Study On Galvanic Corrosion Behaviour Between Typical Marine Materials In Seawater

Copper, Q235steel,907steel and titanium alloy are several metal materials, which are commonly used for marine industry. In the design of industrial products, a pure material need to be coupled with other materials so as to meet the mechanical and electrical demands. Because of the differences in physical or chemical properties, galvanic corrosion happened inevitably, thus causing heavy losses to the industry. So the research of galvanic corrosion of these metals is of great importance.The corrosion behavior of three couples comprised of copper/Ti, Q235steel/Ti and907steel/Ti are studies in this paper. Electrochemical impedance spectroscopy(EIS), electrochemical noise (EN) and scanning electron microscope (SEM) are used to measure the corrosion rate, cerrosion types and corrosion morphology. Compare these characteristics with the pure metals to judge the corrosion pattern of galvanic couples.The study shows that when coupled copper, Q235steel, or907steel with Ti, the general corrosion characteristics of the galvanic couple are nearly the same to the single metal corrosion. The corrosion process of copper/Ti couple experienced diffusion of the corrosion medium, pitting of metal matrix and last a stable uniform corrosion, the corrosion rate increases first and then decreases,which are same as the copper corrosion. The corrosion process of Q235steel/Ti couple and Q235steel are comprised of slow reaction of diffusion, fast pitting reaction and slow reaction of uniform corrosion period. The corrosion rate of both907steel/Ti couple and907steel, increases sharply first, then tends to be stable slowly.It is found that the total energy of galvanic couple copper/Ti is smaller than that of copper, which indicates the copper in galvanic couple is harder to corrode than single copper. The total energy of galvainc couple907steel/Ti and Q235steel/Ti are larger than that of907steel or Q235steel, which indicates that907steel and Q235steel in galvanic couple is easier to corrode than single907steel and Q235steel.