CMC-SiC在线铆焊连接界面的SiC纳米线改性与强韧化机制

CMC-SiC online hybrid (z-pinned/bonded) joining technique is one of the key technologies for the application of the long fiber reinforced silicon carbide (CMC-SiC) composites in the fields such as the next generation aero engine with high thrust-weight ratio and aerospace vehicle. However, the properties and the failure mechanisms of the bonding interphase are different from the counterpart of the CMC-SiC pin. Thus, the bonding interphase and the CMC-SiC pin cannot bear the external load together, and then the CMC-SiC joint properties could be hardly improved. The present proposal aims to firstly improve the strength and the toughness of the bonding interphase via in-situ grown SiC nanowires prepared by polymer infiltration and pyrolysis (PIP), and then form the global load sharing mechanism between SiC nanowire and fibers in CMC-SiC pin, finally realize the common loading between the bonding interphase and the CMC-SiC pin. The formation and grown mechanisms of the in-situ SiC nanowire will be revealed, and the microstructural evolution of the online hybrid (z-pinned/bonded) joining interface will be studied, and the mechanical properties and the failure mechanisms of the joining interface will be analyzed. The effect of the SiC nanowire content on the properties of the joining interface and the global load sharing mechanism will be revealed. Based on above, a novel CMC-SiC online hybrid (z-pinned/bonded) joining method with high properties will be developed. The results will be beneficial to enriching the strengthening/toughening mechanisms of the CMC-SiC joining interface, revealing the application potential of SiC nanowire to the joining of CMC-SiC composites.

连续纤维增韧碳化硅复合材料（CMC-SiC）的在线铆焊连接技术是推动该复合材料应用于高推重比航空发动机和空天飞行器等领域的关键技术之一，但焊接界面性能和失效机制与CMC-SiC铆钉的不同，导致二者难共同承载，制约CMC-SiC连接性能提高。本项目拟通过聚合物浸渍裂解法在焊接界面原位自生SiC纳米线来提高其强韧性，并与铆钉内纤维形成载荷共享机制来实现共同承载，通过研究SiC纳米线生成机理和连接界面微结构调控机制，分析连接界面力学性能和失效机制，揭示SiC纳米线含量的影响规律及其与纤维的载荷共享机制，发展新型高性能CMC-SiC在线铆焊连接方法。本研究成果有助于丰富CMC-SiC连接界面的强韧化机制，拓展SiC纳米线在CMC-SiC连接方向的应用。

连续纤维增韧碳化硅复合材料（CMC-SiC）的在线铆焊连接技术是推动该复合材料应用于高推重比航空发动机和空天飞行器等领域的关键技术之一，但焊接界面性能和失效机制与CMC SiC铆钉的不同，导致二者难共同承载，制约CMC-SiC连接性能提高。本项目通过聚合物浸渍裂解法在焊接界面原位自生SiC纳米线来提高其强韧性，并与铆钉内纤维形成载荷共享机制来实现共同承载，发展了新型CMC-SiC在线铆焊连接方法。通过研究SiC纳米线生成机理和连接界面微结构调控机制，分析连接界面力学性能和失效机制，建立了揭示纳米线和纤维全局载荷共享机制的细观力学模型，丰富了CMC-SiC连接界面的强韧化机制，拓展了SiC纳米线在CMC-SiC连接方向的应用。根据文献报道，以往连接方法获得的连接部位强度在15-78MPa之间，而采用本研究获得的连接强度高达200MPa，是目前陶瓷基复合材料的最高连接强度。本项目研究的陶瓷基复合材料铆焊连接技术解决了连接件与陶瓷基复合材料构件的物理和化学失配问题；采用结构尺寸相对较小的销钉或者铆钉，使制孔对CMC-SiC构件的强度影响降到最低，并采用CMC-SiC相同的制造工艺，将CMC-SiC零件和连接件结合到一起，使二者具有相同的结构和性能，解决了连接部位显著降低陶瓷基复合材料结构强度和韧性的难题；用销钉或者铆钉代替螺栓，并对其多余部位进行加工，使其与零件外形保持光滑过渡，有助于解决连接结构复杂、影响气动外形的难题。