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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