CAREER: Understanding multiscale sintering kinetics and microstructural evolution in binder-based metal additive manufacturing

职业：了解基于粘合剂的金属增材制造中的多尺度烧结动力学和微观结构演变

• 批准号: 2237433
• 负责人: Jerard Gordon
• 金额: $ 65.75万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2027-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2237433&HistoricalAwards=false
• 关键词: CAREER; Understanding; multiscale; sintering; kinetics

NON-TECHNICAL SUMMARY: The process of using heat to turn powder into a porous solid without fully melting said powder is a manufacturing approach known as “solid-state sintering” (SSS). This technology forms the backbone of many important industrial processes for metal and ceramic materials such as powder metallurgy (P/M), metal injection molding (MIM), and field-assisted sintering (FAST). Overall, SSS platforms are advantageous because they do not require high temperatures to fully melt metal or ceramic powders which mean less energy is required to manufacture parts by sintering than by other standard processing methods. However, long-standing challenges still exist for sintering which include issues such as porosity, shrinkage and other changes in final shape that aren’t easily predicted due to events that occur at the scale of micro- and nanometers which aren’t well understood. This research project is revealing fundamental sintering mechanisms across multiple length scales by directly imaging powder surfaces and the internal structure of powders undergoing sintering in real-time using high powered x-ray experiments and high magnification electron microscopes. These state-of-the-art approaches are providing new knowledge on the way defects form and how internal structures change. Binder jet 3D printing (BJ3DP) is used as an example process since BJ3DP is of significant interest to the automotive industry but research findings contribute to new design strategies for a variety of SSS applications. This project also facilitates the training of undergraduate and graduate students in advanced manufacturing to address the current and growing skills gap in the U.S. This is being accomplished by exposing students to state-of-the-art characterization tools, engaging them in manufacturing research and involving them in professional development opportunities with industrial partners in the automotive industry. Additionally, this project is broadening participation through the recruitment and mentoring of graduate students hailing from underrepresented populations and hand-on community outreach events for students in grades K-12 in collaboration with the University of Michigan Museum of Natural History.TECHNICAL SUMMARY: Solid-state sintering (SSS) facilitates the efficient production of metal and ceramic materials, however, long-standing challenges remain due to a lack of fundamental insight of the dominant mechanisms facilitating internal microstructural development. Since the overall driving force for sintering (reduction of interfacial surface energy) can be facilitated by at least six different and potentially competing mechanisms, a robust understanding of SSS has been largely stymied by the absence of in-situ data. This research is employing novel in-situ x-ray computed tomography (XCT) and high energy diffraction microscopy (HEDM) to directly image 3D particle and internal microstructural evolution with micron-scale resolution during SSS in novel binder jet 3D printing (BJ3DP). Binder jet is used as an exemplar due to its strong potential for implementation in the automotive industry. Results are being combined with electron microscopy to understand the primary diffusion mechanisms at work during SSS, and how they are influenced by process, feedstock, and/or material factors. Findings are being used to test fundamental hypotheses on densification and grain-growth in BJ3DP and serve as calibration data for physics-based models. Overall, this new knowledge is enabling enhanced prediction of microstructure evolution applicable to a variety of SSS processes with strong industrial relevance such as powder metallurgy, metal injection molding, and field-assisted sintering. Integrated educational modules are being employed to reduce the currently growing manufacturing skills gap in the U.S. through research experiences for undergraduate and graduate students and professional development opportunities for students with the automotive industry. Educational and outreach activities include actively recruiting and training underrepresented minorities and women and providing accessible, hands-on activities for students in K-12 in collaboration with the U-M Natural History Museum to inspire interest in advanced manufacturing and STEM.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.

非技术性总结：使用热将粉末转变成多孔固体而不完全熔化所述粉末的过程是被称为“固态烧结”（SSS）的制造方法。该技术构成了许多重要的金属和陶瓷材料工业工艺的支柱，如粉末冶金（P/M），金属注射成型（MIM）和场辅助烧结（FAST）。总体而言，SSS平台是有利的，因为它们不需要高温来完全熔化金属或陶瓷粉末，这意味着通过烧结制造零件所需的能量比通过其他标准加工方法少。然而，烧结仍然存在长期的挑战，其中包括孔隙率，收缩率和最终形状的其他变化等问题，这些问题由于发生在微米和纳米尺度上的事件而不容易预测，这些事件尚未得到很好的理解。该研究项目通过使用高功率X射线实验和高放大率电子显微镜对粉末表面和粉末内部结构进行实时成像，揭示了多个长度尺度的基本烧结机制。这些最先进的方法提供了关于缺陷形成方式和内部结构如何变化的新知识。粘合剂喷射3D打印（BJ 3DP）被用作示例过程，因为BJ 3DP对汽车行业非常感兴趣，但研究结果有助于各种SSS应用的新设计策略。该项目还促进了对先进制造业本科生和研究生的培训，以解决美国目前和不断增长的技能差距，这是通过让学生接触最先进的表征工具，让他们参与制造研究，并让他们参与汽车行业工业合作伙伴的专业发展机会来实现的。此外，该项目还与密歇根大学自然历史博物馆合作，招募和指导来自代表性不足人群的研究生，并为K-12年级的学生举办动手社区外联活动，以扩大参与。固态烧结（SSS）促进了金属和陶瓷材料的有效生产，然而，由于对促进内部微观结构发展的主要机制缺乏基本的了解，长期存在的挑战依然存在。由于烧结的整体驱动力（减少界面表面能）可以促进至少六个不同的和潜在的竞争机制，一个强大的理解SSS已在很大程度上阻碍了缺乏原位数据。本研究采用新型原位X射线计算机断层扫描（XCT）和高能衍射显微镜（HEDM），在新型粘合剂喷射3D打印（BJ 3DP）的SSS过程中以微米级分辨率直接成像3D颗粒和内部微观结构演变。Binder jet因其在汽车行业的强大应用潜力而被用作典范。结果结合电子显微镜，以了解在SSS工作的主要扩散机制，以及它们如何受到工艺，原料和/或材料因素的影响。研究结果被用来测试BJ 3DP致密化和晶粒生长的基本假设，并作为基于物理模型的校准数据。总的来说，这种新的知识能够增强对微观结构演变的预测，适用于具有强烈工业相关性的各种SSS工艺，如粉末冶金，金属注射成型和场辅助烧结。通过为本科生和研究生提供研究经验，以及为汽车行业的学生提供专业发展机会，综合教育模块正在被用于缩小美国目前不断增长的制造技能差距。教育和外联活动包括积极招募和培训代表性不足的少数群体和妇女，与U合作，为K-12学生举办实践活动，该奖项反映了NSF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进行评估，被认为值得支持的搜索.