摘要
Ceramic matrix composites have broad application prospects in the aerospace field due to their high temperature resistance and oxidation resistance.The effect of temperature and environment atmosphere on the fracture toughness and failure mechanisms of two-dimensional plain-woven SiC_(f)/SiC composites was investigated.The results show that they exhibit pseudo-plastic deformation behavior at different temperatures.The fracture toughness is as high as 48 MPa m^(1/2)at room temperature,and gradually decreases with rising temperature.The difference in fracture toughness between argon and air initially increases and then decreases with rising temperature.Furthermore,the high-temperature failure mechanisms of these composites were analyzed through macro and micro analysis.Based on this,a physic-based temperature-dependent fracture toughness model considering matrix toughness,plastic power,fiber pull-out,and residual thermal stress was developed for fiber-reinforced ceramic matrix composites.The model has been well validated by experimental results.An analysis of influencing factors regarding the evolution of fracture toughness was conducted by the proposed model.This work contributes to a better understanding of the mechanical performance evolution and failure mechanisms of ceramic matrix composites under multifield coupling conditions,thereby promoting their applications.
陶瓷基复合材料因其耐高温和抗氧化特性在航空航天领域具有广泛应用前景.本文通过单边切口梁三点弯曲法系统研究了温度和环境气氛对二维平纹编织SiC_(f)/SiC复合材料断裂韧性和失效机制的影响.结果表明,SiC_(f)/SiC复合材料在不同温度下表现出伪塑性变形特征,SiC_(f)/SiC室温断裂韧性高达48 MPa m^(1/2),随温度升高断裂韧性逐渐降低,并在氩气和空气中的差异先增大后减小.进一步,通过宏微观形貌和成分分析,深入研究了SiC_(f)/SiC复合材料的高温失效机制和关键影响因素.在此基础上,通过考虑基体韧性、高温塑性功、纤维拔出和残余热应力等因素的影响,针对纤维增强陶瓷基复合材料建立了基于物理机理的温度相关性断裂韧性理论表征模型.模型与实验结果充分验证,据此深入开展了断裂韧性的影响因素分析.该研究有助于理解SiC_(f)/SiC复合材料热力氧耦合失效机制和力学性能演变规律,支撑其行业应用.
基金
supported by the National Natural Science Foundation of China(Grant Nos.12102354,12472214 and 12002288)
the Young Elite Scientists Sponsorship Program by CAST(Grant No.2022QNRC001)
the Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2023A1515012620 and 2024A1515012018)
the independent research project of the National Key Laboratory of Strength and Structural Integrity(Grant No.LSSIZZYJ202305)
the Basic Research Program of Taicang(Grant No.TC2022JC09).
