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本文报道了NH_4NO_3和N_2H_5NO_3的真空差热分析(DTA)的结果。为观察热传递特性改变的影响,在空气中做了NH_4NO_3的DTA实验。在真空实验中,硝酸盐部分地蒸发并凝聚在石英罩管的冷表面上。依据这些事实及定量DTA理论,证明从空气到真空,热传递特性的改变不掩蔽熔融峰,而放热峰也不改变为吸热峰。依据热化学计算,断定Hodgkinson反应是放热反应。因此,推断真空DTA曲线终端的吸热峰是分解放出的热量和液态硝酸盐蒸发而吸收的热量的净结果。显然,硝酸盐的蒸发热是决定真空DTA曲线终端吸热峰的支配因素。这些结论皆不同于Breisacher的解释。
This paper reports the results of vacuum differential thermal analysis (DTA) of NH_4NO_3 and N_2H_5NO_3. In order to observe the influence of the change of heat transfer characteristics, a DTA experiment of NH 4 NO 3 was performed in the air. In the vacuum experiment, the nitrate partially evaporated and condensed on the cold surface of the quartz tube. Based on these facts and the quantitative DTA theory, it is proved that from air to vacuum, the change of the heat transfer characteristics does not mask the melting peak, and the exothermic peak does not change to the endothermic peak. Based on thermochemical calculations, it is concluded that the Hodgkinson reaction is exothermic. Therefore, it is inferred that the endothermic peak at the end of the vacuum DTA curve is the net result of the heat released by decomposition and the absorption of liquid nitrate evaporation. Obviously, the heat of vaporization of nitrate is the dominant factor that determines the endothermic peak at the end of the vacuum DTA curve. These conclusions are different from Breisacher’s explanation.