SiBCN/碳纤维陶瓷基复合材料的界面强韧化机制及性能研究

With the rapid development of aero and space technology, the performance of insulation materials is difficult to meet the requirement of future aircraft, especially in lightweight, toughening and high reliability. In order to solve these problems, hierarchical carbon fiber reinforcement will be synthesized and introduced into SiBCN ceramic matrix to prepare a new heat-resistant composite material. Specifically, chemical grafting, chemical vapor deposition(CVD) and chemical vapor infiltration(CVI) technologies will be used to grow carbon nanomaterials with different dimensions and scales on the surface of carbon fiber to form the hierarchical reinforcement. The dimensions and scales of the carbon nanostructures will be controlled by adjusting the production process. Thus we could achieve the purpose of controllable preparation of carbon nanomaterials with different dimensions and scales on CF surface. Then, the molecular design theory will be used to synthesize novel SiBCN multi ceramic precursor precisely. The hierarchical-carbon-fiber/SiBCN ceramic composites will be fabricated by precursor infiltration pyrolysis (PIP) technique. The impact of different carbon nanostructures on the interface between the carbon fiber and ceramic matrix will be studied. In addition, the project will establish the relationship between microstructure of hierarchical carbon fiber reinforcement, component, microstructure and macroscopic properties of composite materials. The influencing mechanism and regular of different carbon nanomaterials on the microstructure and macroscopic properties of composite materials will be explored.

随着近空间及空间航天技术的快速发展，现有防热材料在轻质化、强韧化、以及高可靠性等方面都难以满足未来飞行器发展需求。针对以上问题，本项目拟采用多层次碳纤维复合增强体增韧SiBCN陶瓷制备新型防热复合材料。具体拟采用化学接枝、化学气相沉积、化学气相渗透等手段在碳纤维表面进行不同维度不同尺度碳纳米材料的生长，制备多层次碳纤维复合增强体。通过对生长工艺的控制对碳纤维表面碳纳米结构进行维度及尺度的微观调控，实现碳纤维表面多维度多尺度纳米碳材料的可控制备，其次通过分子设计精确合成新型的SiBCN多元陶瓷先驱体。采用先驱体浸渍裂解法制备多层次碳纤维复合增强体增韧SiBCN陶瓷复合材料，研究不同碳纳米结构对碳纤维/陶瓷基体之间界面的影响，建立“多层次碳纤维复合增强体微观结构-复合材料组成及微结构-复合材料宏观性能”关系，探索碳纤维表面不同碳纳米结构对复合材料微观结构及宏观性能的影响规律及机制。

现有热防护材料中，陶瓷基复合材料因其具有较高的耐温性而始终受到人们的关注，但其固有的脆性及性能分散性制约了其应用。近年来，先驱体转化陶瓷作为新一代的耐高温结构陶瓷材料备受关注，同时为了改善陶瓷的固有脆性，人们通常采用碳纤维（Cf）对其强韧化。本项目基于不同维度不同尺度碳纳米材料修饰碳纤维复合增强体，采用不同的制备工艺实现碳纤维表面微结构可控制备，分别制备出氧化石墨烯改性碳纤维复合增强体（Cf-PEI-g-GO）、碳纳米管改性碳纤维复合增强体（CNWs-Cf）、碳化硅纳米管改性碳纤维复合增强体（SiCNWs-Cf）以及碳涂层包覆碳纤维复合增强体。从分子设计的角度合成 SiBCN(Zr)陶瓷先驱体，采用一种新型先驱体的合成工艺制备了多层次碳纤维复合增强体增韧SiBCN(Zr)新型陶瓷复合材料，并对其微观结构和宏观性能进行表征，采用静态氧化和氧乙炔烧蚀试验考核了Cf/SiBCN(Zr)复合材料抗氧化烧蚀性能，结果表明Zr改性的Cf/SiBCN(Zr)陶瓷基复合材的抗氧化烧蚀性能更为优异。热震实验表明其具有一定的抗热冲击性能，材料的残余强度随着温度的上升，有一个先下降再上升的趋势，由计算可得材料的临界热冲击温度为736°C。