Robocasting is an extrusion-based additive manufacturing (AM) technique, highly explored in the fabrication of porous structures or thin-walled ceramics. Comparing to other slurry-based AM technologies, robocasting presents a high potential to produce dense bulk ceramics, thanks to the low organic binder contents and high solids loading used in the feedstock. Despite these benefits, the robocasting fabrication of ceramics with similar mechanical performance as those produced by traditional methods remains a challenge.

The goal of this work is to fine-tune the robocasting printing process of dense alumina ceramics by evaluating the influence of in-fill filaments orientation and the medium where the deposition process occurs (air or paraffin bath), on defects and mechanical performance of the sintered parts. Relative density, shrinkage, three-point flexural strength, Young's modulus and hardness were analysed. The specimens with the highest performance were sintered at 1550 °C or 1600 °C temperatures for 2 h holding time and the results were compared with slip casting (SC) samples sintered in the same conditions. Alumina robocasting samples, printed longitudinally in air with controlled humidity and sintered at 1600 °C, exhibited relative density ≈99% with flexural strength (≈350 MPa), Young's modulus (≈366 GPa) and hardness (≈17 GPa) values comparable to those obtained for SC samples. Numerical modelling and simulation were used to analyse the experimental values and the anisotropic behaviour of the printed specimens. Experimental Young's modulus results were compared with the Voigt-Reuss bound and the Hashin-Shtrikman upper-bound, as well as the analytical predictions of a Mooney-type exponential relation.

Robocasting 是一种基于挤压的增材制造 (AM) 技术，在多孔结构或薄壁陶瓷的制造中得到了高度探索。与其他基于浆料的 AM 技术相比，由于原料中使用的有机粘合剂含量低和固体负载量高，机器人铸造具有生产致密块状陶瓷的巨大潜力。尽管有这些好处，但机械性能与传统方法生产的陶瓷机械性能相似的陶瓷制造仍然是一个挑战。

这项工作的目标是通过评估填充细丝取向和发生沉积过程的介质（空气或石蜡浴）对致密氧化铝陶瓷的缺陷和机械性能的影响，微调致密氧化铝陶瓷的 robocasting 打印过程。烧结件。分析了相对密度、收缩率、三点弯曲强度、杨氏模量和硬度。将具有最高性能的样品在 1550 °C 或 1600 °C 的温度下烧结 2 小时，并将结果与​​在相同条件下烧结的粉浆浇铸 (SC) 样品进行比较。氧化铝 robocasting 样品，在控制湿度的空气中纵向打印并在 1600 °C 下烧结，表现出相对密度≈99%，弯曲强度（≈350 MPa），杨氏 s 模量 (≈366 GPa) 和硬度 (≈17 GPa) 值与 SC 样品获得的值相当。数值建模和仿真被用来分析实验值和打印试样的各向异性行为。将实验杨氏模量结果与 Voigt-Reuss 界和 Hashin-Shtrikman 上限以及门尼型指数关系的分析预测进行了比较。