Preparation And Characterization Of Ir-Co/Ti Electrode Used In Soil

With the rapid development of industry, the corrosion and protection of underground metal components has been got further attention. The cathode protection as the most cost-effective method is widely used. The research and development of Ti-based metal oxide electrode as the impressed current cathodic protection with aid anode material have become particularly important.The thermal decomposition process is used to prepare Ir-Co/Ti anodes, and the effect of preparing technology parameter was investigated on the Ir-Co/Ti anodes in this paper. The microstructure, element compositions and distributions, phase compositions and structure of the Ir-Co/Ti anodes had been studied by means of scanning electron microscopy(SEM) with energy dispersive X-ray (EDX), electron probe microanalysis(EPMA), X-ray diffraction (XRD). And the electrochemical property was measured by anodic polarization curve, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). During this experiment, the deactivation mechanism was also explained. At last it was investigated that the best Ir-Co/Ti anodes'electrochemical behavior in soil with different water content, and compared with it in the H2SO4solution.Preparing technology parameter includes the metal ion's concentration, the mole ratio of Ir and Co, the thermal oxidation temperature and the brushing times. Ir-Co/Ti anodes was optimized with the potential of oxygen evolution reaction (OER), the current density and the CV charge as the main assessing items and finally, the optimized process parameters were determined, which was as followed:the metal ion's concentration0.2mol/L, thermal oxidation temperature 450℃, Ir:Co (mol)=2:1, the final surface covered by 1.0g/cm2. From the orthogonal test result it can be inferred that the factor's order was the thermal oxidation temperature, the metal ion's concentration, the mole ratio of Ir and Co, the brushing times. It can be seen the surface of the Ir-Co/Ti anodes had much crack, the number and the depth of it was larger as the thermal oxidation temperature rising. If the metal ion's concentration is bigger, it is hard to brush evenly, but if it is smaller, the metal oxide covered with fewer amounts which indicated it needs more times to finish an electrode. As Co element added into the DSA, it can enlarge the true active area, but if its content is bigger than certain value, the function was becoming weaker. At the same time the service life of the Ir-Co/Ti anodes was shortened. The brushing procedure was investigated. It showed that electrochemical properties in different brushing system were quite different. The best brushing procedure was calcinated after the third solvent evaporated, repeat it again, then, calcinated once the solvent evaporated. The Accelerated Service Test (AST) result showed the reason of electrode deactivation was two mechanisms worked together. One is the coating pulled-off because of the coating unevenly dissolved. And the other is the formation of insulating TiO2-rich layer between coating and substrate.The electrocatalytic performance of the anode were improved at first and then keep steady with the water content increasing during the investigation Ir-Co/Ti anodes behavior in soil, so was the impedance value. The OER mechanism was similar in H2SO4 with in the soil, but the reaction determination step was different.