Abstract:The arcing process of micro-arc oxidation (MAO) on 1015 alloys aluminum (Al) using pulse power source in aqueous solutions with different Na₂SiO₃ concentrations was studied. The morphologies and surface resistance of initial films at arcing moment were analyzed and observed using scanning electron microscope (SEM) and electrochemical test, respectively. The effect of Na₂SiO₃ concentration on energy consumption of arcing process during MAO was calculated based on change curve of voltage. The results indicate that there is no arcing phenomenon but electrolytic etching on Al samples when the Na₂SiO₃ concentration is 0 and voltage is 1 500 V. With Na₂SiO₃ solution concentration increasing from 0.25 g/L to 10 g/L, arcing voltage dropping from 1 217 V to 351 V, arcing time reducing from 270 s to 40 s , the quantity of microspores on surface of initial films increases during arcing process of MAO. The high resistance film with resistance up to 10⁵ order of magnitude formed on the surface of Al samples is the premise of arcing phenomenon emerging in MAO process, and higher Na₂SiO₃ solution concentration is beneficial to forming high resistance film. The energy consumption of arcing process is diminished with Na₂SiO₃ solution concentration increasing, and minimum value is 16 kJ/dm² when Na₂SiO₃ concentration is 10 g/L.

Key words: aluminum alloys; micro-arc oxidation; sodium silicate; arcing process; energy consumption