SCIART: ALD oxide films as diffusion barriers for silver artifacts
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National Science Foundation SCIART: ALD oxide films as diffusion barriers for silver artifacts 100nm 70nm 20nm NC NC FC Bare 0 5 10 15 20 25 30 Unaged 4 hours aged 10 hours aged 22 hours aged Bare silver 2x coated nitrocellulose Brushed nitrocellulose 100nm Al 2 O 3 70nm Al 2 O 3 20nm Al 2 O 3 (ALD) Chalk ɣ Alumina 5% NaOH 0.5% NaOH 0.05% NaOH -100 0 100 200 300 400 500 600 700 Cu - coated samples Ag - coated samples Cu - uncoated samples Concentration (ppb) Removal Technique IC P- MS va lu es : Ni tr ic ac id di ge st io ns ΔE Level of reversibility of ALD oxide film application, via NaOH chemical etching vs. mechanical polishing using precipitated chalk and alumina polishing powders was investigated. While inductively coupled plasma mass spectrometry (ICP-MS) indicates that NaOH preferentially etches copper out of sterling silver, we find that at low NaOH concentrations etching the Al 2 O 3 ALD coatings and brush applied (NC) and flow coated (NCFC) nitrocellulose coatings after aging at elevated H 2 S levels show thicker ALD oxide films affect the color of the object less before aging and last longer than the organic nitrocellulose lacquer. This translates to better protection of art objects with less work on the part of conservators. Raymond J. Phaneuf, University of Maryland College Park, DMR 1041809
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SCIART: ALD oxide films as diffusion barriers for silver artifacts. Raymond J. Phaneuf, University of Maryland College Park, DMR 1041809. - PowerPoint PPT Presentation
Transcript of SCIART: ALD oxide films as diffusion barriers for silver artifacts
Nat
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Nat
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100nm 70nm 20nm NC NC FC Bare0
5
10
15
20
25
30Unaged4 hours aged10 hours aged22 hours aged30 hours aged
Bare silver 2x coated nitrocellulose Brushed nitrocellulose
100nm Al2O3 70nm Al2O3 20nm Al2O3 (ALD)
Chalk ɣ Alumina 5% NaOH 0.5% NaOH 0.05% NaOH
-100
0
100
200
300
400
500
600
700
Cu - coated samples
Ag - coated samples
Cu - uncoated samples
Ag - uncoated samples
Con
cent
ratio
n (p
pb)
Removal Tech-nique
ICP-MS val-ues: Ni-tric acid di-gestion
s
ΔE
Level of reversibility of ALD oxide film application, via NaOH chemical etching vs. mechanical polishing using precipitated chalk and alumina polishing powders was investigated. While inductively coupled plasma mass spectrometry (ICP-MS) indicates that NaOH preferentially etches copper out of sterling silver, we find that at low NaOH concentrations etching the oxide removes significantly less metal than polishing techniques currently used by conservators.
Al2O3 ALD coatings and brush applied (NC) and flow coated (NCFC) nitrocellulose coatings after aging at elevated H2S levels show thicker ALD oxide films affect the color of the object less before aging and last longer than the organic nitrocellulose lacquer. This translates to better protection of art objects with less work on the part of conservators.
Raymond J. Phaneuf, University of Maryland College Park, DMR 1041809
