Department of Metallurgical Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India.
Department of Architectural Engineering, Hanyang University, 1271 Sa 3-dong, Sangrok-gu, Ansan 426-791, Republic of Korea.
Ultrasonics. 2019 Jan;91:180-192. doi: 10.1016/j.ultras.2018.08.011. Epub 2018 Aug 17.
This investigation was carried out following our earlier work on the effect of ultrasonic shot peening (USSP) on corrosion resistance of the 7075 aluminium alloy in 3.5 wt% NaCl solution to optimize the duration of USSP. The samples not treated with USSP and different samples treated with USSP were subjected to potentiodynamic polarization and electrochemical impedance spectroscopy. Among the specimens USSP treated from 5 to 30 s, the one USSP treated for 15 s (USSP 15) was found to exhibit highest corrosion potential (E) and lowest corrosion current density (i). Corrosion products were characterized by Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). Scanning Kelvin Probe Force Microscopy (SKPFM) was used to measure the surface free potential. The enhanced corrosion resistance of the USSP 15 sample was found to be due to combined effect of surface nanostructure of the matrix, homogeneity and refinement of second phase precipitates. There was enhancement in formation of adherent passive layer in the USSP15 specimen.
本研究是在我们先前关于超声喷丸（USSP）对 7075 铝合金在 3.5wt%NaCl 溶液中耐腐蚀性的影响的工作基础上进行的，旨在优化 USSP 的持续时间。未经 USSP 处理和经过不同时间 USSP 处理的样品进行了动电位极化和电化学阻抗谱测试。在经过 5-30s 的 USSP 处理的样品中，发现经过 15s USSP 处理的样品（USSP15）表现出最高的腐蚀电位（E）和最低的腐蚀电流密度（i）。通过扫描电子显微镜（SEM）和 X 射线光电子能谱（XPS）对腐蚀产物进行了表征。采用扫描开尔文探针力显微镜（SKPFM）测量了表面自由电势。USSP15 样品耐腐蚀性的提高归因于基体表面纳米结构、第二相析出相的均匀细化的综合影响。在 USSP15 样品中形成了更附着的钝化层。
