Thermal Decomposition Of HMX Research Articles

Thermal decomposition mechanism of HMX/HTPB hybrid explosives studied by reactive molecular dynamics.

The thermal decomposition process of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine/hydroxyl-terminated polybutadiene (HMX/HTPB) hybrid explosives and pure HMX explosives at different temperatures (2000 ~ 3500 K) was investigated using the reactive molecular dynamics method. This study aimed to analyze the effect of binders on the thermal decomposition of HMX at the atomic scale and reveal the thermal decomposition mechanism of HMX/HTPB. The results showed that the thermal decomposition process of the HMX molecule in the HMX/HTPB hybrid system involves a continuous denitration followed by the disintegration of the main ring. The HTPB chain will experience dehydrogenation, dehydroxylation, and chain fragmentation. Including HTPB in the hybrid system significantly increased the presence of H and OH radicals. These radicals then interacted with HMX and its decomposition products and produced more of the final products H2O and H2 in the HMX/HTPB hybrid system compared to pure HMX. Additionally, it was observed that the HTPB chain fragments attached to the HMX decomposition products prevented the formation of N2 and CO2. Furthermore, the activation energies (Ea) of the initial and intermediate decomposition stages of the HMX/HTPB hybrid system were 98.45 kJmol-1 and 90.69 kJmol-1, respectively. The results showed that the activation energies of the HMX/HTPB hybrid system are lower than the pure HMX system in these two stages. Consequently, HTPB will enhance HMX's thermal decomposition and decreased the system's insensitivity to heat stimuli. The molecular dynamics simulation of the HMX/HTPB hybrid system was performed using the ReaxFF module in the LAMMPS software, and the ReaxFF/lg force field was used to describe the interatomic interactions as well as the chemical reactions.

The unusual effect of paraffin wax on the thermal decomposition of cyclotetramethylenetetranitramine.

The practical application of paraffin wax (PW) in cyclotetramethylenetetranitramine (HMX)-based polymer-bonded explosive (PBX) requires an understanding of its effect on the thermal decomposition of HMX. In this work, by comparing the thermal decomposition of HMX and a HMX/PW mixture, combined with crystal morphology analysis, molecular dynamics simulation, kinetic analysis, and gas product analysis, the unusual phenomenon and mechanism of the PW effect on the thermal decomposition of HMX were evaluated. During the initial decomposition, PW infiltrates the crystal surface of HMX, reduces the energy barrier for chemical bond dissociation, and induces the decomposition of molecules on HMX crystals, resulting in a lower initial decomposition temperature. PW consumes the active gas produced by HMX with further thermal decomposition and inhibits the dramatic increase of the HMX thermal decomposition rate. In decomposition kinetics, this effect is manifested as PW inhibits transition from an n-order reaction to an autocatalytic reaction.

Effects of Two Common Binders on Decomposition Mechanism of HMX Molecule Under Linear Temperature Rise

ABSTRACT The effects of two common binders (BR and F binder) on the thermal decomposition of HMX molecules during linear heating were studied by molecular dynamics simulation. It was found that both binders can induce the decomposition reaction of HMX molecules earlier, promote the conversion of intermediate products to stable products, and reduce the activation energy and potential energy barrier of the system. The induction of the binder in the composite system makes the initial decomposition of HMX molecules appear at the interface between the binder and the HMX molecules, and the binder’s higher heat absorption rate absorbs a large amount of energy released by the hot spots. The promoting effect of binder on the conversion of intermediate products to stable products and the interaction between binder and HMX intermediate products consume excessive active particles, which inhibits the further decomposition of macromolecular intermediate products. The results show that both BR and F binders prolonged the decomposition duration of HMX, and F rubber with better thermal stability has the longest HMX decomposition duration in the composite system. Our simulation revealed the action mechanism of BR and F rubber in HMX thermal decomposition, which provided a new idea for studying the action mechanism of binders on the thermal properties of high explosives.

