Precursor-modified strategy to in-situ fabricate lightweight SiC(Zr, rGO) nanocomposite PDCs for aerospace components

Aimed at making SiC-based composites for thermal protection components to catch up with the increasing Mach number of hypersonic vehicles, a facile strategy is proposed to fabricate lightweight SiC(Zr, rGO) nanocomposite polymer-derived ceramics (PDCs). The key technique is repyrolyzing SiC(Zr, rGO) p /polyzirconocarbosilane–vinyltriethoxysilane–graphene oxide (PZCS–VTES–GO, PZVG) blends. Highly cross-linked PZVG can effectively optimize formability of precursors, and in-situ formed Zr-containing phases are beneficial in preventing further grain growth of β-SiC and improving bonding strength within ceramic network. More interestingly, ZrOSi transition zone tightly coupled with nanocrystals helps to increase structure disorder of amorphous ceramic matrix to tough nanocomposite structure. Particularly, SiC(Zr, rGO) 1300 nanocomposite PDCs own outstanding hardness (8.10 GPa), superior fracture toughness (3.84 MPa·m 1/2 ), high ceramic yield (92.60%), and low linear shrinkage (5.00%). Zr-modification enables them to retain favorable overall performances even after 60 min of oxidation under a 1300°C butane torch flame. Timely self-healing ZrO 2 (ZrSiO 4 )/SiO 2 protective layer can enhance high-temperature oxidation resistance. Meanwhile, ZrO 2 and ZrC have a unique combination of good high-temperature stability/resistance to corrosion, strongly improving structural integrality. As demonstrated, such in-situ construction of nanocomposite system and pyrolytic mechanism open new opportunities for obtaining PDCs with superior high-temperature ablation resistance, toward emerging uses in thermal protection system of hypersonic aerospace vehicles.