Preparation and Properties of Boron‐Based Nano‐B/NiO Thermite

Abstract

Boron particles have several major burning problems, such as incomplete combustion, poor ignitability, and a complex burning process in solid propellants. It is documented that the low ignitability and combustion efficiency of boron are caused by the oxidation of its surface. In order to improve the combustion efficiency of boron particles, a precipitation method was employed to prepare nanometer‐sized NiO and coat it on boron particles. The morphology and coating results of the B/NiO nanocomposite thermite were characterized using different approaches such as SEM, X‐ray Diffraction (XRD), and EDS. The results indicated that the boron particles were well distributed and coated completely by nanocomposite NiO. The B/NiO nanocomposite thermite reaction process was tested by TG‐DTA. The results showed that the reaction temperature of B/NiO particles is about 30 °C lower than that of boron particles. The B/NiO thermite and boron powder were added to Mg/PTFE propellant to be measured for their respective combustion performance. The results showed that the burning rate of the B/NiO‐Mg/PTFE propellant increased by 22.8–25.2 %, mass burning rate by 26.7–30.8 %, and combustion temperature increased by 8–56 °C compared to the B‐Mg/PTFE propellant. The above results indicate that NiO coating of boron particles has a significant effect on the combustion behavior and increases the combustion performance of the propellant compared with uncoated particles.

Enhanced Reactivity and Compound Mechanism of Mg/B Composite Powders Prepared by Cryomilling

“…For Mg/B2 composite powder, the released heat becomes higher after cryomilling since the reactivity of B particles is enhanced. In related studies [15,16], the numerical value of released heat is relatively higher. It can be concluded that the method used in this study has the potential to improve the oxidation of B particles.…”

“…The high viscosity liquid B 2 O 3 layer on the surface of B can prevent further combustion since B has no direct contact with oxygen [8,9]. Previous work has attempted to alleviate these challenges by combining boron with other metals [10], such as fluorinated compounds [11,12], carbides [13], and oxides [14][15][16]. These additives were added by milling and coating.…”

Towards Safer Primers: A Review

“…Electrically initiated devices, otherwise known as electro-explosive devices (EEDs), can either use primary explosives that are easily decomposed under electrical discharge, or resistive elements that heat until a reaction or sublimation occurs [92,93]. Electrical initiation is possible by conductive, inductive and electromagnetic signals, provided the input is greater than or equal to the energy required to thermally initiate the device.…”

“…Electron density is dependent on material, mass and power input with a logarithmic decay of density with increasing distance from the igniter [147]. Differential scanning calorimetry (DSC) on reactive materials can provide very useful information such as heat of reaction and phase transition temperatures [86,92]. Non-contact optical methods to characterise chemical composition and temporal evolution of explosions based on light emission are well developed.…”

Effect of Fluoroalkylsilane Surface Functionalization on Boron Combustion

“…Due to its high volumetric and gravimetric heating values, − B has been regarded as an energetic fuel candidate for applications requiring high-energy fuels, such as propulsion and space exploration. However, B suffers from delayed ignition and a slow and incomplete combustion process due to the existence of boron oxide at the surface and its high melting and boiling temperatures that limit B oxidation to occur at the solid phase. , One common method to promote B ignition and combustion is to incorporate additives, such as combustible metals (Mg, Ti, or Fe), − metal oxides (NiO, CuO, or Bi 2 O 3 ), − fluoropolymer (PTFE), , and functionalized graphene . The other method modifies B by surface coating of hydrocarbons, − metal fluorides, and fluorocarbons .…”