An experimental study of ultra-high temperature ceramics under tension subject to an environment with elevated temperature,mechanical stress and oxygen  

作　　者：HAN XinXing XU ChengHai JIN Hua XIE WeiHua MENG SongHe 

机构地区：[1]National Key Laboratory of Science and Technology for National Defence on Advanced Composites in Special Environments,Harbin Institute of Technology

出　　处：《Science China(Technological Sciences)》2019年第8期1349-1356,共8页中国科学（技术科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11472092,11672088,11502058);the National Basic Research Program of China(Grant No.2015CB655200)

摘　　要：Ultra-high temperature ceramic(UHTC) composites are widely used in high-temperature environments in aerospace applications. They experience extremely complex environmental conditions during service, including thermal, mechanical and chemical loading. Therefore, it is critical to evaluate the mechanical properties of UHTCs subject to an environment with elevated temperature, mechanical stress and oxygen. In this paper, an experimental investigation of the uniaxial tensile properties of a ZrB_2-SiC-graphite subject to an environment with a simultaneously elevated temperature, mechanical stress and oxygen is conducted based on a high-temperature mechanical testing system. To improve efficiency, an orthogonal experimental design is used. It is suggested that the temperature has the most important effect on the properties, and the oxidation time and stress have an almost equal effect. Finally, the fracture morphology is characterized using scanning electron microscopy(SEM), and the mechanism is investigated. It was concluded that the main fracture mode involved graphite flakes pulling out of the matrix and crystalline fracture, which indicates the presence of a weak interface in the composites.Ultra-high temperature ceramic（UHTC） composites are widely used in high-temperature environments in aerospace applications. They experience extremely complex environmental conditions during service, including thermal, mechanical and chemical loading. Therefore, it is critical to evaluate the mechanical properties of UHTCs subject to an environment with elevated temperature, mechanical stress and oxygen. In this paper, an experimental investigation of the uniaxial tensile properties of a ZrB2-SiC-graphite subject to an environment with a simultaneously elevated temperature, mechanical stress and oxygen is conducted based on a high-temperature mechanical testing system. To improve efficiency, an orthogonal experimental design is used. It is suggested that the temperature has the most important effect on the properties, and the oxidation time and stress have an almost equal effect. Finally, the fracture morphology is characterized using scanning electron microscopy（SEM）, and the mechanism is investigated. It was concluded that the main fracture mode involved graphite flakes pulling out of the matrix and crystalline fracture, which indicates the presence of a weak interface in the composites.

关 键 词：ultra-high TEMPERATURE ceramics ENVIRONMENT with elevated TEMPERATURE mechanical stress and OXYGEN UNIAXIAL tensile strength orthogonal experimental design 

分 类 号：TH[机械工程]