The Microstructure and Phase Evolution of Pseudomorphic Polymer-derived Ceramic Papers

Polymer-derived ceramics (PDCs) and their nanocomposites (NCs) are a class of materials accessed through the pyrolytic decomposition of suitable molecular precursors. In contrast to traditional powder sintering techniques, the composition, microstructural characteristics and, consecutively, the performance of PDCs can be conveniently adjusted through the design of the preceramic polymer, which has attracted sustained interest of researchers in the last decades. Most molecular precursors possess exceptional processability in their polymeric state, allowing the employment of advanced fabrication techniques, such as extrusion, coating, infiltration, and even additive manufacturing. Quite recently, heat-treating regular cellulose-based paper templates infiltrated with preceramic polymers have been successfully deployed to conveniently generate polymer-derived ceramic papers (PDCPs) exhibiting structural characteristics closely resembling that of the template. Ceramic papers combine the unique structure of organic papers with the composition and properties of various ceramic materials making them predestined for a wide range of applications, such as filtration, refractories, or as catalyst support. A key concept of the PDCP approach is to unite the processability of cellulose-based papers with the exceptional property design of PDC materials, paving the way for component preform of tailorable ceramics with paper-like structures and complex morphologies. The present dissertation deals with the microstructure and phase characterization of various PDCPs obtained from cellulose paper templates infiltrated with transition metal-modified polysilazane precursors upon heat treatment. The focus lies on assessing the impact of individual synthesis parameters on the structure and phase evolution of the ceramic papers to attain a better understanding of the means applicable to tailor their properties and ultimately, enable future application of this exciting novel material class. Fo