Investigation of the initial stage of crevice corrosion on Al99.5 by electrochemical noise analysis

Abstract

The electrochemical noise analysis (ENA) is a powerful tool to investigate the initial state of local corrosion processes as pitting corrosion or crevice corrosion on aluminium alloys. The focus of this work lays on Al99.5 (AA1050). The electrochemical measurements were carried out in solutions of 0.01 mol/1 Na2SO4 + 0.01 mol/1 NaCl and 0.01 mol/1 Na2SO4 + 0.1 mol/1 NaCl. In spite of the good corrosion protection and the very low passive current density the noise activity in the early state of corrosion can be very well observed. ENA was performed by using current noise measurement under potentiostatic control. The effect of chromate inhibitors on the noise activity of the initial state of corrosion on Al99.5 is surprisingly negligible. This phenomenon is discussed in the paper. The intermetallics are preferred sites for the initiation of corrosion processes. The microstructure investigation has shown that technically pure aluminium has a small content of iron rich intermetallics (Al3Fe). The microstructure of the aluminium alloys (e.g. AA2024 and AA6013) is characterised by a number of intermetallic phases (e.g. Al2Cu, Al2CuMg, Mg2Si). Because of the small content of additional elements in Al99.5 the influence of intermetallics should be negligible. Therefore, the corrosion behaviour of Al99.5 can be considered as a reference for medium and high-strength aluminium alloys. On that score, it is very important to know the liability of Al99.5 against crevice corrosion. Entnommen aus <a href="http://www.fiz-technik.de/db/b_tema.htm" target="_blank">TEMA</a

The corrosion behavior of carbon steel in CO2‐saturated NaCl crevice solution containing acetic acid

“…Many researches have been done to study the crevice corrosion in passive systems 15–19, such as stainless steel in NaCl solution and carbon steel in NaCl + NaHCO 3 solution. However, the crevice corrosion of carbon steel in CO 2 ‐saturated NaCl solution in the presence of acetic acid (HAc) has not been reported though the corrosion behavior of carbon steel in this system is widely concerned 20–22.…”

Susceptibility of 316L stainless steel to crevice corrosion in submersible solenoid valve

“…In recent years, various electrochemical techniques, such as cyclic potentiodynamic polarization [4][5][6][7][8][9], potentiostatic polarization [4][5][6][7], galvanostatic polarization [10], tsujikawa-hisamatsu method [11], electrochemical noise method [12,13] and dynamic electrochemical impedance spectroscopy [14], are being used to asses the crevice corrosion process. The effects of variables, such as crevice former materials, applied torque on crevice formers, chemical elements and crevice geometries on crevice corrosion behavior, have been studied [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”

“…The effects of variables, such as crevice former materials, applied torque on crevice formers, chemical elements and crevice geometries on crevice corrosion behavior, have been studied [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21].…”