Sintering behaviors of micron-sized ceramic rod features

Abstract

When ceramic features decrease to much smaller sizes, such as in the micron range, the dominating sintering mechanism(s) can be different from those of the bulk at large scales. In this work, the sintering behaviors of ZnO rod features of ∼4 μm diameter are studied. The rods and the bulk of the ZnO ceramics have different behaviors in shrinkage, grain growth, and densification. Sintering mechanisms are mainly grain boundary diffusion controlled densification and pore gas diffusion controlled grain growth, but with the major difference associated with a factor Ng/Nb (Ng, average pore number per grain; Nb, average pore number per grain boundary) based on the theoretical modeling and Voronoi diagram simulation. The smaller Ng/Nb for the micron-sized features leads to enhanced grain growth, and the higher exposed surface area leads to larger shrinkage; both can be explained using nominal Dgs/Dgb. Nanoparticle agglomeration can potentially affect grain growth in the rods during sintering and should be further studied.