Research Progress of Detection Techniques for Permeated Hydrogen

In order to achieve the goals of the“peak carbon dioxide emission and carbon neutrality”, it is essential to develop hydrogen energy. During the production, transportation, storage and use of hy drogen, hydrogen permeation is easy to occur and causes hydrogen damage to metal materials, which not only shortens the service life of pipelines and equipment, but also brings serious potential safety hazards. So it is of great significance to promote the development of permeated hydrogen detection techniques. Permeated hydrogen testing technology can be divided into indoor-and field-permeated hydrogen testing techniques. The indoor permeated hydrogen testing techniques include current method, hot/ melt extraction, thermal desorption spectroscopy (TDS), hydrogen micro-contact printing (HMP), scanning Kelvin probe force microscopy (SKPFM), secondary ion mass spectroscopy (SIMS), atom probe tomography (APT) and neutron radiography (NRG). The field permeated hydrogen testing techniques include hydrogenochromic method, hydrogen flux method, hydrogen probe method, hydrogen sensor, as well as field Kelvin probe (FKP) technique. For the indoor testing, the principles and characteristics of several detection techniques were summarized and applicable scope was also introduced. The current method, hot/melt extraction and TDS are used to measure the average hydrogen concentration in materials, but none of the above methods have the ability of spatial resolution. The silver particles produced by the substitution reaction between Ag⁺ and H by HMP reflect the distribution and diffusion path of hydrogen, but it is not certain whether Fe participates in that. By continuously detecting the potential of a certain position, SKPFM can reveal the hydrogen enrichment and the dynamic process of diffusion in a specific position. However, when current/potential is applied on the sample surface, it will disturb the test results. Both SIMS and APT technology rely on mass spectrometry, and have spatial resolution but their measuring chamber need to be filled with deuterium to eliminate the influence of background hydrogen. NRG can judge the concentration and distribution of hydrogen by detecting the hydrogen intensity and bright area, but its spatial resolution can only reach micron level. For the field testing, the parameters of several testing equipment provided on the market are investigated in this article, while the principle, application scope, advantages and disadvantages of each method are also summarized. Finally, some suggestions are put forward for the future development of hydrogen permeation detection methods.