Abstract: The weight-loss and electrochemical methods were used to investigate the corrosion behavior of metallic zinc in phosphoric acid solutions with or without dodecyl amine(DDA). The corrosion rate expressions were formulated and the corresponding kinetic parameters and thermodynamic constants were calculated. From the results of electron spectroscopy for chemical analysis (XPS), it was found that, over the temperature range of 40～70 ℃, zinc showed good self corrosion inhibition due to the coverage of Zn(OH)x produced. On the other hand, in the temperature range of 30～40 ℃, since DDA-H3PO4 and several other compounds were adsorbed on zinc surface, DDA exhibited powerful corrosion inhibition. The mechanism for corrosion inhibition was discussed by the adsorption theory.

Key words: Zinc, Phosphoric acid, Dodecyl amine (DDA), Adsorption, Corrosion inhibition