基于泡沫陶瓷三维互穿网络负压浸渍法制备新型耐高温中子屏蔽材料

A Novel High-Temperature Resistant Neutron Shielding Material Prepared by Negative Pressure Impregnation Method Based on Interpenetrating Network of Foam Ceramics

本工作制备了一种具有互穿网络结构的新型泡沫陶瓷/硼酚醛树脂复合材料,采用有机泡沫浸渍法和惰性气氛烧结制备了莫来石/碳化硼骨架增强体,采用负压浸渍和原位热固化方法制备了碳化硼/硼酚醛树脂基体。实验探究了微粉含量(碳化硼和高岭土各10%~30%)和烧结温度(1 300~1 500℃)对陶瓷骨架和复合材料的影响;当烧结温度设置为1 350℃,粉体原料质量占比设置为氧化铝55%、碳化硼15%、高岭土25%、二氧化钛5%时,烧结而成的陶瓷骨架与20%(质量分数)碳化硼/硼酚醛树脂的填充材料形成新型中子屏蔽复合材料,其综合性能可达到最优化;此时,泡沫陶瓷骨架线收缩率为3.36%,堆积密度为0.54 g/cm^(3),显气孔率为73.7%,骨架抗压强度为0.94 MPa;陶瓷/硼酚醛树脂复合材料显气孔率为0.2%,堆积密度为1.22 g/cm3,抗压强度为86 MPa;300℃保温10 h冷却后,残余抗压强度为54 MPa,抗压残余比为62%,服役温度为180~330℃;10%(质量分数)硼酸溶液浸泡72 h后,失重率为0.31%,残余抗压强度为82.5 MPa,抗压残余比为95.7%。放置于241Am-Be中子源前,复合材料(12~13 mm厚)总中子线性衰减系数为0.356 cm^(-1),总中子屏蔽率为35.5%,热中子线性衰减系数为1.061 cm^(-1),热中子屏蔽率为73.0%。该新型中子屏蔽材料不仅具有三维互穿网络结构,还包含了含硼骨架/含硼树脂/含硼填料的多级结构,为一种性能优良的耐高温新型中子屏蔽材料提供了设计参考。

In this work,a novel ceramic foam/boron phenolic resin composite with interpenetrating network structure was prepared.Mullite/boron carbide skeleton reinforcement was prepared by organic foam impregnation and inert atmosphere sintering,and boron carbide/boron phenolic resin matrix was prepared by negative pressure impregnation and in situ curing.The effects of powder content(10%-30%boron carbide and kaolin)and sintering temperature(1300-1500℃)on ceramic skeleton and composite were investigated experimentally.It was found that when the sintering temperature was 1350℃and the skeleton ratio was 55%alumina,15%boron carbide,25%kaolin and 5%titanium dioxide respectively,the comprehensive performance of the new neutron shielding composite material was optimized with 20wt%boron carbide/boron phenolic resin.At this situation,the linear shrinkage,bulk density,apparent porosity and compressive strength of foam ceramic skeleton were 3.36%,0.54 g/cm 3,73.7%and 0.94 MPa respectively.The apparent porosity,bulk density and compressive strength of ceramic/boron-phenolic resin composites were 0.2%,1.22 g/cm 3 and 86 MPa respectively.After ageing 10 h at 300℃,the residual compressive strength,residual ratio and service temperature of composites were 54 MPa,62%and 180—330℃respectively.After soaking in 10wt%boric acid solution for 72 h,the residual compressive strength,residual ratio and weight loss of composites were 82.5 MPa,95.7%and 0.31%respectively.When placed in front of the 241 Am-Be neutron source,the total neutron linear attenuation coefficient and total neutron shielding rate of composites(12-13 mm)were 0.356 cm^(-1) and 35.5%,while the thermal neutron linear attenuation coefficient and thermal neutron shielding rate of composites were 1.061 cm^(-1) and 73.0%.The novel neutron shielding material not only has a three-dimensional interpenetrating network structure,but also contains a multistage structure including boron skeleton/boron resin/boron filler,which provides a reference for the design of a novel neutron shielding material with excellent performance and high temperature resistance.