Robocasting of carbon-alumina core-shell composites using co-extrusion
Robocasting of carbon-alumina core-shell composites using co-extrusion
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DOI：
10.1108/rpj-12-2015-0191
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发表时间：
2017-01-01
影响因子：
3.9
通讯作者：
Travitzky, Nahum
中科院分区：
文献类型：
--
作者：
Fu, Zongwen;Freihart, Matthias;Travitzky, Nahum
目的：本研究旨在通过机器人铸造结合共挤压的方法，实现三维核-壳-细丝基晶格结构的制造。在芯层和壳层材料方面，分别研制了由亚微米碳粉和氧化铝粉组成的胶体凝胶。同时，通过数值模拟研究了共挤压过程中进料压力与壁厚的关系。设计/方法/方法-由于碳和氧化铝粉末的颗粒形态和表面化学性质的差异，观察到碳和氧化铝凝胶的流变行为存在显著差异。通过改变共挤压过程中使用的进给压力，实现了对芯和壳绿态元件截面直径的精确控制。结果-在氧化气氛（如空气）中进行后续热处理后，碳芯被氧化并烧毁，制成由预定壁厚的空心细丝形成的晶格结构；此外，在氩气气氛中烧制后，可以得到C-Al2O3核壳丝晶格结构。原创性/价值-通过机器人控制共挤压，成功制造出碳芯和氧化铝壳细丝的绿色晶格桁架结构。以碳和氧化铝为原料，制备了具有明显不同流变性能的凝胶。在共挤出过程中，芯浆的黏度明显高于壳浆，有利于共挤出过程的进行。同时，通过岩心和壳的进给压力精确控制岩心和壳的直径，并进行了数值模拟研究。实验和数值计算得到的纤维壁厚在定性上基本一致；在共挤压过程中，随着岩心压力的减小，壁厚增大。
Purpose - This study aims to achieve the fabrication of three-dimensional core-shell filament-based lattice structures by means of robocasting combined with co-extrusion. For core and shell materials, colloidal gels composed of submicron carbon and alumina powders were developed, respectively. Simultaneously, the co-extrusion process was also studied by numerical simulation to investigate the feed pressure-dependent wall thickness.Design/methodology/approach - Significant differences in the rheological behavior of the carbon and alumina gels were observed because of differences of the particle morphology and surface chemistry of the carbon and alumina powders. Precise control over the cross-sectional diameter of the core and shell green state elements was achieved by alteration of the feed pressures used during co- extrusion.Findings - After subsequent thermal treatment in an oxidizing atmosphere (e.g. air), in which the carbon core was oxidized and burned out, lattice structures formed of hollow filaments of predetermined wall thickness were manufactured; additionally, C-Al2O3 core-shell filament lattice structures could be derived after firing in an argon atmosphere.Originality/value - Green lattice truss structures with carbon core and alumina shell filaments were successfully manufactured by robotically controlled co-extrusion. As feedstocks carbon and alumina gels with significantly different rheological properties were prepared. During co- extrusion, the core paste exhibited a much higher viscosity than the shell paste, which benefited the co-extrusion process. Simultaneously, the core and shell diameters were exactly controlled by core and shell feed pressures and studied by numerical simulation. The experimentally and numerically derived filament wall thickness showed qualitative agreement with each other; with decreasing core pressure during co- extrusion, the wall thickness increased.