Micro-tomography based analysis of thermal conductivity, diffusivity and oxidation behavior of rigid and flexible fibrous insulators

Abstract

Material properties and oxidation behavior of low-density felts used as substrates for conformal carbon/phenolic ablators were compared with those of a rigid carbon fiber preform used to manufacture heritage lightweight ablators. Synchrotron x-ray micro-tomography measurements were performed to characterize the materials' microstructure at the scale of the fibers. Using the

From three‐dimensional morphology to effective diffusivity in filamentous fungal pellets

“…We computed the diffusion in the space/liquid between the hyphae (porous medium). The predominant diffusion regime in liquids is bulk diffusion (Becker et al, ; Panerai et al, ), that is, mass transport is mainly driven by collisions between fluid molecules. In our approach, we neglected surface effects on the solid–liquid interface that could influence diffusion.…”

“…In materials science, μCT measurements and subsequent mass‐transfer computations matured into a widely used method to determine the effective diffusivity of porous/fibrous materials. Exemplarily, Panerai et al (), Becker et al (), Coindreau, Mulat, Germain, Lachaud, and Vignoles (), and Foerst et al () investigated the effective diffusivity of fibrous insulators, fuel cell media, carbon‐carbon composites, and maltodextrin solutions, respectively. Thereby, μCT appeared as a non‐destructive technique to measure three‐dimensional micro‐structures.…”

Interactive volumetric segmentation for textile micro‐tomography data using wavelets and nonlocal means

“…The prompt availability of tow parameters such as local orientation angles, cross-sectional area and aspect ratio will allow analysis of material properties based on microCT data. For example, for fibrous structures such as carbon fiber insulators or woven textiles, anisotropic properties of the constituting phases (eg, fiber thermal conductivity or elastic modulus) are approximated as scalar quantities in current simulations [11,30,31], while it is well-known that they substantially vary along different micro-structure directions. Efficient segmentation provides access to local orientation information of tow paths and fiber direction, allowing the formulation of constituent properties as tensorial quantities in computational material simulations.…”

Synchrotron X-ray Micro Tomography at the Advanced Light Source: In-Situ Sample Environments for Advanced Aerospace Materials

“…1) Ceramic matrix composites (CMC) -typically a silicon carbide (SiC) matrix reinforced by SiC or carbon fibers -are a promising class of light weight structural material targeted to withstand operational temperatures approaching 1500 o C and were recently deployed in commercial jet engines [1,2,3]. 2) Ablative heatshield materials for spacecraft -typically porous carbon fiber foams or woven carbon fiber impregnated with phenolic resin -are critical for high velocity entry into the atmosphere of Earth or other planets [4,5]. The performance of these materials depends strongly on the details of how their microstructure forms during fabrication and how it evolves under extreme operational loads and environmental conditions.…”