Investigation of Passive Layer Properties on Nanocrystalline Nickel by Electrochemical Impedance Spectroscopy

Electrochemical corrosion behavior of nanocrystalline Co coatings explained by higher grain boundary density

“…Similarly, some authors reported that nanocrystalline materials exhibited relatively improved corrosion resistance [8,26,34]. On the other hand, the results obtained in other studies indicated that NC materials have relatively higher dissolution and corrosion rates than their conventional coarse-grained counterparts [6,7,12]. There are also some papers demonstrated that the no significant differences in corrosion behavior between NC materials and conventional counterparts [10,37].…”

“…The classic corrosion theory indicated that nanostructuring should accelerate corrosion by forming much more micro electrochemical cells between the huge amount of grain boundaries and the matrix. As a result, the corrosion rate of NC materials was found to be usually degraded because of their metastable microstructure nature [5][6][7][8], which greatly limited their practical utility. Previous observations demonstrate that the effect of nanostructuring on corrosion behavior varies among metal systems and corrosion environments; hence, it is difficult to predict the electrochemical behavior of NC materials from the known properties of their coarse-grained polycrystalline analogs [6][7][8].…”

“…As a result, the corrosion rate of NC materials was found to be usually degraded because of their metastable microstructure nature [5][6][7][8], which greatly limited their practical utility. Previous observations demonstrate that the effect of nanostructuring on corrosion behavior varies among metal systems and corrosion environments; hence, it is difficult to predict the electrochemical behavior of NC materials from the known properties of their coarse-grained polycrystalline analogs [6][7][8]. Thus, nanocrystalline with a unique combination of high strength and better corrosion resistance will be 'ideal' materials for a wide range of functional applications [9]; moreover, better understanding of corrosion mechanism of NC materials in varied environments are necessary for prospective engineering applications.…”