Multifunctional and anisotropic Cf/ZrB2 based composites prepared via a combined injection and vacuum impregnation approach

Abstract

Multifunctional carbon fibers (C_f)/ZrB₂ based composites were synthesized through a series of processes termed as IVI including sequential slurry injection, vacuum impregnation, pyrolysis and reimpregnation cycles, which facilitated the effective incorporation of ZrB₂ powder into the carbon fiber preform. A single IVI cycle reduced the porosity of the preform from ∼77% to ∼40%. Microstructural analysis revealed a preferential distribution of ZrB₂ powders within random layers and pyrolytic carbon effectively bridging the ceramic particles and fibers. Due to the hierarchical 0°/90° carbon fiber architecture, as fabricated C_f/ZrB₂ composites exhibited anisotropy in mechanical and physical properties. Vertically oriented composites demonstrated higher compressive strain and low thermal conductivity (1.00–2.59 W m⁻¹ K⁻¹ from 298 to 1173 K). In contrast, horizontally oriented specimens exhibited higher compressive strength (60.77±20.30 MPa) and thermal conductivity (1.6–4.5 W m⁻¹ K⁻¹ from 298 to 1173 K). Furthermore, the continuous C_f endowed the composites with a positive temperature-dependent electrical conductivity characteristic, not only contributed to their higher electrical conductivity values, but also was helpful for maintaining the excellent EMI shielding effectiveness (19.80–22.51 dB) of C_f/ZrB₂ up to 800°C without obvious degradation. Considering the low-density characteristics of as-prepared composites, their specific performance metrics demonstrate good competitiveness compared to those fabricated via alternative processes.