ERI: Making High-Temperature Alloyed Components by Combining Additive Manufacturing and Spark Plasma Sintering: Enabling Shape Complexity and Predicting Microstructures

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。火花等离子烧结是一种众所周知的制造技术，该技术同时加压和快速加热，即使是高温金属，如钨合金，也能实现颗粒到固体的低缺陷固结。尽管人们对这项技术很感兴趣，但它一直局限于形状简单的部件（即圆柱形部件）。另一方面，尽管增材制造赋予了设计自由，是制造复杂几何形状零件的理想选择，但高温合金的制造并没有取得可靠的成功。在这个项目中，将结合使用增材制造，如粘结剂喷射和火花等离子烧结来克服这些限制。所研究的技术集成代表了一种新的和有前途的方法，以高效和经济的方式生产复杂形状的高温合金部件，同时保证零件尺寸和显微组织的质量。此外，该项目将探索新的可能性，以调查现场辅助烧结过程的基本原理。此外，该项目将有助于教育、推广和留住来自少数民族的本科生和研究生，并通过与相关行业合作伙伴（如加州纳米技术公司）的合作，让高中生接触到高端技术的实践经验，如增材制造和火花等离子烧结。该项目的总体目标是了解和开发火花等离子烧结技术的净成形能力，以生产复杂形状的零件，如斜齿锥齿轮，这些零件由难以使用传统或增材制造制造的材料系统制成。该项目将通过“可控界面”概念来解决这一挑战，该概念将增材制造能力与火花等离子烧结的全部巩固潜力相结合，以生产复杂的形状。可控界面是通过在普通火花等离子烧结工具中引入牺牲材料的三维打印变形体来表示的。为了实现可控界面的理想设计，将对放电等离子烧结过程进行综合建模研究。在这种组合技术中涉及的起始多孔组件的复杂性质需要扩展当前粉末烧结建模框架，以更好地理解火花等离子烧结中的热和非热非平衡现象，从而根据最终产品的微观结构和几何形状预测最终的加工结果。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 award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Spark plasma sintering is a well-known manufacturing technology, in which pressurizing and rapid heating are simultaneously applied to achieve particle-to-solid consolidation with a low level of defects even for high-temperature metals, such as tungsten alloys. Despite significant interest in this technology, it has been, however, limited to simple-shaped components (i.e., in cylindrical forms). On the other hand, though additive manufacturing has empowered the design freedom, ideal for making parts of sophisticated geometry, fabrications of high temperature alloys have not been reliably successful. In this project, a combination of additive manufacturing, such as binder jetting, and spark plasma sintering will be employed to overcome such limitations. The studied technology integration represents a novel and promising approach to produce complex-shaped components, made of high-temperature alloys, in an efficient and cost-effective manner, and yet, ensure the quality in part dimensions as well as microstructures. Moreover, the project will explore new possibilities for the investigation into the fundamentals of the field-assisted sintering processes. In addition, the project will contribute to the education, outreach and retaining of undergraduate and graduate students from minorities and to engaging high school students with hands-on experiences with high-end technologies such as additive manufacturing and spark plasma sintering via the collaboration with industry partners involved, e.g., California Nanotechnologies.The overall goal of this project is to understand and develop the net-shaping capability of the spark plasma sintering technology to produce complex-shaped parts, such as helical bevel gears, made of material systems difficult to be fabricated using either traditional or additive manufacturing. The project will address this challenge through the “controllable interface” concept, which combines the additive manufacturing capability to produce complex shapes with the full consolidation potential of the spark plasma sintering. The controllable interface is represented by a three-dimensionally printed deformable volume of a sacrificial material introduced inside common spark plasma sintering tooling. To achieve the desired design of the controllable interface, comprehensive modeling of the spark plasma sintering process will be researched. The intricate nature of the starting porous assembly involved in this combined technology requires extending the current powder sintering modeling framework to better understand thermal and non-thermal nonequilibrium phenomena in spark plasma sintering to predict the final processing outcomes in terms of the microstructure and geometry of end products.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.