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For ensuring the long-term performance of an Ag/AgCl reference electrode, a calibration technique was developed by using the linear relationship between the electrical conductivity and the KCl concentration of an internal electrolyte. It was observed that the electrical conductivities increased with an increase of the KCl concentration of the internal electrolyte, and the potentials of the Ag/AgCl electrode shifted anodically with a decrease of the KCl concentration. For simulating a long-term exposure of the electrode, we designed a reference electrode with a tiny perforation to accelerate the diffusion of the internal electrolyte. During the acceleration tests, the potentials of the Ag/AgCl electrode were shifted by almost the same amount as the potentials calculated from the change of the electrical conductivity of the internal electrolyte. Consequently, this technique was confirmed to be applicable for the calibration of an Ag/AgCl electrode, especially when exposed to non-electrolytic aqueous solutions.

316L stainless steel is a promising material candidate for a hydrogen containment system. However, when in contact with hydrogen, the material could be degraded by hydrogen embrittlement (HE). Moreover, the mechanism and the effect of HE on 316L stainless steel have not been clearly studied. This study investigated the effect of hydrogen exposure on the impact toughness of 316L stainless steel to understand the relation between hydrogen charging time and fracture toughness at ambient and cryogenic temperatures. In this study, 316L stainless steel specimens were exposed to hydrogen in different durations. Charpy V-notch (CVN) impact tests were conducted at ambient and low temperatures to study the effect of HE on the impact properties and fracture toughness of 316L stainless steel under the tested temperatures. Hydrogen analysis and scanning electron microscopy (SEM) were conducted to find the effect of charging time on the hydrogen concentration and surface morphology, respectively. The result indicated that exposure to hydrogen decreased the absorbed energy and ductility of 316L stainless steel at all tested temperatures but not much difference was found among the pre-charging times. Another academic insight is that low temperatures diminished the absorbed energy by lowering the ductility of 316L stainless steel.

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