Microstructure and mechanical properties of carbon fiber needled felt reinforced sol-derived YAG composite
Microstructure and mechanical properties of carbon fiber needled felt reinforced sol-derived YAG composite
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DOI：
10.1016/j.jallcom.2018.09.080
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发表时间：
2019-01
影响因子：
6.2
通讯作者：
Borong Shan;Q. Ma;Kuanhong Zeng
中科院分区：
文献类型：
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作者：
Borong Shan;Q. Ma;Kuanhong Zeng
虽然YAG是一种理想的热结构陶瓷，但关于第二相增强YAG基复合材料的研究却很少。本文采用低成本的三维碳纤维针刺毡作为增强体来提高YAG的断裂韧性，以高固含量的Y2 O3-Al 2 O3溶胶为原料，通过真空烧结-干燥-热处理制备了碳纤维针刺毡增强YAG（C/YAG）复合材料。研究了C/YAG复合材料的显微结构、力学性能、热稳定性和抗氧化性能。由于C/YAG复合材料的增强体和微观结构的特点，C/YAG复合材料表现出非灾难性的破坏行为，其断裂韧性远高于YAG陶瓷。C/YAG复合材料经1700 °C和1800 °C惰性气氛退火后，弯曲强度保持良好。虽然在1800 °C以下碳纤维和YAG之间的化学惰性得到了证实，但在退火过程中，界面的物理结合得到了增强，这导致了断裂功的降低，特别是在1800 °C。由于YAG对氧化具有免疫性，C/YAG复合材料的抗氧化性与裂纹和气孔有关。对1200 °C、1400 °C和1600 °C氧化后的显微组织和抗弯强度的变化进行了表征和分析。
The study concerning the second phase reinforced YAG matrix composites is few although YAG is well known as a desirable thermo structural ceramic. In this paper, low-cost 3D carbon fiber needled felt was used as reinforcement to improve the fracture toughness of YAG, and the carbon fiber needled felt reinforced YAG (C/YAG) composite was fabricated through vacuum impregnation-drying-heat treatment, using the Y2O3-Al2O3sol with a high solid content as raw material. The microstructure, mechanical properties, thermal stability and oxidation resistance of C/YAG composite were carefully investigated. Due to the characteristics of reinforcement and the microstructure, the as-fabricated C/YAG composite showed non-catastrophic failure behavior and much higher fracture toughness compared with monolithic YAG ceramic. The flexural strength of C/YAG composite was well retained after annealed at 1700 °C and 1800 °C under inert atmosphere. Although the chemical inertness between carbon fiber and YAG was confirmed up to 1800 °C, the physical bonding of interface was enhanced during annealing, which led to the decrease of fracture work, especially at 1800 °C. The oxidation resistance of C/YAG composite was related to the cracks and pores since YAG is immune to oxidation. The changes of microstructure and flexural strength after oxidation at 1200 °C, 1400 °C and 1600 °C were characterized and analyzed.