Quickly screen metal surfaces for corrosion protection

Corrosion protection is of utmost importance for steel research. This protection is commonly obtained by coating the steel.
To screen the electrochemical and dissolution properties of newly developed coatings, the OCAS scanning flow cell with coupled UV-VIS and ICP-MS units, is the ideal tool. Not only because of its multi-reservoir high-throughput, but also thanks to its high lateral resolution obtained by confining the measurement locally.

The OCAS scanning flow cell allows high-throughput screening of corrosion properties to identify key parameters adjusted to real-life exposure conditions. Moreover, it monitors the dissolved elements online using UV-VIS or ICP-MS. As a result, this scanning flow micro-cell – including a dynamic electrolyte exchange system – addresses several issues, making it a highly interesting tool.

Case  – Comparison of pure zinc coating with zinc-aluminium-magnesium coating in different electrolytes

The dissolution current in this example obtained by monitoring Zn using UV-VIS, in  5% Na2SO4 pH 5 on Zn coating, was very high, compared to pH 7 and 9. The same trend was observed on Zn-Al-Mg coating, although its dissolution current is much lower.

In case of a 5% NaCl solution, the dissolution current is lower compared to 5% Na2SO4.  Again, Zn coating shows higher dissolution rates at pH 5 compared to the Zn-Al-Mg coating. In 5% NaCl the Zn-Al-Mg coating shows an offset and the Zn coating shows an irregular profile.

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Scanning flow cell coupled with ICP-MS

Coupling the scanning flow cell with the OCAS ICP-MS device allows to monitor Al, Mg or other elements of interest in addition to Zn. A concentration profile of Al, Zn and Mg is shown below as a function of time. This is obtained when a Zn-Al-Mg coating is in contact with 0.3% NaCl.

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“The scanning flow cell is the perfect tool for high-throughput analysis of metallic surfaces to determine both their local electrochemical, as well as their dissolution properties.”

Myriam Madani, Senior Team Leader inorganic and organic chemistry, electrochemistry & corrosion, OCAS