Sintering temperature is the temperature at which a powder compact is held so that the necks between particles grow and the pore network closes. Densification and coarsening compete, and raising the temperature accelerates both, so the hottest treatment rarely gives the finest microstructure; in a field-assisted process the temperature also fixes phase composition and defect chemistry, and a nitrogen-containing ceramic can lose nitrogen as the temperature rises [1]. The usual way to lower the required temperature is to add a sintering aid that forms a transient liquid, the liquid providing a fast transport path while most of the solid stays undissolved [2]; activated and plasma-assisted routes push densification to lower temperatures by the same logic combined with an enhanced driving force [3]. Under the pressure applied in field-assisted sintering, part of the densification occurs by creep rather than by diffusion alone, so the mechanism depends on stress and temperature together [4]. The practical window is bounded from below by incomplete densification and from above by exaggerated grain growth, loss of a volatile constituent and reaction with the die, and hardness and thermal conductivity track the density reached within that window [5].
- densification
- grain boundary diffusion
- liquid phase sintering
- sintering aid
- microstructure
- porosity
Advanced ceramic materials synthesis·Ceramics and Composites·Materials Science·Physical Sciences
References
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