Influence of chloride ion concentration and temperature on the corrosion of Cu–Al composite plates in salt fog

Abstract

In this work, the effects of temperature and chloride ion concentration were evaluated for the corrosion behavior of Cu–Al composite plates exposed to salt spray. There were three diffusion layers at the interface between Cu and Al, which were Al4Cu9, AlCu and Al2Cu, respectively. Corrosion only appeared on the diffusion layers and the aluminum, amongst which Al2Cu was the most vulnerable to corrosion, AlCu and Al were the second most vulnerable while the corrosion resistance of Al4Cu9 was second to the Cu. When the concentration of NaCl was lower than 3 wt%, the increased concentration had an obvious effect on the mass loss of the corrosion for the Cu–Al composite plates. The kinetic constant of corrosion increased with the increasing NaCl concentration. When the concentration of NaCl increased from 1 wt% to 3 wt%, the kinetic constant of corrosion increased by 31 times. With the concentration of NaCl increasing to 5 wt%, the kinetic constant of corrosion was 4.6 times that of 3 wt% by weight. In addition, the kinetic constant of corrosion was affected by temperature. With an increase of temperature, the kinetic constant of corrosion initially increased, and then decreased. The kinetic constant of corrosion reached its maximum value at 45 °C. Finally, the results of electrochemical testing showed that an increase of the chloride ion concentration (CIC) accelerated the corrosion of Cu–Al composite plates, and the corrosion attack was the worst under 45 °C.