Effect of forming pressure on densification behavior of nanocrystalline ITO powder

Since ultrafine nano-particles easily produce agglomerates, they result in an inhomogeneous particle packing structure within a green body. Nanocrystalline indium tin oxide (ITO) powder was prepared, and the compaction behavior of the powder was investigated by using an Hg porosimetry and a scanning electron microscope (SEM) as a function of the applied cold isostatic pressing (CIP) pressure. In addition, the sintering behavior of the compact was monitored with a thermo-mechanical analyzer (TMA), and the relationship between the inhomogeneity in the green body and the sintering behavior was examined. An increase in the forming pressure enhanced the homogeneity of the powder compact by crushing the larger agglomerates. The first generation agglomerate compact showed a two-step densification process in the shrinkage rate curve of TMA. The two-step densification behavior is explained by the elimination of two kinds of pores, which are small inter-crystallite pores and large inter-first generation agglomerate pores.