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首页> 美国政府科技报告 >Generation of Melamine Polymer Condensates upon Hypergolic Ignition of Dicyanamide Ionic Liquids
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Generation of Melamine Polymer Condensates upon Hypergolic Ignition of Dicyanamide Ionic Liquids

机译：双氰胺离子液体双曲点燃时产生三聚氰胺聚合物缩合物

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Fuels that can be ignited chemically under ambient conditions upon contact with an oxidizing agent are referred to as hypergols. Engines powered by hypergols do not require electric ignition, making them simple, robust and reliable alternatives to conventional fossil fuels. Commonly used hypergolic fuels include hydrazine and its methylated derivatives, which are extremely toxic, corrosive, and have high vapor pressure. Intense research is underway to develop alternative environmentally friendly liquid propellants with lower toxicity to reduce operational costs and safety requirements associated with handling hydrazine. Ionic liquids (ILs) have recently received considerable attention as energetic materials for propellant applications due to lower vapor pressures, higher densities and, often, an enhanced thermal stability compared to their nonionic analogues. Since 2008, a number of ILs have been reported to be hypergolic when reacted with common oxidizers, such as HNO3. Of particular practical interest are hypergolic ILs comprising fuel-rich dicyanamide (DCA) anions. DCA ILs have some of the lowest viscosities among known ILs, which is a very important figure of merit for the efficient fuel supply in bipropellant engines. In this study, using electrospray ionization mass spectrometry (ESI-MS), we discovered that the reaction between DCA ILs and HNO3 yields a precipitate that is composed of cyclic triazines, including melamine and its polymers. The concurrent formation of precipitate siphons materials from the hypergolic reaction pathway, limiting the energy capacity of a fuel. Furthermore, the generation of stable solidstate species during the ignition indeed represents a serious problem for the safe operation of bipropellant engines. We propose a mechanism for the formation of the major polymers via thermal decomposition of DCA ILs, mediated by nitric acid.

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