Hu Fuwen, Mikolajczyk Tadeusz, Pimenov Danil Yurievich, Gupta Munish Kumar
School of Mechanical and Material Engineering, North China University of Technology, Shijingshan Jinyuanzhuang Road 5, Beijing 100144, China.
Department of Production Engineering, UTP University of Science and Technology, Al. prof. S. Kaliskiego 7, 85-796 Bydgoszcz, Poland.
Materials (Basel). 2021 Feb 28;14(5):1137. doi: 10.3390/ma14051137.
Extrusion-based three-dimensional (3D) printing methods are preferred and emerging approaches for freely digital fabrication of ceramics due to ease of use, low investment, high utilization of materials, and good adaptability to multi-materials. However, systematic knowledge still lacks an explanation for what is their 3D printability. Moreover, some uncontrollable factors including extrudate shape retention and nonuniform drying inevitably limit their industrial applications. The purpose of this research was to present a new shaping retention method based on mathematical synthesis modeling for extrusion-based 3D-printing of ceramic pastes. Firstly, the steady-state equilibrium equation of the extrusion process was derived to provide clearer theoretical indications than purely experimental methods. Furthermore, a mathematical description framework was synthesized to better understand the extrusion-based 3D-printing of ceramic pastes from several realms: pastes rheology, extrudability, shape-holdability, and drying kinetics. Secondly, for eliminating shaping drawbacks (e.g., deformation and cracks) originating from non-digital control factors, we put forward a digital shape-retention technology inspired by the generalized drying kinetics of porous materials, which was different from existing retention solutions, e.g., freezing retention, thermally induced gelation, and using removable support structures. In addition, we developed an in situ hot air flow drying device easily attached to the nozzle of existing 3D printers. Confirmatory 3D-printing experiments of thin-walled cone-shape benchmark parts and the fire arrowhead-like object clearly demonstrated that the presented shape-retention method not only upgraded layer-by-layer forming capability but also enabled digital control of extrudate solidification. In addition, many more experimental results statistically showed that both fully solid parts and purely thin-wall parts had higher dimensional accuracy and better surface quality than the offline drying method. The 3D printed ceramic products with complex profiled surfaces conceivably demonstrated that our improved extrusion-based 3D-printing process of ceramic pastes has game-changing potentials beyond the traditional craftsmanship capacity.
基于挤压的三维（3D）打印方法因其使用方便、投资低、材料利用率高以及对多种材料的良好适应性，成为陶瓷自由数字制造的首选且新兴的方法。然而，系统知识仍缺乏对其3D可打印性的解释。此外，一些不可控因素，包括挤出物形状保持和干燥不均匀，不可避免地限制了它们的工业应用。本研究的目的是提出一种基于数学合成建模的新型形状保持方法，用于基于挤压的陶瓷浆料3D打印。首先，推导了挤压过程的稳态平衡方程，以提供比单纯实验方法更清晰的理论指导。此外，综合了一个数学描述框架，以便从浆料流变学、挤出性、形状保持性和干燥动力学等几个领域更好地理解基于挤压的陶瓷浆料3D打印。其次，为了消除源自非数字控制因素的成型缺陷（如变形和裂纹），我们提出了一种受多孔材料广义干燥动力学启发的数字形状保持技术，它不同于现有的保持解决方案，如冷冻保持、热致凝胶化和使用可移除支撑结构。此外，我们开发了一种易于连接到现有3D打印机喷嘴的原位热空气流干燥装置。薄壁锥形基准部件和火焰箭头状物体的验证性3D打印实验清楚地表明，所提出的形状保持方法不仅提升了逐层成型能力，还实现了挤出物凝固的数字控制。此外，更多实验结果统计表明，与离线干燥方法相比，全实心部件和纯薄壁部件都具有更高的尺寸精度和更好的表面质量。具有复杂轮廓表面的3D打印陶瓷产品可以想象地证明，我们改进的基于挤压的陶瓷浆料3D打印工艺具有超越传统工艺能力的变革性潜力。
