熔盐堆石墨控制棒套管碳纤维布增强工艺及性能研究

Study on the reinforcement process and performance of carbon fiber fabric for graphite control rod guide tube of molten salt reactor

在熔盐堆中需要设置控制棒套管,以实现控制棒在反应堆中的自由升降。石墨是理想的控制棒套管材料,但石墨强度与韧性不足,是其作为熔盐堆控制棒套管需要解决的主要问题。首先,在真空环境下用先驱体溶液预浸渍碳纤维布,并将其以一定的张力缠绕在石墨管上。其次,通过先驱体浸渍裂解工艺多次循环压力浸渍、固化、碳化制备不同增密次数和缠绕层数的样品。然后,对碳纤维布增强石墨管材样品和参照样品进行力学性能测试。最后,对测试损伤样品进行微观结构、失效方式分析,进而优化制备工艺以提升材料性能。结果表明:采用碳纤维布缠绕工艺以及先驱体浸渍裂解法可以很大程度上克服石墨管的强度及韧性不足的缺点,有望用于熔盐堆控制套管的制备。

[Background]The control rod guide tube(CRGT)is needed to facilitate the movement of the control rod in the molten salt reactor(MSR).Graphite material is resistant to neutron radiation,high temperature and molten salt corrosion,and has small neutron absorption cross section,hence it is an ideal CRGT material except for the comparatively low strength and toughness.It is believed that reinforcing the graphite CRGT with carbon fiber fabric(CFF)is a promising way to promote its application in molten salt reactor.[Purpose]This study aims to optimize the preparation parameters of the CFF reinforcement for CRGT.[Methods]First of all,the CFF was pre-impregnated with precursor solution in a vacuum environment,and wound on the graphite tube with a certain tension.Secondly,samples with different densification cycles and winding layers were prepared through multiple pressure impregnation,curing and carbonization cycles of the Precursor-Infiltration-Pyrolysis(PIP)process.Then,the mechanical properties of carbon fiber cloth reinforced graphite tube samples and the reference samples were tested.Finally,the microstructure and failure mode of the damaged samples were analyzed for further optimizing the preparation process to improve the material performance.[Results&Conclusions]The results show that the CFF winding and PIP method enhances the strength and toughness of the graphite tube,and the preparation parameters have been optimized that make the reinforced graphite CRGT with carbon fiber fabric(CFF)possible to be applied to MSR.