ベンゾトリアゾールの防錆作用に及ぼす水溶性有機硫化物の効果

Abstract

The effects of water-soluble organic sulfides on the inhibitive effect of benzotriazole for iron were studied. In this paper, sodium dimethyl dithiocarbamate, sodium diethyl dithiocarbamate and sodium dibuthyl dithiocarbamate were used as water-soluble organic sulfides. The inhibitive properties of benzotriazole were determined by measuring the weight loss of iron specimens as usual. By sulfide treatment of iron, that is, putting the iron specimens in sulfide solutions, the inhibitive properties of benzotriazole on iron in neutral solutions were increased and the velocity of dissolution of iron in acid solution was increased. It was shown in earlier paper that the change of potential of iron in benzotriazole solution was agreed to Langmuir's adsorption formula, expressed as follows: x=kk1C/(1+kC), where x is the amount of substances adsorbed per unit area at concentration C, and k and k1 are constants, supposing that the change of potential is in proportion to x as Uhlig and Geary had reported. So the changes of k and k1 by sulfide treatment were studied. As the result, it was recognized that the larger the constants k and k1 are, the more the inhibitive properties of benzotriazole increase. Therefore, it was thought that the surface of iron was activated by sulfide treatment and then the adsorption of benzotriazole on the surface of iron became easy.NMR spectra of each sulfide solutions weree measured and it was found that there was a linear relation between the chemical shift of the nearest proton of N atom and the inhibitive properties of benzotriazole corresponding to each sulfide treatments.