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Superhard B4C-based composites with multifunctionality
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DOI：10.1016/j.actamat.2025.120817.png)
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Abstract
En 中文
Materials with excellent electromagnetic interference (EMI) shielding properties are desired for various structural and functional applications. Compared to mostly investigated polymers, dense ceramics are harder and own better high temperature capability, but their EMI shielding properties and shielding mechanisms had been poorly investigated. In this study, a series of light-weight B4C-(Ti1-xCrx)B-2 (x = 0, 0.1, 0.3, 0.5 and 1, BTCs) composites were reactively densified. Concomitantly with good load-bearing capabilities and high hardness, as-obtained BTCs could effectively shield EMI in X band from room temperature to 700 degrees C. Especially, after incorporating Cr into TiB2, the composites exhibit an enhanced absorption loss. By intentional heat treatments to tailor dislocation densities in BTCs, the enhancements in absorption loss were identified, which were associated with the increased polarizations caused by high-density dislocations in diborides. Among these composites, B4C-(Ti0.9Cr0.1)B-2 with a low density (3.3 g/cm(3)), high hardness (similar to 44 GPa) and modulus (464 GPa) exhibits the best specific EMI shielding performance (similar to 44 dBcm(2)g(-1)), which slightly worsens at 700 degrees C (similar to 30 dBcm(2)g(-1)) but still guarantees an EMI shielding efficiency of similar to 99.9% alongside high absorption loss. This work not only opens a window of functional applications at high temperatures for B4C-TiB2 based composites, but also demonstrates element incorporating and dislocation regulation can significantly enhance EMI shielding performance of materials, especially absorption loss, providing a valuable strategy for developing high-performance ceramics with multifunctionality.
Keywords:
Reactive sintering
Boride
Multifunctionality
Mechanical properties
Electromagnetic interference shielding