A mechanistic study of sulfur-induced passivity degradation of Alloy 800 in a simulated alkaline crevice environment at 300 A degrees C

作者：Xia Da Hai; Behnamian Yashar; Chen Xue Yuan; Luo Jing Li^*; Klimas Stan

来源：Journal of Solid State Electrochemistry, 2015, 19(12): 3567-3578.

DOI：10.1007/s10008-015-2822-y

• Alloy 800
• Thiosulfate
• Passive film
• Alkaline
• Degradation

Sulfur-induced degradation of the passive film on Alloy 800 in a simulated alkaline crevice (AKC) environment at 300 A degrees C was evaluated using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES). The reduced sulfur species (mainly S-2) from thiosulfate was incorporated into the passive film, increasing the Ni/Cr ratio in the film. Film thickness was reduced from 700 nm in an alkaline crevice solution without thiosulfate to 400 nm in an AKC solution with thiosulfate. The results from EIS modeling using an electrochemical equivalent circuit (EEC) and point defect model (PDM) also confirmed that reduced sulfur species increased the dissolution rate of the passive layer.

• 出版日期2015-12