A mechanistic study on sulfur-induced passivity degradation on Alloy 800 in simulated alkaline crevice chemistries at temperatures ranging from 21 degrees C to 300 degrees C

摘要

Sulfur-induced degradation of the passive film on Alloy 800 in a simulated alkaline crevice (ACC) environment at 21-300 degrees C was evaluated using polarization curve, secondary ion mass spectrometry (SIMS) and Auger electron spectroscopy (AES). Experimental results indicated that sulfur has no noticeable detrimental effect on film properties at 21 degrees C and 90 degrees C, which is due to the formation of a negatively charged layer. However, sulfur has remarkable detrimental impact at 150 degrees C and 300 degrees C, which is attributed to the electrochemical reduction of the sulfur in thiosulphate and the subsequent incorporation of sulfur ions into the passive film. (C) 2015 Elsevier Ltd. All rights reserved.