An electrochemical calibration unit for hydrogen analysers

Area of Science:

• Materials Science
• Analytical Chemistry

Background:

• Accurate hydrogen determination in metals (e.g., high-strength steels) at ppb/ppm levels is crucial.
• Existing calibration methods for hydrogen analyzers, such as certified reference materials (CRMs) and gas dosing, have limitations in availability, reliability, and accuracy due to atmospheric pressure dependence and unrealistic transient simulations.

Purpose of the Study:

• To develop and validate a new electrochemical calibration method for hydrogen analyzers.
• To overcome the limitations of current calibration techniques for precise hydrogen quantification in solid materials.

Main Methods:

• An electrochemical cell was designed to generate precisely quantifiable, faradaic amounts of hydrogen (H2) or deuterium (D2) based on Faraday's law.
• The generated hydrogen/deuterium was detected by the hydrogen analyzer, with current and time programmed to simulate realistic effusion transients.
• Electrolytes were varied to produce either diprotium (H2) or dideuterium (D2).

Main Results:

• The electrochemical method allows for exact hydrogen quantification based on transferred charge.
• The method enables the simulation of random effusion transients, matching real sample behavior.
• Quantitative relationships between evolution time, current, and hydrogen amount were established.

Conclusions:

• The developed electrochemical calibration method provides an accurate and reliable alternative for hydrogen analyzers.
• This technique offers precise control over hydrogen generation and transient shaping, improving accuracy for trace hydrogen analysis in metals.
• The electrochemical approach is automatable, cost-effective, and adaptable for both H2 and D2 calibration.