基于前驱体转化制备孔隙梯度分布的碳化硅纤维

Preparation of Silicon Carbide Ceramic Fibers with Gradient Pore Distribution Based on Precursor Conversion

以SiC陶瓷前驱体——聚碳硅烷(PCS)的纤维为原料,经臭氧不熔化和热解至1600℃获得多孔结构的碳化硅(SiC)纤维。采用扫描电镜、X射线衍射仪、元素分析仪和比表面积与孔径分析仪等研究了臭氧不熔化时间和热解温度对纤维形貌与组成的影响。结果表明:当热解温度从1300℃提升至1600℃,SiC纤维呈现出氧元素含量显著降低,比表面积显著增加,形态从无定形转化为结晶形态,以及SiC纤维壁形成多孔结构且孔径从外到内呈梯度缩小等变化;当臭氧不熔化时间为20 min时,所得的多孔结构的SiC纤维还具有中空结构,比表面积为10.45 m^(2)/g,纤维壁富含尺寸介于2~30 nm的介孔。

Silicon carbide(SiC) fibers with porous structure were prepared from the SiC ceramic precursorpolycarbosilane(PCS)fibers by ozonation curing and then pyrolysis to 1600 ℃. Effects of ozone curing time and pyrolysis temperature on fiber morphology and composition were investigated by SEM, XRD, elemental analyzer and surface area and pore size analyzer. The results showed that when the pyrolysis temperature was raised from 1300 ℃ to 1600 ℃, many obvious changes were found in SiC fibers, such as a significant decrease in oxygen content, a significant increase in specific surface area, the transformation from amorphous to crystalline, the formation of porous structure in the walls, and the gradient reduction in pore size from outside to inside. When the ozone curing time was 20 min, the porous SiC fibers with a specific surface area of 10.45 m^(2)/g and mesopores in the range of 2~30 nm also had a hollow structure.