The effects of temperature, dissolved oxygen and the velocity of seawater, on the corrosion behavior of condenser alloys

Abstract

PurposeThe purpose of this paper is to study the effects of temperature, dissolved oxygen (DO) and velocity of seawater on corrosion behavior of three copper‐based alloys (admiralty brass, aluminum brass and Cu‐5Ni alloy used in condenser tubes).Design/methodology/approachA series of electrochemical tests were carried out in seawater at different temperatures and DO contents using both stationary and rotating‐disc electrodes in order to investigate the corrosion behavior of alloys under these conditions.FindingsIt was found that admiralty brass exhibited a significantly higher corrosion rate and Cu‐5Ni alloy was more resistant to corrosion than were the brasses. With increasing temperature, the corrosion rates of the brasses increased. Selective zinc dissolution took place over the whole temperature range. Increasing temperature decreased the corrosion rate of Cu‐5Ni alloy in seawater due to formation of a passive film. The passivation of the alloy could be explained by the presence of greater proportion of nickel at the metal surface. Brasses, especially admiralty brass, exhibited higher corrosion rates in high concentrations of DO, whereas the Cu‐5Ni alloy was virtually immune to corrosion under such conditions. Increasing the water velocity increased the corrosion rate of admiralty brass but velocity had no effect on the corrosion rate of aluminum brass and Cu‐Ni alloy.Originality/valueThis paper provides information about corrosion behavior of three copper alloys used for common condenser tubes. The study fulfilled the objective of the investigation and contributes to research on corrosion behaviors of copper alloys in seawater.