可用于惯性约束聚变靶材的弹性硅基气凝胶研究

Study of elastic silicon-based aerogels for inertial confinement fusion targets

  • 摘要: 在惯性约束聚变(ICF)研究中,氘氚(DT)燃料的储存与快速充填对靶材的结构与性能提出了严苛要求。为同时满足低密度、高比表面积、良好疏水性的多重指标,本文以甲基三乙氧基硅烷(MTES)为前驱体,单羟基封端聚二甲基硅氧烷(PDMS)为有机增强体,异丙醇(IPA)与N,N-二甲基甲酰胺(DMF)为复合溶剂,采用常压干燥方式成功制备出超疏水弹性硅基气凝胶材料。通过监测体系在缩聚前的均一性随PDMS含量、复合溶剂体积比VIPA/VDMF的变化情况,构建体系在IPA-DMF-PDMS三元参数空间中的溶解相图,并揭示了上述关键因素对体系均一性的调控规律。针对均相稳定区间中的体系,系统研究了复合溶剂体积比对材料微观结构及宏观性能的影响。实验结果表明:随着VIPA/VDMF比例增加,气凝胶骨架由各向同性球形颗粒向各向异性哑铃状连通结构演化,同时孔隙呈现出纳米-微米的多级孔结构。所制备材料密度均低于0.2 g/cm3,水接触角大于150°,比表面积均超过500 m2/g;其DT理论吸附容量达到10−2 mol/g量级,与超临界干燥工艺水平相当。此外,材料在45%形变下可实现100%完全回弹,最大压缩强度可达88 kPa。整体来看,所制备材料在高比表面积、超疏水性与弹性可加工性等方面具有优势,为ICF制靶技术中低密度多孔功能材料的开发提供了新思路。

     

    Abstract:
    Background In inertial confinement fusion research, the storage and rapid filling of deuterium-tritium fuel place stringent demands on target materials, which must simultaneously exhibit low density, high specific surface area, and strong hydrophobicity.
    Purpose To address these requirements, this work develops an superhydrophobicity elastic aerogel through a controllable sol–gel system.
    Methods Methyltriethoxysilane (MTES) was used as the precursor and monohydroxyl-terminated polydimethylsiloxane (PDMS) as an organic reinforcing component, while a mixed solvent of isopropanol (IPA) and N,N-dimethylformamide (DMF) was employed, followed by ambient-pressure drying.
    Results By systematically monitoring the homogeneity of the precursor solution before condensation as functions of PDMS content and the solvent volume ratio VIPA/VDMF, a dissolution phase diagram within the IPA-DMF-PDMS ternary parameter space was established, revealing the governing factors for solution stability. For compositions located in the homogeneous region, the influence of solvent ratio on microstructure and macroscopic properties was further investigated. The results show that increasing VIPA/VDMF leads to a structural evolution of the aerogel framework from isotropic spherical particles to anisotropic, dumbbell-like interconnected networks, accompanied by the formation of hierarchical micron–macron pores. The resulting aerogels exhibit densities below 0.2 g/cm3, water contact angles exceeding 150°, and specific surface areas above 500 m2/g, with a theoretical DT adsorption capacity on the order of 10−2 mol/g, comparable to materials prepared via supercritical drying. Additionally, the materials display excellent elasticity, achieving complete recovery after 45% compressive strain and a maximum compressive strength of 88 kPa.
    Conclusions These results demonstrate that the developed aerogel possesses combined advantages of high surface area, superhydrophobicity, and mechanical resilience, providing a promising material strategy for low-density porous components in ICF target fabrication.

     

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