Methods for Electrochemical Corrosion Testing 

Corrosion in concrete or metal can be evaluated with an electrochemical test. Electrochemical corrosion testing is used to characterize corrosion damage and, when possible, estimate corrosion rates based on electrochemical theory.

Electrochemical Corrosion Test and Its Techniques 

Potential and current in oxidation/reduction reactions are measured and/or regulated during electrochemical corrosion testing. Manipulating and measuring these two factors allows for a wide variety of studies to be conducted. The working electrode is usually subjected to a voltage and the resulting current is measured.

Anode and cathode regions form an electrical circuit during the corrosion of steel buried in concrete, an example of an electrochemical process. Electrochemical testing of the concrete and reinforcing steel can reveal details regarding the level of corrosion activity. Corrosion testing is routinely performed to evaluate uncoated, bonded reinforcing steel and normally involves measurements on both the reinforcing steel and the concrete.

The effects of corrosion can be dramatically magnified through electrochemical testing. For the purpose of quantifying corrosion rates, all electrochemical tests resort to some fundamental model of the electrode kinetics related to corrosion processes. These tests allow for extremely exact and sensitive measurements since the electrical impulses produced are amplified.

The following can be determined with electrochemical corrosion tests

• Tableau depicting corrosion rates
• Characteristics of the active/passive nature of a certain sample/solution system
• Rates of Passivation
• Anti-oxidant and anti-corrosion coatings

Some such uses are:

• Examination of the susceptibility of completed medical devices to pitting and crevice corrosion
• Corrosion-related screening by comparing raw materials
• Analyzing the anti-corrosion effects of passivation and other surface treatments
• Processing effects on corrosion characteristics evaluation and comparison
• Galvanic corrosion behavior evaluation of bimetallic combinations

In electrochemistry, there are two primary techniques for taking readings:

• Electrochemical information can be generated at potentials other than the free corrosion potential by applying an external current. The link between electrochemical potential and current is typically investigated in such experiments.
• Without applying an external current, electrochemical tests are taken at the free corrosion potential.

The following methods are used to test for electrochemical corrosion:

• Evaluation of the linear polarization resistance
• Curves of polarization potentials
• Intergranular corrosion electrochemical potentiokinetic reactivation (EPR) testing
• Time-current plots (at a fixed voltage)
• Spectroscopy based on the electrochemical impedance (EIS)
• A Harmonic Look at It
• Evaluation of Electrochemical Noise (EN)

Electrochemical corrosion testing requires tiny, conductor-equipped, polarization-cell-friendly samples. It is possible to test components in their entirety or subsets. Some tests require metal coupons that have been carefully prepared. Also learn about power of  electrochemical corrosion testing.