Interphase degradation of three-dimensional Cf/SiC-ZrC-ZrB2 composites fabricated via reactive melt infiltration

Layer-structured interphase, existing between carbon fiber and ultrahigh-temperature ceramics (UHTCs) matrix, is an indispensable component for carbon fiber reinforced UHTCs matrix composites (C-f/UHTCs). For C-f/UHTCs fabricated by reactive melt infiltration (RMI), the interphase inevitably suffers degradation due to the interaction with the reactive melt. Here, C-f/SiC-ZrC-ZrB2 composite was fabricated by reactive infiltration of ZrSi2 melt into sol-gel prepared C-f/B4C-C preform. (PyC-SiC)(2) interphase was deposited on the fiber to investigate the degradation mechanism under ZrSi2 melt. It was revealed that the degraded interphase exhibited typical features of Zr aggregation and SiC residuals. Moreover, the Zr species diffused across the interphase and formed nanosized ZrC phase inside the fiber. A hybrid mechanisms of chemical reaction and physical melting were proposed to reveal the degradation mechanism according to characterization results and heat conduction calculations. Based on the degradation mechanism, a potential solution to mitigate interphase degradation is also put forward.