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Stabilisation of archaeological copper alloy artefacts using subcritical fluid technology

Nasanen, Liisa Maria Elina 2018. Stabilisation of archaeological copper alloy artefacts using subcritical fluid technology. PhD Thesis, Cardiff University.
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Abstract

The research presented aimed to investigate potential of subcritical fluid technology to effect Cl- release and transform compounds of copper alloy artefacts of cultural significance. The work intended to determine the most effective pH, temperature, and time combination subcritical treatment variables to: 1. transform or solvate insoluble or sparingly soluble copper compounds containing Cl - CuCl and Cu2(OH)3Cl (atacamite and clinoatacamite); 2. examine impact on typical patina compounds Cu2O and ‎Cu2CO3(OH)2 and to establish optimal conditions for their retention throughout treatment. Additionally, the research expected to offer guidance on the values of the operational parameters to use when applying subcritical treatment to archaeological copper alloy objects. The series of experiments yielded preliminary results on solvation, extraction, chemical transformation, and physical modification of the predominant corrosion products found on copper alloy artefacts. Experiments were completed using analogue pressed pellets of corrosion products, naturally corroded copper coupons and archaeological artefacts, with specific focus on corrosion profiles, metallography and microstructure. The results of extraction show significant amounts of Cl- are removed and thus the reactivity of objects is reduced. While this study conclusively demonstrated subcritical treatment is capable of both removal and transformation of Cl-bearing compounds commonly present in copper alloy objects, it cannot be recommended for treating archaeological objects based on these results alone. Aesthetic and physical changes are unpredictable and may be unacceptable. Accepting these changes cannot directly be balanced against the proven effectiveness of subcritical treatment for removing Cl, nor its rapid treatment time.

Item Type: Thesis (PhD)
Date Type: Completion
Status: Unpublished
Schools: History, Archaeology and Religion
Subjects: A General Works > AM Museums (General). Collectors and collecting (General)
C Auxiliary Sciences of History > C Auxiliary sciences of history (General)
C Auxiliary Sciences of History > CC Archaeology
Q Science > Q Science (General)
Q Science > QD Chemistry
T Technology > TA Engineering (General). Civil engineering (General)
Date of First Compliant Deposit: 29 August 2018
Last Modified: 29 Aug 2018 16:00
URI: http://orca.cf.ac.uk/id/eprint/114466

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