three-dimensional reticular melamine foam and regular dodecahedron-shaped metal organic frame material ZIF-67. The prepared composite electromagnetic wave-absorbing foam has a three-dimensional network structure, the three-dimensional carbon-based skeleton generated by high-temperature burning improves the conductivity of the composite foam, the capability of multiple scattering of electromagnetic waves in the composite foam is enhanced, and the magnetic drill-based material derived from ZIF-67 introduces a magnetic loss mechanism, so that the absorption capability of the composite foam to the electromagnetic waves is synergistically enhanced. However, the high-temperature wave absorbing performance of the magnetic material has a certain limitation, and the magnetic material cannot be used at a temperature higher than the Curie temperature. The preparation method of the multifunctional melamine flexible composite wave-absorbing foam is also disclosed in the prior art, and the melamine composite wave-absorbing foam has the advantages of high stability, light weight, high flexibility, good heat insulation, good wave-absorbing performance and adjustability. But also cannot be used at high temperatures and has certain limitations.
Disclosure of Invention
Aiming at the defects existing in the background technology, the invention mainly solves the technical problems of the invention that the light wave-absorbing material with high reflection loss and wide absorption frequency band is invented, and meanwhile, the wave-absorbing material has the characteristics of high temperature resistance, oxidation resistance and stable wave-absorbing performance at high temperature so as to meet the use requirements of part of weapon equipment key parts in a high-temperature environment. The invention provides a broadband wave-absorbing material for 25-1300 ℃ and a preparation method thereof. The wave-absorbing material is made of Al 4 SiC 4 Coating SiC with NWs Electromagnetic parameters and conductivity of the material are improved, the conductivity loss of the material is improved, and meanwhile, a special structural network of the material increases an electromagnetic wave transmission path, so that the wave absorbing performance of the material is improved.
The first object of the invention is to provide a broadband wave-absorbing material for 25-1300 ℃, wherein the wave-absorbing material comprises silicon carbide nanowires which are connected with each other to form a material with a three-dimensional structure;
the surface of the silicon carbide nanowire is coated with Al 4 SiC 4 Ternary compounds.
Preferably, the diameter of the silicon carbide nanowire is between 100 and 150nm.
Preferably, the Al 4 SiC 4 The thickness of the ternary compound coating is between 5 and 20nm.
Preferably, the Al 4 SiC 4 The mass ratio of the ternary compound to the silicon carbide nanowire is 1: 100-200.
Preferably, the use temperature of the wave-absorbing material in the air environment is 25-1300 ℃, and the minimum absorption bandwidth can reach more than 6 GHz.
The second object of the present invention is to provide a method for preparing a broadband wave-absorbing material at 25 ℃ to 1300 ℃, comprising the steps of:
preparing mixed slurry of carbon-silicon precursors by taking a silicon source, a carbon source and aluminum powder as raw materials and ethanol solution as a solvent;
taking melamine foam as a template, immersing the mixed slurry into the template in a vacuum environment, carrying out vacuum degassing, removing excessive slurry, and drying to obtain a precursor material;
the precursor material is prepared by a molten salt method to obtain the broadband wave-absorbing material for 25-1300 ℃.
Preferably, the mass ratio of the silicon source to the carbon source to the aluminum powder is (25-29): (65-69): (1-5); the silicon source is tetraethyl orthosilicate; the carbon source is white granulated sugar solution, rock sugar solution and glucose solution; the grain diameter of the aluminum powder is less than or equal to 5 mu m.
Preferably, the preparation process of the precursor material by the molten salt method comprises the following steps: uniformly mixing molten salt and sintering aid, embedding precursor material, insulating at 1450-1600 deg.C for 2-4 hr under inert atmosphere, and treating at 600-800 deg.C for 2-4 hr to obtain the invented wideband wave-absorbing material for 25-1300 deg.C.
Preferably, the sintering aid is yttrium silicon carbon, yttrium oxide or yttrium powder; the content of the sintering aid is 3-5 wt%.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a broadband wave-absorbing material for 25-1300 ℃ and a preparation method and application thereof, and the wave-absorbing material provided by the invention has the main component of Al 4 SiC 4 /SiC NWs The method comprises the steps of carrying out a first treatment on the surface of the The preparation method mainly comprises the steps of taking melamine foam as a template, taking a carbon source as a sugar solution, taking a silicon source as a tetraethyl orthosilicate solution and aluminum powder (Al) at high temperature, and preparing the material by a molten salt method; wherein the sugar solution is preferably white sugar, crystal sugar or glucose solution, and the Al powder has a particle size of less than 5 μm. The wave absorbing material is Al coated on the surface 4 SiC 4 Ternary compound silicon carbide nanowires (SiC NWs ) And materials with three-dimensional (3D) structures formed by interconnection. Specifically, it is due to Al 4 SiC 4 Is superior to SiC in conductivity by Al 4 SiC 4 Coating SiC with NWs Improves the electromagnetic parameters and conductivity of the material, and when electromagnetic waves enter, al on the surface 4 SiC 4 The material can improve the conductivity loss and polarization loss, and meanwhile, the special structural network of the material increases the electromagnetic wave reflection times and current transmission paths, so that the conductivity loss of the material is further improved, and the wave absorbing performance of the material is improved.
