Cold compression of ceramic spray-dried granules: Role of the spatial distribution of the binder

We report an experimental study of the compaction behaviour of zirconia granules formed by a spray drying process. Using two different binders that were fully characterized, we have investigated the influence of the binder spatial distribution in the granules on compaction of a granule packing. Spatial distributions were modified by tuning binder adsorption on the ceramic nanoparticles in the spray dried suspensions. Granule powders with binder either located between nanoparticles only, or partly concentrated within a segregated layer at the surfaces of granules were thus obtained. We have found the role of the segregated layer is fully negligible during granule compression, and we justify that result by providing estimates of the theoretical compression energies of segregated layers and polymer bridges. We discuss the role of the binder bridges between nano-particles, and we suggest a picture accounting for the experimental influence of binder mechanical properties and concentration on the compaction behaviour of spray-dried granules.