Co-reporter:Mengjie Feng, Shubin Wang, Yalin Yu, Qihang Feng, Jiping Yang, Boming Zhang
Applied Surface Science 2017 Volume 392() pp:27-35
Publication Date(Web):15 January 2017
DOI:10.1016/j.apsusc.2016.09.017
Highlights
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Carboxyl functionalized CF is acquired by simple chemical oxidation method.
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These CF have preserved the tensile strength, better electrochemical properties.
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The presence of H3PO4 prevented the turbostratic carbon from over-oxidization.
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There CF can be used as anodes of multifunctional structural battery.
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The preservation and improvement is result from the hindered over-oxidization.
Co-reporter:Shuang Yi, Shubin Wang, Huiyu Yang
Materials Science and Engineering: A 2017 Volume 707(Volume 707) pp:
Publication Date(Web):7 November 2017
DOI:10.1016/j.msea.2017.09.099
To improve the strong interface between fibers and ceramic matrix in silicon carbide (SiC) fibers reinforced in ceramic matrix composites (CMCs), tremendous efforts have been devoted to the fabrication of fiber coating. However, the design and preparation of these fiber coatings still remain a considerable challenge. In this study, we report a novel strategy to synthesize foldcore sandwich structure formed by boron nitride (BN)-coated graphene nanosheets (GNS) grafted to SiC fibers and analyze how the presence of GNS/BN composite coatings influences the mechanical performance of the fibers. In the fracture process, GNS-grafted SiC fibers coated with BN provide a specific wrinkled and malleable surface, which can be flattened and then broken in the early fracture stage. As a result, the fracture process is changed, resulting in enhanced mechanical performance. Our strategy could be further extended to the fabrication of other composite coatings on fibers with enhanced mechanical properties.
Co-reporter:Jianggao Liu, Shubin Wang, Pengyang Li, Mengjie Feng, Xinwang Yang
Surface and Coatings Technology 2016 Volume 286() pp:57-63
Publication Date(Web):25 January 2016
DOI:10.1016/j.surfcoat.2015.12.023
•We have introduced the sol–gel process into the conventional dip-coating method to prepare BN coatings on SiC fibers.•High quality and uniformity of BN coatings was achieved by this modified dip-coating method.•The modified method improved the mechanical property of SiC fibers.•The effects of polyacrylamide in the formation of BN coating ware investigated.Boron nitride (BN) coatings were synthesized on silicon carbide (SiC) fibers by a modified dip-coating method using boric acid and urea as BN precursors and acrylamide as gel-casting monomer heated at 850 °C for 3 h under N2 atmosphere. For comparison, a conventional dip-coating method was also adopted to prepare BN coatings under the same conditions. The structure of BN coatings was characterized by X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. The morphology of the fibers after impregnation and heat treatment was observed by the electron micrographs. Fiber tensile strength was evaluated by single fiber tensile test. The effects of polyacrylamide on the formation of BN coatings were also investigated. The results show that the BN coatings, prepared by two cycles of impregnation in the modified dip-coating process, covered the SiC fibers well, and exhibited a compact turbostratic–amorphous hybrid structure with a thickness of 550 nm. The tensile strength of the coated SiC fibers increased by ~ 22% after the conventional dip-coating method was modified. The introduction of the sol–gel process enabled the BN precursors to form a film on the surface of SiC fibers with an even distribution in the impregnation process and to retain the evenness in the heat treatment process. Based on the two effects, the conventional dip-coating method was improved.
Co-reporter:Shubin Wang, Yue Li, Xinghong Zhang
Materials & Design 2013 49() pp: 808-813
Publication Date(Web):
DOI:10.1016/j.matdes.2013.01.039
Co-reporter:Shubin Wang, Cheng Xu, Yongbin Ding, Xinghong Zhang
International Journal of Refractory Metals and Hard Materials 2013 Volume 41() pp:507-516
Publication Date(Web):November 2013
DOI:10.1016/j.ijrmhm.2013.06.010
•The addition of TaSi2 improved the thermal shock behavior of ZrB2–SiC ceramics.•The oxidation behavior of ceramics after thermal shock test has been clarified.•The mechanical property was investigated and discussed.The thermal shock behavior of ZrB2–SiC composite ceramics was remarkably enhanced by the addition of TaSi2 particles. TaSi2 enhanced the residual strength within the temperature range resulting from the crack-healing effect, especially at ~ 1400 °C. Residual fracture toughness increased with increasing TaSi2 content from 1000 °C to 1600 °C. The addition of soft phase TaSi2 positively affected the toughening mechanism. Considering the consumption of TaSi2 at ~ 1400 °C, fracture toughness of the TaSi2-containing ZrB2–SiC based ceramic decreased with increasing temperature. The formation of a compressive stress zone beneath the surface oxide layer increased fracture toughness at 1600 °C. The cohesive structure of the TaSi2-containing ZrB2-based material inhibited crack formation and retained higher mechanical properties. Apparent surface changes were observed as a result of oxidation after severe thermal shock test. From the viewpoint of thermodynamics, thermal oxidation resistance improved with the addition of TaSi2.
