材料期刊网

阐述小孔腐蚀在铝电解电容器用铝箔质量评价中的应用机理。首先简要介绍电容器铝箔立方织构的形成过程和特征,及小孔腐蚀的一般电化学特点；然后模拟计算多晶体铝箔材料各晶面弹性模量、各晶面原子密度和各晶向原子密度；最后用HCl、HNO3、HF组成的特定侵蚀剂对电容器铝箔实施小孔腐蚀,用扫描电子显微镜( SEM)和光学显微镜( OM)对小孔腐蚀后的铝箔表面形貌与横截面形貌进行观察分析。电容器铝箔侵蚀后表面呈现大量正方形蚀孔,电容器铝箔发生小孔腐蚀具有方向性,蚀孔隧道总是沿着垂直或平行于铝箔表面的方向发展；<100>、<110>和<111>晶向的原子密度依次为2/a、2.12/a、1.15/a,a为晶胞参数,{100}、{110}和{111}晶面的原子密度依次为5/a2、4.24/a2、13.85/a2,{100}、{110}和{111}晶面的弹性模量依次为98.418、109.449、113.2678 GPa,蚀孔隧道活性尖端由{111}晶面构成以降低表面能,蚀孔隧道钝化壁由{100}晶面组成以保持钝化膜稳定。电容器铝箔正方形点蚀表面形貌与铝箔织构有特定的对应关系,织构{100}<001>含量可以通过计算铝箔表面正方形蚀坑面积的方法来估算。

ABSTRACT:This work aimed to illustrate the application mechanism of pitting corrosion in the quality evaluation of aluminium foil for aluminum electrolytic capacitor. First, the formation process and general characteristics of cubic texture content of Al foil for Aluminum electrolytic capacitor and its pitting electrochemical features were introduced. The elastic moduli of different crystal planes in polycrystalline materials as well as the atomic density of different crystal planes and crystal orientations were simulated and calculated. The Al foil for Aluminum electrolytic capacitor was pitted in the etchant composed of HCl, HNO3 and HF. The sur-face and cross-section of etched Al foil were observed with SEM and OM. The results showed that numerous square etch pits oc-curred on the etched Al foul. Pitting developed perpendicular and parallel to the aluminum foil surface. The atomic densities of<100>, <110> and <111> were 2/a, 2. 12/a and 1. 15/a, respectively. The atomic densities of {100}, 110}and {111} were 5/a2 , 4. 24/a2 and 13. 85/a2 , respectively. The elastic moduli of{100}, 110}and{111} were 98. 418, 109. 449 and 113. 2678 GPa, respectively. The pitting active tip was composed of{111} planes to decrease surface energy. The pit walls were composed of{100} planes to stabilize the passivating film. There was inherent relations between square etch pits and material grain orientation. The {100} <001>cubic texture of Al foil could be estimated with total area of square pits on the etched Al foil, due to the inherent relations between square pitting and grain orientation of Al foil.