Continuous SiCN Fibers with Interfacial SiC_xN_y Phase as Structural Materials for Electromagnetic Absorbing Applications

Abstract

SiCN ceramics are one of the most important electromagnetic wave (EMW) absorbing materials for application in harsh environments, but research studies on optimizing phase distribution in SiCN ceramics for excellent EMW absorbing properties are still lacking. Herein, continuous SiCN fibers with an interfacial SiC x N y phase were prepared through nanochannel diffusion-controlled nitridation of polycarbosilane fibers with an NH3 gas flow. The existence of the interfacial SiC x N y phase distributed between the carbon-rich SiC phase and Si3N4 phase can improve the impedance matching and efficiently promote the production of macroscopic dipole moments in the heterointerfaces of SiC x N y –SiC and SiC x N y –Si3N4 for an enhanced multifarious polarization relaxation loss. The EMW absorption properties can be further improved by optimizing the microstructure with a continuous carbon-rich SiC phase for possessing an excellent conductive loss by converting the EMW energy into current flow. Finally, under the synergy of the interfacial SiC x N y phase and the continuous carbon-rich SiC phase, SiCN fibers can present excellent EMW absorption properties with extremely strong absorption ability (reflection loss of −63.7 dB), ultrathin thickness (1.78 mm), and wide effective absorption bandwidth (4.20 GHz). These obtained SiCN fibers also possess excellent mechanical properties with the tensile strength higher than 2.0 GPa and excellent high-temperature stability up to 1500 °C. This work provides a strategic method for optimizing the microstructure of SiCN ceramics for admirable EMW absorption properties, and the obtained SiCN fibers can be used as reinforcements of ceramic matrix composites for stealth applications under harsh environments.

BCN ceramics with excellent electromagnetic wave–absorbing property derived from high‐yield and soluble precursor polymers

“…[ 7 ] The high‐carbon‐content SiCN fibers synthesized by Long et al have an impedance mismatch and a minimum RL of −3.3 dB. [ 6 ] These examples show that the carbon content has a great influence on its EMW absorption ability. …”

“…[ 3 ] Dielectric materials such as SiC, SiCN, SiOC, and SiBCN have been extensively studied in the field of EMW absorption due to their low density, high‐temperature resistance, oxidation resistance, good stability, and adjustable semiconductor properties. [ 4–8 ] However, there are still many difficulties and challenges to obtain an EMW‐absorbing material that combines strong EMW absorption, a wide effective absorption bandwidth (EAB), good high‐temperature thermal stability, and mechanical properties. [ 9 ] Among all of the EMW‐absorbing materials, BCN ceramics with adjustable bandgap width, excellent high‐temperature stability, and low density have attracted great attention in recent years.…”

Preparation and properties of polyimide/carbon nanotube composite films with electromagnetic wave absorption performance

“…Various electronic and electrical equipment types play a vital role in people's everyday life and social construction. [ 1–4 ] However, the EM radiation and interference have gradually affected people's production and life, which causes EM pollution to human beings. [ 5–7 ] In addition, radar, infrared, and other detection technologies have been widely used in the field of aerospace and aviation with the development of the electronic information technology, [ 8–10 ] making EM wave absorption stealth technology become the focus of research.…”

Effects of Carbonyl Iron Powder (CIP) Content on the Electromagnetic Wave Absorption and Mechanical Properties of CIP/ABS Composites

“…The modification of magnetic fillers, employment of multiple absorbents, and structural design of EWAMs have proven to be effective in reducing the reflection loss (RL) and broadening the effective absorption bandwidth (EAB; RL <−10 dB, for over 90% EMW energy absorbed) [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. In particular, structural EWAMs have drawn deep attention not only due to their ability to adjust the impedance matching of absorbers and enhance the absorbing performance but also due to excellent mechanical properties [ 44 , 45 , 46 ]. Nevertheless, it is difficult and costly to achieve the free design of various structures of structural EWAMs by traditional manufacturing systems.…”