A Comparative Study of the Corrosion Behavior of Mild Steel Nanoparticles in Natural Seawater and in 3.5% NaCl Solution by AFM and KFM Techniques
A comparative study of the corrosion behavior of mild steel nanoparticle in natural seawater and 3.5% NaCl solution was investigated using the atomic force microscopy (AFM) and Kelvin probe force microscopy (KFM). The corrosion behavior of the individual nanoparticle was monitored in natural seawater with different time. Both the size and the surface potential of mild steel nanoparticles decreased with increasing time in natural seawater as well as 3.5% NaCl. The changes in AFM and KFM maps of nanoparticles indicated that the corrosion took place due to the anodic reaction by surface potential. However, the corrosion at mild steel nanoparticle surface occurred more severely in 3.5% NaCl solution than in natural seawater. The decrease in the surface potential and the size of mild steel nanoparticle was more in 3.5% NaCl solution than in natural seawater. The mild steel nanoparticle corroded nearly five times faster in 3.5% NaCl solution than in natural seawater for an exposure time of 5 h. Therefore, the corrosion of mild steel nanoparticle in natural seawater was suppressed by the deposition of calcium carbonate on the surface of nanoparticles. These deposits of calcium carbonate acted as a barrier against diffusion and therefore lowered the corrosion rate. It was proved that 3.5% NaCl solution is more aggressive toward mild steel nanoparticle than natural seawater.
KeywordsAFM KFM Nanoparticles Corrosion Seawater
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