Effect of grain size on corrosion behavior of
electrodeposited bulk nanocrystalline Ni
electrodeposited bulk nanocrystalline Ni
(Key Laboratory of Automobile Materials of Ministry of Education, College of Materials Science and Engineering,
Jilin University, Changchun 130025, China)
Jilin University, Changchun 130025, China)
Abstract: Nanocrystalline (NC) and coarse-grained Ni with different grain sizes (from 16 nm to 2 mm) were fabricated by direct current electrodeposition. Effect of grain size on the electrochemical corrosion behavior of these Ni deposits in different corrosion media was characterized by using potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and immersion corrosion test. Results show that in the NaOH or NaCl solution, the NC Ni exhibits improved corrosion resistance with the decrease of grain size. But in H2SO4 solution, the higher grain boundary density accelerates corrosion due to no passive process and the corrosion resistance of NC Ni decreases with refining grain size. The distinct experimental results of NC Ni in corrosion behavior can be reasonably explained by the positive or negative effect of high-density grain boundaries in different corrosion media.
Key words: Ni; nanocrystalline; electrodeposition; corrosion behavior; grain size