热处理对C/C-SiC接头连接强度的影响

C纤维增强C和SiC双基复合材料(C/C-SiC)的连接是其能否得到广泛应用的关键技术之一。采用硼改性酚醛树脂以及B4C和SiO2填料通过反应成形连接工艺连接C/C-SiC,研究热处理温度(300～1000℃)对连接件强度保留率的影响。结果表明,随着热处理温度的升高,强度保留率先降低,在800℃时达到最低值80.6%,然后随着温度进一步升高,强度保留率又升高,在1000℃时达到88.1%,表明连接件具有较好的耐热性能。随着热处理温度的升高,连接层相组成发生变化。连接件经过1000℃处理30min后,连接层由B4C、SiO2和玻璃碳以及无定型B2O3组成,C、Si、O和B元素分布都较为均匀,并在界面处发生了扩散,连接件断裂方式为混合断裂。

Effect of Heat-Treatment on the Strength of C/C-SiC Joints

Joining of carbon fibers reinforced C-SiC dual matrix composites (denoted by C/C-SiC) is critical for its extensive applications. Joining of C/C-SiC has been realized through a reaction joining process using boron-modified phenolic resin with B4C and SiO2 additives. The effect of the heat-treatment temperature (300-1000 ℃ ) on theretained strength of the joints was studied. At a relatively low temperature the retained strength of the joints decreases as the heat-treatment temperature increases until it reaches the minimum of 80.6% at 800℃, and it increases as the heat-treatment temperature further increases. It reaches 88.1% at 1000 ℃, indicating good heat-resistance of the joints. The composition and structure of the interlayer change as the heat-treatment temperature increases. After the heat treatment at 1000 ℃ for 30 min, the interlayer is composed of B4C, SiO2 , glassy carbon and possibly amorphous B2O3 . The distributions of the elements C, Si, O and B in the interlayer are uniform. The diffusion of the elements takes place at the interfacial area. The fracture surface of the joint is in a mixed-mode.