| Corrosion behavior analysis of glass-flake/epoxy coated carbon steel under dry and immersion condition using DC high resistance measurement |
| کد مقاله : 1017-CNF |
| نویسندگان: |
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پگاه یانی *1، محمد ژیانی2، محمد محمدی تقی آبادی3، سعید برزی4، محمد کریمی4 1شیمی کاربردی، دانشکده شیمی، دانشگاه صنعتی اصفهان، اصفهان 2گروه آموزشی شیمی فیزیک ، دانشکده شیمی ، دانشگاه صنعتی اصفهان ، اصفهان ، ایران 3گروه آموزشی شیمی فیزیک ، دانشکده علوم پایه ، دانشگاه تربیت مدرس ، تهران ، ایران 4واحد پژوهش و فناوری، شرکت پالایش نفت اصفهان، اصفهان، ایران |
| چکیده مقاله: |
| Although the accuracy of electrochemical impedance spectroscopy (EIS) is high enough and its use in the study of corrosion and protective coatings is rich in the literature, data interpretation complexity and high price instrumentation have limited its application to the laboratory [1]. The goal of this study was to establish an in-situ method for quick and simple assessment of corrosion-protective coatings and paints in the industry. For this purpose, a high resistance meter device (Anbai-AT682) was used. In this method, the specimen was located into a cell and an adequate DC voltage was applied between two sides of the specimen, leakage current and resistance were then measured. High and constant values of resistance can be interpreted as high resistance of the coating to corrosion [2, 3]. In the present study the sample was a carbon steel disk (diameter = 27 mm) with primer + glass-flake epoxy applied on both side of it and the corrosive media was 3.5 wt.% NaCl. The resistance of intact and dry sample was first measured (Rinitial = 210 GΩ). For long-term corrosion monitoring test, the salt solution was injected into the cell and then the cell with the specimen inside was kept in the oven at 60 °C to accelerate corrosion process and simulate real operating conditions. Every 24 or 48 hours, the cell was taken out of the oven and let cool to reach room temperature. The resistance was then measured (Figure 2a). After each measurement of resistance under immersion condition (Figure 2a), the saline solution was removed from the cell and the cell was placed back in the oven for another 2 hours to ensure the removal of corrosive solution. The resistance was again measured (Figure 2b) after the cell temperature reached ambient temperature. From intact dry condition to 2-hour immersion of the sample, its resistance drops significantly (Rafter two hours = 22.1 MΩ) which can be related to the penetration of electrolyte into the coating. While no interesting information can be concluded from Figure 2b, in Figure 2a two different trends in sample resistance change over immersion time can be recognized. Initial positive trend (from 175 MΩ at first day to 557 MΩ at 20th day) represents the formation of oxide layer at the metal/coating interface or delamination of paint system. Negative trend (from 557 MΩ at 20th day to 210 MΩ at last day) represents deterioration of coating and development of electrolyte pathways in the coating layers. This test method gives a basic idea of corrosion resistance of coatings and it is a very easy and rapid assessment of coatings with barrier performance against corrosive media diffusion. |
| کلیدواژه ها: |
| Corrosion, Carbon Steel, Glass-Flake Epoxy, EIS, DC Resistance |
| وضعیت : چکیده برای ارائه به صورت پوستر پذیرفته شده است |