Design of a multichannel potentiostat and its application to corrosion testing of a nickel‐aluminum bronze

Abstract

A setup for potentiostatic testing of eight specimens at different potentials in a common electrolyte pool was developed. The potentiostat requires only one reference electrode and one counter electrode to control all working electrodes and its design is easily scalable with respect to the number of channels. The system is applied to assess the effect of chloride, sulfate, and bicarbonate in fresh water‐typical concentration on a nickel‐aluminum bronze, assuming some anodic polarization by stainless steel with and without microbially induced ennoblement. Chloride and sulfate activate corrosion, bicarbonate has a passivating effect, and its combination with chloride and sulfate promotes localized corrosion. The susceptibility of nickel‐aluminum bronze to localized corrosion may be high in fresh water when polarized anodically. Potentiostatic corrosion testing may yield practically relevant results for systems with slow kinetics.

Depassivation and repassivation of stainless steels by stepwise pH change

“…Therefore, the appearance and disappearance of hydrogen evolution were taken as the main basis for determination of depassivation and repassivation pH values. The results clearly indicate that the experimental setup shall be equipped in the future with a multichannel potentiostat as described by Linhardt et al [ 24 ] to enable additional measurement of corrosion rates by determining polarization resistance or performing electrochemical impedance spectroscopy.…”

“…The samples were connected to a multiplexer (34972A LXI Data Acquisition/Switch Unit; produced by Keysight [ 23 ] ), measuring the potential of each sample and recording it every 15 s using a saturated calomel electrode (SCE) during 30°C tests and an Ag/AgCl reference electrode during 80°C tests. The input impedance was set for all channels greater than 10 GΩ in the same way as described by Linhardt et al [ 24 ] In contradiction to them, a multichannel potentiostat was not available. Therefore, only potentials were recorded and no polarization resistance measurements were done in this study.…”

Activation and Repassivation of Stainless Steels in Artificial Brines as a Function of pH

“…Future investigations will focus on more exact identification of activation and repassivation pH as a function of alloying content in steels. For this a flow through cell is currently established that can be loaded with up to eight materials simultaneously because of the use of a multichannel potentiostat and electrochemical measurement device (as described by Linhardt et al [23]).…”

Fluid flow effects on CO2 corrosion: a review of applications of rotating cage methodology

“…Thus, under flow conditions, starting from a bipotentiostat system, it is possible to simultaneously carry out electrochemical tests over time, such as monitoring the open circuit potential and polarisation resistance, at least in two corrosion coupons (working electrode) by sharing a reference electrode (RE) and a counter-electrode (CE). Commercial or homemade instruments (Linhardt et al , 2017) with an alternative circuit design that allow such configuration can be found elsewhere.…”