Papers by Author: Ke Xin Chen

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Authors: Ke Gang Ren, Ke Xin Chen, Hai Bo Jin, Xiao Shan Ning, He Ping Zhou
Abstract: In present work, ultra-fine powders with alpha phase content higher than 95 wt% and specific surface area of 15.33 m2/g were prepared by mechanical activated combustion synthesis (MACS) process. The sinterability of as-fabricated Si3N4 as well as the microstructure and mechanical properties of the sintered bulk were investigated by comparing with a kind of commercial available Si3N4 powders used as diluents in MACS process. Employing hot-pressing method, both powders were sintered equally by using Y2O3 and Al2O3 as sintering aids. Results showed that smaller particle size and higher specific surface area were obtained by MACS process when compared with the commercial one. Bulk Si3N4 appeared approximately the same relative density, hardness, strength and fracture toughness, however, proved to be higher while using MACS powders.
Authors: Ke Xin Chen, M.I.L.L. Oliveira, José Maria F. Ferreira
Authors: Yan An Wang, Ke Xin Chen, He Ping Zhou
Abstract: Titanium carbonitride powders were synthesized directly by a combustion synthesis process between titanium and carbon in a nitrogen atmosphere. The relationships between properties of the final product and the combustion reaction parameters were systematically investigated. Especially, the effects of nitrogen pressure on the phase formation and microstructure of the as-synthesized products were experimentally investigated. The reaction mechanism of Ti(C,N) was proposed through quench experiment, the variation of combustion temperature on time and thermodynamics analysis.
Authors: Ke Gang Ren, Ke Xin Chen, G.H. Liu, Hai Bo Jin, Xiao Shan Ning, He Ping Zhou
Abstract: In present works, the low cost TiO2 powders were partially introduced to raw mixture as playing roles of both reactant and dilution. The experimental results showed that increasing the ratio of TiO2 to titanium powders up to 70wt%, the combustion synthesis reaction could still proceed by self-sustained mode. Single phase of TiNxC1-x with ultra fine particle size could be prepared by using TiO2 as dilution. Influences of TiO2 addition on phase formation and microstructure of product were also investigated. It was found that the combustion temperature and as-synthesized TiNxC1-x particle size decreased as increasing the amount of TiO2 addition.
Authors: Ke Xin Chen, M.I.L.L. Oliveira, José Maria F. Ferreira
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: Ren Li Fu, Ke Xin Chen, José Maria F. Ferreira
Abstract: In this paper, b-SiAlON whiskers were synthesized by combustion of silicon and aluminium powders with SiO2 and Y2O3 as additives and a-Si3N4 or b-SiAlON powders as diluents. SEM observation of the products showed that the crystals with an aspect ratio higher that 5, which could be assigned to almost pure and well crystallized b-SiAlON. The influence of the amount of NH4F additive, the type of diluent on the phase formation and on the morphology of products was investigated.
Authors: Ke Xin Chen, Jun Ming Guo, Ren Li Fu, José Maria F. Ferreira
Authors: Chang Chun Ge, Jiang Tao Li, Ke Xin Chen
Authors: Ren Li Fu, Ke Xin Chen, Xin Xu, José Maria F. Ferreira
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