Structural Characterization and Material Property Evaluation in Polymer-Derived SiOC Ceramics and Ceramic Nanocomposites

Abstract

The field of advanced ceramics will experience significant growth in the upcoming decade to address increasing demands for multifunctional temperature- and corrosion-resistant materials for aerospace, energy, and electronics sectors. Polymer-derived ceramics (PDCs) and specifically polymer-derived silicon oxycarbide (SiOC) are a promising and attractive material class to accommodate the need for novel ceramics with tailorable compositions and material properties. SiOC is a unique member of the PDC family as the polymer precursor route is the predominant fabrication and synthesis method. As the composition and properties of the evolved SiOC ceramic can be tuned by polymer chemistry and choice of additives, a variety of multifunctional SiOC ceramics have been prepared with additional electric, magnetic, or structural characteristics. However, SiOC microstructures have been difficult to resolve as the amorphous matrix that shows nanoscale heterogeneity has not been rigorously characterized due to instrument and detector limitations. Therefore, understanding phase evolution in SiOC is critical for further development and commercial application of SiOC ceramics and ceramic composites. This work focuses on fabrication and characterization of novel SiOC ceramics and ceramic nanocomposites to examine phase formation and functional material properties imbued by reinforcement phases. In particular, SiOC ceramic 2D nanocomposites will be fabricated with montmorillonite (MMT – a naturally-occurring clay comprised of stacked 2D nanosheets) and Ti3C2Tx 'MXene' (a rapidly growing class of two-dimensional transition metal carbides/nitrides) to create nanostructured ceramic composites. Phase formation, porosity, and electrical conductivity will be analyzed to demonstrate attractive multifunctional capabilities of SiOC ceramics. In addition, thermodynamic modeling and advanced electron microscopy techniques will be utilized to better understand the locally-ordered amorphous SiOC matrix. The results and findings from this work will be among the first reported in the SiOC system and address limitations in the current state of knowledge.