Acoustic-Emission Diagnostics of Corrosion Defects in Materials (a Survey). Part. 1. Detection of Electrochemical Corros
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ACOUSTIC-EMISSION DIAGNOSTICS OF CORROSION DEFECTS IN MATERIALS (A SURVEY). PART. 1. DETECTION OF ELECTROCHEMICAL CORROSION AND CORROSION FATIGUE V. R. Skal’s’kyi,1 Z. Т. Nazarchuk,1 І. Ya. Dolins’ka,1, 2 R. Ya. Yarema,3 and Т. V. Selivonchyk4 We analyze the main aspects of acoustic-emission diagnostics of the corrosion processes in structural materials and present the results of numerical investigations of the electrochemical corrosion by the method of acoustic emission. We also discuss the applicability of the method to the investigation of the corrosion fatigue of materials. Keywords: electrochemical corrosion, acoustic emission, corrosion fatigue, pitting corrosion.
Due to significant material losses caused by corrosion and the decrease in the reliability and safety of structures, the interest of the researchers to the investigation of its nature, development of procedures and means of its inhibition, and diagnostics of these processes permanently increases. Note that a noticeable progress has already been made in this field of knowledge. It is known that, by using protective measures, one can substantially reduce corrosion losses. However, the problem remains urgent and every step on the way of its solution is of great social and economic importance.
As one of the promising methods used for the diagnostics of corrosion processes, we can mention the method of acoustic emission (АЕ), which favorably differs from other the methods of nondestructive control by its high sensitivity. In what follows, we analyze its applicability for the detection and monitoring of corrosion processes and, in particular, of electrochemical and corrosion fatigue (CF). Corrosion-Induced Sources of АЕ Due to the sensitivity of the АЕ method to changes in the structural and mechanical characteristics of the material in the process of corrosion, the corresponding source of АЕ has its own specific properties [1]. Thus, the energy of АЕ caused by the dissolution of metal is insufficient for the detection of AE signals. In this case, even the maximum amplitude of АЕ does not exceed 10 µV. The fracture of thick oxide films on the surface of the metal causes explosive-type АЕ with relatively small amplitudes [2–5] due to the low energy consumption of the process. Pulses with an amplitude to 10 µV correspond to the disintegration of oxide films [6–8]. 1 2 3 4
Karpenko Physicomechanical Institute, Ukrainian National Academy of Sciences, Lviv, Ukraine. Corresponding author; e-mail: [email protected].
“Lviv Locomotive Repair Plant” Private Joint-Stock Company, Lviv, Ukraine. Luts’k National Technical University, Luts’k, Ukraine.
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 53, No. 3, pp. 7–17, May–June, 2017. Original article submitted February 9, 2017. 1068-820X/17/5303–0295
© 2017
Springer Science+Business Media New York
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V. R. SKAL’S’KYI, Z. Т. NAZARCHUK, І. YA. DOLINS’KA, R. YA. YAREMA,
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Т. V. SELIVONCHYK
The process of hydrogen release is one of the most powerful sources of AE in the course of corrosion
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