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Soft coating damage evolution on steel

  

A team of researchers has characterized the evolution of damage to soft coatings, a.k.a. “rust preventives,” on steel surfaces when used as a physical barrier to prevent corrosion.

While many researchers have explored the properties of soft coatings on metallic surfaces in the past, few studies have focused on soft coating damage evolution on steel surfaces.

So a research team from the University of Akron’s National Center for Research in Corrosion and Lubrizol Corp. set out to characterize the performance of soft coatings or “rust preventives” when used as a physical barrier to protect steel from corrosive environments.

In the June 2014 issue of CORROSION, the team describes their work, which uses two test methods—a standard salt spray test based on ASTM B117 and electrochemical impedance spectroscopy (EIS)—to characterize soft coating performance.

The team used a salt spray test to expose samples to an extremely corrosive environment within a salt fog chamber so they could qualitatively characterize the performance of the coatings, but then also went a step further with EIS to characterize and quantify the performance of the coatings in corrosive environments. 

“Our research at the University of Akron also involves developing mathematical models with the ability to represent physical phenomena at laboratory scale,” says Homero Castaneda, an assistant professor in the Chemical and Biomolecular Engineering Department. “This is a way of providing plausible validation in real macro-scale of our lab-scale findings.”

By using these models to compare the results of both test methods, the team was able to explain the degradation occurring at the film/steel surface and found a “good correlation” between the experimental and analytical results for each method. 

This is good news because it means that their work can be used in wide-ranging industrial applications to protect steel surfaces from corrosion. It can be “applied to all aspects of corrosion management of infrastructure—including the automotive, chemistry, water, oil and gas, and renewable energy generation sectors—by integrating electrochemistry, transport phenomena, and computer simulation with materials science and the multi-scale (nano to macro) concept,” explains Castaneda.

Electrochemistry “provides the basis for the fundamental research capabilities needed to pursue and unify different areas in corrosion characterization, control, monitoring, mitigation, reliability engineering, new materials design, and control-based models for monitoring technologies,” he adds.

Next, Castaneda and colleagues at the University of Akron plan to explore the multi-stage modeling concept that applies to different scientific and engineering fields. “To some extent, the assumption of using a multi-scale system in real-scale systems relies on the fact that metallic structures are enormous electrodes immersed in heterogeneous electrolytes forming electrochemical cells. These electrochemical cells—with macro-environmental factors inherent to the metallic/electrolyte system—influence the reliability of metallic structures,” says Castaneda. “On the small scale, micro-factors affecting the integrity of metallic structures aren’t visible to the naked eye, but they’re key elements for the initiation and propagation of corrosion.” The link between the two scales can be associated with technologies to measure time-dependent macro magnitudes with the fundamentals of sub-micro-scale transport phenomena mechanisms at the metal/electrolyte level.

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More Information: The paper, “Analysis of Soft Coating Corrosion Performance on Carbon Steel Using Electrochemical Impedance Spectroscopy,” written by X.M. Li, B. Faber, B. Minch, and H. Castaneda, appears in NACE International’s journal, CORROSION, June 2014, Vol. 70, No. 6, pp. 615-626. See: http://dx.doi.org/10.5006/1092

About NACE International: Founded in 1943, NACE International, The Corrosion Society, serves 33,000 members in 130 countries. Based in Houston, Texas, with offices in the U.S., China, Malaysia, Brazil and Saudi Arabia, the organization serves all industries impacted by corrosion and provides the most specified technical training and certification programs, conferences, industry standards, reports, and publications focused on corrosion prevention and mitigation. 

CORROSION is a technical research journal devoted to furthering the knowledge of corrosion science and engineering. The technical articles selected for publication in CORROSION provide a permanent record of the latest progress in the science and technology of corrosion control. The journal is directed at scientists and engineers concerned with the phenomena of corrosion processes and the protection of materials in corrosive environments. For more information, please visit http://corrosionjournal.org.
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