Investgation Of The Corrosion Inhibition Of Organic Inhibitor For Copper In3.0Wt.%NaCl Solution

Due to its excellent thermal conductivity, good corrosion resistance and mechanical workability, copper is a material widely applied to various fields. But severe corrosion of copper and its alloys, however, has been reported in various environments, especially in the presence of chloride ions. To prevent and/or reduce the corrosion of copper, variety of methods have been proposed such as adding corrosion inhibitors and self-assembled monolayer. Among the various methods to avoid or prevent destruction or degradation of copper surface, the adding corrosion inhibitor is one of the best know methods of corrosion protection and one of the most useful on the industry.Corrosion inhibitors, imidazole, benzotriazole, polymer, and their derivatives have been widely investigated and application. All these studies reveal that organic compounds especially those with N, S O, and P show significant inhibition efficiency. But, unfortunately most of these compounds are not only expensive but also toxic to living beings. In order to develop new, cheaper and safer corrosion inhibitor, we investigated different organic compounds as copper corrosion inhibitors in3.0wt.%NaCl solution. The corrosion inhibition efficiency and inhibition mechanism of inhibitor were studied by weight loss, electrochemistry method, and quantum chemical calculation. The surface morphology of copper after adding inhibitor was conducted by surface characterization technique.The main work is carried out as follows:1. Corrosion control of copper in3.0wt.%NaCl solution by1-(4-chlorobenzyl)-1,2,4-triazole-3-thiolA novel and environmentally friendly triazole derivative, namely1-(4-chlorobenzyl)-1,2,4-triazole-3-thiol (CBTT), was synthesized, characterized, and investigated as a copper corrosion inhibitor in3.0wt.%NaCl solution. The corrosion protection effect of CBTT was researched by means of weight loss measurement, polarization, and electrochemical impedance spectroscopy (EIS) methods. The apparent morphology of copper adsorbed by CBTT was characterized by the SEM. The inhibition efficiency on copper increased with increasing inhibitor concentration. The adsorption mechanism of CBTT adsorbed on copper surface was invesitigated by quantum studies and the Langmuir adsorption isotherm was obeyed. The adsorption process of CBTT on copper surface includes both physisorption and chemisorption. The result of those measurements revealed that CBTT is an anodic inhibitor and behaves as good inhibition effect for copper in3.0wt.%NaCl solution.2. Corrosion control of copper in3.0wt.%NaCl solution by dithiothreitolDithiothreitol (DTT) was used as a copper corrosion inhibitor in3.0wt.%NaCl solution. Its corrosion inhibition for copper was investigated using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. Through changing the concentration and temperature of DTT, the optimizing conditions were found out. The results revealed that DTT acted as a mixing type inhibitor by chemisorption and physisorption on the copper surface. The inhibition efficiency on copper increased with increasing inhibitor concentration and decreased as the temperature inceased. The optimizing inhibition efficiency was achieved at3.0mM DTT when the temperature was20℃. The existence of DTT is examined using contact angle testing. Furthermore, quantum chemical study provided insight into the inhibition mechanism.3. Corrosion control of copper in3.0wt.%NaCl solution by polyethyleneimine and2,6-dimercaptopurineThe inhibiting effect of polyethyleneimine (PEI) and2,6-dimercaptopurine(DMP) on corrosion of copper in3.0wt.%NaCl solution was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy. When adding PEI alone in corrosive medium, the inhibition efficiency increased with increasing PEI concentration in a certain concentration range. But beyond this range, the inhibition efficiency slightly decreases with increasing concentration of PEI. After adding the PEI and DMP at the same time, corrosion inhibition efficiency increased significantly. The results revealed that PEI and DMP had synergistic inhibition effect on copper corrosion. The optimizing inhibition efficiency on copper was achieved when the concentration ratio of these two kinds of corrosion inhibitors was8.0mM PEI:0.2mM DMP.