Cathodic reaction kinetics and its implication on flow-assisted corrosion of aluminum alloy in aqueous ethylene glycol solution

Abstract

The cathodic reaction kinetics and anodic behavior of Al alloy 3003 in aerated ethylene glycol-water solution, under well-controlled hydrodynamic conditions, were investigated by various measurements using a rotating disk electrode (RDE). The transport and electrochemical parameters for cathodic oxygen reduction were fitted and determined. The results demonstrate that the cathodic reaction is a purely diffusion-controlled process within a certain potential region. The experimentally fitted value of diffusion coefficient of oxygen is 3.0 9 10 -8 cm 2 s -1 . The dependence of cathodic current on rotation speed was in quantitative agreement with Levich equation. At potentials more positive than the diffusion controlled region, the cathodic process was controlled by both diffusion and electrochemical kinetics. The electrochemical reaction rate constant, k 0 , was determined to be 1.1 9 10 -9 cm s -1 . There is little effect of electrode rotation on anodic behavior of Al alloy during stable pitting. However, fluid hydrodynamics play a significant role in formation of the oxide film and the Al alloy passivity. An enhanced electrode rotation would increase the masstransfer rate of solution, and thus the oxygen diffusion towards the electrode surface for reduction reaction. The generated hydroxide ions are favorable to the formation of Al oxide film on electrode surface.

Corrosion effects of CNT-nanofluids on different metals

“…All of the tests were mostly restricted to ethylene glycol with different concentrations and inhibitors. used rotating disc electrode (RDE) [4][5][6][7]. This work involved rotating the solution instead of the working electrode.…”

Inhibiting effect of cerium ions on corrosion of 3003 aluminum alloy in ethylene glycol–water solutions

“…Previous study conducted in Cheng's group [1][2][3][4][5][6][7][8][9] has demonstrated that Al alloy would experience pitting corrosion, flow-assisted corrosion and erosion-corrosion in the automotive cooling system, even in the inhibited coolant. It was reported [10,11] that, although inhibitors have been added in the commercial coolants, i.e., ethylene glycolwater solutions, most of them are not designed for corrosion inhibition of Al alloys, but for stainless steels and copper alloys that have been the conventional materials for fabrication of the automotive heat exchangers.…”

Inhibition of Corrosion of 3003 Aluminum Alloy in Ethylene Glycol-Water Solutions

“…Previous studies (Ref [1][2][3][4] have demonstrated that aluminum (Al) alloy experiences serious flow-assisted corrosion (FAC) in the automotive cooling system, even in the coolant with a commercial inhibitor addition. It is realized that most of the currently available commercial coolants contain inhibitor that is not designed for Al alloy, but for stainless steels and copper alloys (Ref 5-7).…”