Co-reporter:Yu Zheng, Shubin Wang
Applied Surface Science 2012 Volume 258(Issue 10) pp:4698-4701
Publication Date(Web):1 March 2012
DOI:10.1016/j.apsusc.2012.01.062
Abstract
In this study, quartz fibers were heated at 600 °C, 700 °C, 800 °C and 900 °C for 10 h respectively. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and fiber tensile test were employed to examine the surface morphology, structure and tensile strength of quartz fibers. The SEM images indicated that when fibers were heated up to 600 °C, dot flaws appeared on fiber surface and when the temperature reached 700 °C, new strip flaws appeared on the fiber surface. HR-TEM images showed that when fibers were heated up to 700 °C, some ordered regions (nanometers) appeared on the fiber surface. Furthermore, the nanometer crystallites were found on fiber surface when fibers were heated at 900 °C. The defects on fiber surface, according to fiber tensile test, had a significant effect on mechanical property of quartz fibers and caused drastic reduction in fiber tensile strength. It is considered that the mismatch between the ordered regions and amorphous regions induced new defects on fiber surface, which led to further decrease of fiber tensile strength.
Co-reporter:Qiang Chen, Shubin Wang, Zhen Li
Microporous and Mesoporous Materials 2012 Volume 152() pp:104-109
Publication Date(Web):1 April 2012
DOI:10.1016/j.micromeso.2011.11.053
Aluminum silicate fiber (ASF)/hollow mesoporous silica microspheres (HMSM) composites were fabricated by a vacuum filtration technique, followed by pressureless sintering at 1100 °C. Properties namely: bulk density, microstructure, mechanical strength and thermal conductivity were investigated with the ASF content. Results showed that bulk density of the resultant composites increased from 0.17 to 0.26 g/cm3 with the increase of ASF content, and the ASF was intimately bonded to the HMSM matrix. When the ASF content was 15 wt.%, the composites exhibited the highest compressive strength (5.07 MPa) and flexural strength (3.32 MPa), then the mechanical strength decreased on further addition (20 wt.%). The thermal conductivity of composites ranged from 0.048 to 0.081 W/(m K) at room temperature, which makes aluminum silicate fiber/hollow mesoporous silica microspheres composites a promising choice for thermal insulation.Graphical abstractHighlights► Aluminum silicate fiber/hollow silica microspheres composites were fabricated. ► Properties of the composites as a function of the fiber content were studied. ► Mechanical strength first increases and then decreases with the fiber content. ► Final product has low density and excellent thermal insulating property.
Co-reporter:Yu Zheng, Shubin Wang
Applied Surface Science 2011 Volume 257(Issue 24) pp:10752-10757
Publication Date(Web):1 October 2011
DOI:10.1016/j.apsusc.2011.07.092
Abstract
Boron nitride (BN) coatings were successfully synthesized on quartz fibers by dip-coating in boric acid and urea solutions at 700 °C. The SEM micrographs indicated that the quartz fibers were fully covered by coatings with smooth surface. The XRD, FT-IR, XPS spectra and HR-TEM results showed that the composition of the coatings which combined closely with the quartz fibers was polycrystalline h-BN. By changing the dip circles, the coating thickness was well controlled. The thicknesses of samples dipped less than six circles increased linearly with dipping-circles; and the increment of coating thickness would slow down when the fibers were dipped 10 circles. After being dipped for 10 circles, the thickness was about 300 nm. The coating thickness was also established by calculation and the calculated results were consistent with the results measured by micrograph.
Co-reporter:Mengran Cao, Shubin Wang, Wenbo Han
Materials Science and Engineering: A 2010 527(12) pp: 2925-2928
Publication Date(Web):
DOI:10.1016/j.msea.2010.01.059
