Papers by Author: Chang Chun Ge

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Authors: Chang Chun Ge, Jun Yu, Wei Ping Shen, Cheng Cheng, Guo Hua Ni, Lu Lu Meng, Ming Li, Cheng Xu Zhang, Yue Dong Meng
Abstract: Superfine and nano-sized Fe powders were prepared by a spark plasma discharge process in deionized water. The powders were characterized by Field Emission Scanning Electron Microscope (FESEM) with Oxford Inca EDX, and X-ray diffraction (XRD). The experimental results indicate that the powders prepared by the process have a bimodal size distribution, high purity, single phase, good spherical shape and high yield.
Authors: An Hua Wu, Wen Bin Cao, Chang Chun Ge, Jing Feng Li, Akira Kawasaki
Authors: Wei Ping Shen, Chang Chun Ge, Li Feng Zhang, Tian Yong Pan
Abstract: The paper outlined here uses self-propagating high-temperature synthesis (SHS) or combustion synthesis that employs more efficient and effective high reaction and cooling rates to produce high quality, reproducible nitride fuels. The fundamental SHS processing parameters was determined to produce Mn-Si-C-N ceramic compounds in which Mn is a surrogate for Am. Because manganese nitride has a relatively low heat of formation the reaction can not be self-sustaining when Si was blended with Mn in the Si:Mn=0.25:1 ratio. The purity of MnSiN2 increases with an increase of the Mn content in Mn-Si-N system. Pure MnSiN2 can be synthesized when Si was blended with Mn in the Si:Mn = 0.5:1 ratio. Volume expansion and porosity decreases, so density, strength and hardness increase as increasing the Mn content in Mn-Si-N system. The powders and sintered cake of MnSiN2-Si3N4 or MnSiN2-Si3N4-SiC was produced by combustion synthesis. The sintered cake of MnSiN2-Si3N4-SiC is attacked by atmospheric moisture to fall to a powder.
Authors: Fei Wang, Wei Ping Shen, Ling Bai, Chang Chun Ge
Abstract: A combustion synthesis process was developed for the synthesis of magnesium silicon nitride powders in the Mg-Si-N system. The effects of ammonium halide addition and the nitrogen presssure on the phase composition and microstructure of the final product were discussed in detail. It was found that ammonium halides were helpful to enhance the nitrogen infiltration, decrease the agglomeration degree and improve the nitridation reaction. Furthermore, the nitrogen presssure greatly influenced the reaction process and the properties of the final MgSiN2 products, especially the phase composition. MgSiN2 powders with low level of impurities (MgO and free Si) could be synthesized through combustion synthesis process in the Mg-Si-N system.
Authors: Qing Zhi Yan, Li-Ying Zhao, Xin Tai Su, Wen Feng Zhang, Chang Chun Ge
Abstract: Barium titanate powder has been prepared using sol-gel auto-ignition synthesis process and was compared with two commercial high purity BaTiO3 powders prepared by precipitation from oxalate precursor and by hydrothermal synthesis. Characterization by x-ray fluorescence, XRD, field emission scanning electron microscopy, SEM and BET revealed significant difference, particularly in particle size and agglomerate structure, resulting in different microstructure and dielectric property. The sol-gel auto-ignition synthesis process yielded weakly agglomerated powder with average particle size of 50 nm. This property is favorable for sintering and dielectric property.
Authors: Shu Ming Wang, Feng Hua Kuang, Qing Zhi Yan, Qing Chun Zhang, Chang Chun Ge
Abstract: In this article we present a new kind of large grain transparent glass-ceramics obtained by the method of crystal growth from a homogenous glass, the simultaneous variation of the glass matrix and crystalline compositions during the crystallization results in the high transparency of this kind of large grain, high crystalline volume glass-ceramics, which have suitable refractive indexes between respective phases. The nucleation and crystallization behaviors of this kind of glass-ceramics have been investigated. The optimum heat treatment schedule for the glass was determined by means of DSC, XRD and SEM. The desirable optical property, such as laser characteristics etc, of this new kind of glass-ceramics can be further developed by doping with transition metals or rare-earths.
Authors: Ling Bai, Chang Chun Ge, Wei Ping Shen, Ke Zhang, X.D. Mao
Abstract: The densification and phase transformation of high α-phase silicon nitride powder synthesized by SHS with a combination of Y2O3 and Al2O3 sintering additives were investigated. The densification process occurred rapidly from 1400 to 1500 °C and was nearly finished at 1500 °C. However, the α-β transformation of silicon nitride progressed rapidly from 1500 to 1600 °C, and completed at 1600 °C. The phase transformation of silicon nitride lagged behind the densification of Si3N4 ceramics. It showed that the solution and precipitation process did not play the main role in the densification of silicon nitride. The sufficient amount of liquid phase was crucial to complete the densification.
Authors: Chang Chun Ge, Wen Bin Cao, Zhang Jian Zhou, Zhang Hua Chen
Authors: Chang Chun Ge, Jiang Tao Li, Ke Xin Chen
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