溶胶-凝胶法制备Al_2O_3f/Al_2O_3复合材料及其性能研究

Processing and Properties of Al_2O_3f/Al_2O_3 Composite Prepared by Sol-Gel Method

本文采用化学气相渗透法(CVI)在三维氧化铝纤维预制体上沉积热解碳(PyC)界面层,通过溶胶-凝胶法制备氧化铝纤维/PyC/氧化铝基体复合材料和无界面复合材料。通过三点弯曲实验分析其力学性能,扫描电子显微镜观察其断口微观结构。结果表明,当热解碳界面层厚度分别为0.6μm和0.8μm时,复合材料所对应的弯曲强度分别为231.3 MPa和158.2 MPa,与无界面复合材料弯曲强度55.8 MPa相比,力学性能分别提高314.5%和183.5%。通过微观结构分析发现利用热解碳界面可充分发挥连续纤维拨出、界面脱粘和裂纹偏转等增韧机制,实现材料脆韧转变。

3D-braided Al2O3 fiber preforms were used to prepare Al2O3f/Al2O3 composites by sol-gel method.Before the sol-gel process,the preforms were coated with pyrolytic carbon(PyC)by chemical vapor infiltration(CVI).The mechanical property and microstructure were investigated via the three-point bending experiments and SEM analysis.The results indicated that the flexural strength of the uncoated composite was only 55.8 Mpa,while the coated composites with 0.6μm and 0.8μm PyC interfaces were 231.3 MPa and 158.2 MPa,respectively,increased by 314.5%and 183.5%.Through the microstructure analysis of the fracture surface,it was found that the PyC interface played a vital role in the toughening mechanism of the continuous fiber,such as the fiber pull-out,interface debonding and crack deflection,thus the brittle-ductile transition of composite was achieved.