Rapid advancements in the electronics industry have provided significant convenience for civilian use, but have also contributed to electromagnetic pollution, posing risks to human safety. To meet the diverse requirements of civilian applications, such as devices with varied curved surfaces and clothing for different working environments, EMW absorbers must not only provide effective absorption, but also be lightweight, easily processed, and sufficiently flexible.
Additionally, EMW absorption materials face challenges under extreme conditions commonly encountered in construction and transportation industries, including high temperatures, frequent vibrations, and pressure impacts.
Hence, exploring the materials with exceptional thermal insulation, significant flexibility and resilience, excellent processability, and ultralight characteristics represents a trend in the development of advanced microwave absorbers. Polymer-derived ceramic (PDC) SiOC exhibits robust mechanical and high-temperature performance in extreme environments, combined with low density, high strength, and low raw material costs, which highlight its potential for applications in both thermal and electromagnetic wave (EMW)protection.
However, SiOC ceramics derived from a single precursor polymer suffer from low dielectric properties, limiting their further applications. To improve EMW attenuation performance, it is common to introduce a second phase into the SiOC matrix, leveraging the advantages of various components to enhance the EMW absorption.
On the other hand, the inherent brittleness of SiOC ceramics severely hinders their use in complex environments. In this case, electrospinning is a versatile method for producing one-dimensional micro-nanofiber materials with uniform size distribution and consistent morphology. Aiming to improve both flexibility and EMW absorption performance, a research team has applied the strategy of multi-phase composition and electrospinning to fabricate SiOC nanofibers.
The team published their work in the Journal of Advanced Ceramics on September 9, 2024.
Co and TiO2 modified SiOC nanofibers (CTS) were successfully prepared using a simple and controllable electrospinning technique. Thanks to the excellent three-dimensional continuous network structure provided by electrospinning and the uniform distribution of composite materials within the fibers, CTS composites exhibit outstanding thermal insulation (thermal conductivity <0.0404 Wm-1K-1), remarkable flexibility (less than 4% resistance change after 1,500 cycles of 180° bending), and impressive compressive resistance (residual strain <12% after 500 cycles at 60% strain).
The CTS-800 sample (silicone resin) with a filler content of only 5 wt% achieves an effective absorption bandwidth (EAB) of 8.64 GHz (9.36-18.00 GHz) at a thickness of 3.25 mm, with an RLmin value of -66.00 dB at 17.11 GHz. The successful preparation of such multi-functional CTS nanofiber materials makes it promising for the application of thermal and microwave protection.
The SiOC nanofiber sample exhibits comprehensive multifunctional properties due to its high porosity and multilayer structure along the thickness. EMW or thermal shock waves from the outside can be significantly attenuated. Additionally, outstanding flexibility ensures that these findings can perfectly grapple with the deformations required in various high-demand scenarios, thus enhancing work efficiency.
Provided by
Tsinghua University Press
