In this study, in order to increase surface ability of hardness and corrosion of magnesium alloy, anodizingand sealing with nano-diamond powder was conducted. A porous oxide layer on the magnesium alloy was successfullymade at 85℃ through anodizing. It was found to be significantly more difficult to make a porous oxide layer in themagnesium alloy compared to an aluminum alloy. The oxide layer made below 73℃ by anodizing had no porous layer.The electrolyte used in this study is DOW 17 solution. The surface morphology of the magnesium oxide layer wasinvestigated by a scanning electron microscope. The pores made by anodizing were sealed by water and aqueous nano-diamond powder respectively. The hardness and corrosion resistance of the magnesium alloy was increased by the anod-izing and sealing treatment with nano-diamond powder.

In this study, an aluminum oxide layer for sealing treatment of nano-diamond powder was synthesized byanodizing under constant current. The produced pore size and oxide thickness were investigated using scanning electronmicroscopy. The pore size increased as the treatment time increased, current density increased, sulfuric acid concentra-tion decreased, which is different from the results under constant voltage, due to a dissolution of the oxide layers. Theoxide layer thickness by the anodizing increased as temperature, time, and current density increased. The results of thisstudy can be applied to optimize the sealing treatment process of nano-diamond particles of 4-10 nm to enhance theresistances of corrosion and wear of the matrix.

High-purity and super-hard nano-polycrystalline diamond has been successfully synthesized by direct conversion from high-purity graphite under static pressures above 15 GPa and temperatures above . This paper describes research findings on the formation mechanism of nano-structure and on the contributing factor leading to high hardness.