Nanoscale Sintering Understanding

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

Sintering is an important materials consolidation and densification strategy. It is used to make components with complex shapes, in near net-shapes, and with relatively simple equipment. Also, different compositions and structures can be flexibly tailored using sintering. However, sintering is also a complex process. With the progress of nanoparticle-based materials, many conventional sintering theories cannot predict new sintering behaviors; relying on existing sintering knowledge to guide nanoparticle-based material processing has led to numerous failures and contradictory results. This award supports fundamental research to build our understanding of the sintering process, to test the scalability of sintering equations from nanometers up, and to quantify the function of pores in nanostructure evolution and shrinkage. Successful nano-sintering represents exciting possibilities in improved structural, electrical, optical, and other functional properties and unprecedented nanostructures. The application areas are numerous, including energy storage/conversion, nanophotonic devices, microfluidic devices, catalysts, microreactor devices, and optical components. This program also includes extensive outreach activities (such as HBCU, local schools, camps) to increase the participation of underrepresented groups in engineering, especially in the area of nanomaterials. This award supports research to build direct and quantitative sintering shrinkage-nanostructure evolution correlations, test the scalability of sintering equations from nanoscale and up, and quantify the function of pores in nanostructure evolution and shrinkage. There are three key components to this research. The first is to demonstrate that below a critical density, shrinkage extrapolation from grain neck size is dependent on coarsening-induced grain-reconfiguration; microstructure scalability is only valid for homogenous microstructures. The second is to show that above the critical density, pore size, distribution, and shape are critical factors for decoupling grain boundary diffusion from grain boundary migration and 3D microstructure reconstruction is a unique technique to provide such quantitative data. The third component is to illustrate that sintering of particle packing in unusual configurations is dependent on the balance between packing structures and diffusion mechanisms. The research will provide the much needed linkage between nanoparticle arrangement, microstructural evolution, and shrinkage by using small features that can track individual to multiple nanoparticles and reconstructing 3D nanostructures. The sintering knowledge gained will provide not only effective solutions to nanoparticle-based sintering but also never-before conduits for net-shape sintering, novel nanostructures, and a vast array of complex material design capabilities.