Cell for Simultaneous Synchrotron Radiation X-ray and Electrochemical Corrosion Measurements on Cultural Heritage Metals and Other Materials

Abstract

We describe the construction of an electrochemical cell of the Bragg type suitable for in situ synchrotron X-ray measurements on rough, heterogeneous metals such as cultural heritage alloys and simulants with corroding or passivated surfaces. The cell features a working electrode, which may be moved under remote control from a position close to an X-ray window to full immersion in the electrolyte. A pocket of electrolyte in contact with the bulk can be maintained on the working electrode surface at all times. Its thickness (typically 100-200 µm) can be controlled by adjusting the working electrode position and, independently, altering the conformation of the X-ray window with hydrostatic pressure. Alternatively, the electrode may be lowered into the bulk of the electrolyte. Early results from the cell showing a time-resolved study of the reduction of nantokite to cuprite in sodium sesquicarbonate, accompanied by corrosion potential measurements obtained in parallel, are presented here.The application of electrochemical techniques for the stabilization, cleaning, and protection of metallic cultural heritage objects from silverware to battleships 1-6 is proving to be extremely effective, and research in this area has increased significantly in the past 10 years. The value and uniqueness of some of the objects involved, together with other issues such as their location, means that all conservation treatments must be thoroughly understood and tested, preferably before first use. The consequences of failure range from the loss of an irreplaceable museum object to serious environmental damage (e.g., in the case of fuel leakage from a sunken World War 2 battleship). 7 In addition, there is a need for fully qualified but simple in situ monitoring techniques that can be used by conservators, for example, corrosion potential (E corr ) measurements on artifacts stored in stabilizing media (such as marine objects immersed in sodium sesquicarbonate solution). 8,9 There exist many techniques that can be used for the ex situ study of real and simulated surfaces (e.g., analytical electron microscopy, various electron spectroscopies, mass spectrometric techniques 10-13 ). In most cases, these require that the sample is placed in an untypical environment such as a vacuum and the relationship between such measurements and the surface chemistry in the native state is rarely established. Moreover, it is only recently that it has become possible, using these techniques, to observe reactions at the liquid-metal interface as they occur. 10 In 1980, Fleischmann et al. described the first in situ observation of electrochemical reactions at the liquid-solid interface using X-ray diffraction (XRD). 15 A few years later, Fleischmann et al. published some of the earliest designs for electrochemical cells for use with a variety of synchrotron X-ray (SR-X...) techniques. 16 Since then, the use of SR-XRD, synchrotron X-ray absorption spectroscopy (SR-XAS), and electrochemistry has been described by a number of authors, 17-25 many of who...

Towards a new method for coating heritage lead

“…(a) A polished lead coupon 12.5 mm diameter was immersed in 0.05 mol L −1 tetradecanoic acid in ethanol for 10 hours in an environmental cell, the MkIV eCell [15]. During the immersion the surface was analysed in-situ using synchrotron X-ray diffraction on the UK CRG beamline XMaS (BM28) [16] at the European Synchrotron Radiation Facility (ESRF).…”

In‐situ spectroelectrochemical study of the growth process of a lead decanoate coating as corrosion inhibitor for lead surfaces

“…[6] The work in this paper complements the work by Rocca et al [4 -6] and forms part of a continuing study of the growth and properties of Pb(C 10 ) 2 , produced by immersing the lead substrate in a solution of 0.05 M NaC 10 . [7,8] We have both monitored the deposition of lead decanoate layers in real time using a novel electrochemical/environmental cell (eCell) [9] in a synchrotron beam line (in-situ experiments) and made a wide variety of measurements on separately grown (and growing) layers (exsitu experiments). The in-situ experiments were carried out using synchrotron radiation X-ray diffraction (SR-XRD) on BM28 (XMaS) (ESRF, France) measured simultaneously with electrochemical impedance spectroscopy (EIS), on growing layers.…”

The Use of Synchrotron X-rays To Observe Copper Corrosion in Real Time

“…This is due probably due to redistribution of solution piled behind the wiper on the spinning sample over time, and the resulting deposition of further CuCl under the beam. Furthermore, if the liquid medium is allowed to dry (in a departure from the normal protocol) as discussed below, the copper peaks reemerge, and they are visible in any case after the protocol is complete 15,22 . From these observations we deduce that the slow copper attenuation following initial dispensation is due both to absorption in the surface liquid which becomes rich in copper ions and then precipitated nantokite, and to the formation of the nantokite deposit.…”