Papers by Keyword: Synthesis Mechanism

Abstract: ZrB₂ has some excellent high-temperature performance. However, due to it is easily oxidized in the high-temperature air to impact high-temperature strength, which restricts its applied range. To decrease the oxidization and sintering temperature, and improve the strength of ZrB₂ at high temperature, in this paper, the prepared composite powders is analyzed with XRD, SEM, EDS and TEM, which proves ZrB₂@A1₂O₃-Y₂O₃ core-shell composite powders are successfully synthesized by co-precipitation method, the synthesis mechanism of ZrB₂@A1₂O₃-Y₂O₃ core-shell composite powders is received through the results discussion.

Abstract: Being a new whisker products with high performance to price ratio, magnesium borate whiskers with a length of 10 - 50μm and a diameter of 0.5 - 2μm were prepared by molten salt and characterized by XRD, FT - IR, SEM and chemical titration. The experiments show that the synthesis conditions are as follows: raw materials ratio: Mg:B:flux =1:11.05:1-3.5(mol); reaction temperature: 800 - 950°C;reaction time:6 - 10hours; flux: NaCl、KCl or NaOH.

Abstract: The microstructural characters and refining property of Al-Ti-C grain refinement alloy prepared by ultrasound coupling method were studied by analytical means such as SEM, and the reaction synthesis mechanism of Al-Ti-C grain refinement was discussed. Experimental results show that the Al-Ti-C alloy refiner using “thermite reduction method” under high-energy ultrasound was prepared experimentally. Its microstructure character is that master alloy has smaller size of TiC, its quantities are larger and are dispersed. Melt reaction is generally that the source of titanium releases Ti atoms under high temperature of ultrasonic. Ti atoms react with aluminum to generate TiAl3, and react with carbon to generate TiC.

Abstract: The current status of biodegradable material PHB research was analyzed. The synthesis mechanism of PHB production by methane-oxidizing bacteria and effect factors of PHB yield were summarized. And progress direction about PHB polyester was forecasted, that provide theoretic base for studying PHB.

Abstract: The synthesis mechanism and microstructures of BaIn2O4 particles were analyzed by simultaneous thermogravimetry - differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope (SEM). Firstly, In(OH)3 and BaCO3 precursors were prepared by the co-precipitation method. Next, during the sintering process In(OH)3 initially decomposed into In2O3 and water, and then BaCO3 reacted with In2O3 to synthesize Ba4In6O13. Finally, Ba4In6O13 and In2O3 further reacted to form BaIn2O4. The obtained BaIn2O4 particles were in monoclinic structure and exhibited high crystal quality. The grains were tightly bound together and their boundaries became blurry. The grain sizes increased with increasing the sintering temperature.

Abstract: In this paper, the preparation of mesoporous zeolite by template method is studied that the mesoporous zeolite is made up of pure silica source and pure aluminum source. The synthesis mechanism of mesoporous zeolite is investigated according to the characterization results of FTIR, SEM and N2 adsorption-desorption. The results shows that the water glass and sodium aluminate as the partial raw materials of synthesis process, P123 as the template, reaction at 42°C for 20h, aging at 54°C for 48 h, calcining at 550°C for 5 h. The average pore size of prepared mesoporous zeolite is 6.4nm and the specific surface area is 394.65m2/g. The FTIR shows that the microstructure of the prepared samples is similar to zeolite ore, and the SEM result indicates that the micromorphology of the product is uniform and pore size is within the mesoporous range.

Abstract: This presented a route to utilize the Tungsten Molybdenum Bismuth Polymetallic Tailings in Shizhuyuan of Hunan province to fabricate Ca-substitued α-Sialon eco-materials. The reaction mechanism in carbothermal reduction nitridation process was widely studied by separately considering the effect of sintering temperature and soaking time. Based on the optimized conditions, a composite containing 78% Ca-based α-Sialon has been fabricated at 1600°C for 8h.

Abstract: Rod-like α-sialon was synthesized successfully using pure SiO2 and AlN as the starting materials, carbon black as reductant, CaF2 and Y2O3 as addition agent by carbothermal reduction-nitridation. The effects of reaction temperature (1450°C, 1500°C, 1600°C and 1700°C) and additive (Li2CO3, CaF2, Y2O3 and Y2O3+CaF2) on phases and microstructure of the final products were studied by XRD and SEM. The results showed that α-sialon was synthesized by carbothermal reduction-nitridation at 1700°C for 3 hours. The morphology of the synthesized α-sialon was rod-like.