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

Abstract

Highlights  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.

In Situ Electrochemical Impedance Spectroscopy Measurements and their Interpretation for the Diagnostic of Metallic Cultural Heritage: A Review

“…Amongst the liquid electrolyte cells, the contact cell developed by Letardi (or variations of it) is the one with a longest and more consolidated use. Solid electrolytes are more recent, but results with the agar G‐PE cell are promising and the system has been adopted and further developed by other groups ,. The use of a two surface‐mounted parallel cell configuration is an interesting approach to circumvent the problem of making electrical contact with the base metal, but the quality of the results published using this setup is still too poor to make this a real alternative.…”

Electrochemical noise measurements on stainless steel using a gelled electrolyte

“…The mixture was stirred continuously for 10 min and then cured in a controlled environment where the temperature and relative humidity were kept at 20°C and 80%, respectively. More information about the gel manufacturing process can be found in a previous publication [16]. The conductivity of the gel electrolyte at room temperature was 3.5 mS cm -1 , its pH 6.6, its oxygen content 2.9 ppm, and its viscosity around 2 Pa s [16,17].…”

“…The manufacturing of electrochemical cells with gel electrolytes has already shown some advantages, as the ability to cover different angled surfaces and its easiness to be used as portable electrochemical cell for in-situ corrosion monitoring [13][14][15]. The formulation of the gel electrolyte used in the present work has been optimized in a previous study [16]. It comprises glycerol, which acts as plasticizer and is responsible for the adaptability of the cell, and agar, which provides the mechanical stability of the electrolyte required for the measurements on portable devices and contributes to the conductivity of the gel.…”

“…The usefulness of this innovative electrolyte has already been tested for studying corrosion of stainless steel (SS) surfaces with complex geometry using d.c. polarization techniques [16] and EIS measurements [17]. The present paper presents a pioneering study on the use of the EN technique in ZRA, galvanostatic, and potentiostatic modes for investigating electrochemical processes in an electrochemical cell with gel electrolyte.…”

Agar versus Agarose Gelled Electrolyte for In Situ Corrosion Studies on Metallic Cultural Heritage

“…Agar is a translucent, cheap, non‐toxic, and quick and easy to prepare material, which admits a wide range of aqueous electrolytes and also contributes to conductivity. It's flexibility allows adaptation to irregular surfaces and can be improved by the addition of plasticizers,, and its syneresis helps wetting the surface and allowing good contact. Other proposed materials, have shown other limitations: Commercial or synthetized anionic gels are very limited by the electrolyte choice, and the use of PVA has to be more deeply studied, as preliminary results showed appreciable differences when compared to a traditional cell design.…”