IrOx electrodes were fabricated by cyclic thermal heating and water quenching (CHQ) process and high temperature carbonate oxidation (HCO), respectively. By examining the E-pH relationship, response rate, potential drift behavior of the fabricated electrodes, the electrodes prepared by CHQ process seemed to show better comprehensive performance. Characterization tests such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electrochemical impedance spectroscopy (EIS) were used to characterize the fabricated IrOx electrodes and find out the reason for the better performance of the electrodes prepared by CHQ process. Morphology tests indicate that the CHQ electrode shows a multi-layer structure with more ion channels, which could provide larger surface area for the H+ response process. Furthermore, combining the XPS, Raman and EIS tests etc., more effective response composition, better crystal quality, and smaller response reaction resistance of surface IrOx film could account for the better performance of the CHQ-fabricated IrOx electrode. The film formation process, H+ response mechanism, as well as the response behavior difference between the two kinds of the electrodes are further elaborated.

A finite element model is developed to study dynamics of atmospheric corrosion of carbon steel, focusing on the influence of thin electrolyte film thickness under varying corrosion product porosity. Calculations have been done to evaluate the impact of electrolyte film thickness and corrosion product porosity on oxygen diffusion path, and the hindrance effect of corrosion products on the metal surface activity. The time evolution of corrosion current density and controlling steps in the corrosion process are explored. When the corrosion products are loose, oxygen diffusion is the dominant controlling step, and the thicker the electrolyte film, the lower the corrosion rate. When they are dense, the corrosion process is controlled by the mixture of oxygen diffusion and the surface discharge. The oxygen diffusion path is determined only by the corrosion product porosity, and therefore the corrosion rate is not affected by the electrolyte film thickness.

Corrosion under insulation (CUI) is a crucial issue in the industry. Its importance has been increasingly acknowledged because of the high cost and potential danger of causing severe losses. This review gives essential knowledge of CUI and summarizes the research from several aspects, including lab experiments, field tests, CUI prediction methods and numerical simulation research in porous materials. Insulation material, coating, substrate metallic material of the equipment, operating temperature and surroundings are some critical factors that should be considered in the CUI problem. Experimental research methods of CUI and mass transfer in insulation materials were summarized, as well as the applications of data science in CUI prediction. This review also focuses on simulation researches on heat and moisture transfer in porous insulation materials since numerical simulations are helpful for establishing validated models for CUI by modeling to describe the specific processes and predict environmental conditions of CUI for further corrosion research. Combined experimental and simulation work of CUI would be a practical and effective method for CUI research.

IrOx electrodes were fabricated by cyclic thermal heating and water quenching (H&Q) process and high temperature carbonate oxidation, respectively. By examining the E-pH relationship, response rate, potential drift behavior of the fabricated electrodes, the electrodes prepared by H&Q process seemed to show better comprehensive performance. Characterization tests such as scanning electron microscopy (SEM), X-ray photoelectron spectrum (XPS), electrochemical impedance spectrum (EIS), etc. were used to characterize the fabricated IrOx electrodes and find out the reason for the better performance of the electrodes prepared by H&Q process. Morphology tests show that the H&Q electrode show a relative multi-layer structure, which could provide larger surface area for the H+ response process. At the meantime, combining the XPS and EIS test etc., more effective response composition, smaller response reaction of surface IrOx film could account for the better performance of the IrOx electrode.