Preventing Hydrogen Embrittlement: The Role of Barrier Coatings for the Hydrogen Economy

Abstract

Hydrogen barrier coatings are protective layers consisting of materials with a low intrinsic hydrogen diffusivity and solubility, showing the potential to delay, reduce or hinder hydrogen permeation. Hydrogen barrier coatings are expected to enable steels, which are susceptible to hydrogen embrittlement, specifically cost-effective low alloy-steels or light-weight high-strength steels, for applications in a hydrogen economy. Predominantly, ceramic coating materials have been investigated for this purpose, including oxides, nitrides and carbides. In this review, the state of the art with respect to hydrogen permeation is discussed for a variety of coatings. Al2O3, TiAlN and TiC appear to be the most promising candidates from a large pool of ceramic materials. Coating methods are compared with respect to their ability to produce layers with suitable quality and their potential for scaling up for industrial use. Different setups for the characterisation of hydrogen permeability are discussed, using both gaseous hydrogen and hydrogen originating from an electrochemical reaction. Finally, possible pathways for improvement and optimisation of hydrogen barrier coatings are outlined.

Hydrogen Embrittlement as a Conspicuous Material Challenge─Comprehensive Review and Future Directions

“…The advantages and disadvantages of these different types of H permeation barriers, along with the data of H permeability of some barrier coatings, are summarized in Figure to guide future research efforts in this field. The detailed information of these H permeation barriers and their fabrication methods have been thoroughly reviewed in recent publications (e.g., refs and ). Here we mainly contemplate a few shortcomings associated with this HE mitigating method.…”

“…(b) H permeabilities of various metal and ceramic coatings. Reprinted with permission from ref . Copyright 2023 MDPI under [CC BY 4.0 DEED] [].…”

Titanium Carbide Coating for Hafnium Hydride Neutron Control Rods: In Situ X-ray Diffraction Study

“…One such approach is the deposition of a protective coating onto the surface of HfH x tablets to limit the hydrogen release from Hf-H at high temperatures. Carbide coatings can be more appropriate due to hydrogen impermeability, high melting point, and thermal expansion coefficients close to those of HfH 1.66 , up to 1000 • C [16]. Moreover, carbides do not interact with liquid sodium at the specified temperatures.…”

“…Moreover, carbides do not interact with liquid sodium at the specified temperatures. At present, TiC coating is well studied, and it is widely applied as a protective material [16][17][18][19][20]. Titanium carbide is also characterized by high resistance to radiation damage that can be beneficial for using it as a protective coating for nuclear applications [21][22][23].…”

Stability and Failure Mechanisms of Al2O3|Al Bilayer Coatings Exposed to 300 Bar Hydrogen at 673 K

“…[7] In a recent review article we summarize the different permeabilites reported in literature and possible approaches to measure them. [8] Thin Al 2 O 3 or sacrificial Al coatings are also used as corrosion protection for stainless steel. [9,10] Al 2 O 3 |Al bilayers are reported as coatings to prevent oxidation of Mg alloys.…”