• Journal of the Korean Ceramic Society
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• v.29 no.7
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• pp.511-516
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• 1992

In this study, SiC powder and Si powder were used as the raw materials. Mixture was prepared with addition of Al2O3 and Fe2O3 at 0.1~0.5wt% respectively. After this step, the mixture was pressed and nitrided for 30 hrs at 140$0^{\circ}C$ under NH3-N2 atmosphere. Mechanical properties of sintered specimens were investigated from measurement of porosity, bulk density and three point bending test. nitration reaction extent was observed at the change of mass before and after reaction, and the microstructure and the change of $\alpha$-Si3N4 and $\beta$-Si3N4 were observed by XRD and SEM. In the current work, the results are as follows 1. When Fe2O3 added, the nitridation increased with the content of Fe2O3, and the bending strength was increased from 0.1 wt% to 0.3 wt%, and decreased to 0.5 wt%. 2. When Al2O3 added, the nitridation and the bending strength increased little by little with the content of Al2O3 3. The bending strength of the specimen added with Fe2O3 were higher than that with Al2O3. Because the specimens contained Fe2O3 had much more the whisker type crystal of Si3N4 contributing to strength than contained Al2O3.

• Applied Chemistry for Engineering
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• v.25 no.2
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• pp.188-192
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• 2014

Until now, there has been much efforts for the development of polycyclic molecules as high energy materials because of their high density and potential energy. However, there were only a few reports on the development of highly N-substituted polycyclic compounds due to difficulties of the synthesis. We have designed pentaazapropellanes as new high energy materials and we have recently reported unsubstituted 3,7,9,11-tetraoxo-2,4,6,8,10-pentaaza[3.3.3]propellane (TOPAP) 2 as a new skeleton for high energy materials. Herein, the nitration of TOPAP 2 was reported for the first time. Thus, 2,6-dinitro-3,7,9,11-ttraoxo-2,4,6,8,10-pentaaza[3.3.3]propellane (2,6-DNTOPAP) 5C, which is a new nitro derivative of TOPAP 2, was obtained up to 82% yield by the reaction of $NO_2BF_4$ and anhydrous $HNO_3$. The structure of 5C was determined by spectroscopic analysis.

• Korean Journal of Materials Research
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• v.33 no.7
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• pp.265-272
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• 2023

In this study, the synthesis of nitrobenzene was carried out using sulfated silica catalyst. The study delved into H₂SO₄/SiO₂ as a solid acid catalyst and the effect of its weight variation, as well as the use of a microwave batch reactor in the synthesis of nitrobenzene. SiO₂ was prepared using the sol-gel method from TEOS precursor. The formed gel was then refluxed with methanol and calcined at a temperature of 600 ℃. SiO₂ with a 200-mesh size was impregnated with 98 % H₂SO₄ by mixing for 1 h. The resulting 33 % (w/w) H₂SO₄/SiO₂ catalyst was separated by centrifugation, dried, and calcined at 600 ℃. The catalyst was then used as a solid acid catalyst in the synthesis of nitrobenzene. The weights of catalyst used were 0.5; 1; and 1.5 grams. The synthesis of nitrobenzene was carried out with a 1:3 ratio of benzene to nitric acid in a microwave batch reactor at 60 ℃ for 5 h. The resulting nitrobenzene liquid was analyzed using GC-MS to determine the selectivity of the catalyst. Likewise, the use of a microwave batch reactor was found to be appropriate and successful for the synthesis of nitrobenzene. The thermal energy produced by the microwave batch reactor was efficient enough to be used for the nitration reaction. Reactivity and selectivity tests demonstrated that 1 g of H₂SO₄/SiO₂ could generate an average benzene conversion of 40.33 %.