New insights on protective treatments for marble by FIB-SEM

Sassoni, Enrico ; Graziani, Gabriela ; Franzoni, Elisa ; Scherer, George W. (2018) New insights on protective treatments for marble by FIB-SEM. DOI 10.1088/1757-899X/364/1/012092. In: Florence Heri-Tech – The Future of Heritage Science and Technologies. IOP Publishing, pp. 1-9. In: IOP Conference Series: Materials Science and Engineering
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Abstract

In this study, we investigated by FIB-SEM the microstructure of protective coatings formed by two inorganic treatments (namely, ammonium oxalate and ammonium phosphate solutions), with the aim of identifying the factors limiting the protective efficacy of the coatings and outlining possible improvement strategies. In the case of the oxalate treatment, the resulting layer of whewellite was found to contain vertical channels, which can allow water to reach the marble surface and trigger dissolution. Possible prevention of the formation of these channels by addition of a calcium source to the oxalate solution was attempted, but even micromolar additions led to rapid precipitation in the solution. In the case of the phosphate treatment, the resulting hydroxyapatite and octacalcium phosphate coating was found to be cracked and porous. To prevent cracks and pores, diminishing the ammonium phosphate concentration and adding ethanol to the solution were found to be effective strategies, as cracks were prevented and pores were reduced almost to zero. The resulting protective efficacy of the coating was found to be significantly improved, although still not perfect.

Abstract
Document type
Book Section
Creators
CreatorsAffiliationORCID
Sassoni, EnricoUniversity of Bologna0000-0003-0716-510X
Graziani, GabrielaUniversity of Bologna
Franzoni, ElisaUniversity of Bologna
Scherer, George W.Princeton University
Keywords
Hydroxyapatite; Inorganic coatings; Marble; Calcium oxalate; Protective coatings
Subjects
DOI
Deposit date
07 Sep 2018 10:24
Last modified
07 Sep 2018 10:24
Project name
HAP4MARBLE - Multi-functionalization of hydroxyapatite for restoration and preventive conservation of marble artworks
Funding program
EC - H2020
URI

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