Abstract
The galvanic corrosion behavior of three metal alloys commonly used in water desalination plants was investigated using coupled multielectrode arrays consisting of aluminum-brass (HAl77-2), titanium alloy (TA2), and 316L stainless steel (316L SS). The three electrode types were coupled galvanically and arranged in different geometric configurations. Their corrosion behavior was characterized as a function of the chloride concentration. The potential and current distributions of the three-electrode coupling systems display electrochemical inhomogeneity. Generally, the aluminum-brass wires are anodic versus the titanium alloy and stainless steel. The titanium alloy acts as a primary cathode, and the 316L SS acts as a secondary cathode. The corrosion rate of aluminum-brass depends on the concentration of chloride ion, with a maximum corrosion rate at a chloride concentration of 2.3 wt %. In terms of geometrical arrangements, when the anodic HAl77-2 wires are located on the edge and are connected to the 316L SS wires in the coupling system, the main anodic area enlarges, especially in the area adjacent to the 316L SS wires. When the HAl77-2 wires are located between (in the middle of) the two other types of wires, the corrosion rates are higher than the corrosion rates observed from the other two geometrical arrangements.
Highlights
According to estimates by the United Nations, nearly 1.8 billion people worldwide will experience severe water scarcity by 2025 [1]
The results indicate of the three metal alloys wires showed an electronegative directional shift with various chloride of the three metal alloys of wires showed an electronegative directionalthe shift with various chloride that, for the concentration chloride ionsbecame below
This finding suggests to the total electrode working area, each wire surface can be assumed to be that the corrosion of uniform
Summary
According to estimates by the United Nations, nearly 1.8 billion people worldwide will experience severe water scarcity by 2025 [1]. Desalination has been widely adopted in many countries to meet the demand for fresh water [2]. The three most commonly applied desalination technologies are multi-stage flash (MSF), reverse osmosis (RO), and multi-effect distillation (MED) [3]. The evaporators of the MSF and MED technologies are generally constructed with three metal alloys (aluminum-brass, titanium, and stainless steel) and require long-term operation under the aggressive conditions of seawater desalination. Distillation plants are susceptible to the corrosion induced by high chloride concentrations [4], and galvanic corrosion between dissimilar metals is inevitable over time. The behavior of two galvanically coupled dissimilar metals is relatively well understood, little effort has been made to study the behavior of more than two galvanically coupled metal alloys
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