Porous SiC ceramics were prepared with α-SiC and β-SiC powders
and carboxymethyl cellulose(CMC)as the pore entraining agent. The porosity
open porosity
and the flexural strength as functions of sintering temperatures
shaping pressures
and pore entraining agent content were investigated. The load capacity and the static stiffness of aerostatic bearing assembled by porous SiC ceramics with different permeability were studied. The results show that porous SiC ceramic is able to be prepared when the β-SiC converts to α-SiC by the aggregates connection in high temperature range. The porosity and the open porosity decrease and the flexural strength increases with increasing sintering temperatures and shaping pressures. The porosity and the open porosity increases
and the flexural strength decreases with increase of pore entraining agent content. For the sample with 10%(mass fraction)CMC prepared at 250 MPa and 2 400 ℃
the porosity and open porosity get respectively 28.91% and 24.03%
the permeability reaches to 7.74×10
-13
m
2
flexural strength is 63.8 MPa. The lower the permeability of the porous SiC ceramic
the lower load capacity and the higher static stiffness of aerostatic bearing.
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references
POWELL J W. Design of aerostatic bearing [M]. Brighton, UK: Machinery Publishing, 1970:12-18.
PANZERA T H, RUBIO J C, BOWEN C R, et al. Microstructural design of materials for aerostatic bearings [J]. Cement and Concrete Composites, 2008,30(7):649-660.
UHLMANN E, NEUMANN C. Air bearings based on porous ceramic composites [C]∥ Intelligent Production Machines and Systems: 2nd I*PROMS Virtual International Conference. Cardiff, UK: Elsevier, 2006:211-216.
CHEN Rugang, HOU Yu, YUAN Xiuling, et al. Study of gas lubrication externally-pressurized air bearing for cryogenic turbo-refrigerator [J]. Journal of Xi'an Jiaotong University, 2007,41(7):792-796.
DU Jinming, LU Zesheng, SUN Yazhou. Performance comparison of orifice restricted and porous gas hydrostatic bearings [J]. Lubrication Engineering, 2002, 27(4):2-3.
DING Shuqiang, ZENG Yuping, JIANG Dongliang. Preparation and properties of in situ reaction bonded porous SiC ceramics [J]. Journal of Inorganic Materials, 2006, 21(6):1397-1403.
FUKUSHIMA M, ZHOU Y, YOSHIZAWA Y. Fabrication and microstructural characterization of porous SiC membrane supports with Al2O3-Y2O3 additives [J]. Journal of Membrane Science, 2009, 339(1/2):78-84.
MAGNANI G, ANTOLINI F, BEAULARDI L, et al. Sintering, high temperature strength and oxidation resistance of liquid-phase-pressureless-sintered SiC-AlN ceramics with addition of rare-earth oxides [J]. Journal of the European Ceramic Society, 2009, 29(11):2411-2417.
YI Zhongzhou, XIE Zhipeng, HUANG Yong, et al. Study on gelcasting and property of recrystallized silicon carbide [J]. Bulletin of the Chinese Ceramic Society,2002,21(4):3-7,15.
RYSHKEWITCH E. Compression strength of porous sintered alumina and zirconia [J]. Journal of theAmerican Ceramic Society, 1953,36(2):65-68.
CARMAN P C. Fluid flow through granular beds [J]. Transactions of the Institute of Chemical Engineers, 1937,15:150-156.