低分子量聚碳硅烷制备3D-Cf/SiC复合材料

研究了低分子量聚碳硅烷 (PCS) 通过先驱体浸渍裂解 (PIP) 工艺制备C_f/SiC复合材料。分析表明:PCS的数均分子量为400,活性较强,陶瓷化产率为70％左右,在1200℃基本转化为微晶态的β-SiC。分别通过3种不同升温速率制备了3D-C_f/SiC复合材料试样,其弯曲强度分别为745.2MPa、686.7MPa和762.5MPa,明显高于文献报道3D-C_f/SiC复合材料弯曲强度300~500MPa的水平。试样断口的SEM照片均显示长的纤维拔出,有良好的增韧效果,低分子量PCS裂解得到的基体比较致密。实验结果说明,低分子量PCS适合于制备3D-C_f/SiC复合材料,并且提高升温裂解速率对材料性能影响很小。 

PREPARATION OF 3D-Cf/SiC COMPOSITE WITH LOW-MOLECULAR POLYCARBOSILANE

3D-Cf/SiC composites were prepared with low-molecular polycarbosilane (PCS) using a precursor infiltration pyrolysis (PIP) process.The average molecular weight of active PCS is 400 (Mn) . The ceramic yield is approximately 70%, and PCS was translated into β-SiC crystal at 1200℃. The samples of 3D-Cf/SiC composites were prepared at three different heating rates.Bending strengthes were respectively 745.2MPa,686.7MPa,and 762.5MPa.SEM photographs of sample fracture surfaces indicate that in the micro-structures there are long fibers pulled out,and the fracture toughness is high.The matrix is close-grained.The research indicates that 3D-Cf/SiC composites with low-molecular polycarbosilane have good mechanical performance,and the low-molecular PCS fits the preparation of 3D-Cf/SiC composites by PIP process.