Titanium Hydroxide — a Volatile Species at High Temperature

Titanium hydroxide, TiO(OH)₂ (g), has been identified as the primary reaction product of TiO₂    (s) + H₂O (g) at high temperatures (1,200–1,400 °C) through the use of the transpiration technique. This technique is a well-established method used to measure equilibrium pressures at 1 atm. Reactive O₂ /H₂O mixtures of gases flow over the sample, and react to form volatile Ti hydroxides. The collected reaction gas condensate is analyzed to determine the vapor and dissociation pressures. From the amount of condensate and its relation to the partial pressures of the reactive gases, the identity of the volatile hydroxide can be determined. From the relation of product pressure to temperature, thermodynamic enthalpy and entropy of formation can be calculated.

The reaction of the identified titanium hydroxide is useful to understanding the volatility of titanium-containing materials for high-temperature conditions that contain water vapor (i.e., combustion from hydrocarbon fuels, etc.). The identity of this molecule and thermodynamic data on this molecule contribute to the high-temperature materials database that would directly impact future selection of refractory oxide materials for use in combustion environments. This will also aid in furthering the understanding of oxide stability with high-temperature water vapor.

This work was done by QuynhGiao N. Nguyen of Glenn Research Center. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Materials category.

Inquiries concerning rights for the commercial use of this invention should be addressed to NASA Glenn Research Center, Innovative Partnerships Office, Attn: Steve Fedor, Mail Stop 4–8, 21000 Brookpark Road, Cleveland, Ohio 44135. Refer to LEW-18482-1

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