Collaborative Research: Making Nanostructured Ceramics from Micrometer-Sized Starting Powders

该奖项的研究目标是开发一种场激活处理技术，用于从微米级的起始粉末合成块体纳米结构陶瓷(晶粒度为100 nm)。实验研究了电流密度、升温速率、脉冲频率、烧结温度和保温时间等工艺参数对材料组织演变和致密化的影响，以了解控制纳米结构陶瓷场激活工艺的重要工艺参数。将开发分析模型来研究电热-机械相互作用对材料的场激活固结和纳米结构材料的形成的影响。理论结果将与实验结果相关联，以从根本上了解控制加工的主要机制。将进行机械测试，以表征纳米结构材料的机械行为，并建立所得到材料的机械性能-微观结构关系。如果成功，这项研究的结果将带来一种合成块体纳米结构陶瓷的全新加工技术，并有可能通过场激活工艺开发出功能纳米结构材料。这项工作的主要目标是确定控制纳米结构形成的关键工艺条件。重要的加工条件可以包括电流通过固结材料的分布、电能输入材料以及电热-机械相互作用。了解场激活过程控制的基本机理，将有助于确定获得均匀块体纳米结构陶瓷的最佳条件，并改进块体纳米结构陶瓷工业化生产的设计方法。所提出的工作也将有助于非线性电热-机械问题的数值模拟。

The research objective of this award is to develop a field-activated processing technology for synthesizing bulk nanostructured ceramics (grain size 100 nm) from micrometer-sized starting powders. The effects of processing parameters, such as electric current density, heating rate, frequency of pulse, sintering temperature and holding time, on microstructural evolution and densification of materials will be experimentally investigated to achieve an understanding of the important processing parameters, which control the field-activated processing of nanostructured ceramics. Analytical models will be developed to study the effects of electrothermal-mechanical interactions on the field-activated consolidation of materials and on the formation of nanostructured materials. The theoretical results will be correlated to the experimental findings to obtain a fundamental understanding of the dominant mechanisms controlling the processing. Mechanical testing will be performed to characterize the mechanical behavior of the nanostructured materials and to establish the mechanical property-microstructural relationships of the resultant materials. If successful, the results of this research will lead to a fundamentally new processing technology for synthesizing bulk nanostructured ceramics and potentially to the development of functionally nanostructured materials through the field-activated processes. The primary goal of this work is to determine the key processing conditions that control the formation of nanostructures. The important processing conditions may include distribution of electric current through the consolidated material, input of electric energy into the material, and electrothermal-mechanical interactions. Understanding the fundamental mechanisms in controlling the field-activated processing will help to determine the optimal condition for achieving homogeneous bulk nanostructured ceramics and to improve the design methodology for industrial production of bulk nanostructured ceramics. The proposed work will also contribute to numerical modeling for nonlinear electrothermal-mechanical problems.