Temperature and Pressure Effects on HMX/Graphene via ReaxFF Molecular Dynamics Simulations

Studying the thermal decomposition of energetic materials at high temperatures can provide detailed reaction and mechanistic information, which is critical for understanding the reactivity of energetic materials, designing mixed explosives, and achieving improved safety. In this work, the effects of temperature and pressure on graphene (Gr)-based HMX crystals were investigated using ReaxFF molecular dynamics simulations. The thermal decomposition processes of perfect HMX crystals, HMX crystals with (001), (010), or (100) crystal planes, and HMX/Gr mixed systems were studied at high temperatures and pressures. In the mixed systems, different configurations of HMX molecules adsorbed on the Gr surface were confirmed by theoretical calculation methods. With the pressure ranging from atmospheric pressure to 31 GPa, 3, 5, and 3 configurations of HMX adsorbed on the Gr surface were identified for the (001)/Gr, (010)/Gr, and (100)/Gr systems, respectively. The time-dependent curves for the evolution of fragments, intermediates, and pyrolysis products were analyzed. The rate constant for the thermal decomposition of HMX was found to be significantly affected by the addition of Gr. In particular, the thermal decomposition reaction was strongly inhibited in the (010)/Gr system. This result indicates that Gr promotes an anisotropic thermal effect, resulting from the steric hindrance of the NO2 functional groups and the interaction between Gr and HMX molecules. Gr also affected the initial reaction pathway of homolytic N–NO2 bond cleavage, with C=O, C–OH, and C–OC bonds on the Gr surface participating in the formation of nitro radicals and HONO.

A study of the pore size effect on the formation of hot spot in a 1,3,5,7-tetranitro-1,3,5,7-tetrazocane crystal under a low-to-medium shock velocity

ABSTRACT It is rather difficult to observe, record and analyze the pore-collapse-induced initiation of a 1,3,5,7-tetranitro-1,3,5,7-tetrazocane or HMX crystal via experiment because it is an extreme phenomenon involving multiphysics (such as shock, phase change of HMX) and chemical reactions (thermal decomposition of HMX) occurring in microseconds or even nanoseconds. Herein, a mechanical-thermal-chemical coupled finite element model is proposed to simulate the pore collapse in a HMX crystal under a shock loading at velocities under 500 m/s. A viscoplastic constitutive model and a Birch-Murnaghan equation of state (EoS) are employed to predict the mechanical response of the HMX crystal. The melting of the HMX crystal is also considered. A multi-step thermal-decomposition model is employed to simulate the chemical reaction of the HMX. Firstly, numerical simulations were implemented for a few plane shock experiments and it is demonstrated that the material model of HMX have reasonable accuracy. Then, the pore collapse in a HMX crystal under a shock at 500 m/s was simulated. It is shown that severe plastic deformation and high-velocity impact of HMX jet both contribute to the temperature rise of local materials. Finally, the influence of pore size on the calculated maximum temperature of the HMX crystal was simulated under various shock velocities ranging from 100 m/s to 500 m/s. It seems that there exists an “optimal” pore size for the HMX crystal to obtain the highest temperature under a shock, which is explained with simulation results.

Synergistic Catalytic Effect of Thermite Nanoparticles on HMX Thermal Decomposition

Even though HMX is one of the most vigorous energetic materials for solid propellants, explosives, and pyrotechnics; it has high thermal stability and low sensitivity to common catalysts. Metal oxides with hydrous surface can release active $$\dot{\text{{O}}}$$ H radicals at low temperature. These active radicals could attack HMX heterocyclic ring and alter HMX decomposition mechanism form C-H bond cleave to hydrogen atom abstraction. This study reports on the facile synthesis of Fe2O3 nanoparticles (NPs) of 8 nm average particle size. Aluminum NPs of 80 nm was employed in combination with Fe2O3 NPS; this nanothermite binary mixture can induce not only catalytic effect but also vigorously-exothermic thermite reaction with high heat output. Colloidal thermite mixture Fe2O3/Al was effectively-integrated into HMX crystals via co-precipitation technique. Uniform distribution of nanothermite particles into HMX was confirmed via elemental mapping using EDAX. Nanothermite mixture as high energy density material offered an increase in HMX total heat release by 82% using DSC. Furthermore, nanothermite particles offered superior catalytic effect with decrease in HMX activation energy by 25% using Kissinger method. Kinetic decomposition parameters using KAS model were found to be in good agreement with Kissinger's model. Colloidal nanothermite particles can act as high energy density material, and as a catalyst with decrease in required activation energy.

Mechanism of Two Typical Binders BR and F2604 on Thermal Decomposition of HMX.

