Formation Of Ti2O3 Research Articles

Investigation of Oxygen Adsorption Property of Partially Reduced Tio2(Tio2-X)

The partial reduction of TiO2 was investigated by hydrogen plasma treatment and it was performed to examine the oxygen adsorption property of partially reduced TiO2 (TiO2-x). In this experiment, TiO2-x was analyzed by X-ray diffraction (XRD) and oxygen adsorption of partially reduced TiO2 was measured by gas chromatography (GC). Consequently, it was shown that hydrogen plasma treatment can partially reduce TiO2 by plasma effects and TiO2-x can adsorb oxygen. The H2O formation and the oxygen adsorption were found to be dependent on the heating temperature. The oxygen adsorption property was attributed to the formation of Ti2O3.

Kinetics and phase evolution during carbothermal synthesis of titanium carbide from ultrafine titania/carbon mixture

The kinetics and phase evolution of the TiC formation process by carbothermal reduction of ultrafine titania/carbon mixture were investigated using thermogravimetric analysis (TGA), X-ray diffraction (XRD) and oxygen analysis. Titania (TiO2) first lowered its oxidation state to Ti3O5 via an unidentified phase (possibly one of the Magneli phases). Then Ti3O5 was further reduced to Ti2O3, followed by the formation of titanium oxycarbide (TiCxOy) phase and its purification toward high purity TiC thereafter. Ti2O3 was the oxide phase with the lowest oxidation state before forming TiCxOy phase. In the isothermal TGA trace, the formation of Ti3O5 showed a diffusion-controlled process; possibly carbon diffusion limited the solid state reaction. The formation of Ti2O3 and TiCxOy was interpreted to be associated with CO gas-assisted reduction reaction, based on constant reaction rate for each process. The activation energy for the formation of Ti2O3 (from Ti3O5) and TiCxOy (from Ti2O3) phase were calculated to be 415.6 and 264.3 kJ mol-1, respectively. The TiC powder synthesized at 1550 °C for 4 h in flowing argon atmosphere showed fine particle size (0.3–0.6 μm) with oxygen content of 0.7 wt % and lattice parameter of 0.4328 nm while interparticle agglomeration was moderate. © 1998 Chapman & Hall.

Oxidation kinetics of pure titanium at low pressures

Oxidation of pure titanium was carried out at room temperature under different oxygen pressures (10-8-10-6 torr). The kinetics for each pressure was determined. Measured film thicknesses were larger for higher pressures. Deconvolution of XPS spectra showed than TiO was the major oxide present and TiO2 the minor component. Formation of Ti2O3 and Ti3O5 was also observed.

Preparation of titanium diboride from the borothermic reduction of TiO2, TiOx(OH)y, or Ti(O-n-Bu)4-derived polymers

The reaction between amorphous boron powder and TiO2, TiOx(OH)y or titanium-alkoxide derived polymers (B : Ti = 4 : 1) was studied at 25–1500°C in a flow of argon. The borothermic reduction of TiO2 resulted in formation of Ti2O3 and TiBO3 at 600°C; TiB2 was formed by further borothermic reduction of Ti2O3 and TiBO3 above 700°C; the overall reaction was found to be complete at 1300°C. The particle sizes of TiB2 powders obtained were directly related to the starting material used as the titania source. The largest particles were obtained when TiO2 powder was used as the starting material The particles were smaller when TiOx(OH)y powder was used, and the smallest particles were obtained when the partially-hydrolyzed Ti polymer, [BuOTiO1·5]n, was used as the titanium source. The pyrolysis chemistry of these precursors as well as the morphology of the pyrolysis products were studied by FT-IR, TGA, SEM, XRD, BET, elemental analyses and particle size analyses.

PH effect on the potentiodynamic behaviour of titanium electrodes

Potentiodynamic measurements on mechanically polished titanium electrodes were performed in different solutions in the pH range 0.55–12. Two anodic peaks and one small cathodic peak were observed. Comparison with thermodynamic data revealed the possibility of formation of Ti2O3 or TiO2 at potentials corresponding to the first anodic peak probably directly from titanium hydride. The second anodic peak is interpreted as the oxidation of incorporated H to form H+ ions which partly remain inside the metal. The small cathodic peak represents the back reduction of the incorporated H+ to the metal hydride.