Logo of the Department of Energy Hydrogen Materials Consortium

The Hydrogen Materials Compatibility Consortium (H-Mat), composed of Sandia National Laboratories (SNL, lead), Pacific Northwest National Laboratory (PNNL, lead), Oak Ridge National Laboratory (ORNL), Savannah River National Laboratory (SRNL), and Argonne National Laboratory (ANL), is a framework for cross-cutting early-stage research and development (R&D) on hydrogen materials compatibility. Working in collaboration with partners in industry and academia, H-Mat R&D focuses on the effects of hydrogen on performance of polymers and metals used in hydrogen infrastructure and storage. H-Mat's ultimate goals are to improve the reliability of materials, reduce the costs of materials, and inform codes and standards that guide development and use of hydrogen technologies. H-Mat was launched in 2018 by the U.S. Department of Energy's Hydrogen and Fuel Cell Technologies Office within the Office of Energy Efficiency and Renewable Energy in support of the H2@Scale initiative.

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R&D Activities within H-Mat

H-Mat R&D activities include the study of metals and polymers of interest in hydrogen infrastructure and onboard fuel cell electric vehicles. For examples of recent work in these areas, please see the Hydrogen and Fuel Cells Program's Annual Merit Review and Peer Evaluation Meeting presentations covering R&D on polymers, metals of interest in pressure vessels, and metals of interest in pipelines, along with webinars on hydrogen pipeline materials and recent code modifications.

Current H-Mat R&D activities include the following.

Atomistic to micro- and macro-scale modeling of hydrogen-induced degradation of polymers
Objective: To develop models of hydrogen transport, bubble nucleation, and hydrogen-induced degradation of polymers at multiple length scales to inform materials evaluation and design.

Experimental discovery of the mechanisms of hydrogen-induced degradation in polymers
Objective: To quantify the relationship between hydrogen pressure-temperature-time-damage and polymers by using controlled structure and morphology to inform models.

Develop hydrogen-resistance polymeric formulations
Objective: To discover modified and new materials systems with greater resistance to the environmental effects of pressure and temperature.

Quantify hydrogen effects at microstructural length scales in austenitic stainless steels
Objective: To identify governing physical processes of hydrogen embrittlement in austenitic stainless steels (e.g., for use in piping and fittings at fueling stations) to design microstructures that mitigate the adverse effects of hydrogen environments.

Identify hydrogen-resistant, high-strength ferritic steel microstructures
Objective: To develop a mechanistic understanding of fracture processes in ferritic steel microstructures to improve fatigue and fracture resistance of low-cost steels with tensile strength >950 MPa in high-pressure hydrogen service.

Clarify mechanisms of hydrogen degradation in high-strength aluminum alloys
Objective: To understand the influence of water vapor on hydrogen embrittlement of high-strength aluminum alloys and validate physical models of moisture/hydrogen-surface interactions to enable the use of high-strength aluminum alloys in hydrogen systems (e.g., piping, tubing, fittings).

Develop framework to quantify damage and crack nucleation in hydrogen environments
Objective: To understand the mechanics of hydrogen-induced damage leading to crack nucleation in metals and develop a framework that can quantify the cycles required for crack nucleation.

Evaluate the behavior (e.g., fatigue life, resistance to buckling) of composite materials, austenitic steels, and weld materials in cryogenic conditions (30 K)
Objective: To assess the viability of current and experimental materials for cryo-compressed hydrogen storage onboard fuel cell vehicles, and to identify key technical metrics for viable structural materials in this application.

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National Lab Capabilities within H-Mat

The national laboratories house unique, world-class capabilities that are essential to the study of hydrogen interactions with materials. These capabilities span computational modeling, imaging of hydrogen-materials interactions, and experimental evaluation of materials with applied mechanical load in high-pressure hydrogen environments. The list below provides examples of key capabilities within H-Mat. For more information, please contact h-matinfo@pnnl.gov.

Capabilities in Mechanical Evaluation of Hydrogen Effects on Materials

Mechanical evaluation of materials in the presence of hydrogen is intended to simulate service environments and assess hydrogen-affected properties of materials. Examples of capabilities at the national labs to explore the mechanical response of materials with hydrogen include the following.

Fatigue and fracture testing in high-pressure gaseous hydrogen: Tests can be executed with concurrent gaseous hydrogen exposure at pressure up to 140 MPa and at controlled temperature in the range of 220 K to 450 K. (SNL)

Constant-displacement testing in high-pressure gaseous hydrogen:

  –  Subcritical cracking thresholds can be measured in constant displacement fracture tests. (SNL, SRNL)

  –  Instrumented test specimens enable the measurement of crack initiation, crack velocities, and crack arrest. (SNL)

Pressure cycling: Test coupons can be exposed to pressure cycles at controlled temperature (fixed temperature in the range of 220 K to 400 K). (SNL, SRNL)

Tribology of nonmetals and metals: Measurement of frictional force and vertical wear depth profiles of polymers in 34 MPa hydrogen. (PNNL, SRNL)

Dynamical mechanical analysis of polymers: Measurements of gas, temperature, and pressure effects on polymer structures with in situ dynamic mechanical analysis of 30 MPa hydrogen and within the temperature range of 230 K to 400 K. (PNNL)

Mechanical evaluation of materials for cryogenic hydrogen applications: Testing of materials at cryogenic temperatures from 220 K to 20 K, as well as in simulated cryogenic hydrogen environments. Materials that can be studied include polymers, composites, metals, and welds. Cryogenic environments can be simulated via hydrogen-precharging of specimens prior to testing.