Detailed Description
In order that those skilled in the art will better understand the technical solution of the present invention, the present invention will be further described with reference to specific examples, but the examples are not intended to limit the present invention.
The first aspect of the present invention provides a broadband wave-absorbing material for 25 ℃ to 1300 ℃, the wave-absorbing material comprising silicon carbide nanowires (SiC NWs ) Interconnected to form a material having a three-dimensional structure; the surface of the silicon carbide nanowire is coated with Al 4 SiC 4 Ternary compounds.
The wave-absorbing material provided by the invention has the main components of Al 4 SiC 4 /SiC NWs The method comprises the steps of carrying out a first treatment on the surface of the The melamine foam is mainly used as a template, a carbon source is sugar solution, a silicon source is tetraethyl orthosilicate solution and aluminum powder (Al) is highIs prepared by a molten salt method at the temperature; wherein the sugar solution is preferably white sugar, crystal sugar or glucose solution, and the Al powder has a particle size of less than 5 μm. The wave absorbing material is Al coated on the surface 4 SiC 4 Ternary compound silicon carbide nanowires (SiC NWs ) And materials with three-dimensional (3D) structures formed by interconnection. By Al 4 SiC 4 Coating SiC with NWs Electromagnetic parameters and conductivity of the material are improved, the conductivity loss of the material is improved, and meanwhile, a special structural network of the material increases an electromagnetic wave transmission path, so that the wave absorbing performance of the material is improved.
Wherein the diameter of the silicon carbide nanowire is 100-150 nm. The Al is 4 SiC 4 The thickness of the ternary compound coating is 5-20 nm. The Al is 4 SiC 4 The mass ratio of the ternary compound to the silicon carbide nanowire is 1: 100-200.
The use temperature of the wave-absorbing material in the air environment is 25-1300 ℃, and the effective absorption bandwidth (less than or equal to-10 dB) can reach more than 6GHz at the lowest.
The second aspect of the present invention provides a method for preparing a broadband wave-absorbing material at 25 ℃ to 1300 ℃, comprising the steps of:
preparing mixed slurry of carbon-silicon precursors by taking a silicon source, a carbon source and aluminum powder as raw materials and ethanol solution as a solvent;
taking melamine foam as a template, immersing the mixed slurry into the template in a vacuum environment, carrying out vacuum degassing, removing excessive slurry, and drying to obtain a precursor material;
the precursor material is prepared by a molten salt method to obtain the broadband wave-absorbing material for 25-1300 ℃.
Wherein, the mass ratio of the silicon source to the carbon source to the aluminum powder is (25-29): (65-69): (1-5);
the silicon source is tetraethyl orthosilicate; the carbon source is white granulated sugar solution, rock sugar solution and glucose solution; the grain diameter of the aluminum powder is less than or equal to 5 mu m.
Specifically, the preparation process of the precursor material by the molten salt method comprises the following steps: uniformly mixing molten salt and sintering aid, embedding precursor material, insulating at 1450-1600 deg.C for 2-4 hr under inert atmosphere, and treating at 600-800 deg.C for 2-4 hr to obtain the invented wideband wave-absorbing material for 25-1300 deg.C.
Wherein the sintering aid is yttrium silicon carbon (Y 3 Si 2 C) Yttria (Y) 2 O 3 ) Or yttrium (Y); the content of the sintering aid is 3-5 wt%.
