Utilizing microwave susceptors to visualize hot-spots in trinitrotoluene

In recent years, researchers have shown that the inclusion of susceptors in monomolecular explosives increases microwave absorption where the monomolecular explosive alone is nearly transparent to the microwave energy. In this study, graphite particles are used to absorb microwave energy and decompose trinitrotoluene 1,3,5 (TNT). Aluminum particles were also used with TNT but very little energy was absorbed. Thermal and electric properties of the susceptor affect microwave energy conversion to thermal energy in explosives. The temperature gradients across the broad face of a cylindrical sample of TNT with and without susceptors were spatially observed using an infrared camera. Hot-spots were observed during 120 seconds exposure to microwave energy at a frequency of 3.3 GHz and found to directly correlate with susceptor concentration. When using graphite, the TNT heated above its melting temperature and decomposed as a vapor.