热梯度CVI C/C材料的结构与性能

以炭纤维整体毡为预制体，采用热梯度CVI工艺制备了两种不同结构基体炭的C／C材料，即RL结构和SL结构材料。采用光学金相仪，X射线衍射仪，硬度计，激光导热仪等设备研究了沉积态和热处理态C／C材料的显微结构及热物理性能。对比研究了两种结构材料的力学性能及摩擦摩损性能。结果表明：当密度超过一定值后，密度对C／C材料的力学性能和摩擦性能的影响远不如CVD炭结构的影响大；不管是沉积态还是热处理态，RL结构材料的刹车性能曲线明显优于SL结构材料的刹车性能曲线，这意味着CVD炭的微观结构不同是造成C／C材料摩擦性能差异的根本原因。

Microstructure and properties of C/C composites prepared by thermal gradient CVI process

With the carbon fiber integrated felts used as preforms, two different types of carbon-carbon(C/C) composites, namely, rough laminar (RL) structure materials and smooth laminar (SL) structure materials were fabricated by thermal gradient CVI process. The microstructure and thermal and physical properties of the materials under different conditions were investigated by means of optical microscopy, X-ray diffractometer, hardness tester, thermal conductivity tester respectively. Furthermore, the mechanical, frictional and wear properties of the materials were also investigated. It is shown that the effects of microstructure of pyrocarbon on the mechanical and frictional properties outweigh by far the effects of bulk density on the corresponding properties when the bulk density amounts to a certain degree. It is also shown that, the frictional properties of both as-deposited RL structure material and heat-treated one are obviously superior to those of the SL structure material, which implies that the decisive factor in determining the frictional behavior of C/C composites turns to be the microstructure of pyrocarbon.