1. 上海交通大学 船舶海洋与建筑工程学院， 上海 200240； 2. 上海交通大学 航空航天学院， 上海 200240； 3. 中国航发商用航空发动机有限责任公司， 上海 201180
出版日期:2019-01-28发布日期:2019-01-28通讯作者:张大旭，男，副教授，E-mail：daxu.zhang@sjtu.edu.cn.作者简介:陈明明（1987-），女，天津市人，博士生，主要研究方向为复合材料力学.基金资助:国家自然科学基金（11272207），高等学校博士学科点专项科研基金（20120073120019）Tensile Behavior and Failure Mechanisms of Plain Weave SiC/SiC Composites at Room and High Temperatures
CHEN Mingming,CHEN Xiuhua,ZHANG Daxu,WU Haihui,GUO Hongbao,GONG Jinghai1. School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China; 2. School of Aeronautics and Astronautics, Shanghai Jiao Tong University, Shanghai 200240, China; 3. AECC Commercial Aircraft Engine Co., Ltd., Shanghai 201180, China
Online:2019-01-28Published:2019-01-28摘要/Abstract
摘要： 通过单向拉伸试验，对比研究平纹叠层SiC/SiC复合材料在室温和高温(1200℃)环境下的宏观力学特性，并采用扫描电镜对试验件断口进行观测，以分析其微观损伤模式和破坏机理.结果表明：平纹叠层SiC/SiC复合材料的室温和高温拉伸应力-应变行为均表现为非线性特征，具有较高的轴向拉伸基体开裂应力；两者拉伸强度相差不大，但高温下的断裂应变比室温下的高.从宏观断口分析可知，两者均呈现韧性断裂，但纤维拔出长度和断口平齐程度有所不同.材料内部产生的基体裂纹大部分与加载方向垂直；断面上经向纤维束发生纵向拉伸断裂破坏，内部存在严重的界面脱粘损伤以及纬向纤维束发生轴向劈裂破坏是材料在室温和高温下的拉伸破坏机理.高温下由于纤维与基体间的界面层在一定程度上被高温氧化而退化失效，使界面结合变弱和界面滑移力降低，从而产生较长的纤维拔出长度，所以高温下材料具有较高的断裂韧性.
关键词: 复合材料, 陶瓷基, 力学行为, 损伤, 高温, 破坏机理
Abstract: Monotonic tensile experiments at room temperature and 1200℃ were performed to investigate the mechanical behaviour of 2D-SiC/SiC composites. The microstructures of specimens were observed by using scanning electron microscope to analyse the damage modes and failure mechanisms. The results indicate that the stress-strain responses of 2D-SiC/SiC composites under tensile loading at both room temperature and 1200℃ are bi-linear and damage appears at the high stress level. Their tensile strengths are fairly close, but the fracture strain at 1200℃ is higher than that at room temperature. Specimens at both room and high temperature demonstrate ductile behaviour, but their pullout length of fibre and smoothness of fracture surfaces are different. Transverse matrix cracking, longitudinal tensile fractures of warp tows with serious interface debonding, and axial splitting failure of weft tows with intact fibres are the main damage mechanisms. The high temperature oxidation was found to have an influence on the properties of fibre-matrix interface of 2D-SiC/SiC composites. The weak interface and decrease of interfacial sliding stress result in the longer pullout length of fibre at 1200℃ in the oxidation environment, and therefore, 2D-SiC/SiC composites has high fracture toughness at 1200℃.
Key words: composites, ceramic matrix, mechanical behaviour, damage, high temperature, failure mechanism
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