CAREER: Powder Preparation and Compaction for Ceramic Binder Jet Additive Manufacturing

这项教师早期职业发展（Career）基金支持基础研究，这些研究将产生与陶瓷粘合剂喷射增材制造相关的知识，促进科学进步并产生有益的社会影响。先进的陶瓷材料在许多要求严格或条件恶劣的应用中发挥着至关重要的作用，例如生物医学，航空航天，化学和能源行业。传统的陶瓷零件制造方法存在严重的几何约束、生产时间长、成本高等问题。粘结剂喷射增材制造可以克服这些缺点。然而，目前它还不能生产致密的陶瓷部件，这极大地限制了它的应用。本研究旨在增加对粉末颗粒特性（密度、结构和强度）和粉末压实如何影响最终零件密度的理解。此外，该职业计划还包括一系列教育活动，以加强和多样化先进的制造业劳动力，影响K-12教师和学生，本科生和研究生以及该行业的专业人士。本研究的目标是使用定制的原料粉末和新兴的粉末床形成方法，为陶瓷粘结剂喷射增材制造提供一种新的密度改进方法。原料粉末是由许多纳米颗粒组成的颗粒，这些纳米颗粒弱结合在一起。在粉床成型法中，压实是在每层粉末铺开后进行的。假设实现致密陶瓷零件所需的压实压力受颗粒特性的影响如下：(1)低密度颗粒需要较低的压力才能断裂或塑性变形（积极影响），但具有较低的初始堆积密度（消极影响）；(2)具有多孔结构的颗粒更容易断裂或塑性变形，但具有更多的初始粒内孔隙；(3)低强度颗粒也更容易断裂或变形，但初始颗粒重排减少。将进行实验研究，以确定与每个颗粒特性相关的权衡，并确定其积极或消极影响占主导地位的条件。之后，将在颗粒和纳米颗粒尺度上进行数值模拟，以解释实验结果，并为潜在的压实机制提供物理见解。这项研究将产生关于多薄层颗粒压实的新知识，这对粘合剂喷射增材制造至关重要。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This Faculty Early Career Development (CAREER) grant supports fundamental research that will generate knowledge related to ceramic binder jet additive manufacturing, promoting the progress of science and resulting in beneficial societal impacts. Advanced ceramic materials play a vital role in numerous applications with strict requirements or under harsh conditions, such as those in the biomedical, aerospace, chemical, and energy industries. Traditional manufacturing methods for ceramic parts have severe geometric constraints, long production time, and high cost. Binder jet additive manufacturing can overcome these drawbacks. However, it is currently unable to produce dense ceramic parts, significantly limiting its applications. This research aims to increase understanding of how powder granule characteristics (density, structure, and strength) and powder compaction affect resulting part density. In addition, this CAREER plan includes a series of education activities to strengthen and diversify the advanced manufacturing workforce, impacting K-12 teachers and students, undergraduate and graduate students, and professionals in the industry.The goal of this research is to enable a new density improvement approach for ceramic binder jet additive manufacturing, using a tailored feedstock powder and an emerging powder bed formation method. The feedstock powder consists of granules composed of numerous nanoparticles that are weakly bonded together. In the powder bed formation method, compaction is performed after spreading each layer of powder. It is hypothesized that the required compaction pressure to achieve dense ceramic parts is affected by granule characteristics in the following manners: (1) granules with a low density require a lower pressure to fracture or plastically deform (a positive effect), but have a lower initial packing density (a negative effect); (2) granules with a porous structure can be more easily fractured or plastically deformed, but have more initial intragranular pores; (3) granules with a low strength can also be more easily fractured or deformed, but have a reduced initial granule rearrangement. Experimental research will be conducted to identify the tradeoffs associated with each granule characteristic and to determine the conditions under which its positive or negative effect is dominant. Afterward, numerical simulation at the granule and nanoparticle scales will be performed to explain the experimental results and to provide physical insights on underlying compaction mechanisms. This research will generate new knowledge about compaction of multiple thin layers of granules that is critical to binder jet additive manufacturing.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.