Cf／ZrC—ZrB2-SiC—C超高温陶瓷复合材料的显微结构表征

利用X-射线衍射、扫描电子显微镜和透射电子显微镜对Cf／ZrC-ZrB2-SiC-C超高温陶瓷复合材料的相组成、纤维／热解碳层的界面特征和超高温陶瓷基体的显微结构特征进行了表征。在碳纤维表面有一层厚度为2～3μm石墨化程度较高的热解碳界面层，该界面层可以避免采用PIP工艺制备超高温陶瓷基体时可能对碳纤维造成的损伤。热解碳层与碳纤维之间为弱机械结合，其界面间分布着20～30nm的ZrC纳米颗粒。Cf／ZrC—ZrB2-SiC—C超高温陶瓷复合材料基体主要由ZrC，ZrB2，SiC和石墨相（Cg）组成。基体中石墨的（002）面沿着ZrC，ZrB2或SiC的表面生长。在石墨与ZrB2和石墨与SiC的界面没有观察到取向关系，界面处既没有反应层也没有非晶相存在。在石墨与ZrC之间存在ZrC（111）／／Cg（002），ZrC110]／／Cr010]的取向关系。ZrB，和SiC之间也没有界面反应和非晶层存在。

Microstructure Characterization of Cf/ZrC-ZrB2-SiC-C Ultrahigh Temperature Ceramic Matrix Composites

The phase composition and microstructure features of a Cf/ZrC-ZrB2-SiC-C uhrahigh temperature ceramic matrix composite were characterized using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. A PyC layer of 2 -3 μm in thickness, which was prepared by the CVI process, was observed as the interfacial layer between carbon fiber and the ultrahigh temperature ceramic matrix. The well crystallization combined the good thermal stability of this PyC layer protected the carbon fiber from damage during the cyclic PIP process to make the C/ZrC-ZrB2-SiC- C composites. Nanocrystalline ZrC particles of 20 -30 nm in size were observed at the interface between carhon fiber and the PyC layer, ensuring the weak bonding between carbon fiber and the PyC layer. ZrC, ZrB2, SiC and graphite were identified in the matrix of the Cr/ZrC-ZrB2-SiC-C composite. It was observed that the （002） plane of graphite was parallel to the surfaces of ZrB2 and SiC. No reaction layer or amorphous layer was detected at the interfaces between ZrB2 and graphite, SiC and graphite, and ZrB2/SiC. An orientation relationship of ZrC （111） /Cg （002）, ZrC 1101//Cg /010] was observed between ZrC and graphite.