Geometric characterization of additively manufactured polymer derived ceramics

The high hardness, melting temperature and environmental resistance of most ceramic materials makes them well-suited for propulsion, tribilogical and protective applications. However, these same attributes pose difficulties for manufacturing and machining of ceramics and ultimately limit the achievable design space of these materials. Recently, a new class of preceramic photopolymers has been developed that enables additive manufacturing of ceramics using commercially available stereolithography systems. By consolidating preceramic monomers via layer-wise exposure to ultraviolet light and subsequently pyrolyzing under an inert atmosphere to form a ceramic, this method allows for complex geometry parts that cannot be produced with traditional sintering, pressing or vapor infiltration processes. In order to retain geometric fidelity and generate flaw-free microstructures, volumetric and gravimetric changes during the polymer-to-ceramic conversion must be quantified. To this end, we present x-ray micro-computed tomography (micro-CT) measurements of the dimensional stability and uniformity of additively manufactured silicon-based ceramics as a function of geometry and processing conditions.