Development of quantitative Local Electrochemical Impedance Mapping: an efficient tool for the evaluation of delamination kinetics

Abstract

To cite this version:V Shkirskiy, P Volovitch, Vincent Vivier. Development of quantitative Local Electrochemical Impedance Mapping: an efficient tool for the evaluation of delamination kinetics. Electrochimica Acta, Elsevier, 2017, 235, pp.442-452 AbstractLocal Electrochemical Impedance Mapping (LEIM) methodology was adopted to quantify the propagation of electrochemically active regions with a micrometric precision. The method consisted in the use of the gradient modulus of the admittance map as a parameter for the spatial quantification. Numerical simulations were used to optimize the experimental conditions, namely the AC frequency, the distance between the local bi-probe and the working electrode, and the distances between the probes for the local bi-probe used for the local current mapping. This analysis was reinforced by experimental verifications on coated electrodes. The quantitative LEIM methodology was successfully applied to follow the delamination kinetics on Zn coated with the polyvinyl butyral polymer in NaCl solutions. At 1 kHz, the LEIM response only reflected the position of the anodic front beneath the polymer because oxygen reduction reaction was diffusion limited and hence, independent of the applied potential. This novel LEIM methodology completes the set of usual tools used to investigate the delamination mechanisms on metal substrates.

New experimental approach for intelligent screening of buried metal/oxide/polymer interfaces via local electrochemistry: Example of undamaged model epoxy-coated Zn alloys

“…% of phenolphthalein in a sealed glass cell of 4.4 cm in diameter at room temperature. According to the literature, the influence of the phenolphthalein on the cathodic reactivity of polymer/zinc alloy interface can be neglected 32 . To perform ex situ measurements during immersion, samples were rinsed with milli-Q water and dried with compressed air before measurements and placed back to the immersion solution in less than 5 min.…”

“…However, contrary to LEIM, SVET cannot detect the underpaint reactivity in the absence of a defect in the paint. In addition, a quantitative LEIM was recently proposed to study the disbondment front propagation kinetics [32] during immersion. However, it should be mentioned that most of previously reported studies on local degradation of metal/oxide/polymer interfaces using local electrochemical techniques concerned the interface delamination starting from an artificial defect, intentionally introduced at the metal/oxide/polymer interface or in the coating prior to the aging process.…”

Local electrochemical impedance spectroscopy: A window into heterogeneous interfaces

“…2b) as can be deduced from the low frequency limit of the LEIS diagram which tends towards a negative polarization resistance. The LEIS technique is widespread analysis technique used for mapping coatings delamination [37] or disbondment [38] as well as the study of galvanic coupling using the latest developments in dynamic electrochemical impedance spectroscopy [39]. When performing fixed frequency mapping, it is possible to monitor the evolution of defect size over time, but a quantitative analysis at each position requires a complete impedance spectrum to be recorded at each point.…”

Detection and quantification of defect evolution at buried metal-oxide-polymer interface on rough substrate by local electrochemical impedance mapping

“…Scanning vibrating electrode techniques (SVET) measures the local currents, which can be helpful to characterize defects in coating but cannot overcome the inherent difficulty in measuring currents underneath high resistance coatings [31,32]. Local electrochemical impedance spectroscopy and mapping (LEIS and LEIM) [33,34,35,36,37,38] are becoming widespread techniques to study buried interfaces for the systems in which the polymer does not have initial defects [39,40,41]. SVET and LEIS measure both the local current density, for the former case, the DC component is measured, whereas for the later, the AC component at a selected frequency can be obtained.…”

“…Despite the increasing number of works applying LEIS and LEIM for the description of degradation at metal-oxide-polymer interfaces, very small number of them treat the evolution of the system in a quantitative way [35,36] and to our knowledge no studies were devoted to the verification of the analytical limits of LEIS and LEIM for the detection of the active areas under intact polymer. Moreover, the theoretical limits of LEIS and LEIM techniques are elaborated for flat substrates, while many industrial substrates are electrodeposited alloys, therefore rough.…”