engleski

Corrosion protection of Cu70Ni30 alloy by phosphonic acids

Phosphonic acids are commonly used as corrosion inhibitors for various metals and alloys. Phosphonic acids easily chemisorb on many metals and show good resistance to hydrolysis because of the hydrolytic stability of P-O- metal bonds. In this work several long chain phosphonic acids are examined as possible corrosion inhibitors for cupronickel alloys (Cu70Ni30) in simulated seawater (3% NaCl). Cupronickel alloys are commonly used in marine environment because of their high corrosion resistance and phosphonic acids could be applied in that kind of environment because of their non-toxic properties. Protective layer is formed by immersion in ethanol solutions of phosphonic acid. Different parameters, like solution concentration, drying temperature, surface roughness, etc., are varied during preparation to examine their influence on stability and protectiveness of such formed organic layer. Studies are performed by electrochemical methods: polarization measurements and electrochemical impedance spectroscopy. Contact angle measurements and FTIR spectroscopy are performed for surface layer investigations. The results of this investigation show that long chain phosphonic acids remarkably increase the corrosion resistance of cupronickel alloys in artificial seawater.

Cupronickel alloys; phosphonic acids; self-assembled monolayers; marine corrosion protection

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