Realization of synergism in 1-, 2-, 3-benzotriazole trimolybdate, tungstate, and chromate corrosion inhibitors

The inhibiting action of new 1-, 2-, 3-benzotriazole trimolybdate, tungstate, and chromate compounds is explained by the presence of intramolecular synergism as a result of which the coefficient of inhibition of the corrosion rate of steel in water becomes much higher than the total inhibition coefficient of the rate of corrosion by compositions based on benzotriazole and the corresponding oxoanions. The 1-, 2-, 3-benzotriazole trimolybdate, tungstate, and chromate compounds are inhibitors of mixed action inhibiting both electrode reactions and shifting the compromise potential to less negative values. According to the data of impedance tests and the results of evaluation of the degree of packing of these compounds on the steel surface, we conclude that their inhibiting effect is caused by chemisorption satisfactorily described by the Frumkin-Temkin isotherm.