INVESTIGATION OF THE EFFECT OF PREEXPOSURE TO SOME EXTRANEOUS IONS ONTHE CORROSION OF COPPER-NICKEL-ALLOYS IN SULFIDE-POLLUTED ARTIFICIAL SEAWATER

This paper describes the effect of pre-exposing Cu/Ni alloys for two d ays to various extraneous ions (corrosion inhibitors) on the corrosion rate of this alloy in artificial seawater polluted with sulfide (1000 ppm), under aerated and stirred conditions. The inhibitors tested wer e potassium chromate, sodium tungstate, sodium molybdate, sodium metav anadate, sodium nitrite, sodium benzoate, sodium silicate, sodium tetr aborate and sodium hexametaphosphate. In order to determine the effect of pre-exposure to these inhibitors on the susceptibility of Cu/Ni al loy to local attack, potentiodynamic tests were used. It was concluded that potassium chromate and sodium molybdate have a satisfactory pote ntial for protection of 90/10 Cu/Ni alloy against both uniform and loc al corrosion in highly polluted, aerated and stirred synthetic seawate r.