Unraveling the combustion mechanism of tetramethylammonium perchlorate (TMAP) and TMAP-based energetic composites

•The combustion behavior of compositions of tetramethylammonium perchlorate (TMAP) with inert additives, ammonium perchlorate (AP), and AP-based composite propellants has been investigated in detail.•The reasons for the heat instability of TMAP combustion have been determined.•The conditions have been found under which TMAP plays the role of an additive that increases the burning rate of composite propellants. This study investigated the combustion behavior of tetramethylammonium perchlorate (TMAP) compositions with inert additives, ammonium perchlorate (AP), and in AP-based composite propellants. The explanation for the lack of the combustion of TMAP in its pure form is given. It is postulated that the addition of inert substances, such as Al2O3 and carbon nanotubes (CNTs), to TMAP increases the heat input from the gas zone due to their higher thermal conductivity. This compensates for the heat loss from the reaction zone in the condensed phase, which leads to the occurrence of combustion. As the Al2O3 content increases or CNTs are used, the heat input from the gas phase also increases significantly, causing the burning rate to be determined by the kinetics of the rapid decomposition of a TMAP dissociation product, methyl perchlorate, in the gas zone. Studies on the combustion of mixtures of AP and TMAP have demonstrated that when introduced into a system with the leading reaction in the condensed phase, TMAP acts as an inert additive due to its higher thermal stability and lower heat release rate compared to AP. In compositions with propellants that burn by the gas phase mechanism, dissociative vaporization of TMAP results in the formation of thermally unstable methyl perchlorate in the gas zone, which acts as a rapid heat release agent. Novelty and significance statement: The significance of this work is to establish the causes of heat instability of combustion of methylamine perchlorates derivatives. These derivatives can be considered as model compositions of ammonium perchlorate with hydrocarbon fuels. Moreover, substances that are incapable of combustion within specific pressure ranges are of significant interest for laser-augmented chemical propulsion. The novelty of the work lies in the fact that for the first time (1) the combustion behavior of compositions of tetramethylammonium perchlorate (TMAP) with inert additives, ammonium perchlorate (AP), and AP-based composite propellants has been investigated in detail, (2) the reasons for the heat inst