Investigation On Mechanism Of Heterocyclic Compounds As Corrosion Inhibitors And Its Self-Assembled Film On Copper In Seawater

Corrosion inhibitors hold the important status in the metal protection project, and they are playing more and more important role in the national economy construction. According to the present anti-corrosion of thermal energy equipments and anti-corrosion situation in other industry domain, it is an effective and economic method to use corrosion inhibitor. So, it becomes an interesting subject for chemists to study the corrosion inhibiting mechanism and develop or perfect the theory through various means and techniques.In this paper, two series including six kinds of newly heterocyclic compounds were synthesized to be studied as corrosion inhibitors of copper in seawater using weight loss experiment, electrochemical test, scanning electron micrographs (SEM), quantum chemical calculations and molecular dynamics. And then, we studied their corrosion inhibiting mechanism on copper, discussed theoretically the function way between the corrosion inhibitors and the metal surface and summarized the relationship between the molecular structure and their inhibiting efficiency. In order to extend the usage of inhibitor, the compounds employed to assemble on the copper, forming a solid, dense self-assembled film. Then the anticorrosion property and hydrophobic were detected. The results were drawn as follows:The triazole derivatives and thiadazole derivatives were proved to have positive inhibiting effect through weight loss experiment, electrochemical test and scanning electron micrographs. According to the experiments, the inhibit effective were more than90%when the concentration was100mg/L. Thermodynamic calculation suggests that the adsorption of the inhibitors was found to follow the Langmuir adsorption isotherm, and the adsorption of the inhibitors on copper surface involve physical as well as chemical adsorption. Free volume, interaction between particles and membrane, and self-diffusion performance of inhibitors are the three critical factors influencing the performance for prevention of corrosion particles diffusion by inhibitor membrane. Identical inhibitor membrane has more prevention ability for cations and anions (H3O+and Cl-) than that for H2O molecules.The MPT and MBT synthesized were assembled onto copper surface, and the effects of immersing time, concentration of inhibitors, ultrasonic irradiation and hydrophilic of the function groups are studied. The SEM shown that the morphology of the film is needle-like and globular, the contact angle is increased from72°to100°. The electrochemical tests shown that the layer become more solid after2hours treating or the concentration more than3×10-3M. Employing ultrasonic could reach the same inhibit effective in less treating time.In order to improve the quality of the self-assembled film, PTMS silane hybrid film was successfully prepared. Using electrochemical methods studied the inhibitive effect of PTMS film with different hydrolysis solvent, hydrolysis time, solution concentration and pH value. The results shown that the PTMS form a three-dimensional structure on copper surface, and then we got a density hybrid film with MPT and MBT, which can inhibit the corrosion process and improve the adsorption of the film.