C/C-SiC-ZrC复合材料的制备及其力学性能

利用浆料浸渗技术将纳米ZrC粒子引入到CFRP先驱体中,裂解CFRP获得C/C-ZrC多孔体,然后采用液硅熔渗反应工艺制备了C/C-SiC-ZrC复合材料。使用SEM和XRD对材料微观形貌和组织进行了观察与分析。采用三点弯曲和单边缺口梁法(SENB)对C/C-SiC-ZrC复合材料的弯曲强度和断裂韧性分别进行了测试。结果表明:采用浆料浸渗技术可以将纳米ZrC粒子均匀的弥散在C/C-ZrC多孔体中,随着引入ZrC纳米粒子含量的增多,C/C-ZrC多孔体孔隙率增大。经液硅熔渗反应后,获得的C/C-SiC-ZrC复合材料具有不同微观组织结构。力学性能测试发现,当纳米ZrC粒子含量为5%(质量分数)时,复合材料弯曲强度和断裂韧性达到了最大值;当ZrC粒子含量超过5%时,其弯曲强度和断裂韧性有所下降,表明适量纳米ZrC粒子的引入,可以改善C/C-SiC-ZrC复合材料的力学性能。

Fabrication and Mechanical Properties of C/C-SiC-ZrC Composites

ZrC nano-particles with varied mass fractions were introduced into the CFRP (carbon fiber-reinforced plastics) green body by a slurry infiltration technique. After the pyrolysis of CFRP green body, the C/C-ZrC preform with different microstructure features were obtained. By infiltrating the liquid silicon into the C/C-ZrC preform, the C/C-SiC-ZrC composites were successfully fabricated. The morphologies of C/C-ZrC perform and C/C-SiC-ZrC were observed by scanning electron microscopy (SEM). The porosity was measured by using the Archimedes method. The mechanical properties were evaluated by means of three point bending and single edge notched-beam (SENB) tests, respectively. The morphologies of C/C-ZrC perform show that the ZrC nano-particles distributed homogeneously in the fiber bundle area and had a obvious influence on the microstructure. The measurement of mechanical properties found that the C/C-SiC-ZrC composites with a mass fraction of 5% nano-particles presented the highest value in the flexural strength and fractural toughness. While the mass fraction of nano-particles exceeds the 5%, both the flexural strength and fracture toughness of composites decreased. Combing the mechanical properties with the microstructure analysis, the high mechanical properties could be attributed to the more homogeneous distribution of SiC phase and the moderate fiber/matrix interfacial bonding strength.