Thermodynamics and kinetics of sintering of Y <sub>2</sub> O <sub>3</sub>
Kimiko Nakajima, Ricardo H. R. Castro
Abstract
Abstract Surface energy ( γ S ) and grain boundary energy ( γ GB ) of yttrium oxide (Y 2 O 3 ) were determined by analyzing the heat of sintering (Δ H sintering ) using differential scanning calorimetry (DSC). The data allowed quantification of sintering driving forces, which when combined with a thorough kinetic analysis of the process, provide better understanding of Y 2 O 3 densification as well as insights into effective strategies to improve its sinterability. The quantitative thermodynamic study revealed moderate thermodynamic driving force for densification in Y 2 O 3 (as compared to other oxides) represented by a dihedral angle of 152.7° calculated from its surface and grain boundary energies. The activation energy was determined as 307 ± 61 kJ/mol, consistent with activation energies previously reported for processes relevant to sintering of Y 2 O 3, such as Y 3+ diffusion and grain boundary mobility. Finally, we propose that a refined deconvolution study on the DSC curve for Y 2 O 3 sintering, combined with the associated material's microstructure evolution, may help identify shifts in sintering mechanisms, and therefore, specific activation energies at increasing temperatures.