Thermal Analysis and Stability of Boron/Potassium Nitrate Pyrotechnic Composition at 180 °C

Abstract

Aerospace missions require that pyrotechnic compositions are able to withstand 180 °C. Therefore, this paper studies the thermal stability and output performance of boron/potassium nitrate (abbreviated BPN) used in pyrotechnic devices. Firstly, differential scanning calorimetry (DSC) and thermogravimetric (TG) tests are used to analyze the thermal reaction process of KNO3, boron, and BPN to qualitatively judge their thermal stability. Then, apparent morphology analysis, component analysis, and the p-t curve test, which is the closed bomb test to measure the output power of the pyrotechnic composition, are carried out with BPN samples before and after the high-temperature test to verify BPN stability at 180 °C. The weight change of boron powder caused by chemical reactions occurs above 500 °C. When the temperature is lower than the peak exothermic temperature of decomposition, no obvious chemical reaction occurs with KNO3, and only physical changes (crystal transformation and melting) occur. Combined with a verification test at 180 °C for two days, it is concluded that boron and KNO3 components are stable at 180 °C. With an increase in boron content, the thermal stability of BPN is improved, with the best performance achieved when the ratio is 25:75 (B:KNO3). BPN samples without binder have the best thermal stability. In a test at 180 °C for five days, the binder affects the weight loss and p-t curve of BPN, and BPN with fluororubber binder is better than BPN with unsaturated polyester binder.

Control of the Length of Fe73.5Si13.5Nb3Cu1B9 Microwires to Be Used for Magnetic and Microwave Absorbing Purposes

“…In turn, nitriding evidence from 600 °C is observed in both samples with a slight weight increase close to 1% at 1000 °C (black curves in Figure a,b). This residual nitriding process is probably due to the presence of boron atoms in the Pyrex coating of the MWs, which, at temperatures above 600 °C, is energetically probable . Nevertheless, this mechanism is barely noticeable at 550 °C (annealed temperature), and the physical properties of the MW are assumed to be unaffected by this process.…”

Optimization of Hexagonal Structure for Enhancing Heat Transfer in Storage System

“…Other peaks are observed for temperatures in the region of 130–150 °C (E, characteristic of the yellow curve). In this range, the transition from the rhombic to the trigonal solid phase (change of crystalline system) of KNO 3 takes place [ 31 ]. The location of the peaks may be slightly changed due to the effect of the heating rate.…”

Perspective Chapter: Effect of Laser Key Parameters on the Ignition of Boron Potassium Nitrate with a Changing Working Distance

“…Its military specification is as follows: MIL-P-46994B(AR). Aerospace missions require that pyrotechnic compositions are able to withstand 180°C [24]. Boron is often used as a reducer of energetic materials and in the composition of propellants; thanks to its high heat of reaction, high enthalpy, high temperature of combustion, low molar mass, long shelf life, thermal stability, and output performance.…”

“…Boron is often used as a reducer of energetic materials and in the composition of propellants; thanks to its high heat of reaction, high enthalpy, high temperature of combustion, low molar mass, long shelf life, thermal stability, and output performance. BPN is also listed as a linear reference for the security of pyrotechnic agents [24].…”