Papers by Author: Jiang Tao Li

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Authors: Yi Xiang Chen, Jiang Tao Li, Zhi Ming Lin, Guang Hua Liu, S.L. Yang, Ji Sheng Du
Abstract: Combustion synthesis (CS) of Si3N4 was accomplished by using as-milled Si/NH4Cl as reactants at low nitrogen pressure. The additive of NH4Cl decreased the combustion temperature and promoted the Si nitridation. Full nitridation of Si was achieved by burning Si in pressurized nitrogen with 10 ~ 25 wt. % NH4Cl as additives while no Si3N4 diluent added. The maximum combustion temperature (Tc), the combustion velocity (u) together with the α-Si3N4 content and mean particle size (d50) of the powder products were found to be great dependent on the NH4Cl content added in the reactants. Fine Si3N4 powder products with α-phase content up to 85 wt. % were obtained via steady combustion mode. A mathematical approach named combustion wave velocity methods for the analysis of temperature profiles in CS was proposed and the reaction kinetics was discussed. The apparent activation energy calculated according to the temperature profile analysis method is 29.7 kJ/mol, which agrees well with the corresponding low temperature nitriding combustion of Si.
Authors: G.H. Liu, Ke Xin Chen, He Ping Zhou, Jiang Tao Li, Ji Dong Zhong, José Maria F. Ferreira
Abstract: β-Si3N4 and β-SiAlON powders were prepared by combustion synthesis with SrCO3 and NH4F used as additives. The resultant β-Si3N4 and β-SiAlON powders consisted of elongated prismatic microcrystals. By adding SrCO3, the anisotropic growth of β-Si3N4 and β-SiAlON crystals is improved and their aspect ratios increase. The addition of NH4F enhanced nitridation reactions and reduced the residual Si in combustion products. It was proposed that the elongated prismatic β-Si3N4 and β-SiAlON crystals grew from liquid phase and the composition and property of this liquid was affected by the addition of SrCO3.
Authors: Chang Chun Ge, Jiang Tao Li, Ke Xin Chen
Authors: Guang Hua Liu, Jiang Tao Li, Zeng Chao Yang
Abstract: Both single-phase and multiphase bulk ceramics were prepared by high-gravity combustion synthesis via melt solidification instead of conventional powder sintering. The synthesis process included three steps, namely, combustion reaction, phase separation, and melt solidification. In these steps, phase separation played a key role in producing bulk ceramic materials with high purities and low porosities. It was demonstrated that, in a high-gravity field the phase separation was greatly accelerated, compared with the case under common gravitational condition. In comparison with powder sintering, high-gravity combustion synthesis requires no furnace and can reduce the processing time for the fabrication of bulk ceramic materials.
Authors: Zhi Hui Chen, Jiang Tao Li, Jiu Jun Xu
Abstract: Yttrium aluminum garnet (YAG) nanopowders were synthesized by n-amyl co-precipitation method. Transparent YAG ceramics were achieved by sintering the green body at 1800°C and then 1600°C for ten hours with TEOS as sintering additive. The transmittance of the sample was 75% at visible wavelength of 800nm.
Authors: Tong Wei Lin, Wen Bin Cao, Jiang Tao Li, Chang Chun Ge
Authors: Wen Bin Cao, Jiang Tao Li, Ke Xin Chen, Y.L. Xia, Chang Chun Ge
Authors: Wen Bin Cao, Jiang Tao Li, Ke Xin Chen, Y.L. Xia, Chang Chun Ge
Authors: Jiu Jun Xu, Ying Chun Shan, Jiang Tao Li, Yong Ge Cao
Abstract: Large scale translucent yttrium-doped α-sialon (80 mm in diameter) with the composition of Y0.4Si9.6Al2.4O1.2N14.8 (m=1.2 and n=1.0) was prepared by two-steps hot pressing sintering (first heating to 1850 °C holding for 30 min, then continue heating to 1900 °C holding for 30 min) at 25 MPa in nitrogen, and the optical property was approached over the wavelength range 900-5000 nm. The results showed that dense sample was obtained and its assemblage only consisted of single α-sialon phase. The large scale sialon had uniform and higher infrared transmittance property. The maximum infrared transmittance for 1.0 mm thick specimen could reach 66% at 3200 nm. It is attributed to the dense, uniform, equaxed microstructure. In addition to high optical transmission property, the sample showed higher hardness of 20 GPa and better fracture toughness of 5 MPa•m1/2.
Authors: Jiu Jun Xu, Ying Chun Shan, Jiang Tao Li, Qin Ji Song
Abstract: Multi-step hot pressing sintering was adopted to prepare Y-SiAlON (Y0.4Si9.6Al2.4O1.2N14.8) at 1950°C for 60 min under 25 Mpa in nitrogen atmosphere, and the microstructure was studied. The phase assemblages, microstructures and densification of the sintered samples were discussed in detail. In order to contrast to multi-step sintering, one step sintering also was adopted. The results reveal that single-phase α-SiAlON with elongated grain pattern is formed in the multi-step sintering specimens, because of holding at low temperature in multi-step sintering is helpful to reduce the kinetics of crystal growth, the mount of elongated grain in multi-step sintering samples is more than that of in one step sintering ones.
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