1. B-IMPACT project : eco-friendly and non-hazardous coatings for the protection of outdoor bronzesGiulia Masi, Maëlenn Aufray, A. Balbo, E. Bernardi, Maria Chiara Bignozzi, Cristina Chiavari, J. Esvan, Nina Gartner, V. Grassi, Claudie Josse, Tadeja Kosec, Carla Martini, Cecilia Monticelli, Luka Škrlep, W. Sperotto, Erika Švara Fabjan, E. Tedesco, F. Zanotto, Luc Robbiola, 2020, objavljeni znanstveni prispevek na konferenci Povzetek: Application of protective coatings is the most widely used conservation treatment for outdoor bronzes. Eco-friendly and non-hazardous coatings are currently needed for conservation of outdoor bronze monuments. To fulfil this need, the M-ERA.NET European research project B-IMPACT (Bronze-IMproved non-hazardous PAtina CoaTings) aimed at assessing the protectiveness of innovative coatings for historical and modern bronze monuments exposed outdoors.
In this project, two bronze substrates (historical Cu-Sn-Zn-Pb and modern Cu-Si-Mn alloys) were artificially patinated, by acid rain solution using dropping test and by "liver of sulphur" procedure (K2S aqueous solution) to obtain black patina, respectively. Subsequently, the application of several newly developed protective coatings was carried out and their performance was investigated by preliminary electrochemical tests. In the following steps of the work, the assessment of the best-performing coatings was carried out and their performance was compared to Incralac, one of the most widely used protective coatings in conservation practice. A multi-analytical approach was adopted, considering artificial ageing (carried out in representative conditions, including exposure to rain runoff, stagnant rain and UV radiation) and metal release, as well as visual aspect (so as to include aesthetical impact among the coating selection parameters) and morphological and structural evolution of the coated surfaces due to simulated outdoor exposure. Lastly, also the health impact of selected coatings was assessed by occupational hazard tests. The removability and re-applicability of the best-performing coatings were also assessed. The best alternatives to the conventional Incralac exhibited were: (i) fluoroacrylate blended with methacryloxy-propyl-trimethoxy-silane (FA-MS) applied on patinated Cu-Sn-Zn-Pb bronze and (ii) 3-mercapto-propyl-trimethoxysilane (PropS-SH) applied on patinated Cu-Si-Mn bronze.
Ključne besede: bronze, patina, protective coatings, eco-friendly, corrosion, aging
Objavljeno v DiRROS: 01.03.2024; Ogledov: 131; Prenosov: 69
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2. Development of multi-component fluoropolymer based coating on simulated outdoor patina on quaternary bronzeTadeja Kosec, Luka Škrlep, Erika Švara Fabjan, Andrijana Sever Škapin, Giulia Masi, Elena Bernardi, Cristina Chiavari, Claudie Josse, Jerome Esvan, Luc Robbiola, 2019, izvirni znanstveni članek Povzetek: Bronze reacts with oxygen, humidity, and pollutants in the atmosphere so that a patina forms. Natural exposure to an outdoor atmosphere can be simulated and accelerated in order to achieve a patina that mimics outdoor ancient patina. In order to avoid the uncontrolled dissolving of either the natural or artificially formed patina, protection of the patina is needed.
In this study, a multi-component fluoropolymer based coating for the protection of bronze patina was developed. In order to provide various functionalities of the coating (such as the hydrophobicity of the coating surface, obtaining interactions within the coating itself as well as a bronze substrate and inhibiting the corrosion processes), a fluoroacrylate coating with appropriate adhesion promoter was suggested, with and without a silane modified benzotriazole inhibitor. The protective efficiency and durability of the applied coatings were investigated electrochemically using potentiodynamic tests and electrochemical impedance spectroscopy in a simulated acid rain solution. All of the developed coatings showed a significant decrease in the corrosion current density. The self-assembled single layer coating (FA-MS) also showed 100% inhibition efficiency. After ageing the coating remained transparent and did not change by UV exposure and/or thermal cycling. The patina and coating investigations using FIB-SEM and EDX showed that the latter coating (FA-MS) successfully covered the surface of the patinated bronze. The mechanism of the bonding was proposed and supported with the spectroscopic observation of a thin and even coating.
Ključne besede: bronze, patina, fluoropolymer coating, atmospheric corrosion
Objavljeno v DiRROS: 25.10.2023; Ogledov: 344; Prenosov: 186
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