Crucible for extracting gas from solid samples - using graphite cup with holes around side to allow gas to escape

摘要

Extraction and analysis of gases contained in solid samples is carried out by use of a graphite crucible. This is gripped between cooled electrodes and subjected to an electric current. The heat so generated melts the sample in the crucible and releases the gas which is then carried off by a carrier gas entering from the top of the crucible. The gas leaves at approx. the same temp. as the crucible via openings around the edge of the wall. The crucible is first preheated to 2800 degrees C for =50 sec. and a non-metallic sample injected. It is further maintained at 2000 degrees C for 60-180 sec. and the gas so produced is led off with the carrier gas flowing through. Used to determine the gas content of solid materials, esp. the content of H2, N2 and other elements. The basic system is well known but the hot gases rapidly touch water cooled Cu electrodes which cause various entrained compounds to solidify, thereby blocking the passageway out from the crucible. The system described ensures that the outlets are at the same temp. as the crucible and thus blockage does not occur.