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FIZIKA A 5 (1996) 2, 63-70
 
INFLUENCE OF DECOMPOSITION OF CARBON CONTAINING GASES ON CONTACT
RESISTANCE OF REED SWITCHES
MIRAN MOZETIČ, MELITA MURKO-JEZOVŠEK and TOMO BOGATAJ
Institute of Electronic and Vacuum Technique, Teslova 30, 61000 Ljubljana, Slovenia
Received 7 April 1995
Revised manuscript received 29 March 1996
During the operation of reed switches, a continuous increase of the contact resistance
was observed. After the life time test, AES analyses of the contact surfaces showed an
appearance of carbon, which originally wasn't present. In order to find the origin of
carbon on the surface, model reed switches were prepared, evacuated, and than filled with
a protective gas with intentionally added carbon containing gases. After the lifetime test
of the reed switch models, the contact resistance of switches filled with N2 +
H2 , N2 + H2 + CO and N2 + H2 + CO
+CO2 remained low while the resistance of switches filled with N2
+CO + CO2 and N2 +H2 + C2H2
increased substantially. AES analyses have shown that the quantity of carbon deposited on
contacts of switches filled with N2 + H2 + C2H2
was much greater than that deposited on contacts of switches filled with the other gases.
Since gas chromatographic analysis showed an appreciable lowering of the C2H2
concentration, we concluded that C2 H2 decomposed on the contact
surfaces causing the increase of the contact resistance.
UDC 538.971
PACS 32.80.Hd, 68.35.-p
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