High-temperature mass spectrometric study of the vaporization processes and thermodynamic properties in the Gd2O3-Y2O3-HfO2system
| Autor: | Fedor N. Karachevtsev, Sergey I. Lopatin, Valentina L. Stolyarova, Viktor A. Vorozhtcov, Eugene N. Kablov, Yuriy I. Folomeikin |
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| Rok vydání: | 2017 |
| Předmět: |
Organic Chemistry
Analytical chemistry chemistry.chemical_element 02 engineering and technology Partial pressure Entropy of vaporization Tungsten 010402 general chemistry 021001 nanoscience & nanotechnology Mass spectrometry 01 natural sciences 0104 chemical sciences Analytical Chemistry Gibbs free energy Thermal barrier coating symbols.namesake chemistry Vaporization symbols 0210 nano-technology Spectroscopy Electron ionization |
| Zdroj: | Rapid Communications in Mass Spectrometry. 31:1137-1146 |
| ISSN: | 0951-4198 |
| Popis: | RATIONALE The refractory properties of the Gd2O3-Y2O3-HfO2 system are considered promising for the production of many high-temperature materials, e.g., thermal barrier coatings and casting molds for gas turbine engine blades. At high temperatures, components of the Gd2O3-Y2O3-HfO2 system may vaporize selectively and this may significantly change the physicochemical properties of the materials. Therefore, information on vaporization processes and thermodynamic properties of the Gd2O3-Y2O3-HfO2 system is of great importance. METHODS The vaporization processes and thermodynamic properties of the Gd2O3-Y2O3-HfO2 system were studied using high-temperature Knudsen effusion mass spectrometry with a MS-1301 mass spectrometer. Vaporization was carried out using a tungsten twin effusion cell containing the samples under study and pure Gd2O3 as a reference substance. Electron ionization at an energy of 25 eV was employed in the present study. RESULTS It was shown that at a temperature of 2500 K the vapor over the samples in the Gd2O3-Y2O3-HfO2 system consisted of the GdO, YO and O vapor species. The Gd2O3 and Y2O3 activities in the samples in the Gd2O3-Y2O3-HfO2 system as well as their vaporization rates were derived from the partial pressures of the vapor species. Using these data the HfO2 activities, the Gibbs energy of mixing and the excess Gibbs energy in this system were calculated at 2500 K. CONCLUSIONS The thermodynamic properties of the Gd2O3-Y2O3-HfO2 system, i.e., the components activities in the samples and the excess Gibbs energy, obtained in the present study at 2500 K, exhibited negative deviations from ideal behavior. The concentration dependence of excess Gibbs energy of the Gd2O3-Y2O3-HfO2 system was approximated with an empirical equation. |
| Databáze: | OpenAIRE |
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