Sodium dodecyl benzene sulfonate (“SDBS”for short) is white or light yellow powder or flake solid. It’s difficult to volatilize and soluble in water. It becomes translucent solution in water. Its chemical property is stable for the alkali, dilute acid and hard water. It’s mainly used as anionic surfactants. 

 

Corrosion inhibitor is a kind of chemical substances which can prevent or slow down the corrosion or a mixture of several chemicals and when it exists in the environment in the appropriate concentration and forms. In general, corrosion inhibitors are those used in metal surface protection material. Adding trace or a small amount of such chemicals can make the corrosion speed of metal materials in the medium obviously decrease to zero. At the same time, it also can maintain the original metal materials of physical and mechanical properties unchanged. Fair use of corrosion inhibitors is the effective method to prevent metals and their alloys to occur corrosion in the environment medium. 

 

In recent years, with the enhancement of human environmental protection consciousness, the development and application of corrosion inhibitors are paying more and more attention to the requirements of environmental protection. And traditional inhibitor often has certain harm to the environment. Because tungstate has low toxicity and no harm to the environment, the human body and crops, nor causes microorganism growth, it is environmental friendly corrosion inhibitors and it has aroused widespread interest of people. Because single tungstate corrosion efficiency is not high and the dosage is bigger, the cost is higher. Thus the synergistic inhibition effect of the composite of sodium tungstate and other corrosion inhibitor has drawn attention of people. Corrosion of cast iron in 3.5% NaCl solution is serious. The composite inhibitor of sodium tungstate and SDBS has good synergistic inhibition effect by studied by immersion test, method of weight loss and polarization curves.

 

Through these methods we can draw the conclusions:

(1) In 3.5% NaCl solution, when adding sodium tungstate inhibitor alone and the mass fraction is 0.5%, the cast iron corrosion effect is best and the corrosion rate can reach 82.5%. When adding sodium dodecyl benzene sulfonic alone and the mass fraction is 0.9%, cast iron corrosion effect is best and the corrosion rate can reach 67.5%.

(2) The corrosion effect on cast iron of the composite corrosion inhibitor composed of 0.2%mass fraction sodium tungstate and 0.1% mass fraction sodium dodecyl benzene sulfonic is best. The corrosion rate can reach 91.3%. It has good synergistic inhibition effect. At the same time, it can reduce the dosage of sodium tungstate and SDBS.