AZ91D压铸镁合金微弧氧化的工艺研究

Study of the Technics of Micro-arc Oxidation for AZ91D Die-casting Magnesium Alloys

为了探索AZ91D压铸镁合金微弧氧化的工艺,研究了两种电解液体系中,恒电流时膜层生长动力学规律。分析了恒定电流密度值的大小、电源脉冲频率以及在溶液中添加NaF对膜层生长速率、表面粗糙度的影响。结果表明:电流密度越大,AZ91D压铸镁合金微弧氧化膜层的生长速率越快,同时膜层表面粗糙度也会相应增大;频率越高膜层表面粗糙度越小,但频率的变化几乎对膜层的生长速率不产生影响;在溶液中添加NaF,可以明显地提高膜层的生长速率并降低膜层的表面粗糙度。

The dynamics laws of the film growth under constant current mode in two kinds of electrolytes were studied to explore the technics of micro-arc oxidation （MAO） for AZ91D die- casting magnesium alloys. The effects of constant current density value, impulse frequency of power as well as the addition of NaF in electrolytes on growth speed and surface roughness of the films were researched. The results indicate that the growth speed of MAO film increases with rising of current density, and the surface roughness of the films increased at the same time. Moreover, the surface roughness of the films decreased with the rising of impulse frequency, but the impulse frequency nearly has no influence on the growth speed of MAO film. The addition of NaF in the electrolytes can not only increase the growth speed of MAO film but also decrease the surface roughness of MAO film.