Papers by Author: Jian Feng Huang

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Authors: Wen Dong Yang, Jian Feng Huang, Li Yun Cao, Xie Rong Zeng
Abstract: Cristobalite aluminum phosphate (C-AlPO4) coatings were prepared by hydrothermal electrophoretic process on SiC coated C/C composites at different temperatures. The as-prepared C-AlPO4 coatings was characterized by SEM analyses. The influence of hydrothermal deposition temperature on the microstructures of the as-prepared coatings and the deposition kinetics mechanism were investigated. Results show that dense and homogeneous C-AlPO4 coatings on SiC coated C/C composites can be achieved at 373K and 220V deposition voltage; Kinetics investigations show that the deposition process of the C-AlPO4 coatings on SiC coated C/C composite is controlled by the diffusion rate of the charged C-AlPO4 particles to the cathode; the deposition rate increases with the increase of hydrothermal temperature. The diffusion equation and the kinetic expression of coating process follow the Fick’s second law and Ahrennius relationship. The deposition activation energy of the C-AlPO4 coatings fabricated by the hydrothermal electrophoretic process is calculated to be 21.88kJ/mol.
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Authors: Hui Zhu, Jian Feng Huang, Li Yun Cao, Yan Wang, Xie Rong Zeng
Abstract: Zinc sulphide (ZnS) thin films were deposited on the indium tin oxide (ITO) substrates by a novel, simple cathodic electrodeposition method under atmospheric pressure. These thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and photoluminescence spectrum (PL) at room temperature. The effects of deposition voltage on the phase composition, morphology and photoluminescence behavior of the thin films were investigated. XRD analysis shows that the deposited thin films is highly preferential growth along (200) orientation. Both AFM and XRD analyses indicate that the surface of the ZnS thin films is composed of uniform grains of around 50 nm in diameter. With the increase in the deposition voltages, the crystallization of the obtained thin films improves and the grain size of the ZnS thin films increases. Photoluminescence emission peaks are observed at at 475~490 nm and 500 ~530 nm at room temperature for an excitation of 210 nm.
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Authors: Jian Feng Huang, Yan Wang, Li Yun Cao, Hui Zhu, Xie Rong Zeng
Abstract: Bismuth sulfide (Bi2S3) is an important semiconductor material, which has wide applications in thermoelectricity, electronics, photoelectricity and infrared spectroscopy. Bi2S3 thin films have been deposited on ITO substrates through a cathodic electrodeposition approach at room temperature. The as-deposited thin films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and photoluminescence spectrum (PL). The effects of solution pH values on the structures and optical properties of the thin films were particularly investigated. Results show that uniform Bi2S3 thin films with oriented growth along (240) direction can be obtained at the solution pH value range from 4.5 to 6.5. The as-prepared thin films exhibit stable blue-green photoluminescence properties under the ultraviolet light excitation at room temperature. With the increase of the solution pH values, the crystallization of the Bi2S3 thin films improves while the grain size of the obtained thin films decreases and the light emission intensity of the thin films decreases.
397
Authors: Yu Tao Zhang, Jian Feng Huang, Li Yun Cao, Fei Deng, Jian Peng Wu
Abstract: Yttrium silicates coatings were deposited on SiC-C/C composites surface by a hydrothermal electrophoretic process using yttrium silicates nano-crystallites, isopropanol and siodine as source materials, solvent and charging agent, respectively. The yttrium silicates nano-crystallites were preprepared by a sonochemical process. The influence of deposition temperatures on the microstructures and crystallization of the yttrium silicates coatings were investigated. Surface and cross-section microstructures of the as-prepared multi-coatings were characterized by XRD and SEM. Results show that the coatings are composed by yttrium silicates crystallites with the main phase of Y2Si2O7 and a little Y2SiO5. The thickness and the density of the yttrium silicates coatings increases with the increase of deposition temperatures; and the coating process has little influence on the phase compositions of the coatings.
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Authors: Ya Qin Wang, Jian Feng Huang, Li Yun Cao, Xie Rong Zeng
Abstract: Yttrium silicates oxidation resistance coatings were deposited on SiC-C/C composites surface by a hydrothermal electrophoretic deposition process. The influence of deposition voltage on the yttrium silicates coatings and the deposition amount of coatings were particularly investigated. Results show that with the increase of deposition voltage, the deposition amount of coatings increase, the density and uniformity of the coating surface is improved. When the deposition voltage reaches 210V, dense yttrium silicates coatings are achieved. While increase the deposition voltage continually, the uniformity of coatings decrease. When the deposition voltage arrives to 240V, high deposition voltage will result in cracked coatings. There is a parabola relationship between the deposition amount of coatings and time.
