Size, Morphology and Crystallinity Control Strategy of Ultrafine HMX by Microfluidic Platform

Abstract

The crystal structure has a great influence on mechanical sensitivity and detonation performance of energetic materials. An efficient microfluidic platform was applied for size, morphology, and crystallinity controllable preparation of ultrafine HMX. The microfluidic platform has good mixing performance, quick response, and less reagent consumption. The ultrafine γ-HMX was first prepared at room temperature by microfluidic strategy, and the crystal type can be controlled accurately by adjusting the process parameters. With the increase in flow ratio, the particle size decreases gradually, and the crystal type changed from β-HMX to γ-HMX. Thermal behavior of ultrafine HMX shows that γ→δ is easier than β→δ, and the phase stability of HMX is β > γ > δ. Furthermore, the ultrafine β-HMX has higher thermal stability and energy release efficiency than that of raw HMX. The ultrafine HMX prepared by microfluidic not only has uniform morphology and narrow particle size distribution, but also exhibits high density and low sensitivity. This study provides a safe, facile, and efficient way of controlling particle size, morphology, and crystallinity of ultrafine HMX.

Enhanced Electrostatic Safety and Thermal Compatibility of Special Powders Based on Surface Modification

“…Indeed, charged powders could cause damage ranging from losses in quality and productivity to more severe accidents, such as explosions [ 4 ]. Especially for special energetic powders with flammable and explosive characteristics, electrostatic discharge can easily lead to accidental explosion accidents, resulting in incalculable losses [ 5 , 6 , 7 ]. Therefore, there is an urgent need to eliminate the accumulated electrostatic charge of powders to improve product quality and production safety.…”

Graphene-Material-Modified PMMA Coated with 1,3,5,7-Tetranitro-1,3,5,7-tetraazacyclooctane

“…There are four kinds of crystal type-α, β, γ, δ-but actual applications use the stable β type at room temperature. With a melting point of 281 • C, a density of 1.96 g/cm 3 , no moisture absorption, and a high detonation speed, it is one of the best single-mass explosives, because of its high density and detonation speed and is widely used in military and civilian fields [1][2][3][4]. In the context of the rapid development of blunt projectile technology, HMX shows poor sensitivity to shock, friction, shock wave, thermal energy and electric spark, and does not meet the safety requirements of blunt projectile charge, thus limiting the application of HMX [5,6].…”

“…The results indicated that coating GO on the HMX surface could significantly reduce the overall mechanical sensitivity and improve the material's activation energy and thermal stability. Wang Jingyu et al [4] used GO and fluoroelastomer (Viton) to coat HMX and also prepared HMX/Viton/G and HMX/Viton composites. The results indicated that the HMX/Viton/GO composite particles' thermal stability was higher than those of HMX and HMX/Viton.…”