With the rapid development of modern technology, electromagnetic wave pollution has become a more and more serious problem, not only interfering with the operation of electronic equipment, but also endangering the environment and human health. Therefore, the research of electromagnetic wave absorbing materials has attracted wide attention. To this end, people have extensively studied ceramics, ferrite, MXene and their composite materials. However, shortcomings such as high density, poor stability, and low flexibility hinder their practical application in the field of portable electronic equipment and aerospace. Therefore, people are eager to develop new electromagnetic wave absorbing materials with better characteristics, such as strong absorption capacity, wide absorption band, low density, high strength and good flexibility. Silicon carbide (SiC) is one of the ideal materials for electromagnetic wave absorption due to its adjustable dielectric properties, good stability, high tensile strength and low density. Studies have shown that one-dimensional (1D) SiC materials (such as fibers, nanowires, and whiskers) have better electromagnetic wave absorption characteristics than bulk SiC and SiC particles. However, by changing their dielectric properties, the electromagnetic wave absorption properties of these 1D SiC materials still have much room for improvement.
In response to the above problems, researchers from Harbin Institute of Technology (Weihai) and the Institute of Physics of the Chinese Academy of Sciences successfully synthesized CNTs on SiC fibers by using a new method, which is far more effective than commonly used methods. The resulting CNT/SiCf composite material has excellent electromagnetic wave absorption capability. When the CNT content is 0.72 wt%, the CNT/SiCf filler accounts for 20 wt%, and the sample thickness is 4 mm, the composite has a reflection loss of -62.5 dB and an effective absorption bandwidth of 8.8 GHz, covering almost the entire Ku band and four Three-thirds of the X-band. In addition, composite materials can be added to various matrices to change their electromagnetic wave absorption and other properties. By changing the content of CNTs, the thickness of the sample and the amount of filling, the electromagnetic wave absorption performance can be easily adjusted in a wide range. This work provides a new way to effectively synthesize CNTs, but more importantly, it provides a new way to design high-performance and versatile wave-absorbing materials. Related work was published in the famous journal "ACS Appl. Mater. Interfaces" with the title "High-Performance Electromagnetic Wave Absorbing CNT/SiCf Composites: Synthesis, Tuning, and Mechanism".
In general, using ferrocene to synthesize CNT/SiCf composite materials by short-time induction heating, while providing a catalyst and a carbon source, has a high electromagnetic wave absorption performance and a wide effective absorption bandwidth. CNTs with Fe particles on the tip form a unique conductive network with a large number of interfaces, thereby improving impedance matching and electromagnetic wave attenuation capabilities. For CNT/SiCf composites containing 0.72 wt% CNT, when the thickness is 4.0 mm, the effective absorption bandwidth is 8.8 GHz, and the lowest RL peak is -62.5 dB. In addition, the electromagnetic wave absorption performance of CNTs/SiCf can be adjusted by adjusting the content of CNT, sample thickness and filling amount to adjust the composite material. The research results prove a new effective method for synthesizing carbon nanotubes, and more importantly, provide a novel method for the design of high-performance and multifunctional electromagnetic wave absorbing materials.