In-situ fabrication of lightweight SiC(Al, rGO) bulk ceramics derived from silicon oxycarbide for aerospace components

Abstract An ingenious strategy to prepare in-situ formed SiC(Al, rGO) bulk polymer-derived ceramics (PDCs) from re-pyrolyzing SiC(Al, rGO)p/polyaluminocarbosilane-vinyltriethoxysilane-graphene oxide (PACS-VTES-GO, PAVG) blends is highlighted. Flexible PAVG modified by Al with highly cross-linked structure effectively improves molecular weight and formability of precursors. Rigid SiC(Al, rGO)p fillers provide high mechanical properties owing to their unique microstructure which is consistent with SiC(Al, rGO) bulk PDCs. β-SiC nanocrystals are well dispersed in amorphous SiOxCy/Cfree, and rGO exhibits good compatibility with SiOxCy/Cfree. Besides, possible Al2O3 is beneficial to relaxing thermal stress at β-SiC nanocrystalline boundaries. Interestingly, introduction of Al could avoid coarsening of β-SiC grains to enhance elevated temperature resistance. Furthermore, effect of re-pyrolysis temperature on the formation and microstructure of SiC(Al, rGO) bulk PDCs was also investigated. Particularly, lightweight samples re-pyrolyzed at 1300 °C display optimal fracture toughness (3.32 MPa·m1/2), compressive strength (177.16 MPa) and flexural strength (51.25 MPa), high ceramic yield (94.46%) and low linear shrinkage (4.38%), by far superior to those of most PDCs. As treated via precursor infiltration and pyrolysis (PIP) route and heated by butane gun flame in air, such products possess stable structure under elevated temperature and have potential emerging uses in aerospace components.