氮化硼基气凝胶微球的制备及其热性能研究

该文提出了一种制备新型导热填料的方法：基于液氮驱动和冰模板法自组装，以氮化硼纳米 片和银纳米颗粒为基本组装单元，制备了具有开放孔结构、内部互连的毫米级氮化硼气凝胶球。其 中，对气凝胶球的成型机理进行了初步的探索，并对影响气胶球微观结构的因素，如制备气凝胶球 浆料的固含量等进行研究。另外，该文将环氧树脂灌入到多孔气凝胶球中，从而制得氮化硼球/环氧 树脂和氮化硼-银球/环氧树脂复合材料，并对其结构形貌和导热性能进行了研究，其中重点研究了氮 化硼纳米片的表面改性、氮化硼微球的不同微观结构对复合材料的导热性能的影响。结果显示，当多 孔微球的填充量为 2.7 vol% 时，氮化硼球/环氧树脂复合材料的面外导热系数达 0.57 W/(m·K)，而氮 化硼-银球/环氧树脂复合材料的面外导热系数达 0.64 W/(m·K)，相比于纯环氧树脂的导热系数提高了 276.5%。由此可见，氮化硼气凝胶球微球的加入可有效提高环氧树脂基复合材料的导热系数，在氮化 硼纳米片表面负载银颗粒后可进一步提升复合材料的导热性能；液氮驱动的冰模板法自组装技术在制 备导热填料领域具有巨大的应用前景。

Facile Fabrication of Boron Nitride-based Spongy Sphere and Its Property of Thermal Conduction

In this paper, a novel method based on the liquid nitrogen-driven rotation and ice-templated assembly was proposed to fabricate a new kind of boron nitride nanosheet (BNNS) and BNNS-Ag spongy miscrosphere used as thermally conductive fillers. The liquid nitrogen driven assembly ultimately led to hierarchical 3D BNNS frameworks with radial alignments, forming a sea urchin-like microstructure. BN sphere/epoxy resin composites were finally obtained by infiltrating the as-prepared spongy microsphere with epoxy resin followed by thermal curing. At the sphere content of 2.7 vol%, the through-plane thermal conductivity of BNNS sphere/epoxy resin composite reaches 0.57 W/(m·K), while the value for BNNSAg sphere/epoxy resin composite reaches 0.64 W/(m·K), indicating the corresponding enhancement of 276.5% towards pure epoxy resin. The obtained composites exhibit strong potential for thermal management applications for a variety of technological needs, particularly electronic packaging. The combination of liquid nitrogen-driven rotation and ice-templated assembly was demonstrated to a useful tool to fabricate efficient fillers for thermal management applications.