73 Lars Brock Andersen, Plasmareduktion

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73 Lars Brock Andersen, Plasmareduktion

  1. 1. Brintplasmareduktion Status efter 10 år
  2. 2. • 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
  3. 3. β-FeOOH,xHCl,yH2O
  4. 4. kloridudvaskning Forhindre 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
  5. 5. Metodens perspektiver
  6. 6. A fast and non-destructive method to document and quantify the efficiency of metals conservation Henning Matthiesen & Karen StemannPetersen, National Museum of Denmark
  7. 7. 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 xMe + yO2 → MexO2y Can this be used during daily conservation work?
  8. 8. Optical oxygen measurements Transparent container wall Light transmitted to sensor Oxygen sensor inside container ptic o re Fib be pro Adhesive Light received from sensor
  9. 9. Small air volume: faster decrease in oxygen concentration 𝑂𝑥𝑦𝑔𝑒� 𝑐𝑜�𝑠𝑢𝑚𝑝𝑡𝑖𝑜� 𝑟𝑎𝑡𝑒 ሾ𝑔Τ 𝑑𝑎𝑦ሾ= �𝐼𝑁𝐼� × � × d�/d𝑡 100
  10. 10. Determination of air volume in bag 𝑂𝑥𝑦𝑔𝑒� 𝑐𝑜�𝑠𝑢𝑚𝑝𝑡𝑖𝑜� 𝑟𝑎𝑡𝑒 ሾ𝑔Τ 𝑑𝑎𝑦ሾ= �𝐼𝑁𝐼� × � × d�/d𝑡 100 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
  11. 11. 120 Rivet plate, wrought iron 100 80 ) t a s % ( n e g y x O 60 untreated untreated untreated annealed annealed wax coated 40 20 0 0 0.2 0.4 0.6 Time (days) 0.8 1

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