This study investigates innovative non-toxic organic corrosion protection treatments withcarboxylate compounds upon statuary bronze artefacts. Bronzes and copper alloys have beenwidely used over centuries as modeling material for statues and various artefacts. They are part ofour cultural heritage and crucial to understanding our history. Over the past decades research hasbeen focused on conserving these objects exposed to the outside, under atmospheric conditions,with special care to preserving the patina layer. Recent studies have reported the efficiency of longchain carboxylates in protecting copper patina from subsequent deterioration1. Indeed,carboxylates appear to be very effective corrosion inhibitors, especially when applied byimmersion, penetrating inside of the corrosion layer2 . However, this penetration process ofcarboxylates compounds into the corrosion layer is very difficult when applied by brush on site andremains a main issue. To address this matter, a new method is proposed. The statuary’s surfacelayer is coated with an additional inorganic layer containing high carboxylate concentration. Thisreservoir will allow continuous release of carboxylate into the surface layer, thereby assuring itsprotection over extended period. This protective coating is produced via the sol-gel process3 withvarious carboxylate concentrations and the anti-corrosion efficiency is tested with archeologicalcopper.To better understand the mechanisms of physicochemical interactions between the organictreatment and the corrosion layer formed on the surface of the artwork, a multi-scale analyticalstrategy on treated and aged samples is herby considered. Experiments will be conducted oncentury old copper samples exposed to atmospheric corrosion. The gel chemical composition andporosity will be investigated by X-ray diffraction (XRD) and Infrared spectroscopy (IR) along withBET porosimetry, while the carboxylate penetration process into the corrosion layer observed inthe cross section will be assessed using Scanning electron microscopy (SEM-EDS) and RAMANspectroscopy at the micrometric scale.In this work we will show that the silicate matrix doped with short chain carboxylates such as C3and C5 act as an efficient barrier layer to protect the copper from corrosion. We will also point outthe ease of applicability of such materials on statuary artefacts and the strength of such aprotection method.
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