Conservation state of cast iron metalworks in European street furniture

Abstract

This work evaluates the state of conservation of three artefacts of historical street furniture in cast iron, dating back to the second half of the nineteenth century and coming from foundries located in Italy, France and Great Britain. Form, distribution and size of graphite in cast irons, and the constituents of microstructures were evaluated by optical microscopy, whereas the alloy composition was determined by scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). The same analytical technique, in association with Diffuse Reflectance Infrared Fourier Transform (DRIFT) and micro-Raman spectroscopies, was employed to characterize corrosion attack morphology, patina stratification and thickness. The protectiveness of the corrosion layers on the artefacts was evaluated by Electrochemical Impedance Spectroscopy (EIS). The results showed that the microstructure and alloy composition were similar to those frequently encountered in complex shape castings with variable wall thickness. On the corroded surfaces, the graphitization of the cast irons was detected. This phenomenon ANSWERS TO THE REVIEWERS: REVIEWER #2The authors have improved the manuscript, but some points should be enhanced. I suggest evaluating the publication after clarification of some critical issues concerning especially the electrochemical section. Please indicate pages and lines in the answers, not just using the highlighter, when making changes in the text. Introduction:-The authors added information and bibliography about the use of SEM / EDS, FTIR and Raman. In this way there is an imbalance in the literature review carried out in the introduction. I suggest introducing also the use of EIS for metals of Cultural Heritage, as it is a technique used by the authors in the work, in the same way as the others already mentioned. There are many pivotal works published in the last few years about impedance measurements carried out by the authors.As suggested by the Reviewer, the Introduction was modified by expanding the section dedicated to EIS measurements in the field of cultural heritage (page 3 lines 1-15). Experimental:-Usually the aims and the explanation of the use of certain techniques for solving a problem are added at the end of the introduction (when a dedicated section missing). In the experimental part there must be only information about the instruments used. I therefore suggest moving especially the sentence on page 3 line 42 in the final part of the introduction and possibly discussing in this context the usefulness of the joint use of DRIFT and micro raman.Following the Reviewer's suggestion, the sentence was moved to the Introduction and included in the discussion (page 3 lines 19-24).-In the recent literature on EIS analysis on metals of cultural interest when using mineral water, the composition and origin of the water itself is also indicated. This makes possible the reproducibility of the experiment in the same conditions and using the same electrolyte (in this case a cloth soaked with a natural mineral water...

Metallurgical and Statistical Approaches to the Study of Cast Iron Street Furniture

“…The addition of phosphorous lowers the melting point and improves the fluidity of cast irons, allowing to create nearly unlimited decorative and structural components with thin wall thickness. [2,4,8] There were no detectable differences between the microstructures observed in cross-sections close to the surface and in the center of the cast irons. Therefore, the cast iron samples examined were very uniform in appearance and could be repetitively produced.…”

“…[6] In another study, the authors determined the state of conservation of three artifacts of historical cast iron street furniture by scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS), diffuse reflectance infrared Fourier transform (DRIFT) and l-Raman spectroscopies, and electrochemical impedance spectroscopy (EIS). [7] In a previous study on this topic, the authors evaluated the protectiveness of ancient paints on historical street lamps made of cast iron alloys by X-ray diffractometry (XRD) and SEM/ EDS, DRIFT, and EIS techniques. [8] In this study, twenty-four cast iron metalworks of street furniture dating back to XIX and XX centuries were investigated to determine the evolution of microstructure in relation with dating and nationality of the foundry of origin.…”

“…[7] In a previous study on this topic, the authors evaluated the protectiveness of ancient paints on historical street lamps made of cast iron alloys by X-ray diffractometry (XRD) and SEM/ EDS, DRIFT, and EIS techniques. [8] In this study, twenty-four cast iron metalworks of street furniture dating back to XIX and XX centuries were investigated to determine the evolution of microstructure in relation with dating and nationality of the foundry of origin. Twenty-one came from foundries located in United Kingdom, France, and Italy, and three whose origin was not reported.…”

Cast iron street furniture: A historical review

“…Street furniture was defined as such by the urbanist George Eugène Haussman, prefect of Paris (France) from 1853 to 1870, as "the group of objects or accessories which, installed in the urban space, performs a functional service for the community" (Bassi & Bazzocchi, 2011). Given the requirements of safety, hygiene, comfort and entertainment in the modern city, new elements were introduced in the urban environment (Bassi & Bazzocchi, 2011;de Ruggiero et al, 2018;Soffritti et al, 2018;Soffritti et al, 2019). Thus, street furniture was a class of objects created to improve the quality of life in urban settlements, evolving according to necessities along the years and representing an essential part of the city: street lamps, benches, balconies, grids, fountains and gazebos are common elements in modern cities (de Ruggiero et al, 2018;Soffritti et al, 2018;Soffritti et al, 2019).…”

Developing Pandemic Prevention and Control by ANP-QFD Approach: A Case Study on Urban Furniture Design in China Communities

“…With the expansion of cities, urban furniture became an indispensable part of modern society and it affects most of our daily activities, being involved in accommodation, recreation, transportation, and communication [ 4 ]. People have increasing demands of urban furniture, not only for basic functions but also advanced aspects, such as safety, hygiene, comfort and entertainment, which can improve the quality of ordinary life [ 1 , 5 , 6 , 7 ]. However, people gain new expectations of these urban facilities under emergent circumstances, for example, a pandemic.…”