M. Heydari Nasab, R. Naghizadeh, H. Samadi, A. Nemati,
Volume 12, Issue 1 (3-2015)
Abstract
Ceramic-matrix composites containing TiC-TiN have been used in a variety of application because of their
superior properties such as high hardness, good wear resistance and high chemical stability. In this research, effect of
coke and coke/calcium beds in synthesis of Al
2O3-Ti(C, N) composites using alumino-carbothermic reduction of TiO
2
has been investigated. Al, TiO
2
and active carbon with additives of extra carbon and NaCl and without additives, in
separate procedures, have been mixed. Afterwards, mixtures were pressed and synthesized in 1200oC for 4hrs, in coke
and coke/calcium beds, separately. Al
2O3-Ti(C,N) composite was synthesized in ternary system of Al-TiO
2
-C with
excess carbon and NaCl additives in calcium/coke bed in 1200 . X-ray diffraction patterns (XRD) results showed that
existence of calcium in bed resulted in intensification of reduction atmosphere in samples and formation of Ti(C,N)
phase enriched from carbon was accelerated. Crystallite sizes of synthesis Ti(C,N) at 1200 °C in reducing conditions
were 22-28 nm.
Zahra Zalnezhad, Morteza Sasani Ghamsari, Hamid Haratizadeh,
Volume 21, Issue 0 (3-2024)
Abstract
Silicon carbide (SiC) is one of the most important silicon-based compounds, owing to its favorable physical, chemical, and biological properties, and is widely employed in various fields such as electronics, chemical industries, and quantum computing. Several methods have been reported for synthesizing SiC nanoparticles, including chemical vapor deposition (CVD), hydrothermal synthesis, carbothermal reduction, and sol–gel processing. Among these, the sol–gel method has attracted significant attention due to its high yield, process controllability, biocompatibility, accessibility of precursors, and ability to produce nanoparticles. In this study, SiC nanosized powders were synthesized through the sol–gel route combined with carbothermal reduction, using tetraethyl orthosilicate (C2H5)4SiO4) and sucrose (C11H22O11) as the silicon and carbon sources, respectively. The silica/sucrose composite was subjected to carbothermal reduction under an argon atmosphere at a pressure of 10 mTorr in a vacuum furnace at 1350°C for 3 h. The structural properties of the synthesized SiC nanopowders were analyzed using X-ray diffraction (XRD), while their optical characteristics were investigated through FTIR, diffuse reflectance spectroscopy (DRS), and photoluminescence (PL). This work demonstrates a greener, lower-temperature route to phase-controlled SiC nanoparticles with optically active vacancy centers.
