7A09铝合金电池框架零件阳极氧化膜表面黑斑成因分析

Cause Analysis of Black Spots on the Anodic Oxidation Film on 7A09 Aluminum Alloy Battery Frame Parts

7A09铝合金电池框架零件经铬酸阳极氧化处理后,得到的阳极氧化膜表面出现黑斑现象。通过宏观形貌观察、化学分析、金相分析、扫描电子显微镜分析、X射线能谱分析等手段,讨论了黑斑的成因。结果表明:零件所用原材料芯部存在第二相金属间化合物带状偏析分布,第二相颗粒在阳极氧化过程中脱落在零件表面形成凹坑,从而形成黑斑。针对该零件失效提出了建议。

The black spots appeared on the surface of anodic oxidation film on 7 A09 aluminum alloy battery frame parts after chromic acid anodic oxidation. The causes of black spots were investigated via macroscopic morphology observation, chemical analysis, metallographic analysis, scanning electron microscope analysis and X-ray spectrum analysis. The results showed that the formation of black spots was attributed to the segregation of intermetallic compound in the center of the aluminum alloy bar, the second phase particles fall off during the anodization and form pits on the surface of the parts. According to the experiment results, measures have been suggested to prevent such failure.