White Spots on Smoke Rings by Bruce Nauman: A Case Study On Contemporary Art Conservation Using Microanalytical Techniques

The artwork “Smoke Rings: Two Concentric Tunnels, Non-Communicating” by Bruce Nauman represents a case study of corrosion of a black patina-coated Al-alloy contemporary artwork. The main concern over this artwork was the widespread presence of white spots on its surface. Alloy substrate, patina, and white spots were characterized by means of energy-dispersive X-ray fluorescence and scanning electron microscopy with energy-dispersive spectroscopy. Alloy substrate was identified as an aluminum alloy 6,000 series Al–Si–Mg. Patina’s identified composition confirmed the documentation provided by the atelier. Concerning the white spots, zircon particles were found on patina surface as external elements.

Microstructure characterization of nanocrystalline ZrSiO4synthesized by ball-milling and high-temperature annealing

Microstructure characterization and phase transformation kinetics of a high-energy ball-milled and post-annealed stoichiometric (1:1 mol%)m-ZrO2and amorphous (a-) SiO2powder mixture have been investigated by Rietveld analysis of X-ray powder diffraction data. The experimental results reveal that the ball-milling of stoichiometric powder results in the formation ofc-ZrO2/t-PSZ phases only. The ZrSiO4phase was not found to form even after 30 h of milling. However, an almost stoichiometric ZrSiO4(commercially known as zircon) phase is found to form even when a sample that was ball-milled for 5 min was post-annealed at 1473 K for 1 h. It appears that the intermediatet-PSZ phase plays an important role in zircon phase formation. The content of ZrSiO4phase increases very sharply within 15 min of milling and remains almost unchanged after 30 h of ball-milling. It is also found that nanocrystalline zircon particles are almost free from lattice strain. Contamination by an α-Fe2O3phase from the milling media results in a colour gradient (white to reddish) in the nanocrystalline ZrSiO4phase.