RF Pulsed Discharge for the Metallic Corrosion Removal

book chapter

English

Plasmachemical treatment of archaeological artifacts by RF hydrogen low pressure plasma is a relatively new technique developed during the 1980s. The corrosions as well as their removal are a very complex problem. The mechanism of corrosion removal is not fully understood up to now and thus optimal conditions are not known well. Because each archaeological object is original it is necessary to study the influence of processes and discharge conditions using the model corroded samples. The sample heating due to the interaction with RF field created by plasma as well as heating directly by contact with plasma must be decreased as much as possible to protect the material structure changes. On the other hand, some power is necessary for the creation of plasma with sufficiently high concentration of reactive particles, mainly of atomic hydrogen. Thus the pulsed discharge should be a best way how to solve these antagonistic tasks. Our study was done using model corrosion samples of iron, copper, brass and bronze prepared by the action of HCl, HNO3 and H2SO4 acids. The duty cycle of RF capacitive discharge was varied from continuous regime up to 1:25. The plasma treatment duration was 40-120 minutes depending on the duty cycle. The results showed that the application of pulsed discharge regime can conserve the corrosion removal process at lower mean power as well and thus the treated samples were affected by lower heating stress but the process was significantly longer. Our first results demonstrated applicability of the special software used for the air photography based mapping for the observation of sample surfaces.

RF low temperature plasma, pulsed discharge, metallic corrosion

KRČMA, F.; SÁZAVSKÁ, V.; ZEMÁNEK, N.; PŘIKRYL, R.; ŘÁDKOVÁ, L.; FOJTÍKOVÁ, P.; JANOVÁ, D.; KOZÁK, O.; SLÁMOVÁ, J.

1. 4. 2010

St. Kliment Ochridsky University

Sofia

978-954-9401-41-7

Plasma for Environmental Applications

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