Hydrogen Compatible Materials
Gaseous hydrogen has the unique characteristic that it liberates atomic hydrogen when in contact with surfaces. The released atomic hydrogen dissolves into materials and can alter their structural properties, a process often referred to as hydrogen embrittlement. While the majority of materials do not become brittle when exposed to gaseous hydrogen, most materials are more susceptible to fatigue and fracture when exposed to gaseous hydrogen. Understanding and quantifying hydrogen-assisted fatigue and hydrogen-assisted fracture is necessary for broad usage of hydrogen as an energy carrier.
The High-Pressure Hydrogen Laboratory and several other related laboratories at Sandia National Laboratories in Livermore, California, have served the nation for many decades in hydrogen-related science and technology development and deployment. In particular, several novel facilities have been developed for measuring structural properties of materials in extreme environments with the intent of facilitating structural design. The capabilities related to evaluation of structural properties include
- Thermal Precharging – Materials and test specimens are exposed to high-pressure gaseous hydrogen (up to 140 MPa) at elevated temperature (up to 300 ˚C) before subsequent evaluation.
- Subcritical Crack Growth Testing – Instrumented, preloaded specimens are exposed to gaseous hydrogen at pressure up to 200 MPa and temperatures over the range of -70 ˚C to 170 ˚C, thus allowing for crack growth studies and cracking threshold determination.
- Environmental Testing – Specimens are exposed to gaseous hydrogen at pressure up to 140 MPa while concurrently applying controlled load. Thus allowing for a variety of standardized mechanical testing in gaseous hydrogen, such as fatigue crack growth testing and fracture resistance testing.
- Accelerated-Life Component Testing – Large-scale components are pressure cycled (up to 70 MP) with gaseous hydrogen to failure to analyze cycle life and determine safety margins.
Other complementary capabilities for evaluating hydrogen behavior in materials include measuring hydrogen permeation through materials, thermal desorption spectrometry, and low-energy ion scattering. The latter capability is a unique instrument specifically optimized for determining how hydrogen binds to surfaces at an atomic scale.