DSC–TG–FTIR–MS coupling technology was used to study the mechanism of two typical binders, that is, BR and F2604, on the thermal decomposition behavior of the HMX crystal. The results show that both BR and F2604 can induce premature decomposition of HMX and increase the activation energy of HMX. Especially in the case of HMX/BR particles, the decomposition temperature is the lowest, but the activation energy is the highest. Based on the results of DSC–TG–FTIR–MS, it is found that the rapid mechanism of binder and active intermediate products inhibits the reaction of relatively inert intermediate products and prolongs the continuous generation time of gas products in the composite particles, which delays the decomposition of HMX to a certain extent. This study is helpful for us to better understand the thermal decomposition behavior of HMX composite particles and provides reference for the application of high-energy composites.

Three-Dimensional Mechanical–Thermal–Chemical Coupled Mesoscopic Simulation of the Collapse of an Air Bubble in an HMX Crystal

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is extensively employed in military weapons as the main constituent of HMX-based polymer-bonded explosives (PBXs). It is known that the safety of PBXs is closely related to their microstructures. Discontinuities in PBXs, such as micron-sized pores, air bubbles, and interfaces between the explosive crystal and polymer bonds, may transform into hot spots when subjected to impact. Herein, a three-dimensional mechanical–thermal–chemical coupled mesoscopic model is proposed to study the collapse of an air bubble in an HMX crystal under impact. A viscoplastic constitutive model and the Birch–Murnaghan equation of state are employed for the HMX crystal to predict its mechanical response. Thermal decomposition of HMX is taken into account by using multistep thermal decomposition equations. The viscoplastic model yields results that reasonably agree with data obtained in the plane shock experiment. The influence of the edge length of the mesh elements on simulation results is analyzed. Then more simulations are conducted for studying the feasibility of using the viscoplastic model for different orientations of the HMX lattice. Afterwards, the coupled model is applied to study the collapse of an air-bubble/pore in the HMX crystal for different impact velocities.

Performance optimization of core-shell HMX@(Al@GAP) aluminized explosives

The energy release of aluminized explosives was impeded by the aggregation of aluminum powders, especially for nano-aluminum powders. The core-shell HMX@(Al@GAP) explosives with 5 wt% to 15 wt% aluminum were fabricated, with systematical investigation of morphology, mechanical properties, thermal decomposition, combustion and detonation properties. Compared with the physical mixtures, the aluminized explosives with core-shell microstructure showed better creep resistance and mechanical strength. The thermal decomposition of HMX in core-shell HMX@(Al@GAP) was slightly advanced due to good dispersion of Al@GAP particles. Delayed but more vigorous and longer burning during combustion process was witnessed for the core-shell explosive. For HMX@15 wt%(Al@GAP) aluminized explosives, the detonation velocity and specific kinetic energy was 8567 m/s and 1.412 kJ/g, which was 1.3% and 5.1% higher than the corresponding physical mixtures. The reaction of the core-shell HMX@(Al@GAP) and the physical mixtures were calculated by ReacFF-/g force field, showing remarkable dependent of the average temperature on the microstructure. Present research might provide new insight for synergistically improvement of mechanical and detonation properties in aluminized explosives.

Synthesis and Effects of Two Novel Rare-Earth Energetic Complexes on Thermal Decomposition of Cyclotetramethylene Tetranitramine (HMX).

In order to explore the effect of the energetic complex on the thermal decomposition HMX, two new rare-earth energetic complexes [La(tza)(NO3)2(H2O)4]n (1) and [Ce(tza)(NO3)2(H2O)4]n (2) (Htza = tetrazole-1-acetic acid) were prepared by a solvent evaporation method. The obtained products were structurally characterized by Fourier-transform infrared spectroscopy (FTIR), elemental analysis, powder X-ray diffraction (PXRD), single crystal X-ray diffraction (XRD), and thermogravimetric analysis coupled with differential scanning calorimetry (TG-DSC). In addition, the compatibility of complex 1 with cyclotetramethylene tetranitramine (HMX) was studied by DSC and FTIR, respectively. Structural analysis suggested that complex 1 exhibits an orthorhombic, P 21 21 21 space group, and the La (III) ion was 10-fold coordinated in a distorted double-capped antiprism configuration. Complex 2 featured a one-dimensional, right-handed helical infinite chain. The effect of complexes 1 and 2 on the thermal decomposition of HMX was investigated by DSC, which revealed that complex 1 showed a slightly better effect than 2 on the thermal decomposition of HMX and released more heat. Furthermore, complex 1 had good compatibility with HMX, indicating that it may act as a combustion promoter for nitrate ester plasticized polyether (NEPE) solid propellant.

