Hard Materials Seminar - "Multi-Scale X-ray Micro-Computed Tomography and Morphological Characterization of High Porosity Ceramic Thermal Protection Materials"

Ultra-low-density fibrous ceramics are critical thermal protection materials capable of repeatedly withstanding extreme aerothermal heating during hypersonic atmospheric entry. While macroscopic thermal and mechanical performance depends directly on microstructure, the complex, highly porous morphology of these materials remains challenging to quantitatively characterize and model. This talk presents a high-resolution X-ray computed micro-tomography (μ-CT) framework developed to extract key structural descriptors including fiber diameter distributions, network topology, and pore size distributions. The characterization pipeline integrates deep learning based semantic segmentation, experimental validation against helium gas pycnometry, and Representative Elementary Volume (REV) convergence across multiple structural metrics. The effects of practical imaging constraints in a lab-based submicron X-ray microscope are also evaluated, particularly how geometric magnification, focal spot penumbra blurring, and projection sampling affect segmentation fidelity. Finally, ongoing work addresses multiscale characterization by correlating submicron fiber network structure with macroscale density fluctuations and using energy-dispersive X-ray spectroscopy (EDS) to support constituent fiber segmentation in multi-fiber systems. These quantified descriptors ultimately inform synthetic microstructure generation within the Porous Microstructure Analysis (PuMA) framework, with the broader goal of connecting processing, microstructure, and material properties in fibrous ceramic thermal protection systems.