Barrier coatings for the reduction of hydrogen permeation in tank and transport systems

 
For hydrogen tanks and similar applications, metallic materials (e.g., steel or aluminum) are still predominantly used today, either as solid materials or as liners in polymer materials, presenting significant additional weight. In order to utilize lightweight materials such as fiber-reinforced plastics for fuel tanks, which themselves do not provide an adequate barrier against hydrogen permeation, Fraunhofer IFAM is developing barrier coatings that significantly reduce hydrogen permeability, thereby offering versatile opportunities for lightweight construction in aerospace as well as other sectors. Fraunhofer IFAM possesses extensive expertise in the development of barrier coatings against gases and liquids for a wide variety of applications. The focus is specifically on hydrogen barrier coatings. The need for these coatings extends beyond the aerospace industry to the transport sector and the entire hydrogen energy sector. In recent years, barrier coatings have been successfully developed for the inner walls of fuel tanks in the aerospace sector to prevent hydrogen permeation. The goal is to utilize lightweight materials such as fiber-reinforced plastics for the construction of tanks, which do not provide an adequate barrier against hydrogen. The fuel tanks are intended for liquid hydrogen (LH2), where gaseous hydrogen is also present above the liquid. The barrier coating is designed to function for hydrogen in both aggregation states. The coating solution developed within the "CryoCoat" project is based on a polymeric binder that contains plate-like pigments on a metal or silicate basis, which serve as the actual diffusion barrier. The formulations can be processed using coating technology and applied to large structures via spray application. Within the aerospace project, a prototype coating has been developed, demonstrating its barrier effectiveness against hydrogen. This coating is currently being adapted in further projects. In the "TransHyDE" project, the coating is being tailored for use in gas pipelines and tanks for hydrogen storage as an energy carrier, as completely different requirements for the coating must be met for this application. Here, Fraunhofer IFAM also applies its extensive expertise in the development of barrier coatings against gases and liquids to develop the ideal coating for each specific application.