Effect of shot-peening on the passive film formation and corrosion of carbon steel in LiBr aqueous solution
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DOI 10.1007/s12206-020-2214-9
Journal of Mechanical Science and Technology 34 (10) 2020 Original Article DOI 10.1007/s12206-020-2214-9 Keywords: · Absorption chiller · LiBr aqueous solution · Carbon steel · Corrosion · Shot-peening · Passive film
Correspondence to: Siyoung Jeong [email protected]
Citation: Yoo, J., Han, S., Nam, Y., Jeong, S. (2020). Effect of shot-peening on the passive film formation and corrosion of carbon steel in LiBr aqueous solution. Journal of Mechanical Science and Technology 34 (10) (2020) ?~?. http://doi.org/10.1007/s12206-020-2214-9
Received April 14th, 2020 Revised
June 15th, 2020
Accepted June 15th, 2020 † This paper was presented at ICMR2019, Maison Glad Jeju, Jeju, Korea, November 27-29, 2019. Recommended by Guest Editor Insu Jeon
Effect of shot-peening on the passive film formation and corrosion of carbon steel in LiBr aqueous solution Juhyun Yoo1, Sangmoo Han1, Youngkwang Nam1 and Siyoung Jeong2 1
Department of Mechanical Engineering, Graduate School, Sogang University, Seoul 04107, Korea, Department of Mechanical Engineering, Sogang University, Seoul 04107, Korea
2
Abstract
In absorption chillers using LiBr aqueous solution, corrosion problems of carbon steel heat exchangers become more serious as the temperature of the generator increases. To reduce the corrosion problems, various surface treatment methods are applied such as a shotpeening. In this study, corrosion characteristics were investigated for untreated and shotpeened surfaces. Pyrex tube samples containing the specimens and LiBr aqueous solution with Li2MoO4 were made and put into a high temperature oven at 200 ℃. After 2000 hours, the surface and cross section of carbon steel specimens were observed using field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDS). It was found that the passive films have the characteristic of a double layer consisting of a thick MoO2 layer and thin Fe3O4 layer. Thicker passive films were observed on the shot-peened surface than the untreated one. As a result of corrosion depth measurement, the shot-peened specimens showed a slightly smaller uniform corrosion depth, however, they showed a much smaller pitting corrosion depth than the untreated ones. It is supposed that the shot-peened surface is more effective in preventing the pitting corrosion than uniform corrosion. The results of this study are expected to be applied effectively to the absorption chillers using LiBr aqueous solution to estimate and reduce the corrosion.
1. Introduction
© The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Recently, triple-effect absorption chillers which have higher generator temperature than double-effect ones are under development. In triple-effect absorption chillers, corrosion problems of carbon steel become more serious as the temperature of the generator increases. In order to reduce the corrosion in absorption chillers, some studies on corrosion characteristics of carbon steel in LiBr aq
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