| dc.description.abstract | The purpose of this study is analyzing the thermal-formed oxide on aluminum and magnesium alloys. Four materials, pure aluminum (99.999 wt.%), aluminum ingot (99.82 wt.%), pure magnesium (99.956 wt.%), and magnesium alloy AZ80 were used in this study. The cube samples were prepared in 10 mm × 10 mm × 6 mm. They were then polished by ＃400, ＃800, ＃1200, ＃1500 and ＃2000 abrasive paper. These cube samples were moved to the muffle furnace and then heated to 610℃, 427℃ and hold on for 1 hr, 25hrs.
There are pore/micro-pore structures in the oxide film from the result of experimental. The pores are caused from the particle in the matrix. They are saw in aluminum samples using optical microscope. And the micro-pores of aluminum are caused from the transformation of amorphous oxide film to non-amorphous oxide film, the white dots characters formed at the same time. There are only micro-pores in the magnesium alloys samples. Because the high vapor pressure of magnesium, magnesium diffusion to pore to form oxide and pores become micro-pore.
There are protective layer MgF2 and a little MgS if we use protective gas SF6 during producing pure magnesium oxide film. This layer is the cause of reducing magnesium alloys burring tendency in melting and casting. | en_US |