Stainless steel corrosion scale formed in reclaimed water： Characteristics, model for scale growth and metal element release

Stainless steels generally have extremely good corrosion resistance, but are still susceptible to pitting corrosion. As a result, corrosion scales can form on the surface of stainless steel after extended exposure to aggressive aqueous environments. Corrosion scales play an important role in affecti...

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Bibliographic Details
Published in:Journal of environmental sciences (China) 2016-10, Vol.48 (10), p.79-91
Main Authors: Cui, Yong, Liu, Shuming, Smith, Kate, Hu, Hongying, Tang, Fusheng, Li, Yuhong, Yu, Kanghua
Format: Article
Language:English
Subjects:
Chromium release
Corrosion
Corrosion scale
Materials Testing
Models, Chemical
Reclaimed water
Stainless steel
Stainless Steel - chemistry
Water - chemistry
Water quality
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Summary:Stainless steels generally have extremely good corrosion resistance, but are still susceptible to pitting corrosion. As a result, corrosion scales can form on the surface of stainless steel after extended exposure to aggressive aqueous environments. Corrosion scales play an important role in affecting water quality. These research results showed that interior regions of stainless steel corrosion scales have a high percentage of chromium phases. We reveal the morphology, micro-structure and physicochemical characteristics of stainless steel corrosion scales. Stainless steel corrosion scale is identified as a podiforrn chromite deposit according to these characteristics, which is unlike deposit formed during iron corrosion. A conceptual model to explain the formation and growth of stainless steel corrosion scale is proposed based on its composition and structure. The scale growth process involves pitting corrosion on the stainless steel surface and the consecutive generation and homogeneous deposition of corrosion products, which is governed by a series of chemical and electrochemical reactions. This model shows the role of corrosion scales in the mechanism of iron and chromium release from pitting corroded stainless steel materials. The formation of corrosion scale is strongly related to water quality parameters. The presence of HCIO results in higher ferric content inside the scales. Cl- and SO2- ions in reclaimed water play an important role in corrosion pitting of stainless steel and promote the formation of scales.
ISSN:1001-0742
1878-7320
DOI:10.1016/j.jes.2015.12.035