New Copper Corrosion Inhibition Properties

Copper tends to be corroded when it is in the environments with corrosive medium. To use correctly negative corrodent is to the effective method of preventing metal and its alloy from corroding in the corrosive condition. Rise and development of self-assembled monolayers technology puts forward a new method for the researchers to explore new copper inhibitors, and it has the extremely important theory value and the potential widely applications.In this paper self-assembly technology was used to prepared self-assembled monolayers (SAMs) of p-hydroxybenzoic acid and tributyl phosphate. The anticorrosion mechanism and adsorption behavior for the self-assembled monolayers (SAMs) on the surface of copper in 0.1 mol·L-1 NaCl solution were investigated by electrochemical polarization curves techniques and impedance spectroscopy. And the charge transfer resistance on surface of layers covered electrodes, double electric layer capacitance, corrosion potential, corrosion current density and the surface coverage of the films were studied. Furthermore the effect of the concentration of self-assembly solution, the temperature and macerating time of self-assembly system were discussed. Then protection efficiency was compared with BTA SAMs. The results indicated that: P-hydroxybenzoic acid and tributyl phosphate as new types of inhibitors, were liable to interact with copper forming SAMs on the surface of copper. The self-assembled monolayers (SAMs) of them changed the structure of the double electric layers and restrained both the processes of anodic oxidation and cathodic reduction. Electrochemical impedance spectroscopy (EIS) measurement results indicated that the charge transfer resistance of the copper electrode with SAMs increased greatly and its double electric layer capacitance decreased significantly. EIS measurement results indicated that the degree of coverage of the p-hydroxybenzoic acid SAMs on the surface of copper was 70.8%, the tributyl phosphate SAMs was 62.3%. Electrochemical polarization curves measurement results indicated that the protection efficiency (PE) of p-hydroxybenzoic acid SAMs was 73.4%, the tributyl phosphate SAMs was 67.4%, and the BTA SAMs was 74.7%. The results indicated the SAMs of p-hydroxybenzoic acid was compact and oriented, and effectively prevented the copper substrate from contacting corrosive ions, inhibiting the copper corrosion to a considerable degree, and the anticorrosive efficiency was better than tributyl phosphate SAMs. The adsorption processes of p-hydroxybenzoic acid and tributyl phosphate were exothermic reaction and belong to physical adsorption, and the adsorption behavior followed Langmuir isotherm. In order to improve the protection efficiency, the modification with p-hydroxybenzoic acid and BTA and tributyl phosphate and BTA were done to form a complex film. An increase in PE for the complex films were observed. EIS measurement results indicated that the charge transfer resistance of the copper electrode with complex film increased greatly and its corrosion current densities decreased significantly. The synergistic effect of p-hydroxybenzoic acid inhibitor and tributyl phosphate with BTA improved the protection efficiency. The PE were 89.1% and 80.2% respectively.