In-situ formed intergranular TiB2 into lightweight SiC(rGO) composite PDCs enable elevated temperature resistance for aerospace components

Strengthening interface bonding for superior mechanical/ablation performances of SiC-based aerospace vehicle components remains a major challenge. Attractively, polycarbosilane-vinyltriethoxysilane-graphene oxide with addition of TiN/B (PVG(TiN, B)) were successfully synthesized for the first time. An ingenious route via re-pyrolyzing ball-milling-induced SiC(rGO, TiB 2 ) p fillers/PVG(TiN, B) precursors blends was introduced to prepare lightweight SiC(rGO, TiB 2 ) composite polymer-derived ceramics (PDCs). Interestingly, both SiC(rGO, TiB 2 ) p and PVG(TiN, B) pyrolysis products, composed of β-SiC/SiO x C y /C free (rGO, TiB 2 ), are tightly coupled by each other owing to plentiful Si-dangling bonds. In-situ formed intergranular TiB 2 /B 4 C, well compatible with amorphous ceramic network, can prevent β-SiC grain growth, strengthen interface bonding, and even hinder further crack propagation along the grain boundaries. Particularly, samples re-pyrolyzed at 1300 °C possess unique combination of good hardness (5.44 GPa), excellent fracture toughness (4.70 MPa·m 1/2 ), high flexural strength (41.90 MPa) and outstanding compressive strength (126.33 MPa). Improved high-temperature and ablation resistance gives them distinct advantages of interlocked microstructure under exposure of butane flame. As demonstrated, SiC(rGO, TiB 2 ) composite PDCs were developed into porous ceramics with good thermal insulation , focusing on manufacturing large-size bulk PDCs for thermal protection system of hypersonic vehicles.