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- Author or Editor: D. Sorensen x
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Abstract
A useful alternative to the standard techniques described by the North American Treaty Organization STANAG 4147 for determining thermal compatibilities of an energetic with other materials could be a simple 2-gram scale Differential Thermal Analysis (2gDTA). The 2gDTA system consists of samples introduced into standard size test tubes inserted into a controlled aluminum-heating block. Relatively inexpensive thermocouples are used for both temperature control and data collection. Cost of the entire system is much less than any commercial DSC. Since valuable instrumentation need not be protected, the 2gDTA allows thermal decomposition reactions to proceed to complete runaway, mimicking the true worst-case scenario.
Abstract
Thermal decomposition of BaC2O40.5H2O in air was studied by a combination of stepwise isothermal analysis (SIA) and non-isothermal thermogravimetry. The results from both techniques show that the crystal water is released in one step and that anhydrous barium oxalate is decomposed in one step, while BaCO3 decomposes in three steps to BaO, forming two intermediate compounds with the formulas of BaCO3(BaO)2 and (BaCO3)0.5(BaO)2.5. Reaction mechanism analyses using the data from SIA measurements show that the controlling mechanism for all the five decomposition steps in isothermal conditions is a two-dimensional phase-boundary controlled process. Kinetic parameters are obtained for the five decomposition steps from the non-isothermal thermogravimetric data.
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.
Abstract
The decomposition process of barium, cerium and neodymium oxalates in air was investigated by DTA-TG. Decomposition of an oxalate coprecipitate precursor and formation of barium cerate were examined in air, N2 and CO2 atmospheres, respectively, by employing DTA-TG and XRD. The results showed that, in air, cerium oxalate could easily be decomposed to CeO2 below 350°C and Nd2O3 could be obtained at 670°C, while a high temperature of >1400°C was needed to obtain BaO. Although some amount of BaCeO3 was formed at 500°C in air, at 650°C in N2 and at 800°C in CO2, single perovskite phase of BaCeO3 could only be obtained at a much higher temperature.
