Reducing Hydrogen Diffusion Losses by Modification of Fluoroplastic Barrier Coatings for Increasing Efficiency and Safety of Hydrogen Transportation

Abstract

High pressure hydrogen transport can cause hydrogen embrittlement of steel pipelines, leading to loss of mechanical integrity and failures. Therefore, protective internal coatings are required to reduce hydrogen permeability. In this work, the effect of composite fluoropolymer coatings modified with carbon nanotubes (CNTs), silicon carbide (SiC), and hexagonal boron nitride (h BN) on the hydrogen permeability of 1020 steel was studied using the Devanathan–Stachurski electrochemical method. The effective diffusion coefficient, steady state diffusion flux, and hydrogen concentration in the near surface layer were determined for uncoated steel, steel with a graphite layer, and various nanomodified PTFE coatings. Applying fluoropolymer coatings containing CNTs significantly reduced the effective diffusion coefficient and hydrogen flux compared to uncoated steel. Additional incorporation of SiC and h BN particles enabled further tailoring of the barrier properties. The PTFE based composition filled with CNTs and SiC provided the lowest effective diffusion coefficient and diffusion flux, which is attributed to the formation of a dense, low defect polymer structure with an elongated diffusion path. To evaluate the influence of the nanofiller composition on agglomeration and coating defectiveness, the ratio of reduction coefficients ηJ/ηD is proposed as an additional performance indicator. Diffusion loss calculations for a model pipeline section showed that the developed coatings substantially reduce hydrogen permeation through the steel wall, confirming their potential for internal pipeline protection in hydrogen transport and storage systems.