THE EFFECT OF INHIBITION ON CORROSION RESISTANCE OF AISI 1020 IN SEA WATER

Abstract

This paper aims to study the effect of inhibitor addition to sea water on corrosion ratesof St 1020 according to AISI . Many corrosion specimens were papered from the metalof dimensions of (15*15*3) mm according to ASTM G71-31 then Optical microscopywas used to observe the microstructureCorrosion tests were investigated by electrochemical potential state cell in 3.5% NaClsalt water (sea water) where the test specimen represents the positive electrode (anode)pole while tungsten electrode represents the cathode, the voltage was determined byopen circuit and compared with the positional of metal in the electrochemical series thenvoltage was increased ±100 mv, at each 10mv. then record the current causes the changeof voltage which will called the corrosion current then calculating corrosion rate byusing Tafel equation.The inhibitors Sodium Nitrate (NaNo2) and Sodium molybdate in the concentration of5% in addition to a synergistic inhibition of the both inhibitors in equal percentage of2.5% for each one were added to the prepared sea water to show the effect of theseinhibitors on corrosion behavior, and then corrosion rate calculated using Tafleequation.Results show that all the used inhibitors have contributed to reduce the corrosion ratewhile using the synergistic (blend) inhibitors gives the best results; this is due to thesynergistic action of these inhibitors in reducing the anodic and catholic activities thuspromoting a continuous and protective film on the alloy from corrosion.