Thermal characteristics of ammonium nitrate, carbon, and copper(II) oxide mixtures

Abstract

Ammonium nitrate (AN) has been extensively used as an oxidizer in energetic compositions, and is a promising compound as a propellant and gas generator. It is well-known that metal oxides help to address some of the disadvantages of AN, such as low stability and a low burning rate in these applications. In order to investigate the effects of copper(II) oxide (CuO) on the thermal decompostion of AN mixtures, the thermal characteristics of AN, carbon, and CuO mixtures were measured using simultaneous differential scanning calorimetry and thermogravimetry–differential thermal analysis connected with infrared spectroscopy and mass spectrometry. As a combustible material, activated carbon (AC), and carbon black (CB) were used in this study. In the TG–DTA results for AN/AC/CuO and AN/CB/CuO mixtures in an open cell, an exotherm was observed at approximately 210 and 230 °C, respectively. In addition, the IR and mass spectra of the gases produced from the AN/AC/CuO and AN/CB/CuO mixtures indicated the presence of CO2. Notably, the effect of CuO addition on the oxidation of the AN/AC/CuO mixture was different from that on the AN/CB/CuO mixture; the oxidation of AC shifted to a lower temperature, while the oxidation of CB shifted to a higher temperature. These results suggest that the effect of CuO on the oxidation of different types of carbon depends on the chemical reactivity of the carbon, which is derived from its physical properties.