核电气动橡胶隔膜材料热老化机械性能研究

Research on Thermal Aging Mechanical Properties of Pneumatic Rubber Diaphragm Materials for Nuclear Power Plant

核电气动阀门用三元乙丙橡胶(EPDM)和丁腈橡胶(NBR)隔膜材料分别在100℃和150℃下进行不同时间的热老化试验,采用万能试验机、邵氏硬度计、拉伸疲劳试验机、扫描电子显微镜、傅里叶红外光谱仪对材料拉伸性能、硬度、疲劳性能、微观形貌等进行测试与表征,结果表明:EPDM材料随着老化时间的增加断裂伸长率和断裂强度呈下降趋势,硬度呈缓慢上升趋势。NBR材料在100℃老化下断裂伸长率缓慢下降,断裂强度缓慢增加,硬度缓慢增加;在150℃老化下断裂伸长率和断裂强度急剧下降,硬度呈直线上升趋势。在相同老化时间下,老化温度越高,EPDM和NBR材料的断裂伸长率和断裂强度越小,硬度越大。EPDM和NBR材料的耐疲劳性能随着老化时间和老化温度的增加,均有一定程度的下降,其中NBR材料耐疲劳性能下降较大;红外光谱分析结果表明,随着老化时间的增加,EPDM材料羟基和羰基吸收峰的强度增大,NBR材料吸收峰强度逐渐减小。SEM微观形貌分析显示,EPDM和NBR样品在老化前表面比较平整,随着老化时间增加,样品表面出现较多的堆积物质,老化温度越高,样品表面越粗糙。

The thermal aging tests of EPDM and NBR diaphragm materials for nuclear power were carried out at 100℃ and 150 ℃ for different time.And, the tensile properties, hardness, fatigue properties and micro-morphology of rubber diaphragm materials were tested and characterized by universal testing machine, Shaw hardness tester, tensile fatigue testing machine, scanning electron microscope and Fourier transform infrared spectroscopy. The results showed that the elongation at break and the strength at break of EPDM decreased with the increase of aging time, while the hardness increased slowly. The elongation at break of NBR decreaserd slowly, the strength at break and the hardness increasesd slowly at 100℃. The elongation at break and the strength at break decreased sharply and the hardness increasesd linearly at 150℃.Under the same aging time, the higher the aging temperature, the smaller the elongation at break and the strength at break, and the greater the hardness. The fatigue resistance of EPDM and NBR materials decreased to a certain extent with the increase of aging time and temperature, and the fatigue resistance of NBR materials decreased greatly. The results of infrared spectroscopy analysis showed that the absorption peaks of hydroxyl and carbonyl groups of EPDM materials increased with aging time, while the absorption peaks of NBR materials decreasd with aging time. SEM micromorphology analysis showed that the surface of EPDM and NBR samples was smooth before aging, and with aging time increasing, more accumulation substances appeared on the surface of samples. The higher the aging temperature, the rougher the surface of the sample.