Processing of Fully-Dense Nanocomposites through Novel Design

燃烧合成是一种利用粉末在加热过程中反应产生的化学能的制造工艺。这种内部产生的化学能可以避免使用能源密集型加热炉，从而减少制造过程中的能源消耗。燃烧合成已被用于制造许多先进的材料，包括陶瓷、金属间化合物和复合材料。到目前为止，这种有利的燃烧合成工艺一般还不能生产无孔高强度复合材料和纳米复合材料，除非在制造过程中对材料进行压制，和/或使用额外的制造步骤来完全形成材料。这些都是额外的能源密集和昂贵的步骤。该奖项支持设计粉末和粉末压块的基础研究，这些粉末和压块可以在一个快速反应步骤中形成强无孔复合材料和强无孔纳米复合材料，从而消除了任何额外昂贵和能源密集型制造步骤的需要。这对社会的好处将是显著的，因为有许多材料可以用这种方法生产，它们在航空航天、汽车、生物医学和能源行业都有应用。该研究项目涉及代表性不足和经济条件较差的学生参与研究和教育活动，因此工程教育也将受到积极影响。本研究从新的基础科学的角度解决了燃烧合成中长期存在的残余孔隙率和不均匀性问题。具体而言，将研究粉末和粉末压实多尺度设计对燃烧合成中致密化和均质机制的影响。对于在反应过程中产生液相的材料，将建立对缺陷浓度对有或无外场纳米复合材料快速合成和均质化的影响的基本理解。该研究将完成以前认为不可能完成的任务，即在没有外部压力或后处理热处理的情况下，通过燃烧合成生产全密度或接近全密度的均质复合材料和纳米复合材料。通过深入的表征和力学性能研究，研究还将建立这些新材料的加工-微观结构-性能关系。

Combustion Synthesis is a manufacturing process that utilizes the chemical energy produced from a reaction between powders during heating. Such internally produced chemical energy can avoid the use of an energy-intensive heating furnace, thus reducing energy consumption during manufacturing. Combustion Synthesis has been used to form many advanced materials including ceramics, intermetallics and composites. So far, this advantageous process of combustion synthesis has generally not been capable of producing pore-free high-strength composites and nanocomposites, except by pressing the materials during manufacturing, and/or using an additional manufacturing step to fully form the material. These are extra energy-intensive and costly steps. This award supports fundamental research to design powders and powder compacts which can form strong pore-free composites and stronger pore-free nanocomposites in only one rapid reaction step, thus eliminating the need for any extra costly and energy-intensive manufacturing steps. The benefits to society will be significant, as there are many materials that can be produced using this process, and they have applications in the aerospace, automotive, biomedical and energy industries. The research project involves the participation of underrepresented and economically disadvantaged students in the research and educational activities, thus engineering education will also be positively impacted.  This research tackles the long-standing Combustion Synthesis problems of residual porosity and inhomogeneity from a new fundamental scientific standpoint. Specifically, the influence of powder and powder compact multi-scale design on the densification and homogenization mechanisms in combustion synthesis will be investigated. A fundamental understanding of the effects of defect concentrations on the rapid synthesis and homogenization of nanocomposites with or without external field will be established for materials that generate a liquid phase during the reaction. The research will fulfill a previously thought to be impossible task of producing full or near-full density homogeneous composites and nanocomposites via combustion synthesis without the application of external pressure or post processing heat treatments. Through in-depth characterization and mechanical properties investigations, the research will also establish the processing-microstructure-properties relations for these new materials.