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How does small powder particle size improve ceramic sintering?
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advanced structural ceramics
Figure 1: Resistance to cracking in transformation-toughened zirconia. In a ceramic composed of tetragonal zirconia dispersed in a zirconia matrix, the stress field advancing ahead of a propagating crack transforms the small tetragonal particles to larger monoclinic particles. The larger particles exert a crack-closing force in the process zone behind the crack tip, effectively resisting propagation of the crack.
In the field of advanced ceramics, small particle size is a critical factor for effective sintering. Using powders with small grain sizes—typically in the submicrometre range—improves the process in two primary ways:
- Increased Driving Force: Small particles possess a larger ratio of surface area to mass. Because the fundamental driving force in sintering is the reduction of total surface energy, these high-surface-area powders significantly accelerate the densification process.12
- Reduced Diffusion Distance: Sintering relies on the diffusion of material to form "neck" regions between adjacent particles. Smaller particles reduce the physical distances over which this material must migrate, allowing for more efficient bonding and the elimination of porosity.23
By utilizing these active, fine-grained powders, ceramists can achieve higher density and superior mechanical properties in the final product compared to traditional processing methods.23