ISO 16773-3:2016

Overview

ISO 16773-3:2016 defines a procedure for evaluating EIS (electrochemical impedance spectroscopy) experimental setups used to measure high‑impedance coated metallic specimens. The standard prescribes the use of purpose-built dummy cells (equivalent resistor–capacitor networks) to simulate coated samples, guide measurements in a controlled environment (Faraday cage), and support curve fitting, data presentation and system acceptance. ISO 16773‑3 helps laboratories and manufacturers verify that their EIS hardware and software can reliably measure and extract circuit component values for high‑impedance systems.

Key topics and requirements

• Dummy cell designs: A set of four dummy cells based on two equivalent circuit types (A and B). Component values (resistors in GΩ range and capacitors in nF/pF range) are mounted on PCBs with four connectors to interface with common electrochemical workstations.
• Measurement environment: Perform measurements inside a Faraday cage to minimize electromagnetic interference, which disproportionately affects high‑impedance EIS.
• Test conditions: Recommended potentiostatic mode with a DC level of 0 V and typical excitation amplitude of 20 mV (peak‑to‑zero); measurement duration ~30–40 min (longer for some cells).
• Data analysis: Use curve‑fitting software to extract equivalent circuit component values, produce Bode plots of measured vs. simulated data, and document fitting results and excitation conditions.
• Acceptance criteria: Fitted component values must not deviate from real component values by more than the components’ stated accuracies (resistors: ±2% below 10 Ω, ±5% above 10 Ω; capacitors: ±5%).
• Reporting: Test reports should identify the dummy cell and component accuracies, reference ISO 16773‑3, record environmental conditions, test method (frequency range, amplitude, duration), fitted results, deviations, anomalies and date.
• Precision: The standard includes interlaboratory repeatability and reproducibility data demonstrating typical performance and potential pitfalls across labs.

Applications and users

ISO 16773-3 is valuable for:

• Corrosion and coatings laboratories performing EIS on high‑impedance coatings
• Quality‑assurance teams validating EIS test rigs and protocols
• EIS instrument and software manufacturers verifying measurement accuracy and curve‑fitting performance
• Research groups studying coated metal systems where electromagnetic artifacts must be controlled

Practical benefits include improved confidence in EIS results, identification of electromagnetic artefacts, and standardized reporting for cross‑lab comparison.

Related standards

• ISO 16773-1 / -2 / -4 (other parts of the series covering terms, data collection and example spectra)
• ISO/TR 16208 (dummy cells for low‑impedance range)
• ASTM G106 (precision data for low‑impedance EIS measurements)

Keywords: ISO 16773-3, electrochemical impedance spectroscopy, EIS, dummy cells, high-impedance coated samples, Faraday cage, Bode plot, equivalent circuits, curve fitting, measurement system acceptance.