Electrochemical Quartz Crystal Microbalance Corrosion Sensor for Solid Metals and Metal Alloys

Abstract

In this paper, a new corrosion sensor based on a quartz crystal microbalance is presented. A 50 m thick disk of solid metal is glued directly on the surface of a 2 MHz AT-cut quartz crystal. An electronic oscillator designed for highly damped quartz resonators allows the resonance frequency of the quartz-glue sample system to be followed. Simultaneous electrochemical measurements are possible as the metal sample can be polarized. The mass sensitivity of this electrochemical quartz crystal microbalance was determined by carrying out a copper electrodeposition directly on the sample surface. The potentiostatic dissolution of 304 stainless steel in 1 M HCl is discussed in this paper. The mass loss during potentiostatic dissolution was measured by the frequency shift of the microbalance sensor and compared to the mass loss calculated from Faraday's law. A very good agreement was found as both results had a relative difference lower than 5%.Quartz crystal microbalance ͑QCM͒ is a widespread technique to study mass changes of thin films in various media including liquids. In particular, it has been proposed as a measurement tool for the determination of corrosion rates of metals and for the study of the influence of inhibitors. 1-3 So far, QCM measurements have been limited only to electrodeposited or evaporated metals, whose chemical reactivity, in most cases, is known to be different from that of solid metals. 4 The feasibility of direct QCM measurements on these materials was already demonstrated. 5 In this paper, a novel corrosion sensor based on the QCM is described. This novel microbalance can be used to determine the corrosion rates of solid metals and alloys with a high accuracy, since a foil of the studied metal is directly glued on the crystal. Moreover, simultaneous electrochemical measurements are possible as the metal sample can be polarized. Thus, this sensor is an electrochemical quartz crystal microbalance ͑EQCM͒ for solid materials. In this paper, the feasibility was demonstrated for the dissolution of 304 stainless steel in HCl medium. ExperimentalThe experimental setup included a homemade QCM and a threeelectrode electrochemical measurement system. The probe of the QCM consisted of a quartz crystal on which the studied metal sample was glued on one of its electrodes. A data acquisition system simultaneously recorded the potential, current, and frequency of the probe.Probe.-The piezoelectric transducer was a 2 MHz AT-cut quartz crystal 14 mm in diam ͑CQE, France͒. This frequency was lower than that of common QCMs to allow the crystal to oscillate with much higher loads. The crystal was coated with gold electrodes of 5 mm diam by the manufacturer. An underlayer of chromium provided gold adhesion to the crystal. Gold was chemically removed from the electrode disk on the side where the sample was to be glued in order to improve the adhesion of the metal sample.The metal sample was a disk cut out from a foil of 304 stainless steel ͑Goodfellow, U.K.͒. The disk was 50 m thick and had a 5 mm diam. The glue us...

Mass and charge balance in self-assembled multilayer films on gold. Measurements with optical reflectometry and quartz crystal microbalance

“…The quartz crystal microbalance is a useful tool for chemical applications dealing with thin films [34,35]. Its simplicity makes it attractive, although in many cases resonant frequency measurements do not permit to easily separate the mass contribution from other contributions such as the film viscoelasticity.…”

Corrosion Monitoring in Atmospheric Conditions: A Review

“…All these parameters should be controlled during the measurement, and the calibration of a coated crystal and the instrumentation is required [131,135]. For example, Hoseinpoor et al reported that temperature fluctuations of ± 0.25 °C affect the QCM data while measuring extremely low mass changes in the nanogram range [139]. The authors expected the sensitivity toward temperature fluctuations to decrease with increasing mass changes.…”

“…QCM-D thus provides information about both mass and mechanical properties of the surface layer. For corrosion studies, this approach has been so far used only during laboratory investigations of initial copper oxidation [139,150].…”

“…3 More frequently, R n , ECN and/or EPN evolution in time is used as a corrosion indicator instead of corrosion rate, as, for example, for corrosion monitoring of Fe [88,210] and Al [76,91]. 4 Mass gain in time is frequently presented as a direct measurement output instead of thickness loss in time, as, for example, for corrosion monitoring of Ag [138,[141][142][143][144][145][146], Cu [138,139,147,150,153], Pb [151,152] and Fe [153]. 5 For pre-corroded historical iron artefacts, when the corrosion mechanism is not known, ORR rate cannot be re-calculated to corrosion rate and oxygen consumption is used as a corrosion indicator [199,[201][202][203][204].…”

Cell Attachment and Spreading Processes Monitored by the Thickness Shear-Mode Quartz Sensor

“…T HERE IS growing interest in use of the thickness shearmode quartz-crystal sensor technique in different types of electrochemical [1]- [4] and biological research [5]- [10], either for monitoring in situ adsorption processes, or for studying cell substrate interactions. This technique, based on the transverse propagation of an acoustic shear wave generated by a sinusoidal electric field though the quartz crystal and the foreign material, provides powerful and nondestructive means for characterizing physical materials properties [11], [12].…”