Study on the circumferential tensile behavior of SiCf/SiC composite cladding tubes across a broad temperature range: High temperature interface enhancement effect from a cross-scale perspective

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In nuclear reactors, Silicon carbide fiber reinforced silicon carbide matrix (SiCf/SiC CMC) cladding tubes are susceptible to circumferential damage due to internal gas pressure expansion. However, due to its complex spatial fiber winding structure, investigating circumferential tensile failure under extreme temperatures is challenging. Therefore, using cross-scale methods and experiments from 20 °C to 1100 °C, this study examined circumferential damage at macro, micro, and nanoscale levels. Specifically, as the temperature increases, the material still maintains excellent structural stability; at 1100 °C, the critical damage load decreases by 72.5 % and the critical displacement increases by 197.1 %.The " interface enhancement effect" between the fibers and matrix results in a relatively smooth fracture morphology. At the macroscopic level, morphology evolution reflects the transition from brittle to pseudo-plastic behavior. Additionally, based on the principle of minimum potential energy and the theory of semi-geodesics, the complex macroscopic structure and microscopic Representative Volume Element (RVE) model was reconstructed. The findings show the numerical model accurately represents the circumferential damage of SiCf/SiC CMC under extreme temperatures. Simultaneously, at the molecular level, the interfacial strength at high temperature is 7.5 % higher than that at ordinary temperature, resulting in a distinct adhesive interaction between matrix and fibers. This study opens up new avenues for the fundamental theoretical research of such ceramic matrix materials. interface enhancement effect.