Spatial Variations in the Sintering Rate of Ordered and Disordered Particle Structures

Local sintering rates were measured in two-dimensional, ordered and disordered structures constructed from glass spheres. In ordered arrays, made from monosized spheres, the local sintering rates varied from 1/2 to 2 times the average sintering rate. In contrast, disordered arrays, made from bimodal particle sizes, sintered more homogeneously, the local sintering rate deviating less than 15% from the average. The total average densification strain was also greater for the disordered structures. As a result, for the same time and temperature cycle, the disordered structures sintered to near full density while the ordered structures did not. Poor densification in the ordered structure was attributed to packing defects such as domain walls and dislocations. Some evidence was obtained for a correlation between densification and the average coordination number of particles.