高温热震对具有SiC涂层的C/C复合材料压缩性能的影响

采用化学气相反应法在C/C复合材料表面制备SiC涂层,对SiC涂层C/C复合材料试样进行热震实验。利用X射线衍射仪(XRD)、扫描电镜(SEM)及能谱分析等研究涂层的形貌和结构,采用压缩性能试验研究热震次数及热震温度对SiC涂层C/C复合材料试样压缩性能的影响。结果表明:试样的抗压强度在197.9~237.0 MPa之间,平均抗压强度为210.4 MPa。在1 100℃下进行热震实验,抗压强度随热震次数增加呈近似线性降低趋势;当热震次数一定时(15次循环热震),在900~1 500℃温度范围内,抗压强度随热震温度升高逐渐降低。热震温度为1 500℃时,热震后试样的抗压强度略有升高,主要与热震过程中氧化形成的SiO2玻璃的高温自愈合作用有关。

Influence of high temperature cyclic thermal shock on compression properties of C/C composites with SiC coating

SiC coatings were prepared on carbon/carbon(C/C) composites by chemical vapor reaction(CVR) method.The structure and morphology of the coating were characterized by XRD,SEM and EDS analysis,and then the influence of thermal shock number and thermal shock temperature difference on compressive strength of the composites were investigated by compression tests.The results show that the compressive strength of the SiC coated C/C composites is between 197.9~237.0 MPa and the average strength is 210.4 MPa.The compressive strength of SiC coated C/C after thermal cycling between room temperature and 1 100 ℃ trends to decrease with the thermal shock number increasing,and they follow a quasi-linear manner.In the temperature range of 900~1 500 ℃,after thermal shock for 15 times,the compressive strength of the coated samples reduces as the thermal shock temperature increase,when the thermal shock temperature reaches 1 500 ℃,the compressive strength improves slightly.The improvement of the compressive strength is mainly contributed to the high temperature self-healing ability of the SiO2 glass formed in the thermal shock and oxidation process.