Papers by Author: Wei Pan

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Authors: She Chuang Wang, Shu Zhu Zhou, Wei Zhen Peng, He Zhuo Miao, Wei Pan
Abstract: The composition, microstructures and properties of the Ti(CN) based cermets have been characterized by using SEM/BSE and energy spectrometer. Results shows that the carbon content of the cermets through N2 and Ar sintering was lower by 0.5% than vacuum sintering and the nitrogen content of the cermets through N2 sintering was higher by 20~25% than the Ar and vacuum atmosphere sintering. When sintered in Ar or N2, the balance between the carbon and nitrogen in the cermets was broken to form a surface defects, which would result in poor properties. The structure of vacuum sintering is more uniform and the properties are better.
Authors: Shi He Bai, Wei Pan, Chun Lei Wan
Abstract: A new precipitation route to ammonium aluminum carbonate hydroxide (AACH) was presented. There was an incubation period before AACH precipitated. Effects of synthesis parameters such as pH of ammonium hydrogen carbonate solution, precipitation temperature, concentration of aluminum citrate and type of anions on the precipitation of ammonium aluminum carbonate hydroxide were discussed. It was found that the incubation period decreased with the increasing pH of AHC solution, concentration of aluminum citrate and the decreasing reaction temperature. Compared to NO3 -, SO4 2- delayed the formation of AACH and enlarged the particle size of AACH.
Authors: Jian Qiang Li, Wei Pan, Rui Gang Wang, Jian Chen
Authors: Qiang Xu, Wei Pan, Chun Lei Wan, Long Hao Qi, He Zhuo Miao, Fu Chi Wang
Abstract: Based on La2Zr2O7 ceramic for thermal barrier coatings, LaSmZr2O7 ceramic doped with samarium ion was successfully prepared using solid state reaction method. The pellets were sintered at 1600°C for 10 hours in air. The phase structure, thermal conductivity and thermal expansion coefficient of LaSmZr2O7 ceramic and La2Zr2O7 ceramic were measured by XRD, laser-flash device, high-temperature dilatometry, respectively. The results show that the crystal structure of LaSmZr2O7 ceramic is not affected by the doped samarium ion in the zirconium lattice. The thermophysical results show that the thermal conductivity of the LaSmZr2O7 ceramic is lower than that of La2Zr2O7 ceramic, while the thermal expansion coefficient is higher than that of La2Zr2O7 ceramic. These results indicate that LaSmZr2O7 ceramic or Ln2Zr2O7 ceramics doped with other rare earth ions could be candidate materials for future thermal barrier coatings.
Authors: Qiang Xu, Wei Pan, Chun Lei Wan, Long Hao Qi, He Zhuo Miao
Abstract: Sm1.9Ca0.1Zr2O6.95 ceramic was sintered at 1600°C for 10 h in air by solid-state reaction method. The phase structure and thermal expansion coefficient were measured by XRD and a high-temperature dilatometry, respectively. The results show that the crystal structure of Sm1.9Ca0.1Zr2O6.95 ceramic is still pyrochlore. The doping with calcium cation leads to a shift of the X-ray spectrum of Sm1.9Ca0.1Zr2O6.95 ceramic to lower 2θ values. The experiments also show that the thermal expansion coefficients of Sm1.9Ca0.1Zr2O6.95 ceramic are higher than those of Sm2Zr2O7 ceramic. These results are related to the vacancy induced by doped calcium cation in the samarium lattice.
Authors: Ruo Bing Han, Chun Lei Wan, Hui Wu, Wei Pan
Abstract: A novel templating method for preparing nanoporous materials has been developed. Spherical nickel phosphate particles synthesized through a homogeneous precipitation method were used as templates after annealing to fabricate porous metals. Effort of annealing temperature on the morphology of the spherical particles and the structure of outcome materials were studied. Hierarchical nanoporous metal with a high surface area was obtained using a template annealed at 200 oC.
Authors: Yue Hu, Wei Pan
Abstract: Light scattering caused by pores detrimentally affects the optical transparency of transparent ceramics. Herein, Mie theory has been used to calculate the cross-section of pore scattering in transparent ceramics, and the influence of wavelength, pore size distribution and refractive index has been discussed in detail. For wavelength between 200 nm and 2000 nm, the scattering cross-section decreases with increasing wavelength, which means that pore scattering is more detrimental to short-wavelength transparency. With ZOLD function simulating the pore size distribution inside the ceramic, it has been found that the scattering is strongest when the most-probable diameter dm equals the incident light wavelength λ. And FWHM (full width at half maximum) parameter a also affects the scattering cross-section. a between 0.003 and 0.7 is necessary for obtaining high optical transparency in visible wavelength range. The method presented in this work is available for the estimation of scattering effect in different kinds of materials, which may be useful for future design of high-transparency ceramics.
Authors: Rong Ti Li, Wei Pan, Sano Masamichi
Authors: Zhi Jian Peng, He Zhuo Miao, Wei Pan, Liang Qi, S. Yang, Chao Liu
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