Nanoscale oxidation behavior of carbon fibers revealed with in situ gas cell STEM

Thomas J. Cochell, Raymond R. Unocic, José Graña-Otero, Alexandre Martin

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Thermal protection systems are used to protect spacecraft payloads during the extreme conditions of atmospheric entry. The backbone of the composite material often used for NASA mission is carbon fiber, which oxidizes at these conditions. This study presents the direct observation of carbon oxidation using in situ Scanning Transmission Electron Microscopy (STEM). A thin section of a commercially-available carbon fiber material containing multiple structures was examined by STEM in a closed-environmental cell in which temperature was raised from 25 to 1050 °C under a steady flow of air. Results show that the random polycrystalline carbon structure oxidized more uniformly and rapidly than the single crystallite region, which oxidized more anisotropically. These findings are the first to directly observe the structural dependence of carbon oxidation rates at these length-scales while also giving important insight into the onset of pitting at various active surface sites, important pieces in fundamentally understanding of carbon oxidation.

Original languageEnglish
Article number113820
JournalScripta Materialia
Volume199
DOIs
StatePublished - Jul 1 2021

Bibliographical note

Funding Information:
The authors thank D. Coffey (Oak Ridge National Laboratory) for her expert FIB specimen preparation and useful discussions, N. Briot (Electron Microscopy Center, University of Kentucky) for his help in preparing the samples as well as T. Dolan (College of Medicine, University of Kentucky) for his illustrations. This research was supported in part by a grant from the Kentucky Science and Engineering Foundation as per Grant/Award Agreement KSEF-3939-RDE-020 with the Kentucky Science and Technology Corporation. Partial support was also provided by the NASA Space Technology Research Grants Program, Early Stage Innovations (ESI) award NNX15AD73G, as well as by the Air Force Office of Scientific Research, award FA9550-18-1-0261. In situ STEM experiments and HRTEM imaging were conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

Funding Information:
The authors thank D. Coffey (Oak Ridge National Laboratory) for her expert FIB specimen preparation and useful discussions, N. Briot (Electron Microscopy Center, University of Kentucky) for his help in preparing the samples as well as T. Dolan (College of Medicine, University of Kentucky) for his illustrations. This research was supported in part by a grant from the Kentucky Science and Engineering Foundation as per Grant/Award Agreement KSEF-3939-RDE-020 with the Kentucky Science and Technology Corporation. Partial support was also provided by the NASA Space Technology Research Grants Program, Early Stage Innovations (ESI) award NNX15AD73G, as well as by the Air Force Office of Scientific Research , award FA9550-18-1-0261 . In situ STEM experiments and HRTEM imaging were conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility.

Publisher Copyright:
© 2021 Acta Materialia Inc.

Keywords

  • Ablation
  • Carbon fibers
  • In situ STEM
  • MEMS-based closed-cell gas
  • Oxidation
  • Thermal protection systems (TPS)

ASJC Scopus subject areas

  • Materials Science (all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys

Fingerprint

Dive into the research topics of 'Nanoscale oxidation behavior of carbon fibers revealed with in situ gas cell STEM'. Together they form a unique fingerprint.

Cite this