Enhancing SiCf/SiC Composite Fabricated by PIP Process with In-situ Formed SiC Nanowires

Introducing SiC nanowires into SiC fiber-reinforced SiC matrix (SiC f /SiC) composites is an effective multiscale reinforcement strategy. In this study, nickel acetate tetrahydrate (Ni(Ac) 2 ·4H 2 O) was incorporated into a liquid polycarbosilane (LPCS) and converted stepwise into metallic Ni and Ni₂Si during pyrolysis. However, transmission electron microscopy and oxidation test indicated that the resulting fibrous products were mainly carbon nanotubes (CNTs). To obtain SiC nanowires, additional nano Si was introduced into LPCS containing Ni(Ac) 2 ·4H 2 O, with EDS and TEM confirming their successful formation. Furthermore, the introduction of nano Si yielded SiC with larger grain size compared to that derived from pure LPCS or LPCS containing Ni(Ac) 2 ·4H 2 O. To evaluate the impact of these changes on the mechanical properties of SiC matrix composites, SiC f /SiC composites were prepared using the impregnation-pyrolysis process with two types of LPCS as raw materials: one containing nano Si and the other containing both Ni(Ac) 2 ·4H 2 O and nano Si. The resulting composites exhibited flexural strengths of 285 ± 32 MPa and 577 ± 52 MPa, respectively. The improved flexural strength of the latter was explained by the presence of SiC nanowires.