Corrosion of an archaeological find from the Roman period in Serbia

Abstract

The degree of preservation of iron artifacts depends on the type of underground environment and the type of corrosion products formed on their surface. This paper analyses the conditions of an archaeological find made of iron and originating from the Roman period and belonging to the collections of the Museum of Science and Technology in Belgrade. The radiographic method has been used to determine the quantity of non-corroded metal as well as to determine the presence of cracks and other defects in the artefact. The composition of the corrosion products has been analyzed by the X-ray diffraction method (XRD). In addition to iron corrosion products (goethite α-FeO(OH) and magnetite Fe3O4), the presence of a significant quantity of akaganeite β-Fe8O8(OH)8Cl1.35, has been noticed on the artifact. The content of chloride, sulphate and other ions in the corrosion products has been determined by ion chromatography (IC). The analyses have pointed to the necessity of having artifacts treated in adequate solutions immediately after their excavation in order to eliminate chloride and sulphate anions. The aim of this paper is to determine the type of corrosion products and their influence on the corrosion behavior of an archaeological artefact.

Koroziona postojanost eksponata od gvožđa zavisi od tipa podzemne sredine i vrste korozionih produkata koji se formiraju na njegovoj površini. Ovaj rad analizira stanje arheološkog predmeta koji potiče iz rimskog perioda i koji pripada kolekciji Muzeja za nauku i tehniku u Beogradu. Radiografska metoda je korišćena za određivanje količine nekorodiralog metala, kao i prisustva prslina i drugih defekata u eksponatu. Sastav korozionih produkata je analiziran difrakcijom X-zraka (XRD). Pored korozionih produkata gvožđa (getita α-FeO(OH)I magnetita Fe3O4), uočena je značajna količina akagenita β-Fe8O8(OH)8Cl1.35 u sloju korozionih produkata. Metodom jonske hromatografije (IC) je određen sadržaj hloridnih, sulfatnih i drugih jona u korozionim produktima. Pomenute analize su ukazale na neophodnost tretmana arheološkog predmeta u odgovarajućem rastvoru za desalinaciju, neposredno posle iskopavanja, u cilju uklanjanja hloridnih i sulfatnih anjona. Cilj ovog rada je određivanje tipa korozionih produkata i njihovog uticaja na koroziono ponašanje arheološkog predmeta.