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摘要: 以W丝作为成孔剂,采用孔隙预置技术制备了发汗多孔C/SiC复合材料,对其孔隙结构进行表征,研究了材料的力学性能和渗透行为。结果表明: 采用孔隙预置技术能够有效的控制多孔C/SiC材料开孔率和孔隙结构,其孔隙主要由W丝去除后形成的直通孔组成,开孔率决定于W丝的体积含量,所制备的材料具有良好的力学性能和渗透性能。其弯曲强度达到358MPa、弯曲模量达到124GPa,断裂韧性达到16.7MPa · m1/2,空隙率为23.5%,渗透率为1.02×10-3mm2,材料表现为韧性断裂模式,其孔隙的存在并没有对材料的力学性能产生明显的影响。
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关键词:
- 多孔C/SiC复合材料 /
- 孔隙预置技术 /
- 开孔率 /
- 渗透率
Abstract: Preforms made of carbon fibers and sacrificial tungsten fibers as a pore forming agent were repeatedly infiltrated with polycarbosilane and pyrolysed for 14 cycles, followed by aqua regia leaching to remove the tungsten fibers to form porous C/SiC composites. The pore structure, mechanical properties and permeability of the porous C/SiC composites to water and kerosene were respectively studied by a scanning electron microscope, a universal materials testing machine and home-made permeation equipment based on a fluid flow model in capillaries. Results showed that the pores of the porous C/SiC composites were mostly straight and that the open porosity can be controlled by the volume fraction of tungsten fibers used. The bend strength, Young’ s modulus and fracture toughness were 358MPa, 124GPa and 16.7MPa · m1/2 respectively when the open porosity of the composite was 23.5%. The fluids permeated through the porous C/SiC composites by linear laminar flow(the osmosis rate value is 1.02×10-3mm2). The composites exhibited tough fracture behavior and the presence of pores didn’t lead to a significant deterioration of their mechanical properties.
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