Electrochemical corrosion characterization of nickel aluminides in acid rain

Abstract

Nickel aluminides have been extensively studied in recent decades to replace superalloys, in some components of aircraft turbines, because they have excellent corrosion resistance. Many industrial cities have the problem of air pollution, which has forced the study of the degradation of these alloys in the presence of acid rain. The aim of this work is to study the electrochemical corrosion behavior of nickel aluminides in a medium of simulated acid rain. Potentiodynamic Polarization, Linear polarization resistance curves, Rp, Nyquist data and Bode curves obtained by electrochemical impedance spectroscopy were used to study the corrosion behavior of two intermetallic compounds. The polarization curves show that both intermetallic Ni 3 Al and NiAl have very similar corrosion potential, showing a slightly nobler behavior the NiAl intermetallic. The intermetallic Ni 3 Al has an active-passive behavior where the anode branch presents a general dissolution of the alloy, indicating that it is under cathodic control. NiAl intermetallic shows an active dissolution region, followed by a passive behavior. At longer immersion times, Ni 3 Al intermetallic has a higher polarization resistance, which means a lower corrosion rate.

EFFECT OF HEAT TREATMENT ON CORROSION RESISTANCE OF Al-Ni-Mn EUTECTIC ALLOY IN 3.5% NaCl SOLUTION

“…These results are in full agreement with the open circuit potentials (685 mV, -693 mV and -761 mV) found in our study. Engelbert H. Padilla et al [18], in their study investigating the corrosion behavior of NiAl and Ni3Al intermetallics in acid rain, stated that both intermetallic phases have similar corrosion potential. They found the Ecorr and Icorr values for Ni3Al intermetallic to be -339.21 mV/SCE and 0.54x10 -3 mA/cm 2 , respectively.…”

“…Similarly, Wislei R. Osório et al [17], in their study on the electrochemical corrosion behavior of Al-5%Ni(wt) alloy powders in 0.05 M NaCl solution, they stated that samples with a finer structure approached the positive side more and had higher corrosion resistance. In another study, Engelbert H. Padilla et al [18], in their study on the corrosion behavior of NiAl and Ni3Al intermetallic in acid rain, stated that both intermetallic phases have similar corrosion potential.…”

Corrosion of an Additively Manufactured Ti6Al4V Alloy in Saline and Acidic Media

“…Most of the published reports were focused on transport-related environments such as HCl, H 2 SO 4 , and mostly NaCl [27]. The effect of the so-called acid rain, resulting from the presence of NOx, SO, and H 2 S, among other pollutants in the air, has raised concerns in the construction [28,29] and aviation industries [30]. However, there is a general lack of literature dealing with the electrochemical response of Ti and its alloys in acid rain conditions [31].…”