Revealing the dynamic arrangement mechanism of SiCw under combined AC-DC electric fields for composite performance enhancement: Modeling, analysis, and experiments.

Employing electric fields to induce directional arrangement of one-dimensional nanofillers within specific regions is a powerful strategy for enhancing the performance of composites. However, conventional single-mode electric fields (AC or DC) exhibit inherent "orientation-distribution" contradiction. Specifically, AC fields are effective for orientation but lack spatial control, while DC fields promote filler enrichment but fail to optimize orientation state. This study presents an innovative approach by establishing a theoretical framework that integrates both AC and DC electric fields along with a corresponding microscale dynamic model. This approach enables the precise and flexible manipulation of complex filler arrangements, thereby expanding opportunities for advanced material design. The model refines classical dielectrophoresis theory, incorporating interfacial charge and local electric field effects, elucidating the dynamic mechanisms of fillers under combined AC-DC electric fields. Numerical simulations reveal that AC fields primarily control orientation through dielectrophoresis, while DC fields regulate spatial distribution via electrophoresis. The synergistic combination of these two electric fields yields a pronounced "orientation-enrichment" effect, enabling the controlled and orderly arrangement of fillers within targeted areas. Moreover, high-aspect-ratio fillers promote chain formation but restrict rotation and migration, and frequencies above 1 kHz suppress alignment and interparticle attraction. Preliminary material design and preparation for enhanced electrical properties of renewable energy transmission device further indicate that this method is effective and flexible for complex application scenarios. This work advances our understanding of complex filler behavior in hybrid electric fields and offers a novel strategy for designing high-performance composites, paving the way for future innovations in material design.