Lee Gyoung-Ja, Pyun Su-Il, Rhee Chang-Kyu
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1, Guseong-dong, Yuseong-gu, Daejeon, 305-701, Republic of Korea.
J Colloid Interface Sci. 2007 Apr 15;308(2):413-20. doi: 10.1016/j.jcis.2006.12.043. Epub 2007 Jan 29.
In the present work, the electrophoretic deposition of Ni nanoparticles used for self-repairing of pits in organic suspension was investigated on pitted fractal Ni alloy 600 with respect to surface fractality of the pits. For this purpose, Ni nanoparticles prepared by levitation-gas condensation were dispersed into an ethanol solution with the addition of a dispersant. Four kinds of pitted fractal specimens with different surface fractal dimensions dF,surf were prepared by applying various anodic potentials above pitting potential to alloy 600 in aqueous 0.1 M NaCl solution. From the scanning electron microscopy (SEM) images, it was observed that the pits repaired under applied electric field E of 100 V cm-1 comprised more agglomerates of Ni nanoparticles than those repaired under E of 20 V cm-1. This suggests that the higher the value of E is, the more agglomerates of Ni nanoparticles are deposited on the specimen due to more depletion of OH- in suspension near the specimen surface. Moreover, the specimen with higher dF,surf gave a higher value of electrophoretic current Ip than one with lower dF,surf due to the increased electrochemical active area Aea of the specimen. From the above, it is concluded that the surface irregularities of the pit enhance the deposition of Ni nanoparticles on pitted fractal specimen during electrophoretic deposition.
在本工作中，针对点蚀分形镍合金600表面点蚀的分形特性，研究了用于有机悬浮液中点蚀自修复的镍纳米颗粒的电泳沉积。为此，通过悬浮气体冷凝制备的镍纳米颗粒在添加分散剂的情况下分散到乙醇溶液中。通过在0.1 M NaCl水溶液中对合金600施加高于点蚀电位的各种阳极电位，制备了四种具有不同表面分形维数dF,surf的点蚀分形试样。从扫描电子显微镜（SEM）图像中观察到，在100 V cm-1的外加电场E下修复的点蚀比在20 V cm-1的E下修复的点蚀包含更多的镍纳米颗粒团聚体。这表明E值越高，由于试样表面附近悬浮液中OH-的消耗越多，沉积在试样上的镍纳米颗粒团聚体就越多。此外，由于试样的电化学活性面积Aea增加，具有较高dF,surf的试样比具有较低dF,surf的试样给出更高的电泳电流Ip值。由此得出结论，在电泳沉积过程中，点蚀的表面不规则性增强了镍纳米颗粒在点蚀分形试样上的沉积。
