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Metastable intermolecular composites (MICs) typically use Al as fuel and transition metal oxides as oxidizers, while their reactivities are hindered by the inert Al 2 O 3 passivation layer on the surface of Al particles. Recently, transition metal fluorides have emerged as novel fluorine-containing oxidizers for promoting the reactivity of metal fuels through interfacial fluorination of oxide layer. In this work, nanosized CoF 2 and Co 3 O 4 were prepared through pyrolysis of CoF 2 ·4H 2 O precursor using different calcination conditions. To investigate the function of CoF 2 in reaction and the influence of CoF 2 content on reactive performances, a series of MICs composed of n-Al, Co 3 O 4 , and CoF 2 were prepared through ultrasonic dispersion method. Thermal analysis indicated that Al/CoF 2 composite had significantly higher specific heat release (2.30 kJ/g) than that of Al/Co 3 O 4 composite (1.45 kJ/g), and CoF 2 facilitated the occurrence of exothermic reaction at a relatively lower temperature. AlF 3 was found as main reaction products of Al/CoF 2 at 650 °C, and AlF 3 sublimes at the temperature above 850 °C. Although the pressure output and flame intensity of Al/CoF 2 composite is lower than that of Al/Co 3 O 4 composite, hybrid Al/Co 3 O 4 /CoF 2 composites with 20 %–35 % CoF 2 showed significantly enhanced energetic performances compared with sole Al/Co 3 O 4 , suggesting that CoF 2 can function as an effective reaction modifier. [ABSTRACT FROM AUTHOR]

To establish the influence of atmospheric and temperature factors on the stability of LA, a combined environmental stress testing device was designed to simulate reaction characteristics. Morphological characterization methods of SEM and FTIR were carried out to explore the changes of crystal structure, as the pyrolysis behavior of LA under the combined environmental stress was investigated by DSC with two isoconversional kinetic methods and thermal safety software (TSS). The research indicates that CO 2 and H 2 O react with LA to generate basic lead carbonate in the air atmosphere, together with the stimulation of thermal stress, the synergistic effect formed microvoids to erode the crystal structure of LA. The microvoid effect reduced the apparent activation energy (E a) from 156.47 to 29.52 kJ/mol as the order of degradation of thermal stability of LA was Air > N 2 > CO 2 , which demonstrated that CO 2 and N 2 atmosphere have a particular protective effect for LA storage, transportation, and application. The pyrolysis reaction mechanism model of LA under the combined environment factors testing was the same as the original LA through the calculation of TSS, thereby the findings could contribute to a better understanding of available boundary conditions for LA. [Display omitted] • The impact of atmospheric and temperature effects on LA's stability was studied. • SEM and FTIR were utilized to scrutinize the microstructural changes. • The microvoid effect on LA's crystal surface was observed under the air condition. • The pyrolysis reaction mechanism was elucidated using TSS. • N 2 and CO 2 conditions were conducive for LA production, storage, and application. [ABSTRACT FROM AUTHOR]