Influence of Particle Arrangement on Sintering.
Abstract
The change in free energy of identical cylinders arranged in rings to enclose one pore shows that the pore can either shrink to an equilibrium size or disappear depending on the number of cylinders coordinating the pore and the grain boundary energy to surface energy ratio as expressed by the dihedral angle. The same result is obtained for symmetric, closed arrays of spheres (rings and polyhedral). The shrinkage and strain rates of these closed arrays depends on both the dihedral angle and pore's coordination number; viz, arrays with a lower coordination number. When arrays with different coordination numbers are packed together, the differential shrinkage strain and strain rate between the arrays. The movement of particles during initial mass transport, commonly termed rearrangement, is due in part to differential strains and strain rates between particle clusters. Longer range (transparticle) mass transport gives rise to grain growth within an array. Grain growth in a powder compact is driven by the difference in external surface curvature between particles within the different arrays. Grain growth will lower a pore's coordination number and thus will overcome the thermodynamic barrier to pore closure. Additional keywords: Particle arrays; Densification.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1985
- Accession Number
- ADA155337
Entities
People
- B. J. Kellett
- F. F. Lange