Electrical discharge erosion is widely applied in the fabrication process of the metallic particles in liquids. The Ultrasonic aided electrical discharge erosion is based on the spark discharge in pure water. The synthesized colloids were classified in accordance with the nano size and micron size. The higher magnifications of morphology, chemical compositions, the crystal structure of the multi-scale particles were observed and analyzed by SEM, TEM, EDS, and XRD. It is verified that ultrasonic wave influenced the morphology of micro/nanoparticles and the roughness of inner and external surfaces of hollow micro-particles. Besides, based on results of EDS, XRD, and Quantitative phase analysis, it is confirmed that nickel oxide was detected only on the surface of microparticles but the nickel oxide was easily obtained when nanoparticles were formed. In addition, ultrasound wave affected the oxidation reaction in both scales but the reaction was remarkably enhanced on nanoparticles. The DLS and LPSA were used to measure the size distributions for the nano and micron scale, respectively. The D-Values of both conditions shown that the ultrasound has an enhanced effect on decreasing the size distribution in both scales.
