PLANAR MULTIELECTRODE-ARRAY-SENSOR FOR CORROSION MONITORING

Corrosion is a constant threat to industries in particular the oil and gas. Its adverse effects on assets such as pipelines and equipments may lead to losses in millions of dollars. Since it is a natural process, it cannot be eliminated altogether. However, appropriate corrosion monitoring techniques and preventive measures can help to control it to a greater extent. In this research, a PCB-based multielectrode array sensor (MAS) for localized corrosion rate monitoring is demonstrated. It is fabricated using typical PCB processes with Cu discs acting as the planar sensing electrodes. It is ~2x2 inches in size and truly planar making it more suitable to be used in confined spaces as compared to other techniques like probe-based MAS or corrosion coupons.
It is tested in 3%wt sea salt solution to check its corrosion detection capability. Its response to change in corrosive environment is also assessed by varying the solution concentration from 3%wt to 9%wt. The obtained corrosion rates are validated using established corrosion monitoring technique like electrochemical impedance spectroscopy (EIS). Furthermore, robustness of PCB-based MAS is checked in HCl and NaCl solution using three types of conformal coatings namely; acrylic, cyanoacrylate and epoxy. Effects of these three types of conformal coatings on PCB-based MAS performance is also tested and analyzed in detail.
The results show that the corrosion rates obtained from the PCB-based MAS agrees reasonably well with published corrosion rates. It also shows that the MAS can detect the change in corrosive solution concentration efficiently. As for the conformal coatings, it is found that acrylic coated PCB-based MAS provides reasonably accurate corrosion rate although with a shorter sensor lifetime. Cyanoacrylate and epoxy, on the other hand, inhibits corrosion increasing the sensor lifetime but at the expense of inaccurate corrosion rates.