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Electrically conductive and thermally stable SiC‐TiC containing nanocomposites via flash pyrolysis
Author(s) -
Zheng Jiaqi,
Lu Kathy
Publication year - 2021
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17663
Subject(s) - materials science , nanocomposite , pyrolysis , amorphous solid , ceramic , composite material , amorphous carbon , sintering , carbon fibers , carbothermic reaction , chemical engineering , carbide , composite number , organic chemistry , chemistry , engineering
Flash pyrolysis, which combines conventional pyrolysis with flash sintering, was first conducted to produce polymer derived SiC‐TiC nanocomposites. Pre‐pyrolysis at 800℃ allows the conversion from titanium isopropoxide (TTIP) modified polysiloxane to an amorphous SiTiOC ceramic. The subsequent application of an electric field gives rise to the formation of turbostratic carbon and creates Joule heating to obtain a sample internal temperature of ~1400℃. The precipitation of β‐SiC, TiC, as well as titanium oxides is realized upon carbothermal reduction of extensively phase separated SiO 2 and TiO 2 with carbon. Increasing TTIP content embodies the nanocomposites with prominent electrical percolation behaviors. The electrical transport of the synthesized ceramics follows an amorphous semiconductor mechanism. High thermal stability in air is guaranteed, thanks to the in‐situ formed TiC nanocrystals and preferentially reduced amorphous carbon. Flash pyrolyzed nanocomposite with a Ti:Si molar ratio of 0.20 exhibits the highest electrical conductivity (0.696 S/cm) and minimum mass change (~2%) at 1000℃, serving as a competitive candidate for electro‐discharge machining (EDM) applications or self‐standing conducting devices that must withstand high temperature conditions.