Electrically conductive and thermally stable SiC‐TiC containing nanocomposites via flash pyrolysis

Abstract

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 SiO2 and TiO2 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.

Single source precursor‐derived SiOC/TiOxCy as an anode component for Li‐ion batteries

“…Similarly, the deconvoluted Si 2p peaks of the AST12 sample showed an increase in SiO 2 bonds and a decrease in SiO 4 bonds, as well as the presence of Si‐O‐C bonds (Figure 3N). Formation of amorphous SiO 2 , SiC, and C (free carbon) are energetically favored at higher annealing temperatures (>1000°C), due to the carbothermal reaction occurs between TiO 2 and free carbon in amorphous SiOC, which results in the formation of TiC and increase in SiO 2 bonds 32 …”

“…Formation of amorphous SiO 2 , SiC, and C (free carbon) are energetically favored at higher annealing temperatures (>1000 • C), due to the carbothermal reaction occurs between TiO 2 and free carbon in amorphous SiOC, which results in the formation of TiC and increase in SiO 2 bonds. 32 The PST9 sample deconvoluted XPS spectrum of Ti 2p3/2 (Figure 3Q) exhibited three peaks corresponding to Ti 4+ /Ti-O, Ti 3+ /Ti-O, and Ti 2+ /Ti-O, respectively. These peaks prove that the Ti-O bonds are in different oxidation states (Ti 4+ / Ti 3+ / Ti 2+ ).…”

“…[27][28][29]30 Similarly, the addition of TiO 2 nanoparticles in SiOC preceramic polymer and pyrolysis at higher temperature (>1000 • C) results in the formation of conductive TiC phases, which improves the electrical conductivity of SiOC/TiO 2 composites, and the incorporation of TiO 2 nanoparticles in SiOC hybrid anodes causes exceptional rate capability and cyclic stability. [31][32][33] Recent studies have demonstrated that PDCs modified with transition metal oxide precursors improves electrical properties, dielectric properties, and photocatalytic response, but their potential as LIB anodes has not been explored. 22,23,34 Therefore, this work conducted an unprecedented investigation of the electrochemical performance of Ti modified SiOC, using titanium (IV) butoxide (TB) as metal oxide precursor to modify the polymethylhydrosiloxane (PMHS) precursor.…”

“…Furthermore, the introduction of carbon nanomaterials such as CNTs, graphene, and graphite in PDCs was shown to improve electrical and ionic conductivity, reduce first‐cycle loss, and decrease capacity fading during high cycles 27–29,30 . Similarly, the addition of TiO 2 nanoparticles in SiOC preceramic polymer and pyrolysis at higher temperature (>1000°C) results in the formation of conductive TiC phases, which improves the electrical conductivity of SiOC/TiO 2 composites, and the incorporation of TiO 2 nanoparticles in SiOC hybrid anodes causes exceptional rate capability and cyclic stability 31–33 …”

Joule-heating Pyrolysis-derived Fe, N Co-doped Carbon and Its Performance in Direct Peroxide-Peroxide Fuel Cells

“…The Jouleheating pyrolysis approach, i.e., directly powering the conductive precursor to enable the pyrolysis of precursor, can tackle this problem conveniently. [9][10][11] Lu et al discovered that with the application of an electric field, the samples experienced Joule heating that resulted in similar ceramic yield and linear shrinkage values at >500 °C lower pyrolysis temperatures. 10 Although no one has yet used the Joule heating method to prepare heteroatom-doped carbon materials, we can expect this method to reduce the hours required for conventional electric furnace pyrolysis to within minutes.…”