Search Results
Abstract
Titanium hydride/potassium perchlorate (THPP) is a pressure producing pyrotechnic composition consisting of a mixture of titanium dihydride and potassium perchlorate with a small percentage of a Viton binder. The initial phase of the study focused upon chemical analysis of THPP downloaded from parts ranging up to 25 years in age. The DSC curves were too erratic for kinetic analysis; however, high resolution TG curves for the THPP samples revealed a significant difference in the temperature at which the aged materials began displaying mass loss. Isothermal DTA and variable heating rate TG kinetic analysis were employed to determine the activation energy of the THPP.
A study has been made of the differential thermal analysis of (i) potassium perchlorate in powdered form, (ii) potassium perchlorate in pelletized form, (iii) potassium perchlorate recrystallized from liquid NH3, and (iv) potassium perchlorate preheated for 24 hours at 375°. Pretreatment of potassium perchlorate leads to a desensitization of both endothermic and exothermic processes. Additionally, the pretreatment tends to convert the symmetric exotherm into an asymmetric exotherm due to merging of the two exotherms. An analysis of the factors causing asymmetry in the exotherm has thrown fresh light on the mechanism of thermal decomposition of potassium perchlorate.
Abstract
Studies have been carried out on the boron-potassium perchlorate-nitrocellulose pyrotechnic system by DSC, simultaneous TG-DTA-mass spectrometry and chemical analysis. Quantitative measurements have been made on the exothermic pre-ignition reaction which took place above 360°C and the results have been compared with those obtained previously for the corresponding systems containing zirconium and a zirconium/nickel alloy.
The acceleratory effect of potassium perchlorate on the reactivity of the red lead-silicon system has been studied by employing DTA and DSC. Supporting investigations on pure potassium perchlorate and the binary system red lead-potassium perchlorate suggest that the complex decomposition kinetics of potassium perchlorate drastically influences the oxidation of silicon. Further, the ternary system also undergoes a transition from exothermic smooth decomposition to ignition at a certain critical mass, as noted in the red lead-silicon and iron(III) oxide system. The criticality should be a result of the rise in temperature expressed as a perturbation of the steady-state energy conservation conditions, as postulated by Gray.
The feasibility of the use of potassium nitrate and potassium perchlorate as temperature standards in Differential scanning calorimetry has been studied. The solid-state phase transition temperatures of KNO3 and KClO4 were determined by means of DSC. The metrological properties of these salts as calibration materials were examined. The reliability of KNO3 and KClO4 calibrations was investigated by twofold determination of the bismuth melting temperature after the apparatus had been calibrated with indium and lead, and with KNO3 and KClO4. Conclusions were drawn concerning the suitability of these salts for use as DSC temperature calibrants.
. Berger , B , Charsley , EL , Rooney , JJ , Warrington , SB 1995 Thermal analysis studies on the zirconium/nickel alloy–potassium perchlorate-nitrocellulose pyrotechnic system . Thermochim Acta 269 : 687 – 696 10
While normal ammonium perchlorate (AP) decomposes in two stages (at 315 and 375 °C), its 20% weight loss occurred even at 160 °C when it had absorbed 1.0 MGy dose. Increased crystal size caused further changes in the TG/DTA curves. Characteristics: the above weight loss approached 85% for 20 times larger particles. AP mixed with KCl/KBr in 1∶1 ratio showed formation of potassium perchlorate on heating and the quantity increased progressively when the AP was pre-treated by irradiation.
permanganate, potassium nitrate, potassium perchlorate, barium nitrate, lead dioxide, ammonium perchlorate (mesh 300) and lactose monohydrate powders (10 μm) were purchased from Merck (Tehran, Iran). Apparatus A thermobalance
inorganic oxidizers and fuels [ 1 , 2 ]. Potassium perchlorate (KClO 4 ) has long been a main oxidizer in many civil/military pyrotechnics for its mild phase transition, moderate sensibility, and fast ignitability [ 3 – 5 ]. Magnesium (Mg) powders are
