Find out how material scientists have created this low-weight, porous Si3N4 ceramic with uniform fine structures that could lead to incredible new developments in hypersonic jets.
An Innovation in Radomes and Antenna Windows
For the design of the antennas that transmit high frequency electromagnetic waves there are two main protective elements to consider: Radomes and wave-transmitting antenna windows, which protect the radar antennas from outside interference without degrading communication.
Ceramic oxides and nitrides are currently the most used materials for transmitting waves. Some of the ceramic materials exhibit high temperatures resistance, but as dielectric and thermal insulation material properties, it needs to carry forward with dense Si3N4 ceramics, which has limits for temperature of ( 1100 ) C at least required for flight of high speed closing to HSF in order to get a step ahead.
Those same material scientists have figured out how to improve the dielectric, mechanical and thermal properties of wave-permeable materials by making tiny changes at the microstructure level. The use of porous Si3N4 ceramics has been identified as a critical material for radome and antenna window development for hypersonic aircraft due to the high-temperature loadings, thermal stresses, and relatively lower dielectric constants required to operate effectively with radar.
A New Frontier in Pore Structure Control
Historically, the trade-off between wave transmission efficiency and mechanical strength has led to new methods aimed at enhancing both performances.
A surge in international research effortsHowever, new hope has emerged after a group of material scientists, spearheaded by Dr Zhilin Tian and Bin Li from Sun Yat-sen University in China developed a new approach to prepare porous Si3N4 ceramics with uniform nanostructures.
Their technique, which uses a dual-solvent templating and freeze-casting approach, allows them to tailour pore size and structure (important for the performance of high-temperature wavelenght trancer materials).
These conventional methods usually are not capable of creating this sort of in-depth uniform and regular pore structure, though the new system is capable to transform anisotropic prismatic pores into isotropic spherical pores. Such synergic properties improvement of mechanical, thermal and dielectric resulting innovations in air-space industries for porous Si3N4 ceramics.
Conclusion
Here, we report the generation of wave-transparent substances by developing porous Si3N4 ceramics with homogenous and fine structures using dual-solvent templating and freeze-casting methodologies. This revolutionary approach provides unique control over the pore size and configuration which results with significantly improved mechanical/thermal/dielectric properties that are essential for hypersonic flight condition. These porous ceramics could be utilized in nearly any extreme environment, making them a game change for the entire aerospace industry and enabling high-speed flight into the next generation.
