Effect of Milling Speed and Time on Ultrafine ZnO Powder by High Energy Ball Milling Technique

Abstract

The particle size of commercial zinc oxide (ZnO) powder has been found in micron scale. For the improvement of ZnO properties, size reduction in nanoscale is required. In this work, the particle size of ultrafine ZnO powder was reduced by high energy ball milling technique. commercial grade ZnO powder with average size 0.8 μm was used as starting material. Milling speed and time of high energy milling process are considered as crucial parameters affecting size reduction of ZnO particles. Crystalline structure, surface morphological and particle size of the milled samples were investigated by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and particle analyzer, respectively. The results suggested that ZnO patterns after milling process with various milling speed and time were identically in hexagonal crystalline phase affirmed by XRD result. SEM images indicate that size of ZnO products distinctly decrease according to the increase of milling time and speed. ZnO particle size after milling process was found in ultrafine power in range of 200-400 nm. These results suggest that particle size of the commercial ZnO powders can be effectively minimized to few hundred nanometer range depending on force attraction and suitable rotation during milling process with specific speed and time. Moreover, the significant milling parameters will be studied to find the optimum condition for the production of ZnO particles in nanoscale.