Papers by Keyword: Silica Fiber

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Authors: Yong Gang Jiang, Chang Rui Zhang, Feng Cao, Si Qing Wang, Bin Li
Abstract: Braided silica fibers reinforced nitride composite (SFRN), which was prepared by the polymeric precursor infiltration and pyrolysis (PIP) process with the precursor polyborosilazane (PSBZ), was a new typed microwave transparent material with high mechanical and ablation resistance performance for high-temperature application. The thermal ablation performance of the SFRN was evaluated by the ablation equipment with the kerosene and liquid oxygen as the heating source. The ablation surface texture of the SFRN including macrostructure and roughness were measured by Three-dimensional Macrostructure and Contour Scale System (TMCSS). Results showed that there are no concurrent observation of thermal delaminations or cracks and the specimen remains intact. The SFRN has an excellent thermal shock resistance and good ablation resistance with the linear recession rate of 0.038mm/s. The ablation surface texture of the SFRN can be well illuminated by the TMCSS. And the ablation performance will be improved by enhancing material density and homogeneous intertextures.
Authors: Qi Hong Wei, Chong Hai Wang, Hong Sheng Wang, Ling Li, Qiang Luan, Rong Liao, Bo Dong
Abstract: Silica fibers are widely used in superhigh velocity radome and antenna windows. The methods of eliminating the agents on the surface silica fibers were sdudied in this paper. SEM was engaged in studying the effects of silica fibers disposed by different methods,and the tensile strength of disposed silica fbers was compared with the originals. The results show that the heat treatment in the high temperature was a useful means to eliminate the agent on the surface of silica fiber, but there was great thermal damage for silica fibers,and the tensile strenth decreased significantly. The combination of volvent treatment and heat tratment could eliminate the agent on tht surface of silica fibers completely,and the tensile strength retained more, which was a good means to eliminate the agents on the surface of silica fiber.
Authors: Gong Jin Qi
Abstract: Sizing removal of silica fibers was carried out by air heat-treatment, and the mechanical strength, surface condition, microstructures were studied by tensile breaking force measurement, X-ray photoelectron spectroscopy, field emission scanning electron microscope and high-resolution transmission electron microscope. Heat-treatment at 600°C in air was suitable for sizing removal of silica fibers, with the residual strength ratio of 26.6%. The effects of sizing removal by air heat-treatment on the silica fibers are: (a) the sizing acts as an protective layer for the silica fibers to cover the surface defects and decrease the sensitivity under external forces, and the tensile strength drops a lot after the sizing removal; (b) the decomposition and combustion of the epoxy sizing also lead to the embrittlement of the silica fibers.
Authors: Qiang Wu, Li Zhao
Abstract: Uniform growth of WO3 with macroscopic structures was successfully achieved by using carbon nanofibers (CNFs) as template. Field emission scanning electron microscopy (FE-SEM), coupled with X-ray diffraction (XRD) analysis confirmed the template effect and the existence of WO3 immobilized on the macroscopic silica fiber.
Authors: H. Chen, Lian Meng Zhang, L.M. Hu, G.Y. Jia, Wen Hai Luo, S. Yu, Zhi Qiang Cheng
Authors: Qiang Wu, Jiang Wu, Wataru Ueda
Abstract: The growth of carbon nanofibers (CNFs) with ordered macroscopic structures could be achieved by CVD technique. Silica fiber, alumina fiber, and AAO membrane were selected as the typical ordered macroscopic substrates for CNFs growth. It turned out that silica fiber could act as the promising and effective substrate for CNFs growth on its surface. While alumina fiber and AAO membrane could also be expected to act as the potential substrates for CNFs growth on their surface.
Authors: Qiang Wu, Ruo Bing Han, Peng Fei Chen
Abstract: Uniform immobilization of BiFeO3 on silica fiber was successfully obtained by a combined impregnation method with carbon nanofibers (CNFs) template route. The physicochemical properties of the obtained material were characterized by means of X-ray diffraction, field emission scanning electron microscopy, and ultraviolet-visible diffuse reflectance spectroscopy. It turned out that BiFeO3 immobilized on silica fiber can exhibit visible light photocatalytic degradation of rhodamine B (RhB) to some extents. It is expected that such kind of material would possess many potential applications in photocatalysis.
Authors: Y.T. Dai, Gang Xu, Wei Lai Li
Abstract: Owing to the large photo energy, 157nm laser is considered as one of promising micro-fabrication tools. In this paper, a micromachining system based on the 157nm laser is introduced. 2D laser direct-writing and 3D micro-structuring experiments are carried out for silica glasses, fibers and diamond. For natural diamond, the ablation threshold by 157nm laser is about 2.0J/cm2. Material removal is dominantly due to photon-chemical effect for 157nm laser ablation. Effectiveness of using 157nm laser for 3D micromachining is clearly demonstrated.
Authors: Ying Na Zhao, Cai Fen Wang, Hai Xu, Jia Chen Liu
Abstract: The high-temperature resistance compression material of lightweight porous ceramics and fiber joining is becoming a kind of promising seal parts in high-temperature industries and aerospace field. A combination of the lightweight mullite matrix porous ceramics and the elastic 3-D silica woven fibre, a novel joining material was studied. The low cost fly ash cenosphere as raw materials, mullite porous ceramics with density 0.92 g/cm3, and the thermal conductivity 0.13 w/m.K, were prepared. Using microwave selective heating properties, designing the interlayer composition, the bonding materials were attained by microwave sintering. The flexural strength of joint materials was about 23 MPa, which was higher than porous ceramics matrix.
Authors: Gon Jin Qi, Chang Rui Zhang, Hai Feng Hu, Feng Cao, Shao Qing Wang
Abstract: Perhydropolysilazane was synthesized by the ammonolysis of dichlorosilane-pyridine adduct, and used as precursor to prepare three-dimensional silica fiber reinforced silicon nitride matrix composites via preceramic polymer infiltration and pyrolysis at 1073Kin anhydrous ammonia atmosphere. The polymer-derived ceramic matrix was amorphous near-stoichiometric silicon nitride with an empirical formula of SiN1.34O0.02C0.01H1.21. The as-received composites were amorphous with a high density of 1.96g/cm3 after five infiltration-pyrolysis cycles. The process was successful to fabricate dense silicon nitride matrix composites reinforced by three-dimensional silica fiber due to the low viscosity, good wettability and high ceramic yield of perhydropolysilazane.
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