Study On The Anti-corrosion Technology In Splash Zone And Inhibition Effect Of Inhibitors In Wet/Dry Cyclic Conditions

Splash zone is the most severe corrosion damage area in marine environment.Petrolatum tape cover (PTC) has been proved to be an effectively technology toprotect the steel structures away from corrosion in splash zone. Petrolatum is one ofthe important components in PTC, which properties affect the stability and durabilityof PTC. It would be significantly to optimize the composition of petrolatum. Testmethods according to the local standards of Shandong Province such as temperaturefluidity and cone penetration, as well as salt spray and electrochemical impedancespectroscopy were performed to detect the properties of petrolatum. Kinds of base oil,pour point depressant, and calcium stearate were added to improve the petrolatum.The petrolatum based on liquid paraffin make a good performance when the contentof calcium stearate up to3%.Note that wet/dry cyclic conditions greatly account for corrosion of steelstructures in the splash zone. Inhibitors in petrolatum can protect the steels from theviewpoint of electrochemical corrosion. By studying the corrosion in wet/dry cyclicconditions, the important influence factors of corrosion as well as corrosion inhibitionin the real system can be determined. The inhibition effect of tannic acid andpolyaspartic acid on mild steel corrosion in seawater wet/dry cyclic conditions wasstudied by weight loss and electrochemical methods. X-ray diffraction, and Fouriertransform infrared reflection are performed to study the corrosion inhibition. Resultshows that the inhibition efficiency run up to86%when the concentration of tannicacid was1g/L. The inhibition effect of the compound is attributed to ferric tannatefilm formation on the steel surface. The mixed inhibitors contain polyaspartic acidleading to higher inhibition efficiency up to92.6%. The metal surface immersed inmixed inhibitors was in better condition compared to others according to the results ofSEM.In order to enlarge the use of polyaspartic acid, the inhibition effect ofpolyaspartic acid and its synergistic effect with KI on mild steel corrosion in H2SO4 solution are studied by weight loss, electrochemical methods, SEM, and XPS. Theinhibition efficiency increases to95%with the presence of KI. Results show thatiodide ion promotes the film formation of polyaspartic acid greatly.