Design of gel electrolytes for electrochemical studies on metal surfaces with complex geometry

•Agar mixed with plasticizer can be used as electrolyte in corrosion cells.•Designed gels can have excellent adaptability to complex surfaces.•Designed gels avoid the risk of undesired crevice corrosion in pitting tests.•Polarization test of stainless steel in gel is comparable to tests in aqueous NaCl.

Electrochemical cells commonly employ liquid electrolytes. These cells can present limitations, like studying irregular surfaces or the generation of crevices as a result of delimiting the surface of the working electrode. The current study has developed a gel electrolyte based on agar-glycerol as an alternative to the saline aqueous solutions often used in anodic polarization tests of stainless steels.Texture analysis and rheological tests were performed to characterize the gel electrolytes and determine the best composition in function of their characteristics of adaptability to provide a suitable contact to complex surfaces. Comparisons between typical aqueous and gel electrolytes in ionic conductivity and electrochemical measurements (anodic polarization curves) were carried out to validate the gel electrolytes for the evaluation of pitting corrosion behavior of metals. Moreover, lack of risk of interference of undesirable crevice corrosion in tests carried out with this type of sensor is also demonstrated.

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