Effects of Trace Cl−, Cu2+ and Fe3+ Ions on the Corrosion Behaviour of AA6063 in Ethylene Glycol and Water Solutions

Abstract

The effects of Cl − , Cu 2+ and Fe 3+ ions and their combinations on the corrosion behaviour of aluminium alloy 6063 (AA6063) in ethylene glycol and water solutions at 50 °C were investigated by electrochemical and immersion methods. Cl − resulted in pitting corrosion of the alloy. In the Cl − -free solutions, Fe 3+ was prone to accelerate uniform corrosion, while Cu 2+ tended to accelerate pitting corrosion. Severe pitting corrosion of AA6063 was observed in the cases of Cl − combined with Cu 2+ or Fe 3+ , especially in the case of Cl − combined with Cu 2+ and Fe 3+ ions.

Synthesis and Mechanism of Co2+/Sr2+ Codoped Magnetic Lanthanum Cuprate with Excellent Corrosion Resistance

“…Therefore, Cu 2+ was easily released from the lattice and then participated in the formation of the corrosion products. In addition, in the infrared spectrum, the characteristic peak of Fe–O bonding located between 454 and 548 cm –1 in the La 1.96 Sr 0.04 Cu 0.98 Co 0.02 O 4 coating was significantly red-shifted compared with the pure epoxy coating, indicating the appearance of a more stable structure, which was likely to be the conclusion of Cu 2+ on the Fe–O structure and the formation of a stable Fe–O–(Cu) structure on the iron oxide surface . La 1.96 Sr 0.04 Cu 0.98 Co 0.02 O 4 coating showed a Cu–OH characteristic vibrational peak at 1061 cm –1 , indicating the formation of more diverse passivation species, thus providing better interfacial protection for the Fe substrate …”

“…In addition, in the infrared spectrum, the characteristic peak of Fe−O bonding located between 454 and 548 cm −1 in the La 1.96 Sr 0.04 Cu 0.98 Co 0.02 O 4 coating was significantly red-shifted compared with the pure epoxy coating, indicating the appearance of a more stable structure, which was likely to be the conclusion of Cu 2+ on the Fe−O structure and the formation of a stable Fe−O−(Cu) structure on the iron oxide surface. 42 La 1.96 Sr 0.04 Cu 0.98 Co 0.02 O 4 coating showed a Cu−OH characteristic vibrational peak at 1061 cm −1 , indicating the formation of more diverse passivation species, thus providing better interfacial protection for the Fe substrate. 43 The passivation effect of the corrosion products was further evaluated by observing the morphological structure of the rust of each coating after 30 days of corrosion in 3.5 wt % NaCl solution.…”