CONVENTIONALLY HEATED MICROFURNACE FOR THE GRAPHITIZATION OF MICROGRAM-SIZED CARBON SAMPLES

A new type of miniaturized, externally heated graphitization reaction furnace, the microconventional furnace (MCF), was constructed following our development of the laser heated furnace (LHF). The MCF is comprised of a gas reactor, a cold finger cooling system, and a compact resistive heater, which can raise the temperature of the hot finger to 850 degrees C. The gas reactor is provided with three integrated valves to connect with the hydrogen/vacuum manifold, to isolate the reactor, and to connect with sample vessels. We made two types of MCF: the type 1 furnace (volume of 0.9 mL), with an integral stainless steel cold finger, and the type 2 furnace (volume from 1.3 to 10 mL), with a changeable glass cold finger. The MCF is designed for above atmospheric pressure (up to 2500 mbar) operation to decrease the overall graphitization time and improve the carbon yield. The MCF provides an effective solution for producing graphite from carbon dioxide (CO2) sample gas from 5 to 2000 mu g of carbon with only 0.083 g of 100 pMC extraneous carbon added. Cross-contamination tests show that the MCFs have no memory effect from previous samples.