Metal 3D printing with freeze casting

现代社会的全球需求需要能够通过可持续技术生产的耐用材料。在这个项目中，我们的目标是建造一台最先进的3D金属打印机，不仅能够精确地制造金属物体，而且能耗更低，没有任何温室气体排放。一旦成功，这款设备将被誉为最环保的3D金属打印机-它将打印出不同强度、不同孔形状和大小的金属物体。我们建议通过将3D打印(添加剂制造)与磁场存在下的冷冻铸造过程相结合来实现这一点。最后，冷冻铸造作为一种可行的环境友好型方法已经成为合成有序多孔材料的一种可行的方法。它包括通过在特定方向上诱导温度梯度来控制悬浮液(分散在流体中的颗粒)的冻结。不断增长的冰层拒绝来自移动前沿的悬浮颗粒，并将它们聚集在晶间空间。固化后，溶剂在减压下升华，然后进行后续处理(烧结/致密)。因此，浆料的定向冻结具有充当硬模板和施加具有空间取向的宏观孔隙率和各向异性属性的自组装的双重目的。通过将冷冻铸造与添加剂制造技术相结合，我们可以制造出一系列全新的复杂和不规则几何形状。这种方法不会涉及任何化学反应，从而避免了任何与副产品去除相关的问题，使其成为一项安全、清洁和绿色的技术。该工艺简单，模板容易移除，使我们能够使用除陶瓷、聚合物、碳纳米管和生物大分子等金属以外的各种材料作为“构建块”，否则这些材料无法与其余技术一起使用。显然，可持续发展的梦想在于绿色未来，清洁制造技术和3D金属冷冻打印肯定是实现可持续发展的关键。在艾伯塔省寒冷的气候中，气温远远低于冰点，在这种条件下，一种在心脏进行冷冻的技术可以相当容易地蓬勃发展。

The global needs of modern society demand durable materials that can be produced via sustainable technologies. In this project, we aim to build a state-of-the-art 3D metal printer, capable of not only building metal objects precisely but also with less energy consumption and without any GHG emissions. Upon success, this device will be coined as the most environment-friendly 3D metal printer - which will print metal objects of varied strength with different pore shapes and sizes. We propose to achieve this by integrating 3D printing (additive manufacturing) with the freeze casting process in the presence of a magnetic field.Lately, freeze casting has gained prominence as a viable environment-friendly approach to synthesize well-ordered porous materials. It involves the controlled freezing of a suspension (particles dispersed in a fluid) by inducing the temperature gradient in a particular direction. The growing ice lamella rejects the suspended particles from the moving front and accumulate them in the inter-crystal space. After solidification, the solvent is sublimated under reduced pressure, followed by subsequent posttreatment (sintering/densification). The directional freezing of the slurry thus serves the dual purpose of acting as a hard template and imposing self-assembly with spatially oriented macro-porosity and anisotropic properties. By combining freeze casting with additive manufacturing techniques, we can fabricate a whole new range of complex and irregular geometries.This approach will not involve any chemical reactions, thus avoiding any associated problems with the by-product removal, making it a safe, clean and green technology. The simplicity of the process, with easy template removal, allows us to employ a wide array of materials as "building blocks" apart from metals such as ceramics, polymers, carbon nanotubes, and biomacromolecules, which are otherwise unfeasible to use with the rest of the techniques. Evidently, the dream of sustainability lies in a green future and clean manufacturing techniques and 3D metal freeze printing surely do hold a key to it. In the cold climate of Alberta, where temperatures drop far below freezing point, a technique that employs freezing at its heart could thrive on rather easily in such conditions.