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Ding W.,University of Jinan | Chen J.,University of Jinan | Liu J.,University of Jinan | Pang Z.,Beijing Composite Materials Co. | Guan R.,University of Jinan
Asian Journal of Chemistry | Year: 2013

The influences of vinyl ester resin type sizing agent on the properties of carbon fiber and composite were studied. The yarn abrader, X-ray photoelectron spectroscopy were used to characterize wear resistance and chemical element of carbon fiber. Interlaminar shear strength of composite was tested by universal testing machine. The results indicated that wear resistance of sized carbon fiber was significantly improved. X-Ray photoelectron spectroscopy results demonstrated that the activated function groups of sized carbon fiber were more than desized one. The interfacial adhesion of sized carbon fiber/vinyl ester resin (CF/VE) composite was strengthened and interlaminar shear strength of sized carbon fiber/vinyl ester resin composite reached 45.9 MPa. Source


Li S.,Beihang University | Li S.,Beijing Composite Materials Co. | Zhang Y.,Beihang University
Cailiao Yanjiu Xuebao/Chinese Journal of Materials Research | Year: 2011

Amorphous Si-Al-C-N ceramics with varied aluminum contents, which were derived from polyaluminasilazanes at 1200°C, were heat-treated at 1400-1800°C. The structures of precursors and the crystallization behaviors, free-carbon and microstructure of Si-Al-C-N were characterized by Infrared spectrometry, X-ray diffraction, Raman spectra and transmission electron microscopy. The effects of aluminum contents, crystallization temperatures and times on crystallization properties of amorphous Si-Al-C-N were investigated. The results show that amorphous Si-Al-C-N ceramics are amorphous at 1400°C, but include free-carbon. Nano-scale β-Si3N4 and α-Si3N4 nuclei are precipitated at 1500°C. The α-Si3N4 nucleus transforms into β-Si3N4 after treated at 1600°C, at the same time, a minute quantity of α-SiC and 2H-SiC/AlN solid solution nuclei precipitated. At 1700°C a large number of 2H-SiC/AlN solid solution crystals and a few α/β-SiC crystals precipitated besides β-Si3N4, and the β-Si3N4 phase in the Si-Al-C-N ceramic with lowest aluminum content disappears. At 1800°C only β-SiC and 2H-SiC/AlN solid solution crystal are observed. But phase separation takes place at this temperature, leading to the formation of AlN-rich and SiC-rich solid solution region, respectively. With increasing aluminum content, crystallization ability of amorphous Si-Al-C-N ceramics and quantities of grain increase. Nano-scale crystals precipitate from the amorphous Si-Al-C-N at 1500°C, but even until 1800°C the precipitated crystals are still nano-scale crystals. The high-temperature crystallization process of amorphous Si-Al-C-N with high covalence is a process controlled by thermodynamics. © Copyright. Source


Li S.,Beihang University | Li S.,Beijing Composite Materials Co. | Zhang Y.,Beihang University
Chinese Journal of Inorganic Chemistry | Year: 2011

Polyaluminasilazanes with nominal Si/Al molar ratio of 3 were synthesized by reaction of poly (methylvinyl)silazane with aluminum isopropoxide at 90, 100 and 120°C, respectively. The structures of the precursors were characterized by FTIR and NMR. The results indicate that, with the synthesis temperature increasing, the intensities of Al-N FTIR vibration peak (1 450 cm-1) and AlON2 (8 ppm) and AlO2N (-1 ppm) groups of 27Al NMR increase. The higher the reaction temperature is, the more the Al-N bonds are. The dehydrocoupling process may be a three-stage reaction process and the structure of polyaluminasilazane synthesized at 120°C is the most complicated one due to the highest synthesis temperature. The pyrolysis processes of the precursors were studied by TG/DTA, FTIR and gas chromatography (GC). The synthesis temperatures have no significant effect on ceramization process and ceramic yield. Based on DTA curve, a further crosslink takes place at 475°C during pyrolysis process. Besides, the released gases during pyrolysis process are identified by GC analysis as oligosilazane, CH4, C2H4, H2 and NH3. According to the XRD and SEM results, the product pyrolyzed at 1 200°C under nitrogen atmosphere is a homogenous amorphous phase. Source


Fu Y.,Beijing Institute of Technology | Song J.,Beijing Composite Materials Co. | Song J.,Beijing University of Chemical Technology | Zhu Y.,Beijing Institute of Technology | Cao C.,Beijing Institute of Technology
Journal of Power Sources | Year: 2014

Amorphous mesoporous Ni(OH)2 nanoboxes are synthesized by template-engaged routes. The nanoboxes are characterized by SEM, TEM, XRD, XPS and BET methods. The nanoboxes have uniform morphology of 450-500 nm, high surface area of 214.6 m2 g-1 and mesoporous structure of 4-20 nm. Electrochemical characterization are tested using cyclic voltammetry, chronopotentiometry and impedance spectroscopy, respectively. These amorphous mesoporous Ni(OH)2 hollow nanoboxes shows high specific capacitance of 2495, 2378, 2197, 1993 F g-1 at discharge current of 1, 2, 5 and 10 A g-1 respectively. The property tests demonstrate the high specific capacitance and excellent cycling of the amorphous Ni(OH)2 nanoboxes material for high-performance electrochemical pseudocapacitors. © 2014 Elsevier Ltd. All rights reserved. Source


Ren M.,Dalian University of Technology | Huang Q.,Beijing Composite Materials Co. | Liu C.,Dalian University of Technology | Li T.,Queensland University of Technology
Journal of Reinforced Plastics and Composites | Year: 2015

The co-curing process for advanced grid-stiffened (AGS) composite structure is a promising manufacturing process, which could reduce the manufacturing cost, augment the advantages and improve the performance of AGS composite structure. An improved method named soft-mold aided co-curing process which replaces the expansion molds by a whole rubber mold is adopted in this paper. This co-curing process is capable to co-cure a typical AGS composite structure with the manufacturers recommended cure cycle (MRCC). Numerical models are developed to evaluate the variation of temperature and the degree of cure in AGS composite structure during the soft-mold aided co-curing process. The simulation results were validated by experimental results obtained from embedded temperature sensors. Based on the validated modeling framework, the cycle of cure can be optimized by reducing more than half the time of MRCC while obtaining a reliable degree of cure. The shape and size effects of AGS composite structure on the distribution of temperature and degree of cure are also investigated to provide insights for the optimization of soft-mold aided co-curing process. © The Author(s) 2015. Source

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