| Ceria-yttria co-doped zirconia-based multi-components ceramics, with superfine alumina dispersed in the matrix, possess excellent fracture toughness, strength and thermal stability. However, the mechanical properties and microstructure are strongly dependent on the composition and the fabrication procedure, especially the composition of zirconia containing multi-component ceramics. Therefore, precise phase diagrams of zirconia-based multi-components systems can be considered as the "map" for the development of advanced ceramics. Due to the experimental difficulties, the phase diagrams and thermodynamic data of zirconia systems are very limited and dispersive. Further more, the constitutes of phases and mechanical properties of ZrO2-CeO2 system change drastically when it is under the reduced atmosphere and elevated temperatures. The thermodynamic properties of ZrO2-CeO2-Ce2O3 system is very important to obtain the quantitative relation among oxygen pressure, temperature, composition, phase constituents and mechanical properties. In this paper, with the calculation technique CALPHAD, phase diagrams of ZrO2-CeO2-Y2O3, ZrO2-CeO2-Al2O3, ZrO2-CeO2-Ce2O3 systems are optimized and extraploated by Thermo-Calc and Lukas Programme with suitable thermodynamic models and experimental data. Meanwhile, the thermodynamic properties of ZrO2-CeO2 system under reducing atmosphere is also assessed with substitutional and compound energy model. Based on the calaculated phase diagrams, different compositions of CeO2-Y2O3-ZrO2/Al2O3 are selected and ceramics with commercial meaning are fabricated with the powder coated method.First, comprehensive descriptions of experimental information and thermodynamic properties in the binary systems, ZrO2-CeO2, ZrO2-Y2O3, and CeO2-Y2O3 are given and thermodynamic models of these systems are discussed. The calculated phase diagrams of binary systems are consistent with the experimental data. With the substitutional model (ZrO2,CeO2,YO1.5), the thermodynamic databese of ZrO2-CeO2-Y2O3 is constructed, and with muggianu's formula, the isothermal sections are extraploated under different temperatures. The experimental section at 2073K is well reproduced bythe thermodynamic calcualtion. From the calcuated phase diagrams, 12 mol% CeO2-ZrO2 is in the tetragonal phase range, 3mol%Y2O3-Zr02 is with 11 mol% cubic phase, 12mol%CeO2-3mol%Y2O3-ZrO2 has 30.9mol% cubic phase, which is totally different from the tradional idea that considers it as a full tetragonal phase. The calculated result provides the theoretic basis for the weak fracture toughness of this composition.Using compound energy model and substitutional model, the thermodynamic properties of in CeO2-Ce2O3 and in Zr02-CeO2-Ce2O3 system are evaluated. The evaluation is based on the optimization of ZrO2-CeO2 and ZrO2-CeO1.5 systems, as well as the miscibility gap in CeO1.5-CeO2 system. The model parameters are evaluated through fitting the selected experimental data by means of thermodynamic optimization. A set of parameters with thermodynamics self-consistency is obtained that satisfactorily described the complex relation between y in and the partial pressure of oxygen at different temperatures, also the interdependence among miscellaneous factors such as temperature, oxygen partial pressure, the reduction amount of CeO2 as well as the nonstoichiometry in cubic phase The calculated results seem to be reasonable when put into the explanation of pressure-less sintering of CeO2-stabilised ZrO2 powder compacts under a controlled oxygen partial pressure.ZrO2-CeO2-Al2O3 system has been assessed with CALPHAD technique using PARROT procedure. The experimental information on the ZrO2-Al2O3, Al2O3-CeO2 systems as well as the isothermal sections of the ternary system at 1673K and 1873K are well reproduced. No alumina dissolves into the tetragonal zirconia phase from the calculated phase diagram.Different compositions are selected from the calculated isothermal section at 1723K of ZrO2-CeO2-Y203 system. With...
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