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Effect of silicon additions on the hot pressing of B4C
Hongkang Wei,Yu-Jun Zhang,Xiangyu Deng 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.5
In the present study, the effect of silicon additions on the hot pressing of boron carbide was investigated. B4C-based ceramic composites with the addition of silicon powder up to 12 wt.% were prepared by hot pressing at 1850 oC under a vacuum and 60 MPa pressure. The results show that addition of silicon powder affected the sintering behavior of B4C significantly. Silicon powder reacted with free-carbon originating in the B4C phase and formed a solid solution in the B4C structure. For the B4C-8 wt.%Si specimen, a high fracture toughness of 5.04 MPa·m1/2 and modest flexural strength of 354 MPa were obtained. It seems that the improvement in fracture toughness is attributed to the high relative density and the change of fracture mode by the formation of the SiC phase.
Haozhan Lia,Hongkang Wei,Huijuan Qiu,Yukang Wanga,Chang-an Wang,Zhipeng Xie 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.1
Sub-micron boron carbide powders were synthesized through a gas-solid reaction process using ZIF-8-derived nanoporouscarbon and boron oxide as raw materials. The effects of calcination temperature and atmosphere, amount of boron oxide, andgas-solid reaction apparatus on phase composition and morphology of the synthesized boron carbide powders were studied. The results show that, even with sufficient boron oxide addition, it is not feasible to obtain boron carbide powder of high purityin argon environment. Although vacuum environment can significantly improve the purity of the synthesized boron carbidepowder, there are a large number of large particles of step morphology in the synthesized boron carbide powder. The improvedgas-solid reaction apparatus can effectively impede the formation of boron carbide particles of step morphology. Nearlyspherical submicron boron carbide particles with a median particle size of 480 nm and good particle size consistency couldbe synthesized at 1600 °C with 0.3 g nanoporous carbon and 10 g B2O3 under vacuum by using the improved apparatus
Huijuan Qiu,Hongkang Wei,Shifeng Ren,Lingjun Sun,Jia Li,Zihan Wang,Lin Zhao,Chang-an Wang,Zhipeng Xie 한양대학교 청정에너지연구소 2024 Journal of Ceramic Processing Research Vol.25 No.2
Titanium carbide powders were synthesized under an argon atmosphere using titanium dioxide and pyrolysis carbon derivedfrom pyrolyzed phenolic resin as raw materials. The effects of synthesis temperature, holding time, and C/Ti molar ratio onthe phase composition and morphology of the synthesized powders were investigated. The results show that the pyrolyzedphenolic resin at 1000 ℃ is a carbon source composed of amorphous and crystalline carbon. Increasing the C/Ti molar ratio ofthe mixed powder can reduce the content of titanium oxide impurity, indicating the improvement in the purity of TiC powder. In addition, the C/Ti molar ratio can also significantly affect the morphology of the synthesized TiC powders. SEM and EDSresults exhibit that the atomic content on the surface of TiC particles is closely correlated with the atomic distribution on thesurface of the particles. TiC powder with a median particle size of 384 nm could be synthesized at 1500 ℃ for 30 min at the C/Ti molar ratio of 2.3:1. In addition, the sinterability of the synthesized TiC powder was preliminarily discussed. The hardnessand fracture toughness of the TiC ceramic sintered at 2000 ℃ under 40 MPa with a dwell time of 2 h are 15.92 GPa and 3.22MPa·m1/2, respectively.