This study investigated the effects of milling speed on the structure evolution of spray-dried (SD) Fe2O3 agglomerate as a precursor for fabricating Fe nanopowder agglomerate. For fabrication, the milling speed was controlled at four different rotation speeds of 1000, 1400, 1800 and 2400 rpm (revolution per minute) for 10 hrs. For quantitative analysis, a microstructural observation was conducted. The particle size first decreased rapidly until it finally reached a saturation value of about 60 nm as the milling rpm increased to 1800 rpm. Moreover, it was found that excessive milling energy was consumed to form secondary agglomerates in spherical agglomerate at milling condition of 2400 rpm. The evolution of powder characteristics is also discussed in terms of the crystallite size and surface area and then compared to the particle size distribution analyzed by the microstructure.

Keywords: Fe2O3 nanopowder, Spherical agglomerate, Bead milling, Particle size distribution, Crystallite size.