Papers by Keyword: Thermal Reaction

Abstract: In order to obtain the critical temperatures of energetic materials thermal reaction in different scales, a multi-scale thermal reaction test system has been developed. In this experiment, the measurement method of thermal diffusivity of energetic materials under test conditions is added. Based on the measured thermal diffusivity in thermal reaction test, activation energy and pre exponential factor measured in laboratory. The critical temperatures of thermal reaction in different scales of DINA are calculated, the calculation results are verified by two different scale thermal reaction tests, and the test results are in good agreement with the calculation results. According to the above calculation method, the critical temperature of thermal reaction of DINA under actual process conditions is obtained; it provides the basis of safety data for enterprise safety production.

Abstract: The thermal reactions of mechanically milled wolframite and thermal coal mixtures have been investigated using Differential thermal analysis /thermogravimetry (DTA-TG), X-ray dffraction (XRD) and Scanning electron microscope (SEM). Mixtures were prepared according to stoichiometry and also with a 30% excess of coal. Samples were milled with a planetary ball mill for 4 h, then heated at 1000°C and 1100°C for 1 h in a tube furnace under Ar gas. Phase identification was performed by XRD and morphology of the milled powders by SEM. A large difference in thermal reactions between stoichiometric and 30% excess coal containing samples was observed. In the stoichiometric mixture, the product was dominated by Fe₆W₆C with only a small amount of W₂C, WO₃ and Fe₂WO₆. The mixture with excess coal consisted of only Fe₃W₃C phase without any traces of other phases in the XRD. Homogeneity of composition with the excess amount coal was higher than stoichiometric mixture. It does not appear possible to form WC by this route.

Abstract: The thermal reaction and phase evolution of APP/Al (OH)₃/α-SiO₂ with different mass ratios during heating were studied by TG, FTIR, XRD and SEM, respectively. When the temperature is not higher than 300 ^oC, mass ratio of m_APP:m_{Al (OH)3}:m_SiO2 has no effect on the phase evolution of APP/Al (OH)₃/α-SiO₂ and the main interaction product is AlNH₄HP₃O₁₀. APP/Al (OH)₃/α-SiO₂ with lower content of APP, appears larger weight loss rate due to the thermal decomposition of Al (OH)₃. The thermal reaction of APP/Al (OH)₃/α-SiO₂ is significantly influenced by the APP content as temperature rises to higher than 300 ^oC. The decomposition products of APP can chemically interact with Al (OH)₃ to generate Al₂P₆O₁₈ and Al (PO₃)₃ during 600 ^oC ~900 °C. When the content of APP increases, much more APP can chemically react with Al (OH)₃ and also with part of α-SiO₂ to generate SiP₂O₇. SEM shows the relatively dense microstructure due to micro-bridges of liquid phase with phosphate content increasing.

Abstract: Lungu atmospheric residue (LGAR) was separated systematically to analyze the distribution of sulfur in subfractions. Based on this, the distribution and conversion of sulfur in products and residue subfractions were investigated at different thermal reaction temperatures. The result shows that the sulfur in each subfraction of LGAR had the same polarity and distribution tendency as corresponding fraction. At the same thermal reaction temperature, the distribution of sulfur in LGAR was in the descending order of aromatics, asphaltenes, resins I, resins II and saturates, which was similar with the distribution of sulfur before thermal reaction. In addition, a relatively uniform variation trend was found between each subfraction and its sulfur in LGAR thermal reaction, suggesting that the conversion of sulfur in LGAR was accompanied with the cracking and condensation of subfractions during thermal reaction. Moreover, the desulfurization rate of LGAR increased from 55.24% to 69.24%, while the desulfurization rates of LGAR subfractions were at the range of 45%-90% after thermal reaction. The desulfurization rates of both LGAR and subfractions increased with the reaction severity.

Abstract: The two dimensional nanoplates of WSe2 and MoSe2 are the result of solid-state thermal (750oC) reaction between micrometer-sized W or Mo with micro-size Se powder under inert atmosphere via carving phenomena in a closed reactor. This is a distinct top-down approach presented for the fabrication of inorganic nanoplates, where micron-sized metal particles having very high melting and boiling points are converted into a Se–M–Se sandwich structure employing a single-step, scalable, and environmentally- friendly chemical reaction under autogenic pressure at elevated temperature (RAPET). The mechanistic elucidation of the creation of WSe2/MoSe2 nanoplates is suggested on the basis of the crystal structure with the support of data obtained from compositional, structural, and morphological characterizations.