三叶形截面SiC纤维缺陷及其断裂镜面分析

Defects of Y-shaped cross-section SiC Fibers and Their fracture mirror model

通过SM等手段分析了三叶形碳化硅纤维的常见缺陷及其成因,并给出了其断裂镜面模型。研究表明,三叶形碳化硅纤维常见的表面缺陷为凸状粘附物,其次为表面脱层。常见内部缺陷有:颗粒夹杂、较大的孔洞和网状微裂纹。三叶形SiC纤维断口形貌由断裂源、镜面区、雾化区和放射褶皱区组成。断裂源大部分在三叶形碳化硅纤维的某个叶顶附近。放射褶皱区由一叶放射到另外两叶。镜面半径越小、褶皱区域越大,纤维强度越高。

The popular surface and internal defects and their originations for the Y-shaped SiC fiber were analysed by the SEM and TEM techniques, and the fiber fracture mirror model was given. The surface defects were found mainly in form of convexity strumas and surface layer crack, and the convexity strumas were the most popular surface defect. The internal defects Were found mainly in form of inclusions, pores and network form microflaws. The internal network mieroflaws of the Y-shaped SiC fibers were smaller and more uniform than those of the circular SiC fiber at＇the same conditions. The Y-shaped SiC fiber fracture mirror was consisted of defect origin, fracture mirror, mist, hackle, and radial drape. The defect origin was found frequently in the lobal tip of the fiber, and the hackle and drape emanated from one lobal tip to anothers. The smaller the mirror radius and the bigger the drape area are, the higher the tensile strength of the fibers have.