In situ synthesis of MgWO4–GO nanocomposites and their catalytic effect on the thermal decomposition of HMX, RDX and AP

For solving phase separation of nanoparticles and graphene oxide (GO) in the application process, MgWO4–GO nanocomposites were successfully synthesized using three different dispersants via a facile solvothermal-assisted in situ synthesis method. The structure and morphology of the prepared samples were characterized by X-ray diffraction, Scanning electron microscopy, Transmission electron microscopy, Fourier transform infrared and Raman techniques. The experimental results show that MgWO4 nanoparticles are tightly anchored on the surfaces of GO sheets and the agglomeration of MgWO4 nanoparticles is significantly weakened. Additionally, MgWO4–GO nanocomposites are more stable than self-assembly MgWO4/GO, which there is no separation of MgWO4 nanoparticles and GO sheets by ultrasound after 10 min. The catalytic results show that, compared with bare MgWO4, MgWO4–GO nanocomposites present better catalytic activities on the thermal decomposition of cyclotetramethylenete tranitramine (HMX), cyclotrimethylene trinitramine (RDX) and ammonium perchlorate (AP). The enhanced catalytic activity is mainly attributed to the synergistic effect of MgWO4 nanoparticles and GO. MgWO4–GO prepared using urea as the dispersant has the smallest diameter and possesses the best catalytic action among the three MgWO4–GO nanocomposites, which make the decomposition temperature of HMX, RDX and AP reduce by 10.71, 11.09 and 66.6 °C, respectively, and the apparent activation energy of RDX decrease by 68.6 kJ mol−1.

A comprehensive mechanism for liquid-phase decomposition of 1,3,5,7-tetranitro-1,3,5,7-tetrazoctane (HMX): Thermolysis experiments and detailed kinetic modeling

The nitramines 1,3,5,7-tetranitro-1,3,5,7-tetrazoctane (HMX), and 1,3,5-trinitro-1,3,5-triazinane (RDX) are energetic materials commonly used in solid propellants and explosives. In order to predict ignition and deflagration of propellants containing these ingredients, their thermal decomposition behaviors must be thoroughly understood. In this study, the thermal decomposition of HMX was investigated using synergetic application of experimental and computational methods. Mole fraction profiles of the gaseous decomposition products evolving from the liquid-phase HMX were obtained using Fourier transform infrared (FTIR) spectroscopy for two types of thermolysis experiments – thermogravimetric analysis (TGA) and confined rapid thermolysis (CRT). Four heating rates (5, 10, 15, and 20 K/min) in TGA experiments and four set temperatures (290, 300, 310 and 320 °C) in CRT experiments were considered. In the TGA and differential scanning calorimetry (DSC) results, steep mass loss and rapid decomposition were observed after the melting of the HMX at 280 °C. CH2O and N2O were identified as the major decomposition products. Smaller quantities of H2O, HCN, NO and NO2, CO and CO2 were also formed. In the complementary computational study, liquid-phase elementary reactions were investigated using quantum mechanics calculations at B3LYP/6-311++G(d,p) level of theory with the conductor-like polarizable continuum model (CPCM). A zero-dimensional model was developed to simulate the TGA and CRT experiments based on conservation of mass and species in the condensed-phase and the gas-phase control volumes. The predicted mass loss and gas-phase mole fraction profiles of the decomposition products are in good agreements with the corresponding experimental results, indicating that the comprehensive mechanism proposed here captures the important reactions occurring during liquid-phase decomposition of HMX.

