Investigation of contact surfaces in model reed switches filled with selected gases

M. Murko-Jezovšek, M. Mozetič, B. Praček, L. Nagy

Research output: Contribution to journalArticle


The physical and chemical processes which take place in miniature reed switches under electrical load have been investigated. The temperature of the contact spot just before the break was determined from measurements of the bridge voltage. Model reed switches were filled with the protective gas mixture N2-H2 containing small quantities of CH4 or C2H2. These two gases decompose at the contact spot, since its temperature rises to approximately the boiling point of gold. Contamination spots consisting mostly of carbon were detected on the contact surfaces after the lifetime test. Auger electron spectroscopy showed that the quantity of carbon in the spots is the highest if the protective gas is doped with C2H2. IR analysis of the spots showed that they are of pure amorphous carbon. Because of the carbon deposition a considerable increase in the contact resistance of the switches was observed. Traces of carbon were also found on the surfaces of the contacts of switches filled with pure N2-H2, although in this case the contact resistance remained low.

Original languageEnglish
Pages (from-to)172-175
Number of pages4
JournalApplied Surface Science
Issue numberPART 1
Publication statusPublished - Jun 2 1993

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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