TITLE:
Green Microstructural Visualization of Dry-Pressed Spray-Dried Alumina (Al2O3)
AUTHORS:
Ian P. Maher, Richard A. Haber
KEYWORDS:
Spray-Dried Alumina, Uniaxial Dry-Pressing, SEM, Green Microstructural Imaging
JOURNAL NAME:
Materials Sciences and Applications,
Vol.9 No.12,
November
15,
2018
ABSTRACT: Slurry
parameters were controlled prior to spray-drying to visualize and govern an
understanding of which parameters govern hollow coring and granule morphology
during spray-drying. An aqueous alumina using a polyvinyl alcohol binder (PVA) system was analyzed and granules were processed
by altering the slurry specific gravity and viscosity value prior to
spray-drying. Spray-dried granules were uniaxial dry-pressed at varying
moisture contents to show the plasticizing effects of moisture during
compaction. A novel characterization method using a field emission electron
microscope (FESEM) was implemented to image the green microstructures of the
granules and compacted samples. Slurries with a higher specific gravity and
viscosity resulted in denser granules with spherical shapes. Viscosity affected
the binder segregation during the spray-drying process. Granules stored at
higher moisture contents resulted in denser compacts with fewer intergranular
pores and cracks along granule boundaries. Using a FESEM resulted in higher
resolution for green microstructural characterization.