Synthesis and thermal performance study of C60-polyglycidyl nitrate (C60-PGN) maleic acid copolymer lead salts

A C60-polyglycidyl nitrate (C60-PGN) maleic acid copolymer lead salt was synthesized through two steps using C60-PGN, maleic acid, and lead nitrate as raw materials. The synthesized product was characterized by Fourier transform infrared, X-ray diffraction, X-ray photoelectron spectroscopy. The thermal stability of the C60-PGN maleic acid copolymer lead salts was investigated by differential thermal analysis and thermogravimetric analysis. The results showed that it exhibited good resistance to thermal decomposition at 546.93 K. The thermal decomposition kinetic parameters of the C60-PGN maleic acid copolymer lead salts are also obtained through the Kissinger and Ozawa-Doyle methods, with Ea = 166.31 and 166.99 kJ mol−1, respectively. Moreover, C60-PGN maleic acid copolymer lead salts exhibited high catalytic activity for the thermal decomposition of HMX, indicating that the salt can be used as a combustion catalyst in solid propellants.

Numerical study of countermeasure against thermal stimuli for HMX-based polymer-bonded explosives

ABSTRACTAn accurate thermal decomposition model of Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)-based polymer-bonded explosives is indispensable to the design of countermeasure against environmental thermal stimuli for certain explosive devices. However, the complicated chemical reactions occurring in decomposition of HMX-based polymer-bonded explosives pose great challenge to scientists. In this study, the thermal ignition kinetic model proposed by Tarver is implemented to study thermal decomposition of HMX-based polymer-bonded explosives using commercial software Abaqus, which does not only consider the thermal decomposition of HMX but also the polymer binders. The simulation results are compared to ODTX and Scaled Thermal Explosion Experiment (STEX) and reasonably good agreements are achieved. Then the thermal decomposition model is applied to analyze an explosive device exposed to environmental thermal stimuli. Furthermore, countermeasure against environmental thermal stimuli is suggested and analyzed quantitatively for the explosive device. The time to explosion and environmental temperature before ignition is calculated and analyzed for the explosive device under various heating rates.

Ionic Ferrocenyl Coordination Compounds Derived from Imidazole and 1,2,4‐Triazole Ligands and Their Catalytic Effects During Combustion

Alkylferrocene‐based burning‐rate catalysts (BRCs) show conspicuous migration tendency and volatility during prolonged storage and fabrication process of a composite solid propellant. To enhance anti‐migration ability of the BRCs, forty novel ionic coordination compounds, [M(L)4(H2O)2]mXn (M = Mn2+, Co2+, Cu2+, Ni2+, Zn2+, Fe2+, Pb2+, Cr3+, Bi3+, or Cd2+; L = ferrocenylmethyl imidazole or ferrocenylmethyl‐1,2,4‐triazole; X = picrate or trinitroresorcinolate), were synthesized and characterized by FT‐IR, UV/Vis, and elementary analysis. Additionally, the crystal structures of six compounds were confirmed by single‐crystal X‐ray diffraction. The TG analyses revealed that the new compounds show high thermal stability. Cyclic voltammetry studies suggested that theyare irreversible redox systems. Their catalytic activities in the thermal degradation of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclo‐hexane (RDX) and 1,2,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) were examined by DSC technique. The results indicated that all the new compounds exert great effects on the thermal decomposition of AP and RDX, among them some compounds are more active than catocene. Compound 26 has good catalytic ability in the thermal decomposition of HMX, representing a rare example of the reported ferrocene‐based BRCs which show catalytic activity during combustion of HMX.

Synergistic Catalytic Effect of a Series of Energetic Coordination Compounds based on Tetrazole‐1‐acetic Acid on Thermal Decomposition of HMX

A series of energetic coordination compounds [Co(tza)2}n (1), [Bi(tza)3]n (2), {[Cu4(tza)6(OH)2]·4H2O}n (3), [Mn(tza)2]n (4), {[Bi(tza)(C2O4)(H2O)]·H2O}n (5) and [Fe3O(tza)6(H2O)3]NO3 (6) based on tetrazole‐1‐acetic acid (Htza) were synthesized though environmentally friendly methods. The coordination compounds were characterized by elemental analyses, IR spectroscopy, single‐crystal and powder X‐ray diffraction (PXRD), thermogravimetric analyses (TG), and differential scanning calorimetry (DSC). Their catalytic performances and the synergetic catalytic effects between 1 and 2, 3 and 4, 5 and 6 on the thermal decomposition of octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) were all investigated by DSC. The results revealed that compounds 1–6 are thermally stable energetic compounds and they all exhibit high catalytic action for HMX thermal decomposition. The catalytic effects of the compounds on HMX thermal decomposition are closely related to the oxides, which come from the decomposition of the compounds, but have no positive relationships with the heat releases of the compounds themselves. Moreover, the synergetic catalytic effects between 1 and 2, 3 and 4, 5 and 6 were observed. Their mixtures at different mass ratio have different synergetic catalytic effects, and the sequence of the biggest synergetic index (SI) in each system is copper‐manganese system (compounds 3 and 4) > iron‐bismuth system (compounds 5 and 6) > cobalt‐bismuth system (compounds 1 and 2), indicating that the synergistic catalytic effects are mainly related to the combination and the proportion of the compounds.

