A Mechanism of Flash Sintering of Ionic Ceramics

非技术描述：传统的陶瓷粉末致密化成功能部件通常需要至少几个小时。2010年，一组科学家发现，当高水平电压或电流通过这些陶瓷粉末的压块时，某些陶瓷几乎可以瞬间完全致密化（五秒内）。因此，这种快速致密化技术被称为闪速烧结。从那时起，闪速烧结已成为最有前途的陶瓷加工技术之一。然而，这种快速烧结过程的机制尚不清楚;本项目试图揭示其根本原因。在这项研究中的实验工作的补充计算建模，使更全面的了解快速致密化的陶瓷粉末的快速烧结机制。这一新的知识，然后作为基本的指导，扩展到更广泛的陶瓷材料的闪速烧结技术。研究生和本科生（包括少数民族和其他代表性不足的学生）正在接受机械工程和材料科学与工程方面的培训，以从事学术界或高科技制造业的职业。虚拟现实技术用于为材料科学主题提供沉浸式和交互式的教学环境，并有助于培养能够在快速变化的社会中使用适应性新技术的劳动力。技术优势：该技术，即快速烧结，已证明能够快速致密陶瓷材料的粉末压坯。在该技术中，施加的电场引发“闪光”事件，并且烧结在几秒内发生（在给定施加电场的阈值温度下）。虽然闪速烧结已被观察到在各种陶瓷系统中，电场或电流的确切效果，提高致密化速率和影响的微观结构演变仍然难以捉摸，除了已知的热失控焦耳加热欧姆机制。目前正在对离子陶瓷系统进行一系列的实验和理论模拟研究活动，以阐明闪速烧结过程中电场的热因素和非热因素。原位纳米成像是用来观察闪速烧结过程中的钇稳定氧化锆陶瓷系统作为一个功能的外加电场，提供见解闪速烧结机制。此外，多尺度原子-连续介质模型正被用于模拟离子陶瓷在电场作用下的快速烧结过程。该模型在原子水平上揭示了离子陶瓷快速致密化的机理。学生正在接受教育，成为陶瓷烧结技术的实验和计算方面的实践专家。因此，毕业生为创造可持续的工程解决方案以解决复杂问题做好了充分的准备，从而为陶瓷加工和材料科学的尖端科学技术做出了贡献。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标准进行评估，被认为值得支持。

NON-TECHNICAL DESCRIPTION: Traditional densification of ceramics powders into a functional component usually takes at least several hours. In 2010, a group of scientists discovered that nearly instantaneous full densification can occur (within five seconds) for certain ceramics when a high-level voltage or current pass through a compact of these ceramic powders. Thus, this rapid densification technique was named flash sintering. Since then, flash sintering has become one of the most promising techniques for ceramics processing. However, the mechanisms for this rapid sintering process are unclear; this project attempts to reveal the underlying reasons. The experimental work in this study is complemented by computational modeling, enabling a more comprehensive understanding on the rapid densification mechanisms of flash sintering of ceramic powders. This new knowledge then serves as fundamental guidance to extend the flash sintering technique into a wider range of ceramic materials. Graduate and undergraduate students (including minority and other underrepresented students) are being trained in mechanical engineering and materials science and engineering for careers in academia or high-technology manufacturing. Virtual reality technology is used to provide an immersive and interactive teaching and learning environment for materials sciences topics, and helps to educate a workforce capable of using adaptive new technologies in a rapidly changing society.TECHNICAL DETAILS: The technique, flash sintering, has demonstrated the ability to rapidly densify powder compacts of ceramic materials. In this technique, an applied electric field initiates a "flash" event and sintering occurs within a few seconds (at a threshold temperature for a given applied electric field). Although flash sintering has been observed in a variety of ceramic systems, the exact effects of electric field or current on enhancing the densification rate and influencing the microstructure evolution remain elusive, apart from the known thermal runaway Joule heating ohmic mechanisms. A series of experimental and theoretical modeling research activities are being carried out on ionic ceramic systems to clarify the thermal and non-thermal factors of electric field in the flash sintering process. In situ nanoscale imaging is used to observe the flash sintering process of yttrium-stabilized zirconia ceramic systems as a function of applied electric field, providing insights into the flash sintering mechanism. In addition, multiscale atom-to-continuum modeling is being used to simulate the flash sintering process of ionic ceramics in the presence of an electric field. The modeling is revealing the rapid densification mechanisms of flash sintering of ionic ceramics at the atomic level. Students are being educated to become experts in the practice of experimental and computational aspects of ceramic sintering technologies. As a result, graduates are being well prepared to create sustainable engineering solutions to complex problems, and thereby contributing to the cutting-edge of science and technology of ceramics processing and materials science.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.