Capabilities in Environmental Hydrogen Interactions: Hydrogen Uptake, Transport, and Trapping

Hydrogen uptake into materials and chemical interactions with materials are the first steps of hydrogen-induced degradation phenomena. Environmental interactions are measured to inform and validate fundamental models of hydrogen transport phenomena in materials. Below are some of the unique capabilities at the national labs to probe these phenomena.

Gas-phase permeation: Measurement of permeation and diffusion of gaseous hydrogen through materials as the result of a pressure differential. (SNL, SRNL, ORNL, PNNL)

  –  Thin layers of metal or polymer are extracted from a material of interest, and one side is exposed to hydrogen or deuterium while the other side is maintained at ultra-high vacuum. The evolution of the hydrogen/deuterium on the down-stream side of the material can be measured to characterize diffusion transients and permeation rate.

  –  Both low-pressure and high-pressure systems exist at the labs. Tests on metals are usually performed at elevated temperature and can be conducted at up to 1,000°C. Evaluation of permeation in polymers can be performed at temperature as low as -40°C.

Thermal desorption spectroscopy (TDS): Characterization of the interaction between a material's microstructure and hydrogen, so-called "hydrogen trapping". (SNL, PNNL, SRNL)

  –  Hydrogen-precharged specimens are heated at controlled rates to release the hydrogen. The release is characterized as a function of temperature and heating rate. The resulting spectrum is analyzed to characterize the "strength" of the interactions between hydrogen and microstructural features of the material.

Chemical analysis: Chemical analysis of hydrogen gas interaction with polymers and fillers. National lab capabilities include Raman spectroscopy, GC-mass spectroscopy, solid-state NMR (1H, 13C), small-angle and wide-angle neutron scattering, small-angle and wide-angle X-ray diffraction, and annihilation proton spectroscopy. (ORNL, PNNL, ANL)*

Hydrogen surface interactions: Use of advanced characterization techniques to measure hydrogen interactions with material microstructures at the nanometer length scale. Examples of capabilities available include the following.

  –  Low Energy Ion Spectroscopy (LEIS) can be used to probe hydrogen-surface interactions and hydrogen uptake, in some cases providing crystallographic information about the interactions. (SNL)

  –  Methods that utilize scanning probe microscopy to probe hydrogen on metal surfaces in relationship to the underlying microstructures are being developed. (SRNL)

  –  A variety of additional surface sensitive imaging techniques and expertise are available at the national laboratories to investigate hydrogen interactions. Lab points of contact can assist interested stakeholders in identifying the appropriate tools for given areas of research.

* Several of these tools are within user facilities administered by DOE's Office of Science. Access will ultimately require submission and approval of requests through the Office of Science.

Capabilities to Evaluate Hydrogen-Microstructure Interactions

Hydrogen-materials interactions can be sensitive to the microstructure of the material. Model microstructures and simulated welds can be synthesized for mechanical and environmental interrogation. Additional tools are used to saturate (i.e., "precharge") materials with hydrogen for subsequent evaluation and measurement of relevant properties. Key capabilities at the national labs include the following.

Thermal precharging: Test specimens are exposed to high-pressure gaseous hydrogen or deuterium (up to 140 MPa) at elevated temperatures (up to 300ºC) for weeks to months to produce controlled hydrogen content within specimens prior to evaluation. (SNL, SRNL)

Gleeble apparatus: Weld microstructures and experimental base metal microstructures can be synthesized for subsequent testing. (SNL, ORNL)

Advanced imaging techniques: Environmental electron microscopy, high-resolution scanning transmission electron microscopy, scanning nanobeam diffraction, and crystallographic orientation mapping are just a few of the techniques available throughout the national labs to indirectly observe hydrogen interactions with surfaces, defect sites, and other microstructural features. Lab points of contact can assist interested stakeholders in identifying the appropriate tools for given areas of research, including recommendations for specialized neutron scattering, X-ray diffraction, and other unique characterization tools available at user facilities managed by the national laboratories*. 

 * Several of these tools are within user facilities administered by DOE's Office of Science. Access will ultimately require submission and approval of requests through the Office of Science.    

Capabilities for Computational Materials Science of Hydrogen Interactions

High-performance computing and computational materials science expertise is available across the national labs for the study of hydrogen effects in materials across multiple length scales from atoms to engineering. Computational tools are available for studying materials at all relevant length scales, including (but not limited to):

  • Density functional theory
  • Molecular dynamics
  • Dislocation dynamics
  • Crystal plasticity
  • Phase-field methods
  • Continuum finite element methods.

* Several of these tools are within user facilities administered by DOE's Office of Science. Access will ultimately require submission and approval of requests through the Office of Science.

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Data Portals within H-Mat

A key activity in the H-Mat Consortium is sharing of nonproprietary data publicly, to accelerate R&D in materials compatibility nationwide.

Data on metallic materials is being stored at https://granta-mi.sandia.gov/mi-viewer/index.aspx.

A database for polymeric materials is under development.

Stakeholders are encouraged to participate in the database above. Please contact h-matinfo@pnnl.gov to submit data.

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Engaging with H-Mat

Collaboration with H-Mat is through cooperative research and development agreements (CRADAs), strategic partnership projects (SPPs), and funding opportunity announcements (FOAs). Find information on open FOAs through EERE Exchange.

For more information on how to engage with H-Mat, please contact h-matinfo@pnnl.gov.

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