Mono‐ and Dinuclear Ferrocenyl Ionic Compounds with Polycyano Anions. Characterization, Migration, and Catalytic Effects on Thermal Decomposition of Energetic Compounds

AbstractNeutral ferrocene‐based burning rate (BR) catalysts show strong migration trends and volatility during long‐time storage and curing of the composite solid propellants. To reduce these disadvantages thirty‐two ferrocenyl quaternary ammonium compounds, paired with polycyano anions, were synthesized and characterized by 1H NMR, 13C NMR, and UV/Vis spectroscopy, as well as elemental analysis. Additionally, crystal structures of eight compounds were confirmed by single‐crystal X‐ray diffraction. TG and DSC analyses indicated that the compounds containing 1,1,2,3,3‐pentacyanopropenide anions show high thermal stability. Cyclic voltammetry studies suggested that they are quasi‐reversible or irreversible redox systems. Anti‐migration tests verified that the tested compounds show very low migration tendency and some of them exhibit no migration after 30 days aging at 70 °C. Their catalytic efficiency in the thermal decomposition of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), and 1,2,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) were examined by DSC analyses. The results revealed that most of the compounds exhibit distinct effects on the thermal degradation of AP and RDX. Two compounds have good catalytic ability in the thermal decomposition of HMX, representing rare examples of the reported ferrocenyl ionic compounds, which display catalytic property during combustion of HMX.

Dependence of the parameters of thermal decomposition of energetic materials on the experiment conditions

The causes of large scatter of the published data on the kinetic parameters of thermal decomposition of energetic materials, determined by methods of thermal analysis, are analyzed. It is shown that this scatter is mainly due to different contribution of secondary reactions involving gaseous products in devices differing in the design of the measurement cells. The influence of nitrogen pressure in the interval 1–100 bar on the characteristics of thermal decomposition of HMX and ammonium perchlorate in open measurement cells (crucibles with perforated lids) is examined by DSC. An increase in pressure leads to significant changes in the temperature intervals, in the shape of the heat release peaks, and in the heat of the overall decomposition reaction, ΔН d. The kinetic parameters of the thermal decomposition of HMX, calculated from the results of experiments in open and sealed crucibles at heating rates of 0.1–1.0 deg min−1, are compared.

The Thermal Decomposition Behavior of Graphene Oxide/HMX Composites

Graphene oxide (GO) was prepared by Hummers method and GO/1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) composite was prepared via an ultrasonic compounding method. The structure of GO was characterized using XRD and SEM, the thermal decomposition of HMX and GO/HMX composite was analyzed by DSC/TG test. The results show that interlayer space of GO increases markedly, the thermal decomposition process of HMX can be promoted with the nanolayer structure of GO, resulting the reduced thermal decomposition activation energy of about 50 kJ/mol with 1% GO.

Effect of catocene on the thermal decomposition of ammonium perchlorate and octogen

Simultaneous TG/DSC-FT-IR was employed to study the effect of catocene with a high concentration (5, 15, and 25 %) on the thermal decomposition of ammonium perchlorate (AP) and octogen (HMX) with different particle sizes. The experimental results show that catocene has effect on the thermal decomposition of AP and HMX, but the role that catocene playing changes with the concentration of catocene and the particle size of AP and HMX. High concentration of catocene (more than 15 %) benefits the decomposition of fine AP and HMX at low temperature, but has little effect on the decomposition of median and coarse AP. The thermal decomposition of HMX is affected by catocene mainly through increasing the heat release of the first decomposition step, while through both increasing the heat release and decreasing the decomposition temperature of the first decomposition step for the thermal decomposition of AP.