Carbon Nanohorns Silicon Dioxide Core-Shell Microwave Absorption
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Solution Overview
Problem
Current carbon nanohorns-based microwave absorbing materials suffer from narrow absorption frequency bands and weak microwave absorption due to impedance mismatch and single microwave loss mechanism, requiring complex synthesis processes and high energy consumption for core-shell structures.
Innovation Solution
A method using arc plasma technology to create a core-shell structure of carbon nanohorns wrapped in silicon dioxide, allowing for tunable microwave absorption by adjusting the shell thickness and composition, thereby enhancing impedance matching and absorption performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If carbon nanohorns are used alone as microwave absorbing material, then the material is lightweight with excellent electrical conductivity, but the absorption frequency band is narrow and microwave absorption performance is weak due to impedance mismatch and single microwave loss mechanism
Solution Approach 1:
The patent combines carbon nanohorns with silicon dioxide to form a core-shell composite structure. The carbon nanohorns core provides lightweight properties and electrical conductivity, while the silicon dioxide shell introduces additional microwave loss mechanisms through interface polarization and relaxation, thereby broadening the absorption frequency band without significantly increasing density.
Solution Approach 2:
The patent creates a core-shell structure where different regions have different properties: the carbon nanohorns core provides conductivity and the silicon dioxide shell provides dielectric loss and interface polarization. This local differentiation of material properties enables multiple microwave loss mechanisms to operate simultaneously, expanding the effective absorption bandwidth while maintaining lightweight characteristics.
2Reliability
If core-shell structure is constructed to improve impedance matching and microwave absorption, then absorption performance is enhanced, but the synthesis process becomes complex and synthesis time increases to a day or even longer
Solution Approach 1:
The patent combines the core formation and shell coating processes into a single integrated arc plasma treatment step. The carbon nanohorns are formed and simultaneously coated with silicon dioxide in one continuous process, eliminating the need for separate synthesis and coating steps that would extend the total synthesis time to a day or longer.
Solution Approach 2:
The patent replaces complex multi-step chemical synthesis and hydrothermal coating processes with arc plasma technology. This physical/chemical plasma process achieves both core formation and shell deposition in a single step, dramatically reducing synthesis time from a day or longer to a much shorter duration while maintaining the desired core-shell structure and impedance matching properties.
3Reliability
If multi-layer core-shell structures are synthesized through multi-step coating, then microwave absorption performance is improved, but energy consumption increases due to harsh reaction conditions such as high temperature and long-term hydrothermal reaction
Solution Approach 1:
The patent replaces energy-intensive multi-step hydrothermal reactions and high-temperature treatments with a single arc plasma process. The plasma provides localized high-energy conditions sufficient for both core formation and shell coating without requiring prolonged high-temperature hydrothermal conditions, thereby significantly reducing overall energy consumption while achieving the desired multi-layer core-shell structure with excellent microwave absorption performance.
Solution Approach 2:
The patent skips the intermediate steps of separate core synthesis, drying, and multi-step coating processes by using arc plasma to directly form the core-shell structure in one rapid process. This 'rushing through' of the synthesis pathway eliminates the need for energy-intensive intermediate heating and drying steps, reducing total energy consumption while maintaining the structural integrity and absorption performance of the multi-layer core-shell material.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method simplifies the synthesis process, reduces production time, and achieves broadened absorption frequency bands with excellent microwave absorption performance, including controllable adjustment of absorption capabilities across different frequency bands.
Implementation Method 1
a) A mixture of carbon and silicon precursors is placed in a plasma reactor, where plasma is generated to synthesize the core-shell structure
Implementation Method 2
Arc plasma technology is used to construct a core-shell structure of CNHs wrapped in silicon dioxide
Implementation Method 3
Carbon nanohorns (CNHs) have great application potential in the field of electromagnetic wave absorption due to their excellent electrical conductivity, abundant defects, large specific surface area
Implementation Method 4
the ingenious combination of the core layer and the shell layer can form multiple interfaces, and the corresponding interface polarization and multiple relaxations can further enhance the dielectric and absorbing properties of the system
Data Source
AI summary
The present disclosure relates to a method for production of CNHs composite material. The method includes the following steps: a first step: the silicon particles and graphite powder are mixed for a preset time by planetary ball mill device, and the weight ratio of silicon element to carbon element is 10-40%, then the Si/C precursor is obtained; a second contact step: the Si/C precursor is pressed into a precursor block, then using precursor block to the CNHs composite material by a DC arc plasma device.