Post on 09-Dec-2014
description
Brintplasmareduktion Status efter 10 år
• Plasmabehandlingens virkemåde og forventningerne til metoden
• Reaktivitet af plasmabehandlet materiale
• Udvaskning af klorider fra arkæologisk jern
• Bestemmelse af behandlingens slutpunkt
• Metodens perspektiver
• Et spændende nybrud
β-FeOOH,xHCl,yH2O
kloridudvaskningForhindre korrosion under processen• Hindre iltadgang• Passivere med base eller inhibitor
Sikre adgang til alle klorider• Omdanne til ikke klorholdige korrosionsprodukter f.eks.
αFeOOH, Fe3O4, eller Fe2O3
Sikre udvaskningshastigheden• Øge porøsiteten ved omdannelse af korrosionsprodukter• Undgå udfældning af hydroxyder
Metodens perspektiver
A fast and non-destructive method to document and quantify
the efficiency of metals conservation
Henning Matthiesen & Karen Stemann-Petersen, National Museum of Denmark
Oxygen Consumption
Concept: the decrease in oxygen concentration is measured in an enclosed air volume around the artifact
Assumption: a high oxygen consumption indicates an unstable object
Can this be used during daily conservation work?
xMe + yO2 MexO2y
Fibre optic
probe
Light received from sensor
Adhesive
Oxygen sensor inside containerTransparent container wall
Light transmitted to
sensor
Optical oxygen measurements
Small air volume: faster decrease in oxygen concentration
𝑂𝑥𝑦𝑔𝑒𝑛 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 𝑟𝑎𝑡𝑒 ሾ𝑔 𝑑𝑎𝑦Τ ሿ= 𝑉𝐼𝑁𝐼𝑇 × 𝐾× d𝐶/d𝑡100
Determination of air volume in bag
A known volume of air or nitrogen is introduced in the bag
The air volume is calculated from the reative change in oxygen saturation
The volume is determined with an accuracy of approx 10%
Example: 20 mL of air is introduced after 3 days
𝑂𝑥𝑦𝑔𝑒𝑛 𝑐𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 𝑟𝑎𝑡𝑒 ሾ𝑔 𝑑𝑎𝑦Τ ሿ= 𝑉𝐼𝑁𝐼𝑇 × 𝐾× d𝐶/d𝑡100
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