Hydrogen transport conditions and effects in cathodically polarized AF1410 steel

Hydrogen permeation of AF1410 steel membranes due to cathodic polarization using the Devanathan and Starchurski double cell (DSDC) with 0.1M H2SO4 + 1 g/L Na2HAsO47H2O, and 0.1M NaOH media in the input and exit cells, respectively, under Galvanostatic conditions depended on the polarization current density, membrane thickness, and surface roughness. For a 0.35-mm-thick membrane, the steady-state hydrogen permeated using increasing polarization currents from 1.00 to 10.00 mA varied correspondingly from 0.6*10-5 (mol H/m2s) to 1.03*10-5 mol H/m2s, with accompanying transient rates or permeation rates of 1.07*10-4 A/m2s to 4.40*10-4 A/m2s. With a constant polarization current density of 20 A/m2, the steady-state permeated hydrogen was in the range of 1.00*10-5 (mol H/m2s) to 3.50*10-5 (mol H/m2s), for 0.30-mm and 0.09-mm-thick membranes, respectively. The breakthrough times decreased from 2130 to 300 seconds with decreasing membranes thickness from 0.30 to 0.09 mm. The formation of blisters was observed more on the input side surface than on the exit-side surface and occurred for polarization charging current densities greater than 30.0 A/m2. The tendency for blister formation increased with decreasing material s surface roughness. Cracks accompanying blisters tended to form on both the input and exit-side surfaces only with continued charging following the attainment of steady-state permeation, though they were generally lower on the potentiostated exit side. The average effective permeation coefficient of hydrogen was determined to be 2.89*10-12 m2/s for membrane thicknesses ranging from 0.09 to 0.30 mm based on the slope method.