Hydrogen permeation with a single instrument according to ASTM G148

Significance of the Topic

This study addresses hydrogen permeation in metallic membranes, a critical factor in assessing hydrogen embrittlement, material durability, and performance in energy and industrial applications. Accurate measurement of hydrogen transport parameters helps improve corrosion resistance, optimize alloy design, and ensure safe operation of hydrogen-based systems.

Objectives and Overview

The aim of this work is to demonstrate a streamlined approach for hydrogen permeation measurements according to ASTM G148 using a single multi-channel instrument. Two iron sheet samples are evaluated to extract key transport parameters and illustrate the capabilities of the Metrohm DropSens μStat-i Multi16 combined with dedicated software tools.

Methodology and Instrumentation

Hydrogen permeation is studied using a Devanathan-Stachurski cell, which comprises a charging compartment to generate atomic hydrogen and a detection compartment to oxidize permeated hydrogen. Key elements include:

• μStat-i Multi16 potentiostat/galvanostat with galvanic isolation in floating mode for simultaneous control of two channels.
• H-Cell with two 250 mL PTFE-capped compartments sharing a 2 mm thick iron sheet as working electrode.
• Charging cell electrolyte: 0.1 mol/L HCl with 0.2 g/L As2O3; detection cell electrolyte: 0.1 mol/L NaOH.
• Platinum counter electrodes and Ag/AgCl reference electrodes in both compartments.
• DropView 8400M software’s H2 Permeation module for automated transient fitting and parameter calculation.

Samples are pretreated at 80 °C overnight to remove absorbed hydrogen before measurement. Charging transients are recorded at –1 mA/cm2, followed by decay transients with hydrogen generation halted.

Main Results and Discussion

Two iron sheets exhibit distinct permeation behaviors. Sample 1 shows a higher steady-state flux and shorter lag time, indicating faster hydrogen diffusion. Sample 2 displays lower flux and a longer delay, reflecting reduced permeability. Key parameters extracted are:

• Sample 1: Effective diffusivity (Deff) = 1.35 × 10−5 cm2/s, subsurface concentration (C0) = 4.23 mol/m3, lag time (tlag) = 500 s.
• Sample 2: Deff = 1.11 × 10−5 cm2/s, C0 = 3.14 mol/m3, tlag = 600 s.

The automatic fitting routines in DropView simplify data analysis by overlaying calculated and normalized flux curves on experimental transients.

Benefits and Practical Applications

The integrated μStat-i Multi16 and DropView system offers:

• Multi-channel capability allowing up to eight simultaneous permeation cells.
• High sensitivity for low hydrogen flux detection.
• Automated analysis of hydrogen transport parameters for quality control, alloy development, and failure analysis in industrial R&D.

Future Trends and Applications

Advances may include extension to alternative membrane materials (e.g., alloys, composites), integration with in-situ spectroscopic techniques, real-time monitoring in harsh environments, and machine-learning-driven data interpretation. Scalable multi-cell arrays could accelerate screening of novel materials for hydrogen economy applications.

Conclusion

This application note demonstrates a unified approach to hydrogen permeation testing using a single multi-channel potentiostat/galvanostat and dedicated software. The methodology yields reliable transport parameters in line with ASTM G148 and supports efficient material evaluation in research and industrial settings.

References

• ASTM International. Standard Practice for Evaluation of Hydrogen Uptake, Permeation, and Transport in Metals by an Electrochemical Technique; ASTM G148-97(2018); ASTM International, 2018. DOI:10.1520/G0148-97R18.