2003 Volume 43 Issue 4 Pages 482-488
A Scanning Laser-Enhanced Electrochemical Microscope for Hydrogen detection (H-SLEEM) has been developed in order to in-situ visualize the distribution of hydrogen localized on a steel surface. Introduction and detection of hydrogen for the steel sheet was conducted by hydrogen permeation technique with a pair of electrochemical cells. When the hydrogen detection side under hydrogen permeation is irradiated with focused Ar laser, anodic current relating to hydrogen oxidation reaction is thermally enhanced at the irradiation spot and then anodic current increment corresponding to the hydrogen permeation rate at the spot is expected to be determined. In the case that whole the hydrogen detection side was irradiated with diffused laser, the anodic current increased and the current increment increased with an increase in the hydrogen permeation current. The use of focused laser also permitted the measurement of the anodic current increment depending on the hydrogen permeation current. The modulated laser provided more stable and reproducible current increment. When the specimen whose hydrogen entry side was masked except for a small exposed area in center was employed and the modulated laser was raster-scanned under hydrogen permeation, a very clear image of the two-dimensional distribution in the current increment corresponding to local hydrogen permeation rate on the detection side was obtained. It is concluded that the H-SLEEM can successfully visualize the localized hydrogen distribution on the steel surface.
