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

这项学院早期职业发展(Career)补助金支持基础研究，这些研究将产生与陶瓷粘结剂喷射添加剂制造相关的知识，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有严格要求或苛刻条件下的应用中发挥着至关重要的作用，例如在生物医学、航空航天、化工和能源行业。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。粘结剂喷射添加剂制造可以克服这些缺点。然而，它目前无法生产致密的陶瓷部件，大大限制了其应用。这项研究旨在增加对粉末颗粒特性(密度、结构和强度)和粉末压制对所产生的部件密度的影响的了解。此外，这项职业计划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，影响到K-12教师和学生，本科生和研究生，以及该行业的专业人员。这项研究的目标是实现一种新的密度提高方法，用于陶瓷粘结剂喷气添加剂制造，使用定制的原料粉末和新兴的粉床形成方法。原料粉末由许多纳米粒子组成的颗粒组成，这些纳米颗粒弱结合在一起。在粉末床形成方法中，在铺开每一层粉末后进行压实。假设获得致密陶瓷部件所需的压制压力受颗粒特性的影响：(1)密度较低的颗粒需要较低的压力才能断裂或塑性变形(正效应)，但具有较低的初始堆积密度(负面效应)；(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气孔；(3)强度较低的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。然后，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，并提供对潜在压实机理的物理见解。这项研究将产生关于多层薄层颗粒压实的新知识，这对粘结剂喷射剂的制造至关重要。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.