Nanostructure of polymer-derived silicon nitride

Although silicon nitride (Si3N4) ceramics have considerable potential for use in high temperature applications such as engines, processing-related difficulties and associated high cost have hindered their acceptance. While chemical processing methods, such as those based on preceramic polymers, have the potential to overcome many of the difficulties inherent to traditional techniques, many features of polymer-derived Si3N4 are poorly understood. Transmission electron microscopy (TEM) has been used to characterize the nanostructure of polymer-derived Si3N4. The polymer-derived material is found to consist of large grains composed of very fine crystallites, as well as fibrils 40–50 nm in diameter. If the factors responsible for the formation of these structures were understood, the understanding could be harnessed to produce Si3N4 components with enhanced fracture resistance and other engineering properties.