School of Mechatronics Engineering, Harbin Institute of Technology, West Da-zhi Street 92, Harbin, Heilongjiang, PR China 150001.
Lab Chip. 2020 Dec 15;20(24):4600-4610. doi: 10.1039/d0lc00730g.
Syntactic foams with fly ash cenospheres or commercial microballoons as fillers have been widely used in various applications ranging from aerospace to marine fields and the automotive industry. However, these two extensively adopted fillers possess multiple shortcomings, such as variations in the composition, material degeneration and distinct structural heterogeneity, which will inevitably hamper accurate prediction of the structure-property relationship and the corresponding design of the syntactic foams, reducing material utilization. Here, we present a microfluidic-based approach integrated with a subsequent heat treatment process to engineer syntactic foam fillers with a predefined composition, specified dimensional scope and reduced structural heterogeneity. These fillers are fully guaranteed by the synergy of the flexible and controllable generation of droplet templates with hydrodynamic regulation and rational selection of the nanoparticle dynamic response with respect to the heating temperature. In addition, two distinct surface morphologies have been observed with a temperature demarcation point of 1473 K, further endowing the fillers with multiplicity and optionality, simultaneously laying the foundation to regulate the properties of the syntactic foams through the diversity of the filler selection. Then, we fabricated a syntactic foam specimen by mold casting, and the integrity of the fillers inside was verified using an elaborate buoyancy comparison experiment, exhibiting its potential value in lightweight related applications. As the fillers derived from our approach show significant advantages over conventional ones, they will provide considerable benefits for the regulation and improvement of syntactic foam fillers in many practical applications.
以粉煤灰漂珠或商用微球为填料的复合泡沫材料在航空航天、海洋和汽车等多个领域得到了广泛的应用。然而，这两种广泛使用的填料存在多种缺点，如成分变化、材料退化和明显的结构异质性，这将不可避免地阻碍对结构-性能关系的准确预测和相应的复合泡沫设计，降低材料利用率。在这里，我们提出了一种基于微流控的方法，结合后续的热处理工艺，以工程化具有预定组成、特定尺寸范围和降低结构异质性的复合泡沫填料。这些填料通过液滴模板的灵活可控生成与流体动力学调节的协同作用，以及对加热温度下纳米颗粒动态响应的合理选择来得到充分保障。此外，在 1473 K 的温度分界点观察到了两种截然不同的表面形貌，进一步赋予了填料多样性和可选择性，同时为通过填料选择的多样性来调节复合泡沫的性能奠定了基础。然后，我们通过模具铸造制备了一个复合泡沫试件，并通过精心设计的浮力比较实验验证了内部填料的完整性，展示了其在轻质相关应用中的潜在价值。由于我们的方法得到的填料与传统填料相比具有显著优势，因此它们将为许多实际应用中对复合泡沫填料的调节和改进提供重要的参考价值。
