碳化硅纳米纤维改性C/C复合材料微观织构优化及摩擦磨损行为与机理研究

With the development of axes sealing material for aeroengine, the traditional carbon/carbon composites shows disadvantages of friction instability and large wear, especially at high temperature. these disadvantages restrict their widespread application in the field of axes sealing material with high performance and high reliability for aeroengine.In this project, SiC nanofibers (SiCNF) are designed to optimized the microtexture and tribological properties of C/C composites. SiCNF grow on the carbon fibers by catalytic chemical vapor deposition and carbon matrix are prepared by chemical vapor deposition. The modified C/C composites are obtained. The influence of SiCNF on the deposition of pyrolytic carbon are studied. The formation mechanism of microtexture of fiber/PyC interface are investigated. The mechanical properties and failure mechanism of nanofiber-modified C/C composites are investigated. The friction and wear behavior and mechanism under different conditions are investigated. The relationship between tribological properties and material microstructure, the match between tribological properties and mechanical properties are explored, and the optimal control method is proposed. The modified C/C composites with both excellent tribological and mechanical properties are obtained, which will provide theoretical guidance and methodological basis for design and preparation of high-performance sealing materials.

随着航空发动机轴间密封材料的发展，常规C/C复合材料存在摩擦系数不稳定，高温磨损量偏大等不足，制约了其在新一代航空发动机密封材料领域的应用。本项目设计具有优异耐磨性能的碳化硅纳米纤维（SiCNF）新组元，优化C/C复合材料微观织构，提高其摩擦磨损性能。采用催化化学气相沉积法在预制体炭纤维表面原位生长SiCNF，然后采用化学气相渗透工艺制备基体热解炭，得到纳米纤维改性C/C复合材料。研究SiCNF对热解炭沉积模式的影响机理，探讨炭纤维/热解炭界面层微观织构形成机制，获得组织优化控制；研究不同载荷、对偶件和环境下改性C/C复合材料的室温及高温摩擦磨损行为、SiCNF对材料摩擦磨损性能的影响机制，揭示改性材料的摩擦磨损机理及其与材料微观组织结构的内在关联，提出优化控制方法，获得优异摩擦磨损性能的改性C/C复合材料，为设计制备新一代高性能航空发动机密封材料用C/C复合材料提供理论指导和方法基础。

航空发动机密封系统对整个发动机的工作性能及可靠性具有至关重要的作用。用于航空发动机的轴间密封材料，如主密封环，是主轴密封的关键零件，它与密封跑道相对高速旋转，两者间形成极小的间隙，限制流体泄露从而实现密封。随着航空发动机轴间密封材料的发展，常规C/C复合材料存在摩擦系数不稳定，高温磨损量偏大等不足，制约了其在新一代航空发动机密封材料领域的应用。本项目提出在母体炭纤维上原位生长二次SiCNF，利用准一维线性结构，在CVI过程中干预碳氢气体在其表面的热解沉积过程，调控炭纤维/热解炭界面层的微观织构，大大提高了材料的热物理性能，最终显著改善了C/C复合材料的摩擦磨损性能。系统研究了SiCNF对C/C复合材料的微观组织结构的影响机理，深入分析了SiCNF在改性复合材料在室温以及高温摩擦磨损过程中的作用机制，所研制的SiCNF-C/C复合材料有效满足新一代航空发动机轴间密封材料对摩擦磨损性能的要求。