Electrochemical Sensors for Monitoring Hydrogen in Steel Available to Purchase

Information obtained from two amperometric sensors and from a potentiometric sensor for monitoring hydrogen (H) in steel in contact with corrosive solutions saturated with hydrogen sulfide (H₂S) at ambient temperature was compared. The apparent diffusion coefficient (D_app) for H in the steel as determined by experiments using the amperometric sensors was shown to be independent of H concentration in the steel (c_H). Experiments with the potentiometric sensor indicated D_app values increased with increasing c_H. The calculated H concentration at the surface of the steel in contact with the corrosive medium (c_hi), as obtained from the two amperometric sensors, showed poor agreement. The equivalent pressure of H in the steel $(pH2eq)$⁠, as calculated from the voltage measurement of the potentiometric sensor, was strongly dependent on pH of the corrosive solution.