【作者】 方鹏；

【导师】 成来飞；

【作者基本信息】 西北工业大学 ， 材料学， 2005， 硕士

【摘要】 连续碳纤维增强的碳化硅基复合材料(C/SiC)是一种有希望满足航空发动机热端部件工作温度的重要结构材料。由于多组份以及编织、制备工艺的特点,C/SiC复合材料的力学行为和损伤断裂过程十分复杂。因此,传统研究材料的方法不能适应复合材料损伤过程的研究,而声发射(Acoustic Emission,AE)技术的应用可以有效解决这一难题。本文利用声发射技术实时监测C/SiC复合材料在室温单向拉伸、热震、高温疲劳和蠕变时的损伤破坏过程,利用声发射参数表征了C/SiC复合材料不同的损伤模式,揭示了其损伤演变规律。主要研究内容和结果如下: [1] 利用AE监测和研究了C/SiC复合材料在室温单向拉伸的损伤演变。研究表明,AE信号主要来自基体开裂、界面开裂和纤维断裂。不同的损伤模式产生AE信号的持续时间、能量、频率等参数各不相同。 [2] 利用AE监测和研究了C/SiC复合材料在多种环境下的热震行为。研究表明,热震时裂纹的生长和扩展主要发生在冷却过程中。在Ar气氛下,热震对C/SiC复合材料的损伤是有限的,存在一个临界循环次数。在腐蚀气氛中,C/SiC复合材料不断受到外界腐蚀气体的化学损伤,在循环热应力的作用下,材料性能不断下降,不存在临界循环次数。 [3] 利用AE监测和研究了C/SiC复合材料高温疲劳的损伤演变过程,确定了C/SiC复合材料高温疲劳的主要损伤机理。C/SiC复合材料在受交变载荷时,要经历了基体开裂、基体裂纹饱和、纤维/基体界面处脱粘、纤维沿界面往复滑动、纤维断裂和纤维拔出等阶段。这些基本损伤形式还会相互影响和组合,导致材料的刚度、强度下降以及其它一些物理性能的变化。 [4] 利用AE监测和研究了C/SiC复合材料高温蠕变的损伤演变过程,确更多还原

【Abstract】 Carbon fiber reinforced silicon carbide composite (C/SiC) is one of important promising structure materials that can meet the need of the thermal-part of aero engines. Because of multi-constitute and characteristics of knitting and preparation, its mechanical behaviors and damage mechanics were extraordinary complicated. So the traditional method cannot be adapted to the research on damage evolution of composites. However, acoustic emission (AE) can deal with the problem effectively. The whole damage evolution of C/SiC composite during monotonic tensile, thermal-shock, fatigue and creep at high temperature were inspected in real-time by AE. The different failure modes of C/SiC composite were described by AE parameters and its rules of damage evolution were also revealed. The main contents and conclusions are as follows,[1] The damage evolution of C/SiC composite during monotonic tensile at room temperature was investigated by AE. The results showed that AE signals of C/SiC composites mainly came from matrix crack, interface debonding and fiber breakage. The parameters, such as duration, energy and frequency, of AE signals produced by different damage modes were different.[2] The damage evolution of C/SiC composite during thermal shock at different atmosphere was investigated by AE. The growth and expansion of crack occur in the course of cooling. At argon atmosphere, the thermal shock damage to C/SiC composites was limited and there existed a critical thermal shock cyclic times. At corrosion atmosphere, C/SiC composites were corrupted by corrosive gas continuously, and the cyclic thermal-stress degraded the mechanical properties of C/SiC composites. [3] The damage evolution of C/SiC composite during fatigue at hightemperature was investigated by AE and the main damage mechanism was understood. Under the condition of cyclic fatigue load, matrix crack, interface of fiber/matrix debonding, sliding, fiber breakage and fiber pull out occurred. These damage patterns effected and combined each other. As a result, the rigidity and strength of C/SiC composites descended and the other physical properties were changed.[4] The damage evolution of C/SiC composite during creep at high temperature was investigated by AE and the main damage mechanism was understood. During the creep at high temperature, the AE cumulative energy coordinates with the creep strain. So, the behaviors of C/SiC composites during creep at high temperature, could be described by AE cumulative energy. The creep strain of C fiber controlled the whole creep strain of C/SiC composite. The difference of interface status could cause great change of strain during creep.更多还原