铝硅合金阳极氧化表面黑斑缺陷形成机制研究

Formation mechanism of black spot defects on surface of Al-Si alloy during anodic oxidation

研究铝硅合金阳极氧化表面黑斑缺陷的形成机制,可以为铝硅合金阳极氧化工艺的调控提供一定的理论和实践依据。文章采用扫描电子显微镜、光学显微镜、能谱分析和X射线衍射等测试技术,分析了铝硅合金工件阳极氧化过程中出现的黑斑缺陷。结果表明:与正常区域组织相比,铝硅合金工件黑斑缺陷区域的组织形貌、相分布和体积分数发生了明显的变化;正常区域组织中的针片状化合物和缺陷区域组织中鱼骨状化合物主要相成分为二元铁铝化合物,黑斑缺陷区域的富铁相发生共晶转变会使其形态复杂化;而由相转变产生的黑斑缺陷与阳极氧化过程中的电化学工艺有关。

Investigating the formation mechanism of black spot defects on the surface of anodized Al-Si alloy can provide a theoretical foundation and insights for the regulation of anodic oxidation process of Al-Si alloy.Utilizing scanning electronic microscopy,optical microscopy,energy disperse spectroscopy and x-ray diffraction,this study analyzes the black spot defects that occur during the anodizing process of Al-Si alloy workpieces.The results reveal that compared to the normal region,the microstructure morphology,phase distribution and volume fraction of the black spot defect area of Al-Si alloy workpieces change obviously.The needle-like compounds in the normal area and the fishbone compounds in the defect primarily consist of binary Fe-Al compounds.The eutectic transformation of the Fe-rich phase in the black spot defect area contributes to its complex morphology.It is evident that the black spot defect,generated by phase transition,is linked to the electrochemical processes during the anodic oxidation.