Thermochemistry of Nanoceramics: Understanding and Controlling Densification and Grain Growth

纳米陶瓷的热化学：理解和控制致密化和晶粒生长

• 批准号: 1609781
• 负责人: Ricardo Castro
• 金额: $ 37.5万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1609781&HistoricalAwards=false
• 关键词: Thermochemistry; Nanoceramics; Understanding; Controlling; Densification

NON-TECHNICAL DESCRIPTION: Ceramic materials can exhibit unique physical and chemical properties when their feature size approaches nanometer dimensions. These properties have inspired a variety of applications in several fields and opened the development of solutions in response to current U.S. challenges such as the increasing demand for energy and national security. However, design and fabrication of optimal and durable ceramics at the nanoscale still face significant difficulties, and more understanding at the fundamental level of these processes is required. Within this project, Prof. Castro focuses on the larger volume fraction of interfaces present in nanoscaled ceramics to improve processing control by targeting modifications on their intrinsic thermodynamic properties. This approach challenges old paradigms in the field that infer thermodynamics is irrelevant on processing optimization, and offers opportunities for unprecedented breakthroughs. Prof. Castro works on the science behind products, i.e. the consolidation of powders. The goals are to enable faster, less expensive, and more controlled processing, and more durable materials. This research investigates a technologically-important material (magnesium aluminate). The project also has important education components that focus on the promotion of engineering in middle and high-schools; and training of undergraduate and graduate students in research and development. The K-12 program involves demonstrations of interesting processing and properties at school events to expose students to basic materials' concepts. The undergraduate program involves competitions and hands-on research opportunities in contemporary technologies, while the graduate students are directly involved in cutting-edge research.TECHNICAL DETAILS: This project uses highly-sensitive calorimetric techniques to measure interface energies of nanoscaled ceramics with the goal of improving the control of sintering and grain growth by monitoring and manipulating driving forces. The aim is to quantify the effects of dopants on the interface energies and correlate them with processing parameters and kinetics. The effect of dopants in processing is typically considered exclusively on a kinetic basis, but with the advent of high-resolution calorimetry available at University of California-Davis, Prof. Castro?s group is capable of quantifying the effect of composition change on the energetics of the system, opening a new avenue for processing control on a thermodynamic basis. Within this project, differential scanning calorimetry, oxide melt drop-solution calorimetry and water adsorption microcalorimetry are used to thermodynamically characterize magnesium aluminate properties ? a material of strategic interest for armor, laser, and refractory applications. The data is then correlated with sintering and grain growth behavior. A better understanding of the role of interface energetics and dopants in processing fosters improvement of composition design in industries, enabling more energy and cost efficient products, with more stable grain sizes (a key element on the control of ceramics? properties). From an education perspective, students participating in the project are being mentored, are working with strategic materials and processes, and are receiving training for their future careers as materials? professionals.

非技术描述：当陶瓷材料的特征尺寸接近纳米尺寸时，它们可以表现出独特的物理和化学性质。这些特性激发了多个领域的各种应用，并开启了解决方案的开发，以应对当前美国面临的挑战，例如对能源和国家安全日益增长的需求。然而，在纳米级的最佳和耐用的陶瓷的设计和制造仍然面临着显着的困难，并在这些过程的基础水平需要更多的理解。在这个项目中，Castro教授专注于纳米陶瓷中存在的较大体积分数的界面，以通过针对其固有热力学性质的修改来改善加工控制。这种方法挑战了该领域中推断热力学与处理优化无关的旧范式，并为前所未有的突破提供了机会。Castro教授致力于产品背后的科学，即粉末的固结。目标是实现更快，更便宜，更可控的加工和更耐用的材料。本研究调查了一种技术上重要的材料（铝酸镁）。该项目还有重要的教育部分，重点是在初中和高中推广工程学;以及对本科生和研究生进行研究和开发方面的培训。K-12计划包括在学校活动中展示有趣的加工和特性，让学生了解基本材料的概念。本科课程包括竞赛和当代技术的实践研究机会，而研究生则直接参与尖端研究。技术专长：本项目使用高灵敏度量热技术测量纳米陶瓷的界面能，目的是通过监测和操纵驱动力来改善烧结和晶粒生长的控制。目的是量化掺杂剂对界面能的影响，并将其与工艺参数和动力学相关联。掺杂剂在加工过程中的影响通常被认为是完全在动力学的基础上，但随着高分辨率量热法的出现，可在加州大学戴维斯分校，卡斯特罗教授？的小组是能够量化的组成变化对系统的能量学的影响，打开了一个新的途径，在热力学基础上的处理控制。在这个项目中，差示扫描量热法，氧化物熔体滴溶量热法和水吸附微量热法被用来表征铝酸镁的性能？一种具有战略意义的材料，用于装甲、激光和耐火材料应用。然后将数据与烧结和晶粒生长行为相关联。更好地理解界面能量学和掺杂剂在加工过程中的作用，促进了工业中成分设计的改进，使更多的能源和成本效益的产品，更稳定的晶粒尺寸（控制陶瓷的关键因素？属性）。从教育的角度来看，参与该项目的学生正在接受指导，正在使用战略材料和流程，并正在接受培训，为他们未来的职业生涯作为材料？专业人士