Synthesis of ultra-high temperature silicon oxycarbide (SiOC) glass by an organic-inorganic hybrid route
Biplab Kumar Paul (1), Karthiga Parthiban (2), Saheli Bhattacharya (1) and Dipayan Sanyal (1, *)
(1) Non-Oxide Ceramics and Composite Division, CSIR-Central Glass and Ceramic Research Institute 196, Raja S.C.Mullick Road, Kolkata-700032.
(2) Department of Ceramic Technology, Alagappa College of Technology, Sardar Patel Road, Anna University, Guindy, Cennai-600025.
Carbon - Science and Technology 10/4 (2018) 67 - 75.
© Applied Science Innovations Private Limited, India.
Full Text (OPEN ACCESS): CST-319.pdf
Keywords: Photocatalysis, TiO2, water purification, water pollution, grand challenges.
Abstract: Silicon oxycarbide is a new generation amorphous glassy ceramic possessing unique
electrical, mechanical, optical properties and ultra-high temperature stability upto 2730°C. It has
numerous engineering applications in additive manufacturing, lithium-ion batteries, brake disks
for sports car, ultra-fast and high voltage LEDs, MOSFETs, thyristors for high power switching,
astronomical telescope, nuclear power reactor etc. In this work, SiOC was prepared by sol-gel
technique using organic-inorganic hybrids as precursors. Tetraethoxysilane (TEOS) and
Polydimethylsiloxane (PDMS) were used as silica and carbon sources respectively. SiOC sols
were formed through hydrolysis of TEOS and PDMS. The used chemicals in this process
involved isopropanol, distilled water and hydrochloric acid, which is used here as solvent,
hydrolytic agent and catalyst respectively, at different refluxing condition, alkoxide to water
ratios, pH levels etc. The sols thus formed were allowed to gel over a varying period (upto
maximum of 10 days). After drying the gels for 24 hours, the same was pyrolysed at 1100°C
under inert nitrogen atmosphere to yield SiOC. Phase formation was carried out by X-Ray
Diffraction (XRD) technique, X-ray Photoelectron Spectroscopy (XPS) analysis and Raman
Spectroscopic analysis. XRD data showed formation of a broad peak at 2θ~22 degrees
indicating formation of amorphous SiOC and absence of any crystalline peaks indicating no SiC
or Si was formed during pyrolysis. XPS data shows the presence of Si, O and C peaks in the
range 100-200 eV, 530 eV and 285 eV, respectively, confirming formation of SiOC. It was
revealed that within the random network of Si-O tetrahedra, islands of only C-C bonds were
responsible for coloring the SiOC glass black. The estimation of mechanical properties revealed
that the hardness value and Young’s modulus, of the synthesized SiOC ceramic sample, was
determined to be 11.67 GPa and 75.79 respectively which indicating the better mechanical
properties than other reported SiOC systems.
