CAREER: Thermochemistry of Nanoceramics: Understanding and Controlling Phase Transformation and Sintering via Interface Energetics

职业：纳米陶瓷的热化学：通过界面能量学理解和控制相变和烧结

• 批准号: 1055504
• 负责人: Ricardo Castro
• 金额: $ 45万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1055504&HistoricalAwards=false
• 关键词: CAREER; Thermochemistry; Nanoceramics; Understanding; Controlling

NON-TECHNICAL DESCRIPTION: Ceramic materials often exhibit novel physical and chemical properties as their sizes approach nanometer dimensions. These new properties have inspired a variety of new applications in several fields, ranging from nanosensors to cathode materials for fuel cells and lithium batteries. As well, the possibility is opened for the development of new materials in response to the current energy problems such as the U.S. increasing demand for energy, dependence on foreign oils, and climate change. However, the optimization of nanoceramic processing is still a challenge, and understanding the fundamental concepts requires further research. Within this project, Prof. Castro focuses on the larger volume fraction of interfaces present in nanoceramics to improve processing control. He hypothesizes that manipulation of the interface composition can be used to change processing and product properties on a thermodynamic basis. In particular, Prof. Castro works on improving densification and phase transformation, two fundamental parts of processing, by controllably changing interface energies by tuning composition, enabling faster, less expensive, and more controlled processing and products. This unique thermodynamic approach is carried out by providing unprecedented data on interface energetics (rarely found in the literature) on technologically important materials, bringing those significant advances closer to industrial manufacturing. The project also has an important educational component that focuses on the promotion of engineering in middle and high-schools. The program, Materials&You, involves demonstrations of interesting processing and properties at school events to expose students to basic materials' concepts. Two high-schools with significant Latin American students and the underlying goal of getting all students to graduate have been selected.TECHNICAL DETAILS: This project uses unique calorimetric techniques to measure interface energies of nanoceramics and use them to improve the control of sintering and phase transformation 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 the University of California at Davis laboratories (recently developed by the Prof. Castro and collaborators), 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. Within this project, high-temperature drop solution calorimetry is used to measure the interface energies (both surface and grain boundary) of three technologically relevant oxides: tin dioxide, zinc oxide, and zirconia, and those data correlated with sintering and polymorphic stability. The better understanding of the role of interface energetics and dopants in nanoceramic processing enables improvement of composition design in industries, enabling more energy and cost efficient products, with predictable phases/sizes/densities. From the educational perspective, students participating in the project are mentored and work with strategic materials and processes, providing training for their future careers as materials' professionals.

非技术描述：陶瓷材料通常在尺寸接近纳米尺寸时表现出新颖的物理和化学性质。这些新属性激发了多个领域的各种新应用，从纳米传感器到燃料电池和锂电池的阴极材料。同样，为应对当前的能源问题（例如美国对能源的需求，对外国油的依赖和气候变化）的响应而开发新材料的可能性也开发了。但是，纳米陶瓷处理的优化仍然是一个挑战，理解基本概念需要进一步的研究。在该项目中，卡斯特罗教授专注于纳米陶瓷中存在的界面的较大体积分数，以改善加工控制。他假设对界面组合物的​​操纵可用于以热力学为基础改变加工和产品性能。尤其是，卡斯特罗教授致力于改善致密和相变，这是处理的两个基本部分，通过调整组成，更快，更便宜，更可控的处理和产品来控制界面能量。这种独特的热力学方法是通过提供有关技术重要材料的界面能量学（很少发现）的前所未有的数据来实现的，从而使这些重大进展更接近工业制造。该项目还具有一个重要的教育组成部分，重点是在中学和高中促进工程学。该计划，材料和您涉及学校活动中有趣的处理和财产的演示，以使学生了解基本材料的概念。两种具有重要拉丁美洲学生的高中生，以及使所有学生进入毕业生的基本目标。技术细节：该项目使用独特的量热量技术来测量纳米陶瓷的界面能量，并通过监测和操纵动力力量来改善它们的控制，并通过监测和操纵动力来改善烧结和相位转换的控制。目的是量化掺杂剂对界面能量的影响，并将其与处理参数和动力学相关联。通常以动力学为基础考虑掺杂剂在加工中的效果，但是随着加利福尼亚大学戴维斯实验室的高分辨率量热法的出现（最近是由卡斯特罗教授和合作者开发的），卡斯特罗教授的小组能够量化对该系统的构图变化的效果，以打开一个新的Avenue的组成效果，并将其量化。在该项目中，高温滴溶液量热法用于测量三种与技术相关的氧化物的界面能（表面和晶界）：二氧化锡，氧化锌和氧化氧化物，以及与烧结和多态性稳定性相关的数据。更好地理解界面能量和掺杂剂在纳米陶瓷加工中的作用，可以改善行业的组成设计，从而具有可预测的阶段/尺寸/密度，从而实现了更多的能源和高效的产品。从教育的角度来看，参加该项目的学生得到了指导，并与战略材料和流程一起工作，为他们作为材料专业人士的未来职业提供培训。