کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1475600 | 991123 | 2010 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Fabrication and properties of ultra highly porous silicon carbide by the gelation–freezing method Fabrication and properties of ultra highly porous silicon carbide by the gelation–freezing method](/preview/png/1475600.png)
Silicon carbide (SiC) with ultra high porosity and unidirectionally oriented micrometer-sized cylindrical pores was prepared using a novel gelation–freezing (GF) method. Gelatin, water and silicon carbide powder were mixed and cooled at 7 °C. The obtained gels were frozen from −10 to −70 °C, dried using a vacuum freeze drier, degreased at 600 °C and then sintered at 1800 °C for 2 h. The gels could be easily formed into various shapes, such as cylinders, large pipes and honeycombs using molds. Scanning electron microscopy (SEM) observations of the sintered bodies showed a microstructure composed of ordered micrometer-sized cylindrical cells with unidirectional orientation. The cell size ranging from 34 to 147 μm could be modulated by changing the freezing temperatures. The numbers of cells for the samples frozen at −10 and −70 °C were 47 and 900 cells/mm2, respectively, as determined from cross-sections of the sintered bodies. The resulting porous SiC with a total porosity of 86%, exhibited air permeability from 2.3 × 10−11 to 1.0 × 10−10 m2, which was the same as the calculated ideal permeability, and high compressive strength of 16.6 MPa. The porosity, number of cells, air permeability and strength of the present porous SiC were significantly higher than that reported for other porous SiC ceramics.
Journal: Journal of the European Ceramic Society - Volume 30, Issue 14, October 2010, Pages 2889–2896