In one embodiment, the broadband wave-absorbing material for 25-1300 ℃ is prepared by the steps of proportioning, dipping, drying, sintering, decarbonizing and the like, and specifically comprises the following steps:
step one, tetraethyl orthosilicate in volume ratio: ethanol: h 2 Mixing three solutions according to the ratio of O=2:2:1, and adjusting the pH value of the solution to about 3 by using hydrochloric acid as a pH regulator; magnetically stirring for 24 hours; then adding a sugar solution containing 10% by weight of the carbon-silicon precursor into the mixture according to the volume ratio of 1:1 to form a mixed solution containing the carbon-silicon precursor, then adding 1-5% by weight of Al powder, and magnetically stirring the mixture for 24 hours to obtain premixed slurry;
immersing a melamine foam serving as a template into a premixed slurry containing a carbon solution, a silicon solution and Al powder in a vacuum environment, and performing vacuum degassing for 1-3 h to thoroughly fill pores with the slurry; after immersing, compressing and removing excessive slurry, and drying in a drying oven at 100 ℃ for 12-24 hours;
step three, during sintering, placing the dried sample into a crucible, firstly uniformly mixing molten salt and sintering aid, then burying the sample, and placing into an atmosphere furnace; heating the sample to 700 ℃ at a temperature of 1 ℃/min, then heating to 1500 ℃ at a temperature of 5 ℃/min, and keeping the sample in an argon environment for 2-4 hours; finally, heating in air at 600-800 deg.c for 2-4 hr to obtain the wideband wave absorbing material at 25-1300 deg.c. Wherein, sintering aid is added in the synthesis process to obtain yttrium silicon carbon (Y 3 Si 2 C) Yttria (Y) 2 O 3 ) Or yttrium (Y) powder, the content of which is 3-5 wt%.
It should be noted that, the experimental methods adopted in the invention are all conventional methods unless otherwise specified; the reagents and materials employed, unless otherwise specified, are commercially available.
Example 1
A preparation method of a broadband wave-absorbing material for 25-1300 ℃ comprises the following steps:
step one, tetraethyl orthosilicate in volume ratio: ethanol: h 2 Mixing three solutions according to the ratio of O=2:2:1, and adjusting the pH value of the solution to about 3 by using hydrochloric acid as a pH regulator; magnetically stirring for 24 hours; then adding a sugar solution containing 10% by weight of carbon-silicon precursor according to the volume ratio of 1:1 to form a mixed solution containing carbon-silicon precursor, then adding 1% by weight of Al powder, and magnetically stirring for 24 hours to obtain premixed slurry;
immersing a melamine foam serving as a template into a premixed slurry containing a carbon solution, a silicon solution and Al powder in a vacuum environment, and performing vacuum degassing for 1.5 hours to thoroughly fill pores with the slurry; after immersion, excess slurry was removed by compression and dried in an oven at 100 ℃ for 15h;
step three, during sintering, placing the dried sample into a crucible, firstly uniformly mixing molten salt and sintering aid, then burying the sample, and placing into an atmosphere furnace; the sample is firstly heated to 700 ℃ at the temperature of 1 ℃/min, then is heated to 1500 ℃ at the temperature of 5 ℃/min and is kept for 2 hours under the argon environment; finally, heating in air at 650 ℃ for 2 hours to obtain the broadband wave-absorbing material for 25-1300 ℃. Wherein, the sintering aid is yttrium (Y) powder with the content of 3wt% in the synthesis process.
Example 2
A preparation method of a broadband wave-absorbing material for 25-1300 ℃ comprises the following steps:
step one, tetraethyl orthosilicate in volume ratio: ethanol: h 2 Mixing three solutions according to the ratio of O=2:2:1, and adjusting the pH value of the solution to about 3 by using hydrochloric acid as a pH regulator; magnetically stirring for 24 hours; then adding a sugar solution containing 10% by weight of the carbon-silicon precursor into the mixture according to the volume ratio of 1:1 to form a mixed solution containing the carbon-silicon precursor, then adding 5% by weight of Al powder, and magnetically stirring the mixture for 24 hours to obtain premixed slurry;
immersing a melamine foam serving as a template into a premixed slurry containing a carbon solution, a silicon solution and Al powder in a vacuum environment, and performing vacuum degassing for 1h to thoroughly fill pores with the slurry; after immersion, excess slurry was removed by compression and dried in an oven at 100 ℃ for 12h;
step three, during sintering, placing the dried sample into a crucible, firstly uniformly mixing molten salt and sintering aid, then burying the sample, and placing into an atmosphere furnace; the sample is first heated to 700 ℃ at a temperature of 1 ℃/min, then heated to 1500 ℃ at 5 ℃/min and kept under argon for 4 hours; finally, heating in air at 600 ℃ for 4 hours to obtain the broadband wave-absorbing material for 25-1300 ℃. Wherein, sintering aid is added in the synthesis process to obtain yttrium silicon carbon (Y 3 Si 2 C) The content was 5wt%.
