摘要:
界面改性涂层对调节复合材料的力学性能起到重要作用。特别是在气相渗硅(GSI)制备Cf/SiC复合材料时, 合适的界面改性涂层一方面保护C纤维不受Si反应侵蚀, 另一方面调节C纤维和SiC基体的界面结合状况。通过在3D-C纤维预制件中制备先驱体浸渍-裂解(PIP)SiC涂层来进行界面改性, 研究了PIP-SiC涂层对GSI Cf/SiC复合材料力学性能的影响。结果表明:无涂层改性的GSI Cf/SiC复合材料力学性能较差, 呈现脆性断裂特征, 其弯曲强度、弯曲模量和断裂韧性分别为87.6 MPa、56.9 GPa和2.1 MPa·m1/2。具有PIP-SiC界面改性涂层的Cf/SiC复合材料力学性能得到改善, PIP-SiC涂层改性后, GSI Cf/SiC复合材料的弯曲强度、弯曲模量和断裂韧性随着PIP-SiC周期数的增加而降低, PIP-SiC为1个周期制备的GSI Cf/SiC复合材料的力学性能最高, 其弯曲强度、弯曲模量、断裂韧性分别为185.2 MPa、91.1 GPa和5.5 MPa·m1/2。PIP-SiC界面改性涂层的作用机制主要体现在载荷传递和"阻挡"Si的侵蚀2个方面。
Abstract:
The interphase modified coating plays a vital role in adjusting the mechanical properties of composites, in particular for those Cf/SiC composites prepared from the gaseous silicon infiltration (GSI) process. The ideal interphase modified coating should not only prevent the etching of C fiber by Si vapor, but also render a good interface bonding between C fiber and SiC matrix. With SiC coatings from the precursor infiltration-pyrolysis (PIP) route as the interphase modified coating in 3D-C fiber preform, we discuss the effects of PIP-SiC coating on mechanical properties of Cf/SiC composites made from GSI. The results show that, without coating modification, the GSI Cf/SiC composites have poor mechanical properties and show brittle fracture characteristic, with the flexure strength, flexure modulus and fracture toughness 87.6 MPa, 56.9 GPa and 2.1 MPa·m1/2, respectively. Those composites with PIP-SiC interphase modified coating exhibit better mechanical properties, with PIP-SiC coating modification, with the increase of the PIP-SiC cycles, flexure strength, flexure modulus and fracture toughness of GSI Cf/SiC composites decrease, in particular those with the PIP-SiC coatings after one cycle, with the flexure strength, flexure modulus and fracture toughness 185.2 MPa, 91.1 GPa and 5.5 MPa·m1/2, respectively. The improvement effects from the PIP-SiC interphase modified coating are attributed to the transfer loading and prevention of etching by Si.
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