The effect of high temperature on the release of heavy metals from AgCdO and AgSnO2 contacts

An experiment was undertaken to study the release of heavy metals from AgCdO and AgSnO/sub 2/ contacts when they were subjected to high temperatures similar to those that would occur in a fire. Samples of AgCdO ( approximately 15 wt.% CdO) and AgSnO/sub 2/ ( approximately 15 wt.% SnO/sub 2/) were placed in a furnace and heated for 1 h at temperatures ranging from 800 degrees C to 1240 degrees C. The contact mass loss was measured at each temperature and the material evolved from the contacts was captured and analyzed using ESCA analysis. Cadmium was released from the AgCdO contact samples, but even at the highest temperature (1240 degrees C) only 8% of the original Cd was lost from the contact. In the case of AgSnO/sub 2/ no Sn was released, but a very small amount of Ag was captured from the heated contacts. The major conclusion is that, unless these contact materials were directly exposed to hot flames for long periods of time, very little heavy metal would be released into the environment during a fire.<>