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Authors: Bo Wang, Jian Feng Huang, Miao Liu, Li Yun Cao, Xie Rong Zeng
Abstract: In order to improve the oxidation resistance of carbon/carbon (C/C) composites, a nano-SiC (SiCn) coating for SiC pre-coated C/C was prepared by a hydrothermal electrophoretic deposition process. The phase compositions, surface and cross-section microstructures of the SiCn coatings deposited at different voltages were investigated. XRD and SEM analyses show that SiCn outer layer without penetrative holes and cracks can be achieved at the deposition voltage range from 120 V to 210 V. The thickness and density of the SiCn coatings improve with the increase of deposition voltage. The multi-layer coatings deposited at 210 V can effectively protect C/C composites from oxidation in air at 1773 K for 202 h with a weight loss of 0.79%.
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Authors: Jian Feng Huang, Fei Deng, Li Yun Cao, Jian Peng Wu, Hong Jie Luo
Abstract: Oxidation resistant SiC coating for graphites was prepared by a pack cementation process with mixture powders of Si, C, SiC and some infiltration additives containing MgO, Al2O3 and Cr2O3. The influence of different infiltration additives on the phase, microstructure and oxidation resistance of SiC coating was primarily investigated. The results showed that adding infiltration additive in the pack powders is helpful for depositing denser SiC coating on graphite substrate; and the coating prepared by using MgO as infiltration additive exhibited better oxidation resistance at high temperature. XRD analyses revealed that SiC coating prepared by adding of MgO as infiltration additive possessed more free silicon; and the SEM analyses displayed that the free silicon could effectively fill the small holes of the SiC coating, which resulted in a perfect dense surface structure of SiC coating. Oxidation test showed that the as-prepared SiC coating could effectively protect graphite materials at 1500oC for 200 hours and the corresponding weight loss of the coated graphite was only 0.13%.
1756
Authors: Zhi Qing Zhang, Jian Feng Huang, Li Yun Cao, Jian Peng Wu
Abstract: Nanocrystalline TiO2 films were deposited on polymethylmethacrylate (PMMA) substrates by dip–coating process from colloidal anatase aqueous solutions. Microwave–hydrothermal process treating TiO2 colloidal solutions was applied to enhance crystallization under a mild condition and avoid post–treatment. The as–prepared TiO2 films were characterized and analysed by X–ray diffraction (XRD), UV–visible spectroscopy and atomic force microscopy (AFM). The photocatalytic degradation of Rhodamine B (RhB) under ultraviolet radiation was explored. Results show that pure anatase TiO2 is achieved rapidly using microwave hydrothermal process. The TiO2 suspension becomes uniformly disperse, stable and deposit-free after ultrasonic dispersion. The thin films deposited on unmodified PMMA substrates from the dispersive TiO2 colloidal solution are dense, homogeneous, crack–free, without visible agglomerates and show high photocatalytic activity without post-treatment. Rhodamine B has been degraded over 99 % after 180 minutes under UV irradiation.
1682
Authors: Yan Wang, Jian Feng Huang, Li Yun Cao, Hui Zhu, Xie Rong Zeng
Abstract: ZnS is one of the most important semiconductors with wide direct band-gap (3.68 eV) and it is widely used as electroluminescence, flat panel display and cathode ray luminous materials. Uniform ZnS optical thin films were deposited on Si (111) substrates by a vacuum evaporation method. The influences of evaporation temperature, deposition time and the distances between substrates and evaporation sources on the phases and morphologies of the ZnS thin films were investigated. The as-prepared thin films were characterized by X-ray diffraction and atomic force microscopy. Results show that the as-prepared thin films are composed of sphalerite ZnS with a little wurtzite phase. The obtained thin films exhibit an oriented epitaxial growth along (111) direction. The evaporation temperature has a great effect on the phases and morphologies of ZnS thin films. Uniform ZnS thin films can be achieved at the evaporation temperature of 1200°C for 30 min. The crystallization of ZnS thin films improves with the increase of evaporation time.
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Authors: Bo Zhang, Jian Feng Huang, Cui Yan Li, Li Yun Cao, Hai Bo Ouyang, Lei Zhou, Zhe Bai
Abstract: Mullite coatings were prepared on C/C-SiC composites surface by pulse arc discharge deposition using mullite powder as source materials. Phase composites and microstructures of the as-prepared mullite coatings were characterized by XRD and SEM. Deposition kinetics and influence of pulse frequency on the phase composites and microstructures were investigated. The results indicate that the outer layer is composed of mullite phase, density and homogeneity of the mullite coatings are achieved when the pulse frequency reaches 2000 Hz. The deposition amount of the mullite coatings also increases with increasing deposition temperature. The deposition mass of the coatings and the square root of the deposition time at different deposition temperatures according to linear relationship, and the deposition activation energy is calculated to be 32.24 kJ/mol.
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