JIAO Jian, JIANG Zhuoyu, GAO Ye, ZHOU YiRan, WANG Jiaqi
As one of the key performance indicators of composites, thermal shock performance may be related to sample size. In order to explore the thermal shock performance of SiCf/SiC composites, high temperature water quenching experiments at 1,200℃ were conducted with SiCf/SiC rectangle composite samples prepared by polymer infiltration pyrolysis (PIP) process. In addition, the above water quenching experiments were simulated by ABAQUS finite element software. In this study, three samples (i.e., S4, S8, S12) from SiCf/SiC composites with bending strength and interlaminar tensile strength of 553 MPa and 19.2 MPa, respectively were taken as the subjects of water quenching experiments. During the water quenching experiments, the samples started to form microcracks after 3 cycles, which expanded with the increase of the number of cycles. After 8 cycles, matrix cracks started to appear in S8 and S12 while a crack was observed extending along the 0° fiber direction in 5/6 layer at one end of S12. According to the finite element analysis results, the cracks in the 6/7 layers of S4 and S8 were firstly cracked and then closed, which might be due to space occupation of the secondary cracks caused by main cracks's propagation. The outcomes of stress calculation demonstrated that the thermal stress of the samples in this study increased with the increase of sample size due to the temperature gradient. The thermal stresses in S8 and S12 reached 40 MPa, resulting matrix cracks and extension.
