Study On The Corrosion-Preventing Efficiency And Synergistic Action Of PhAMT

Metallic corrosion by acid cleaning is becoming more severe even if it's the effective way for surface pretreatment to remove the rust and dirt. Therefore, adding appropriate amount of corrosion inhibitors is the operative way to prevent metallic corrosion. Research of the synergistic effect of corrosion inhibitors is considered to have great significance in improving the performances of various components, and reducing the consumption and the cost of corrosion inhibitors.In this paper, a novel mercapto triazole kind corrosion inhibitor called PhABMT was synthesized, and then was mixed with corrosion inhibitors of various types, which included cathodic, anodic, precipitated, and mixed types. The inhibitor mechanism was discussed. Experiments proved the compounded system composed of PhABMT and other corrosion inhibitors played an important role on the surface of carbon steel mainly through the geometrical covering effect and the negative catalytic effect.The influences of temperature and pre-film time on corrosion inhibition efficiency were investigated. The results showed temperature made a big difference on most corrosion inhibitor systems. The corrosion inhibition efficiency had a dramatic reduction at a higher temperature. However, the system of PhABMT and urotropine showed a better adaptability:in particular the efficiency could still remain about 88% when the temperature reached 75℃above. The corrosion inhibition efficiency would be increased with the pre-film time prolonging, but it would be decreased when soaking in hydrochloric acid for a longer time. When it took more than 8 hour soaking, the corrosion inhibition efficiency would decline obviously or even disappeared.The corrosion inhibition efficiency of 0.2g/L PhABMT with other corrosion inhibitions, named cathodic, anodic, precipitated, and mixed types, was measured by electrochemical methods and SEM. It was found that the system of PhABMT with cathodic corrosion inhibitors had a protective effect on corrosion when the 45# steel was soaked in lmol/L HCl solvent, and also showed a great synergistic effect in the event that triethanolamine was chosen as the cathodic corrosion inhibitor. The corrosion inhibition efficiency would be more than 94% when the concentration of triethanolamine reached 1.6g/L, therefore, the concentration of the inhibitor mentioned above had a deep influence on the efficiency.Compared to the corrosion inhibitor of the single component,0.4g/L PhABMT, the maximum efficiency of the system of PhABMT and anodic inhibitor called sodium benzoate, could reach 91% or higher, but was lower than the system of PhABMT and triethanolamine. The result showed a better synergistic effect between sodium benzoate and PhABMT.In addition, the system of PhABMT and precipitated corrosion inhibitor called sodium acetate had a good synergistic effect. The corrosion inhibitor efficiency could reach more than 96% when its concentration was 1.4g/L.On the contrary, the efficiency of the system of PhABMT and mixed corrosion inhibitor, named sodium silicate, was around 88%, which was lower than that of 0.4g/L PhABMT. The reason for which might be that adding sodium silicate to the solution would easily lead to precipitate, further causing the system to be instable, and consequently the corrosion inhibitor efficiency declined.