In order to clarify the effect of C/Ti atom ratios(χ) on the deformation behavior of TiCχ at high temperature, singlecrystals having a wide range of χ, from 0.56 to 0.96, were deformed by compression test in a temperature range of 1183~2273Kand in a strain rate range of 1.9×10−4~5.9×10−3s−1. Before testing, TiCχ single crystals were grown by the FZ method ina He atmosphere of 0.3MPa. The concentrations of combined carbon were determined by chemical analysis and the latticeparameters by the X-ray powder diffraction technique. It was found that the high temperature deformation behavior observedis the χ-less dependent type, including the work softening phenomenon, the critical resolved shear stress, the transitiontemperature where the deformation mechanism changes, the stress exponent of strain rate and activation energy for deformation.The shape of stress-strain curves of TiC0.96, TiC0.85 and TiC0.56 is seen to be less dependent on χ, the work hardening rate afterthe softening is slightly higher in TiC0.96 than in TiC0.85 and TiC0.56. As χ decreases the work softening becomes less evidentand the transition temperature where the work softening disappears, shifts to a lower temperature. The τc decreasesmonotonously with decreasing χ in a range of χ from 0.86 to 0.96. The transition temperature where the deformationmechanism changes shifts to a lower temperature as χ decreases. The activation energy for deformation in the low temperatureregion also decreased monotonously as χ decreased. The deformation in this temperature region is thought to be governed bythe Peierls mechanism.
TiC-TiB2-SiC system was a ternary eutectic, whose eutectic composition was 34TiC-22TiB2-44SiC (mol%). TiC-TiB2-SiC ternary eutectic composite were synthesized by a floating zone method using TiC, TiB2 and SiC powders as starting materials. The TiC-TiB2-SiC eutectic composite showed a lamellar texture. TiC(022), TiB2(010) and SiC(111) of the eutectic composite were perpendicular to the growth direction. TiC-TiB2-SiC ternary eutectic composite had specific relationship among the crystal planes: TiC[011]//TiB2[010]//SiC[112], TiC(200)//TiB2(001)//SiC( 402 ) and TiC( 111 )//TiB2(101 )//SiC( 220 ).
Zeolite (FZ) prepared using coal fly ash from an Ulsan industrial complex was immobilized with polysulfone (PS) to fabricate PS-FZ beads. The prepared PS-FZ beads were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The optimum ratio for preparing PS-FZ beads was 1 g of PS to 2 g of FZ. The removal efficiencies of Sr and Cu ions by the PS-FZ beads increased as the solution pH increased and nearly reached a plateau at pH 4. A pseudo-second-order model morel fit the adsorption kinetics of both ions by the PS-FZ beads better than a pseudo-first-order model. The Langmuir isotherm model fit the equilibrium data well. The maximum adsorption capacities calculated from the Langmuir isotherm model were 46.73 mg/g and 62.54 mg/g for the Sr and Cu ions, respectively. Additionally, the values of thermodynamic parameters such as free energy (ΔG˚), enthalpy (ΔH˚) and entropy (ΔS˚) were determined. The results implied that the prepared PS-FZ beads could be interesting an alternative material for Sr and Cu ion removal.
Zeolite (FZ), prepared from fly ash, was immobilized with polyacrylonitrile (PAN) to fabricate PAN/FZ beads. The prepared PAN/FZ beads were characterized by scanning electron microscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The optimum ratio to prepare PAN/FZ beads was 0.3 g of PAN to 0.3 g of FZ. The diameter of the prepared PAN/FZ beads was about 3 mm. Sr and Cu ion adsorption experiments were conducted with PAN/FZ beads. A pseudo-second-order model fit the kinetic data for Sr and Cu ion adsorption by PAN/FZ beads well. The equilibrium data fitted well with the Langmuir isotherm model, and the maximum adsorption capacities were 96.5 mg/g and 74.6 mg/g for the Sr and Cu ions, respectively. Additionally, the values of thermodynamic parameters such as Gibbs free energy (ΔGo), enthalpy (ΔHo) and entropy (ΔSo) were determined. The positive values of ΔHo revealed the endothermic nature of the adsorption process and the negative values of ΔGo were indicative of the spontaneity of the adsorption process.