Nano-sized Zinc selenide (ZnSe) powder was successfully synthesized using Zn and Se precursors in a hydrothermal process. Temperature for the synthesis was varied from 95 oC to 180 oC to evaluate its influence on the microstructural properties of the synthetic particles. ZnSe powder thus fabricated was characterized using various analytical tools such as SEM, XRD, TEM and UV-Vis methods. Two types of ZnSe particles, that is, the precipitated particle and the colloidal particles, were identified in the analysis. The precipitated particles were around 100 nm in average size, whereas the average size of the colloidal particles was around 20 nm. The precipitated particles made at 150 oC and 180 oC were found to be a single phase of ZnSe; however, an inhomogeneous phase was obtained at the lower synthesis temperature of 95 oC, suggesting that the temperature for the synthesis should be over 100 oC. The precipitated particles were inactive in the UV-Vis absorption investigation, whereas the colloidal particles showed that absorptions occurred at 380 nm in the UV-Vis spectrum.

Cobalt coated tungsten carbide-cobalt composite powder has been prepared through wet chemical reductionmethod. The cobalt sulfate solution was converted to the cobalt chloride then the cobalt hydroxide. The tungsten carbidepowders were added in to the cobalt hydroxide, the cobalt hydroxide was reduced and coated over tungsten carbidepowder using hypo-phosphorous acid. Both the cobalt and the tungsten carbide phase peaks were evident in the tungstencarbide-cobalt composite powder by X-ray diffraction. The average particle size measured via scanning electron micro-scope, particle size analysis was around 380 nm and the thickness of coated cobalt was determined to be 30~40 nm bytransmission electron microscopy.

Nano-sized cobalt powder was fabricated by wet chemical reduction method at room temperature. The effects of various experimental variables on the overall properties of fabricated nano-sized cobalt powders have been investigated in detail, and amount of NaOH and reducing agent and dropping speed of reducing agent have been prop- erly selected as experimental variables in the present research. Minitab program which could find optimized conditions was adopted as a statistic analysis. 3D Scatter-Plot and DOE (Design of Experiments) conditions for synthesis of nano- sized cobalt powder were well developed using Box-Behnken DOE method. Based on the results of the DOE process, reproducibility test were performed for nano-sized cobalt powder. Spherical nano-sized cobalt powders with an average size of 70-100 nm were successfully developed and crystalline peaks for the HCP and FCC structure were observed without second phase such as Co(OH).