Dependence of mechanical properties on microstructure of high-textured pyrocarbon prepared via isothermal and thermal gradient chemical vapor infiltration
Dependence of mechanical properties on microstructure of high-textured pyrocarbon prepared via isothermal and thermal gradient chemical vapor infiltration
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DOI：
10.1016/j.compositesb.2020.107982
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发表时间：
2020-07
影响因子：
13.1
通讯作者：
Tiyuan Wang;Hejun Li;Q. Shen;Kun Li;Wei Li;Q. Song;Shouyang Zhang
中科院分区：
文献类型：
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作者：
Tiyuan Wang;Hejun Li;Q. Shen;Kun Li;Wei Li;Q. Song;Shouyang Zhang
为了研究高织构热解炭（HT PyC）微观结构对力学性能的影响，采用等温等压化学气相渗透（ICVI）和热梯度化学气相渗透（TCVI）工艺制备了HT PyC试样，研究了试样的微观结构和力学性能。与TCVI相比，ICVI的HT PyC是均匀的，并且表现出更明显的长程有序。此外，TCVI的HT PyC内存在纹理的空间梯度，表明整个基质的微观不均匀性。TCVI中HT层的取向角（OA）从纤维表面向外逐渐增大，而ICVI中微晶较好的HT层的OA几乎相同。三点弯曲和显微压痕测试结果表明，TCVI试样的弯曲强度、界面断裂强度和显微硬度均略高于ICVI试样。TCVI试样的残余热应力分布较为复杂，而ICVI试样的残余热应力分布相对均匀。该研究为C/C复合材料的工艺选择和工业应用提供了有意义的指导。
In order to explore the dependence of mechanical properties on the microstructure of high-textured (HT) pyrolytic carbon (PyC), the microstructure and properties of HT PyC specimens prepared by isothermal isobaric chemical vapor infiltration (ICVI) and thermal gradient chemical vapor infiltration (TCVI) processes were investigated. The HT PyC of ICVI was uniform and exhibited a more distinct long-range order compared to that of TCVI. Besides, a spatial gradient in texture existed within the HT PyC of TCVI, demonstrating the micro-nonuniformity of the whole matrix. The orientation angle (OA) of HT layers in TCVI increased gradually from the fiber surface to outside, whereas the OA of HT layers in ICVI with better microcrystalline was nearly similar. According to the results of three-point bending and micro-indentation, the flexural strength, interfacial fracture strength, and micro-hardness of TCVI specimens were slightly higher than those of ICVI specimens. Furthermore, the residual thermal stress distribution of TCVI specimens was complex owing to the spatial gradient in temperature of TCVI process, while the residual thermal stress distribution of ICVI specimens was relatively uniform. This work provides meaningful guidance for the process selection and industrial applications of C/C composites.