Electrochemical Kinetic Analysis of Carbon Steel Powders Produced by High-Energy Ball Milling

Abstract

This work reports on the electrochemical kinetic analysis of carbon steel powders produced during the milling of carbon steel chips for 2, 3, and 5 h under an air atmosphere in a high-energy ball miller. This work aims to fill the gap in the literature regarding the transformation processes that affect carbon steel powder production. This information can be crucial for specific powder metallurgy systems. The results obtained using the Rietveld refinement method showed a decrease in the crystallite size, an increase in the microstrain, and no changes in the lattice parameter with the milling process. The electrochemical results revealed a strong influence of anodic electroactivity with milling time in NaCl solution, in contrast with NaOH, where the influence of the milling process was not significant. These results clearly show the significant role of chloride ions in preventing the formation of a passive film in milling with NaCl solution and in contrast to the formation of a passive film that notoriously inhibits both the anodic and cathodic reactions in milling with NaOH solution. The novelty of this work lies in the experimental demonstration of milling’s influence on the surface properties of carbon steel powders that directly affect their electrochemical response.

Corrosion of Titanium Electrode Used for Solar Saline Electroflotation

“…A kinetic study was accomplished by applying non-linear fitting to experimental polarization data, considering the superposition model and mixed potential theory according to the methodology described in our previous works in terms of charge transfer, mass diffusion, and passivation mechanism controls [47,[69][70][71][72]. Applying the non-linear fitting methodology, a set of kinetics expressions for the cathodic ORR, HER, and TOR, in terms of the current density was expressed as follows:…”

Corrosion of Reinforced A630-420H Steel in Direct Contact with NaCl Solution

“…The kinetic analysis was studied by applying non-linear fitting to the experimental polarization curves obtained from the LVS measurements. The superposition model, based on mixed potential theory, was utilized following the methodology described in our previous work concerning controls related to mass diffusion, charge transfer, and passivation mechanisms [31][32][33][34]. The following set of kinetic expressions (Equations ( 1)-( 4)) is used as part of the non-linear fitting methodology, which considers the total current density (i) as a function of the partial current densities for the ORR (i O 2 ), IOR (i Fe ), and HER (i H 2 ):…”

“…The analysis of the polarization data for A630-420H steel in contact with NaCl solutions has demonstrated that mixed potential theory can be successfully applied to decompose the total current into a linear contribution of the partial electrochemical HER, ORR, and IOR, as shown in Figure 4 [31,[33][34][35]. While the partial HER and IOR follow a charge transfer kinetic mechanism, the ORR follows a kinetic expression under a mixed mechanism of charge transfer and diffusion control.…”