某核电站应急柴油机冷却水系统用橡胶膨胀节因贯穿开裂导致泄漏，采用超景深三维显微镜和电子万能材料试验机，分别从力学性能、形貌特征及环境因素等方面，分析了橡胶膨胀节老化开裂的原因。结果表明：橡胶膨胀节材料存在混淆使用的问题，在热空气、水以及外力的综合作用下，橡胶力学性能下降导致严重老化，在外力的周期性作用下，橡胶最终发生贯穿开裂。

The penetrating cracking of rubber expansion joint used in the water system of emergency diesel engine in a nuclear power plant led to leakage. Using ultra-depth of field three-dimensional microscope and electronic universal material testing machine, the causes of aging and cracking of rubber expansion joint were analyzed from the aspects of mechanical properties, morphological characteristics and environmental factors. The results showed that rubber expansion joint materials had the problem of mixed use. Under the combined action of hot air, water and external forces, the deterioration of mechanical properties of the rubber led to serious aging. Under the periodic action of external forces, the rubber eventually underwent penetration cracking.