ISO 16773-2:2016

Overview

ISO 16773-2:2016 - "Electrochemical impedance spectroscopy (EIS) on coated and uncoated metallic specimens - Part 2: Collection of data" provides practical, consensus-based guidelines for collecting reliable EIS data, with a particular focus on high-impedance systems. In the context of intact coatings, high impedance is defined as greater than 10^9 Ω·cm², though the document also applies to lower-impedance measurements. The standard addresses instrumental setup, measurement procedures, data validation and presentation, but does not prescribe methods for data interpretation.

Key topics and technical requirements

• Instrumental set-up and pitfalls
  • Design of the electrochemical cell (materials, leak-proof seals, exposed area) and electrode arrangements (working, reference, counter).
  • Grounding, shielding and cable grounding to minimize noise.
• Data validation and confidence testing
  • A recommended “confidence” test using dummy cells or interlaboratory test cells to check system suitability and maximum measurable impedance.
  • Error estimation and accuracy checks for the measurement range.
• Specimen and cell considerations
  • Requirements for specimen preconditioning, exposed area determination (Annex C), and environmental control for both laboratory and field specimens.
• Instrumental parameters
  • Guidance on potentiostatic EIS (also applicable under galvanostatic control), conditioning potential/time, frequency spectrum selection, data point spacing and points per decade, DC potential control, perturbation amplitude, current range and data averaging.
• Data presentation
  • Recommended methods for presenting EIS results, including Bode plots and Nyquist plots, and an exchange file format for data reporting.
• Reporting and annexes
  • Test report content requirements and informative/normative annexes (open-lead test for max impedance, data exchange format, exposed area considerations).

Practical applications and intended users

ISO 16773-2:2016 is intended for professionals who collect EIS data to evaluate coating performance and corrosion behavior, including:

• Corrosion scientists and electrochemists
• Coating formulators and quality control engineers
• Materials testing laboratories and field technicians
• R&D teams assessing protective coatings on metals and alloys

Typical applications include assessing coating integrity, monitoring barrier properties of polymer coatings, measuring high-impedance barrier layers, and standardizing laboratory and field EIS measurement protocols.

Related standards

• ISO 16773-1: Terms and definitions for EIS on coated and uncoated metallic specimens
• ISO 16773-3 and ISO 16773-4: Processing/analysis (Part 3) and example spectra (Part 4)
• ISO/TR 16208: Additional guidance for uncoated samples

Using ISO 16773-2:2016 ensures consistent, high-quality EIS data collection for meaningful comparisons across labs and reliable assessment of coating and metallic specimen performance.