Effect of urea on detonation characteristics and thermal stability of ammonium nitrate

• The thermal stability and detonation properties of AN-urea samples were studies.
• Urea can substantially stabilize thermal stability of AN.
• Urea can't reduce the ability of propagation of detonation.

A study has examined the effect of urea on the thermal stability and detonation characteristics of ammonium nitrate (AN). The thermal decomposition temperature and surface morphology of samples were investigated by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). For further research on the thermal sensitivity and shock sensitivity of the samples, the Koenen test and UN gap test were conducted. The results indicate that urea can substantially increase the thermal stability of AN (the greatest exothermic peak is increased by more than 100 °C) and reduce the thermal sensitivity of AN. However, AN-50wt. % urea mixtures can still produce a steady detonation in the UN gap test. Urea cannot reduce the ability to propagate a detonation. Possible explanations for these results are discussed.