Papers by Keyword: Reaction Bonded

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Authors: Frank L. Riley
Authors: Zhen Lin Lu, Yong Xin Zhou, Min Zhang, Qing Wei Huang
Abstract: The dry friction behaviors of reaction-bonded silicon carbide (RB-SiC) with different particle sizes were studied at high temperature using pin-on-dick friction testing method. The results showed that the friction coefficient of RB-SiC was the highest at 300°C, and lower at room temperature and 600°C, but the wear rate of RB-SiC would be increased with the increase of temperature. The XRD analysis of grits showed that there was only the amorphous silica in grits at room temperature, whereas the amorphous and crystal silica combined in grits tested at 600 °C. The wear mechanisms of RB-SiC at room temperature and elevated temperature were analyzed by of scanning electron microscopy (SEM) observation on worn surface morphology of RB-SiC.
Authors: Shao Chun Xu, Zi Jing Wang, Ya Ming Zhang, Qiang Zhi, Jun-Ichi Matsushita, Jian Feng Yang
Abstract: In this paper, reaction bonded silicon carbide (RBSC) was prepared by silicon infiltration with silicon carbide and carbon black as raw materials. The effects of the mixing methods with different binders on density of green body were compared. The influences of phenolic resin content, forming pressure, sintering temperature of samples on the performance of green body, mechanical microstructure and properties of RBSC were studied. The result shows that the density of green body by wet-mixing with alcohol-soluble binder (phenolic resin) was much better than semi-dry-mixing with usual water-soluble binders (polyvinyl alcohol and carboxy methyl cellulose sodium). The bending strength of green body prepared with phenolic resin at the content of 12 wt.% reached to the maximum value. The density of RBSC increased generally with phenolic resin content increasing at temperature range from 1550 to 1650 °C. The bending strength of RBSC increased firstly and then decreased with phenolic resin content increasing at a sintering temperature of 1600 °C. The optimum condition for fabricating RBSC was sintering at 1600 °C with 12 wt.% phenolic resin, the density, porosity and bending strength of the obtained RBSC was 3.06 g·cm-3, 0.05% and 370±54 MPa, respectively.
Authors: Tie Song Lin, De Chang Jia
Abstract: The influences of different sintering aids, including Fe2O3, Fe(NO3)3·9H2O, Y2O3+Al2O3 and MgO+Al2O3+SiO2, on the nitridation of reaction bonded Si3N4/BN ceramics were conducted at 1350°C for 2h. Results indicate that the addition of sintering aids could facilitate the nitridation process resulting in higher nitridation percent due to the reactions between sintering aids and surface silica on silicon powder. When 5wt. % of Y2O3 and 2wt. % Al2O3 were added, the nitridation percent reached to 94.4%. The addition of sintering aids has obvious effect on the ratio of α-Si3N4/β-Si3N4. The increase of β-Si3N4 ratio was attributed to the direct reaction of silicon with nitrogen.
Authors: Peng Cheng, Guan Jun Qiao, Di Chen Li, Ji Qiang Gao, Hong Jie Wang, Zhi Hao Jin
Abstract: Reaction bonded silicon carbide (RB-SiC) was fabricated by phenol resin, starch, solidified agent and silicon powder through the following steps: first, carbonizing at high temperature for 7-9h, infiltrating silicon at 1450-1600oC for 0.5-2h, and then removing excessive silicon at 1700oC for 0.5h. Scanning electron microscopy and X-ray diffraction were employed to characterize and analyze the microstructures and phase composition of the preforms and the final RB-SiC products. In addition, the effect of carbonization temperature, the amount of starch and solidified agent on strength and apparent porosity of final RB-SiC were also discussed. The results showed that the carbonization process of phenol resin can be divided into three steps: at temperatures from 400oC to 600oC, the structure of polymer changes less; at temperatures from 600oC to 1000oC, the fundamental chain of polymer is destroyed, and inverts to glass-like carbon; at temperatures from 1000oC to 1200oC, with the increasing of carbonization temperature, the structure of glass-like carbon changes into the structure of disorder graphite. And the increased micro-pores could be obtained by adding starch.
Authors: Jan Luyten, J.F.C. Cooymans, Frans M.M. Snijkers
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