Example 3
A preparation method of a broadband wave-absorbing material for 25-1300 ℃ comprises the following steps:
step one, tetraethyl orthosilicate in volume ratio: ethanol: h 2 Mixing three solutions according to the ratio of O=2:2:1, and adjusting the pH value of the solution to about 3 by using hydrochloric acid as a pH regulator; magnetically stirring for 24 hours; then adding a sugar solution containing 10 wt% of carbon-silicon precursor according to the volume ratio of 1:1 to form a mixed solution containing carbon-silicon precursor, then adding 3wt% of Al powder, and magnetically stirring for 24 hours to obtain premixed slurry;
immersing a premixed slurry containing a carbon solution, a silicon solution and Al powder in a vacuum environment by taking melamine foam as a template, wherein the vacuum degassing time is 3 hours, so that the slurry completely fills pores; after immersion, excess slurry was removed by compression and dried in an oven at 100 ℃ for 24h;
step three, during sintering, placing the dried sample into a crucible, firstly uniformly mixing molten salt and sintering aid, then burying the sample, and placing into an atmosphere furnace; heating the sample to 700 ℃ at a temperature of 1 ℃/min, then heating to 1500 ℃ at a temperature of 5 ℃/min, and keeping the sample in an argon environment for 2-4 hours; finally, heating in air at 600 ℃ for 2 hours to obtain the broadband for 25-1300 DEG CA wave absorbing material. Wherein, the sintering aid is yttrium oxide (Y 2 O 3 ) The content was 4wt%.
To illustrate the performance of the wave-absorbing material provided by the present invention, only the wave-absorbing material provided in example 1 was tested for wave-absorbing performance.
Table 1 shows the wave-absorbing properties of the wave-absorbing material provided in example 1 tested at different temperatures
| Examples | Testing temperature (. Degree. C.) | Effective bandwidth (less than or equal to-10 dB) | Minimum loss (-dB) | Thickness (mm) |
| 1 | Room temperature | 6.8 | 36 | 4.0 |
| 1 | 500 | 7.1 | 42 | 4.0 |
| 1 | 800 | 7.6 | 45 | 4.0 |
| 1 | 1000 | 6.4 | 37 | 4.0 |
| 1 | 1300 | 6.1 | 33 | 4.0 |
As can be seen from table 1, the wave-absorbing material prepared by the above steps has a minimum absorption bandwidth of 6GHz or more, a reflection loss of generally more than 30dB, and a superior wave-absorbing performance can be maintained even when tested at 1300 ℃ under the conditions of a thickness of 4.0mm and different temperatures.
The present invention describes preferred embodiments and effects thereof. Additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (9)
1. The broadband wave-absorbing material for 25-1300 ℃ is characterized by comprising silicon carbide nanowires which are connected with each other to form a material with a three-dimensional structure;
the surface of the silicon carbide nanowire is coated with Al 4 SiC 4 Ternary compounds.
2. The broadband wave-absorbing material for 25-1300 ℃ according to claim 1, wherein,
the diameter of the silicon carbide nanowire is 100-150 nm.
3. The broadband wave absorbing material for 25 ℃ to 1300 ℃ according to claim 1, wherein said Al 4 SiC 4 The thickness of the ternary compound coating is 5-20 nm.
4. The broadband wave absorbing material for 25 ℃ to 1300 ℃ according to claim 1, wherein said Al 4 SiC 4 The mass ratio of the ternary compound to the silicon carbide nanowire is 1: 100-200.
5. The broadband wave absorbing material for 25 ℃ to 1300 ℃ according to claim 1, wherein the use temperature of the wave absorbing material in an air environment is 25 ℃ to 1300 ℃, and the minimum absorption bandwidth can reach more than 6 GHz.
6. A method for preparing the broadband wave-absorbing material for 25 ℃ to 1300 ℃ according to any one of claims 1 to 5, comprising the following steps:
preparing mixed slurry of carbon-silicon precursors by taking a silicon source, a carbon source and aluminum powder as raw materials and ethanol solution as a solvent;
taking melamine foam as a template, immersing the mixed slurry into the template in a vacuum environment, carrying out vacuum degassing, removing excessive slurry, and drying to obtain a precursor material;
the precursor material is prepared by a molten salt method to obtain the broadband wave-absorbing material for 25-1300 ℃.
7. The method for preparing a broadband wave-absorbing material for 25-1300 ℃ according to claim 6, wherein the mass ratio of the silicon source to the carbon source to the aluminum powder is (25-29): (65-69): (1-5);
the silicon source is tetraethyl orthosilicate; the carbon source is white granulated sugar solution, rock sugar solution and glucose solution; the grain diameter of the aluminum powder is less than or equal to 5 mu m.
8. The method for preparing a broadband wave-absorbing material for 25 ℃ to 1300 ℃ according to claim 6, wherein the preparation process of the precursor material by a molten salt method comprises the following steps: uniformly mixing molten salt and sintering aid, embedding precursor material, insulating at 1450-1600 deg.C for 2-4 hr under inert atmosphere, and treating at 600-800 deg.C for 2-4 hr to obtain the invented wideband wave-absorbing material for 25-1300 deg.C.
9. The method for preparing a broadband wave-absorbing material for 25-1300 ℃ according to claim 6, wherein the sintering aid is yttrium silicon carbon, yttrium oxide or yttrium powder; the content of the sintering aid is 3-5 wt%.
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