Scientific Reports (Mar 2024)

Hierarchical channel morphology in O-rings after two cycling exposures to 70 MPa hydrogen gas: a case study of sealing failure

  • Chang Hoon Lee,
  • Jae Kap Jung,
  • Kyung Sook Kim,
  • Chang Jong Kim

DOI
https://doi.org/10.1038/s41598-024-55101-w
Journal volume & issue
Vol. 14, no. 1
pp. 1 – 11

Abstract

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Abstract This study investigates the impact of high-pressure hydrogen gas exposure on the structural and morphological characteristics of O-ring materials. O-ring specimens undergo two cycles of sealing under 70 MPa hydrogen gas, and their resulting variations are examined using advanced characterization techniques, including powder X-ray diffraction (PXRD), small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Our findings reveal that the lattice parameters of the O-ring material show no significant changes when exposed to 70 MPa hydrogen gas. However, in the micrometre range, the formation of a hierarchical channel morphology becomes evident. This morphology is accompanied by the separation of carbon black filler from the rubber matrix, contributing to mechanical weakening of the O-ring. These observations can be attributed to the pressure gradient that develops between the inner and outer radii of the O-ring, resulting from compression forces acting perpendicularly to the radial direction due to clamp locking.