Synthesis and Characterization of Nanosized Titanium Carbide by Carbothermal Reduction of Precursor Gels
AbstractInvestigations have been made on obtaining of nanosized powders of titanium carbide (TiC) by carbothermal reduction of a precursor prepared by sol-gel process. Two methods of precursor gels fabrication of TiC were used: Ti (IV) chloride, ethyleneglycol and citric acid (series A) and Ti (IV) n-propoxide, saccharose and acetic acid (series B). The resulting xerogels are calcined under flowing argon at different temperatures ranging from 800°C to 1400°C with holding time from 0.5 h to 10 h. TiC nanopowders were obtained with the specific surface area of 30 m2/g–200 m2/g and the size of TiC crystallites of 40 nm–45 nm. Only the TiC phase has been found by the XRD analysis, but the presence of also some oxygen and free carbon depending on synthesis conditions has been found by chemical analysis. For compacting investigations with spark plasma sintering (SPS) method (1800°C, heating rate of 100°C /min and dwelling time of 5 min.) TiC nanopowder (SSA of 88 m2/g, containing 72.7 wt.% Ti, 6.6 wt.% O, 20.5 wt.% Ctotal and 7.2 wt.% Cfree)was used. The sintering begins at 1150°C, but change of density ends at 1650°C. The density at this temperature reaches only 89 % of the theoretical and does not rise until 1800°C. This is probably due to the presence of free carbon in investigated sample, retarding sintering. A significant decrease of admixtures has been observed in ceramic material during sintering.
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