Energetic Materials Combustion Catalysis: Necessary Conditions for Implementation

Abstract

The features of the catalysis of combustion of aromatic nitro compounds (trinitrates of toluene, resorcinol, phenol, etc.) have been studied. It has been shown that catalysts have a significant effect on the combustion of aromatic nitro compounds, and, as in the case of double-base propellants, their efficiency increases with the addition of carbon materials, especially carbon nanotubes (CNTs). For example, the addition of 3% nickel salicylate in combination with 1% CNTs to trinitroresorcinol leads to an increase in its burning rate by 4.3 times. It has been shown that, as in the case of double-base propellants, a necessary condition for the catalysis of nitro compounds is the formation of a carbon frame (deposit char layer) on the burning surface, on which catalyst particles accumulate and accelerate exothermic reactions. This fact, combined with the high thermal conductivity of the carbon frame, leads to an increase in the heat flux into the condensed phase and an increase in the burning rate. As pressure increases, the formation of the frame becomes more difficult, and the effect of catalysts decreases, as a result of which the value of pressure exponent reduces. The proposed mechanism of combustion catalysis is applicable to almost any individual explosives and propellant compositions based on various plasticizers (nitroesters, linear liquid nitro compounds and nitramines, etc.), as well as containing powerful explosives (RDX, HMX, CL-20, etc.), the combustion of which proceeds due to the heat of redox reactions.

Thermal Decomposition, Ignition Process and Combustion Behavior of Nitrate Ester Plasticized Polyether Propellant at 0.1–3.0 MPa

“…Meanwhile, a carbon frame (deposit char layer) was formed on the burning surface, and catalyst particles accumulated on this skeleton without clumping. In a high pressure environment, the exothermic 9 International Journal of Aerospace Engineering reaction of the catalyst was more intense, which further increased propellant burning rate [47].…”

Burning rate catalysts action on the trinitroresorcinol combustion wave parameters

“…In refs. [1, 2], it was established that the regularities of the combustion catalysis of aromatic nitro compounds are similar to those for the double‐base propellants 3 : first, a carbon frame should form on the combustion surface, on which the accumulation of catalyst particles accelerating exothermic reactions occurs, and, second, the thermal conductivity coefficient of the carbon frame should be significantly (up to ∼10 times) higher compared to the gas zone above the combustion surface of the sample without a catalyst. As a result, the heat flux to the condensed phase (c‐phase) increases and the burning rate grows.…”

“…Such experimental data for nitro compounds have not been obtained and does not allow us to compile the heat balance of the c-phase and identifying the leading stage (zone) that determines the burning rate. Therefore, this work aims to study the effect of catalysts on the parameters of the combustion wave of trinitroresorcinol (THR), for which the most significant catalytic effect (Z value) of the studied nitro compounds is observed, 1,2 as well as to study the structure and elemental composition of the carbon frame on the combustion surface of quenched TNR samples with 3% nickel salicylate (NS) combined with 1% carbon nanotubes (CNT).…”

Functionalized Carbon Nanotube Guided Growth of HMX Crystals with Improved Thermal Stability and Reduced Sensitivity

“…The CNTs are nanostructured materials with hexagonal shapes that interconnect to form tube-like structures. In fact, CNTs have been used in the field of EMs for years, including combustion catalysts, − enhancements in physical properties, , and desensitization of energetic composites. − However, because of the limited inherent interactions between pure CNTs and HMX molecules, functionalization of CNTs is an essential for better modification of HMX crystals. In this study, carboxylated CNTs and fluorinated CNTs have been employed for intercalating of HMX crystals as nucleation centers.…”